International Journal of Powder Metallurgy Volume 46 Issue 1

1-Page View

2-Page View

Search

Table of Contents

Next

e-version

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Here’s how easy it is to use the e-version of the International Journal of Powder Metallurgy with these built-in navigation buttons Use this button to go to the previous page

Use these buttons to toggle between a 1-page view (shown below) and a view of 2 facing pages

Use this button to go to the next page

Use this button to go to the table of contents of this issue, from where you can go anywhere with a single click

Use this button to access the most powerful feature of the e-version of the Journal: the search capability. In some versions of the Adobe Reader, clicking this button will bring up the following window:

If this is the case, click on the arrow next to “Find:” and then click on “Open Full Reader Search” which will bring up the following window:

Type in the term you want to search for, click on the “Search” button, and the results will include every instance of the term in the current issue.

JAN.FEB.10.IJPM cover_July_August IJPM cover 1/18/2010 11:30 AM Page 1

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

January/February 2010

REACH Update Optimization of Compressibility and Hardenability: Admixing and Prealloying Static and Dynamic Properties of Sinter-Hardened PM Steels: Effect of Sintering Temperature OUTSTANDING TECHNICAL PAPER: PowderMet2009 Influence of Chemical Composition and Austenitizing Temperature on Hardenability of PM Steels

46/1

FRONT MATTER_ FRONT MATTER 1/18/2010 11:32 AM Page 15

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

FRONT MATTER_ FRONT MATTER 1/18/2010 11:32 AM Page 1

Previous

1-Page View

EDITORIAL REVIEW COMMITTEE P.W. Taubenblat, FAPMI, Chairman I.E. Anderson, FAPMI T. Ando S.G. Caldwell S.C. Deevi D. Dombrowski J.J. Dunkley Z. Fang B.L. Ferguson W. Frazier K. Kulkarni, FAPMI K.S. Kumar T.F. Murphy, FAPMI J.W. Newkirk P.D. Nurthen J.H. Perepezko P.K. Samal D.W. Smith, FAPMI R. Tandon T.A. Tomlin D.T. Whychell, Sr., FAPMI M. Wright, PMT A. Zavaliangos

INTERNATIONAL LIAISON COMMITTEE D. Whittaker (UK) Chairman V. Arnhold (Germany) E.C. Barba (Mexico) P. Beiss, FAPMI (Germany) C. Blais (Canada) P. Blanchard (France) G.F. Bocchini (Italy) F. Chagnon (Canada) C-L Chu (Taiwan) O. Coube (Europe) H. Danninger (Austria) U. Engström (Sweden) O. Grinder (Sweden) S. Guo (China) F-L Han (China) K.S. Hwang (Taiwan) Y.D. Kim (Korea) G. L’Espérance, FAPMI (Canada) H. Miura (Japan) C.B. Molins (Spain) R.L. Orban (Romania) T.L. Pecanha (Brazil) F. Petzoldt (Germany) G.B. Schaffer (Australia) L. Sigl (Austria) Y. Takeda (Japan) G.S. Upadhyaya (India) Publisher C. James Trombino, CAE [email protected] Editor-in-Chief Alan Lawley, FAPMI [email protected] Managing Editor James P. Adams [email protected] Contributing Editor Peter K. Johnson [email protected] Advertising Manager Jessica S. Tamasi [email protected] Copy Editor Donni Magid [email protected] Production Assistant Dora Schember [email protected] Graphics Debby Stab [email protected] President of APMI International Nicholas T. Mares [email protected] Executive Director/CEO, APMI International C. James Trombino, CAE [email protected]

2-Page View

Table of Contents

Search

Contents

Next

46/1 January/February 2010

2 Editor’s Note 4 Consultants’ Corner Kenneth J.A. Brookes HEALTH & ENVIRONMENT 9 Update on REACH, the CLP Regulation, and Their Implementation in the European Union PM Industry O. Coube and P. Brewin

RESEARCH & DEVELOPMENT 17 Optimization of Compressibility and Hardenability by Admixing and Prealloying N. Giguere and C. Blais

ENGINEERING & TECHNOLOGY 31 Effect of Sintering Temperature on Static and Dynamic Properties of Sinter-Hardened PM Steels F. Chagnon

OUTSTANDING TECHNICAL PAPER: PowderMet2009 43 Influence of Chemical Composition and Austenitizing Temperature on Hardenability of PM Steels P.K. Sokolowski and B.A. Lindsley

DEPARTMENTS 55 PM Industry News in Review 56 Web Site Directory 64 Advertisers’ Index Cover: Fracture surface in a low-alloy steel powder. Photo courtesy François Chagnon, Rio Tinto Metal Powders. The International Journal of Powder Metallurgy (ISSN No. 0888-7462) is a professional publication serving the scientific and technological needs and interests of the powder metallurgist and the metal powder producing and consuming industries. Advertising carried in the Journal is selected so as to meet these needs and interests. Unrelated advertising cannot be accepted. Published bimonthly by APMI International, 105 College Road East, Princeton, N.J. 08540-6692 USA. Telephone (609) 4527700. Periodical postage paid at Princeton, New Jersey, and at additional mailing offices. Copyright © 2010 by APMI International. Subscription rates to non-members; USA, Canada and Mexico: $100.00 individuals, $230.00 institutions; overseas: additional $40.00 postage; single issues $55.00. Printed in USA. Postmaster send address changes to the International Journal of Powder Metallurgy, 105 College Road East, Princeton, New Jersey 08540 USA USPS#267-120 ADVERTISING INFORMATION Jessica Tamasi, APMI International 105 College Road East, Princeton, New Jersey 08540-6692 USA Tel: (609) 452-7700 • Fax: (609) 987-8523 • E-mail: [email protected]

FRONT MATTER_ FRONT MATTER 1/18/2010 11:32 AM Page 2

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EDITOR’S NOTE

S

ince 1993 the MPIF Outstanding Technical Paper Award has recognized excellence in scientific/technical content and written communication. Selected from the PowderMet2009 technical program, the paper was authored by Peter Sokolowski and Bruce Lindsley, Hoeganaes Corporation. Their study coupled the Jominy end-quench test with sintering studies to quantify the effect of austenitizing temperature on the hardenability of commercially available PM steels. Of particular note is the recommendation that hardenability data in MPIF Standard 35 should be reevaluated in relation to the austenitizing temperature for alloys with high levels of carbon and molybdenum. In content, the papers by Chagnon, and Giguere and Blais complement the Outstanding Technical Paper and give this issue of the Journal a “focus” on sinter hardening and hardenability. The former study details the effect of sintering temperature and composition on the static and dynamic properties of sinter-hardening steels. Of importance is the ratio of retained austenite to martensite in the microstructure. Giguere and Blais utilize design of experiments methodology to model, evaluate, and optimize the influence of admixing and/or prealloying on the compressibility and hardenability of sinter-hardened powders. Prealloyed chromium, molybdenum, and nickel exhibit the strongest effect on these two properties. As the European REACH regulation moves into high gear, it is a fitting time to update the status of its implementation in the European Union PM industry and to extrapolate likely ramifications for the PM industry in North America. To this end, Coube and Brewin trace the chronology of the REACH regulation since 2007, and the introduction of the closely related regulation on classification, labeling, and packaging (CLP) of substances and mixtures in 2008. We extend a welcome to Ken Brookes from the United Kingdom on his first venture into the “Consultants’ Corner.” An international authority on hardmetals and related materials, Brookes responds to readers’ queries on grain growth during-liquid phase sintering of WC/Co, the origin of porosity in WC/Co, and PM machining from the perspective of the cutting-tool industry.

Alan Lawley Editor-in-Chief

Recently, for no specific reason, I found myself browsing through previous issues of the Journal. To my surprise, I discovered that the arrival of a new decade marks the anniversary of my serving as your editor for a quarter of a century! My predecessor, the late Henry Hausner, was the editor of the Journal from its founding in 1965 to 1984. It has been a rewarding professional experience which has allowed me to forge a close relationship between academe and the PM and particulate materials industry. By my reckoning, to date I have written the “Editor’s Note” 133 times. Salutations from prospective authors have run the gamut, the classic (and my favorite) being “Dear Steamed Editor”, presumably a unique spelling of “esteemed.” At least this is better than being “half baked.” It is always a challenge responding to authors when one external reviewer cites the manuscript as “outstanding” and the other questions the time and effort expended on the study. Who knows what the next 25 years will hold for the Journal?

2

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

FRONT MATTER_ FRONT MATTER 1/18/2010 11:32 AM Page 3

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

PoP Centre Inaugurated in October 2009, the PoP Centre’s aim is to support our customer more effectively, in application and process development metal powder components. The resources of the PoP center include FEA/CAD-design support, stateof-the art multi-level CNC compaction press, advanced CNC machining, CNC milling centre for rapid protyping, and component fatigue and tribology testing. These resources are complemented with the metal powder knowledge and experience of North American Höganäs.

www.nah.com

CONSULTANTS' CORNER_ CONSULTANTS' CORNER 1/18/2010 11:35 AM Page 4

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

KENNETH J.A. BROOKES, FIMMM* Q A

What is the mechanism of grain growth in liquid-phase sintering in the WC+Co system? The basis of liquid-phase sintering in the WC/Co system is the high solubility of WC in molten cobalt and its correspondingly low solubility in solid-state cobalt binder. As the temperature is increased during the sintering operation to that of the cobalt liquidus, the cobalt particles melt and coalesce, after which WC particles begin to dissolve in the cobalt. Ideally, for an even dispersion, the cobalt particles should be much finer than the WC particles, but this is seldom so in practice. If one assumes a constant rate of solution at each surface, the finest particles will be the first to dissolve and disappear, though an entropy effect has been described that causes finer particles to dissolve at an even faster rate. After sintering, as the compact cools to room temperature, excess WC dissolved in the cobalt comes out of solution and deposits on the largest remaining WC particles, again enhanced by the entropy effect. A combination of surface tension and diffusion pulls the particles and liquid phase together and rejects the residual gaseous phase (which would otherwise be seen as porosity) from the compact surface. Theoretically, if the original carbide and binder particles in the grade mix were all of the same shape and size, and evenly mixed, their surfaces would dissolve equally at the sintering temperature and each would grow uniformly during cooling, but to a slightly smaller size than possessed initially, because of the permanent loss of some WC by solution in the cobalt. No grain growth would take place, even in the absence of graingrowth inhibitors. If the grade mix had a poorer grain-size distribution (the well-known “bell curve”), perhaps with a relatively high proportion of extra-fines and a few significantly larger parti-

cles, the final microstructure would be likely to show none of these extra-fine constituents but occasional giant grains instead. Such grains are similar to, though less injurious than, porosity, in their effects on mechanical properties. If the starting grade powder contains agglomerated WC in addition to discrete particles, grain growth may also occur by grain-boundary movement or diffusion at solid/solid interfaces. But agglomeration becomes a bigger problem in liquidphase sintering as ultimate particle sizes decrease. As first explained in detail in the excellent but long out-of-print 1960 publication Principles of Comminution by Dvorak et al., there is an equilibrium state for any type of milling where comminution appears to cease but in fact does not do so, being exactly balanced by agglomeration. When the equilibrium state is approached, milling efficiency appears to diminish, but in reality the particle size within the agglomerates continues to decrease. As a corollary, if you start milling with a grain size less than equilibrium, agglomeration will increase the apparent grain size. Change the milling liquid, for example acetone for heptane, and the equilibrium agglomerate size may change, even though the ultimate particle size remains the same. For best results, milling conditions should be controlled to give a very restricted grain-size range, with a nominal grain size above the “equilibrium” value. What happens, though, in the industrial liquidphase sintering of ultrafine (so-called “nanosize”) WC/Co powders? Nowadays, such powders are frequently made by the high-energy impact milling (in planetary mills or attritors) of coarser powders.

*Proprietor, International Carbide Data, 33 Oakhurst Avenue, East Barnet, Herts EN4 8DN, United Kingdom; Author, compiler and publisher, World Directory and Handbook of Hardmetals and Hard Materials; E-mail: [email protected]

4

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

CONSULTANTS' CORNER_ CONSULTANTS' CORNER 1/18/2010 11:35 AM Page 5

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

The final mix may be largely made up of agglomerates, in which the ultimate size of many particles in these agglomerates may be too difficult to see or measure by conventional means. During sintering, molten cobalt binder penetrates between these particles, separates and dissolves them, but in cooling from the sintering temperature the WC precipitates preferentially on any “large” particles that may be present. The extremely fine particles in the original mix are not nucleated and regenerated. Thus a host of tiny agglomerated particles, each only a few nanometers in size, may be partially transformed by liquid-phase sintering into a few (relatively) giant grains, of ≥10 µm. In addition to grain-size control in the grade powders, this effect is typically minimized, either by a degree of solid-state sintering or lower-temperature liquidphase sintering (employing thin films of segregated impurities in complex eutectics), during the risingtemperature phase, each of which shortens the sintering time, or by the presence of specific graingrowth inhibitors.

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Q A

What factors affect the porosity of WC/Co hardmetals? Porosity in sintered hardmetals is of a different magnitude from that found in most other PM products. 1 v/o porosity would be considered an excellent result in many PM materials, but an immediate cause of rejection in a cemented carbide. Though the target of virtually zero porosity is effectively achieved with the aid of hot isostatic pressing (HIPing), results close to this are attained with conventional liquid-phase sintering. Porosity in “green” or unsintered carbide is something else. In order to minimize grain growth during sintering, all WC grains in a grade mix should ideally be of the same size, with no fine particles to fill in the empty spaces. Thus green porosity in WC/Co tends to be unusually high compared with that of many other PM products, and the shrinkage during sintering is typically between 19% and 23% linear, depending on the grade and pressing parameters. Reducing porosity from more than 50 v/o to a value close to zero is a

5

CONSULTANTS' CORNER_ CONSULTANTS' CORNER 1/18/2010 11:35 AM Page 6

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

considerable challenge, but carbide sinterers must either succeed or go out of business. Most of them succeed. Only in a minority of niche applications, such as wear-resistant air bearings, is controlled porosity actively sought as a key property of the finished product. In the final product, porosity is of two varieties: residual porosity from incomplete sintering, and “new” porosity arising from physical and chemical reactions during the sintering process itself. Both types may be present in the same compact. Incomplete sintering typically results from too low a sintering temperature, from too short a time at temperature, or from inadequate mixing of the starting powders. Inefficient mixing may result in the aggregation of carbide particles, containing little or no metallic cobalt, into which the cobalt binder, molten at sintering temperature, penetrates slowly or not all. Thus the liquid-phase sintering of the WC/Co mix is incomplete within the sintering cycle and some of the original porosity is retained. The most common contaminant in grade powders is oxygen, generally in the form of an extremely thin oxide film on the surface of each carbide particle. This film forms rapidly when the powder is exposed to air, especially if the powder is warm, as when coming from a carburizing furnace or a spray drier. Pressing lubricant acts as a barrier, though an imperfect one, to oxidizing atmospheres, and is therefore added at an early stage. It is, of course, removed during presintering, but nowadays lubricant removal and presintering are simply the first stages of the sintering cycle. Nevertheless, there is nearly always some oxygen present, either adsorbed or as a thin oxide layer, when a compact enters the sintering furnace. The oxygen is removed by chemical reaction, either with hydrogen when sintering is carried out entirely in this atmosphere or as the first stage of a sequence based on vacuum sintering, or else in vacuo or in a non-reactive gas such as argon. With the first alternative, the oxygen reacts to form water vapor, which is carried away by the gas flow: O2 + 2H2 = 2H2O

(1)

In the second case, oxygen typically reacts with some of the WC to form W2C and CO (or CO2): O2 + 2WC = W2C + CO

(2)

W 2 C then reacts with cobalt to form η-phase,

6

which locks up some of the binder and consequently causes mild or severe embrittlement. To prevent this, many manufacturers either employ a hydrogen atmosphere to precede vacuum sintering, in the same furnace, or add a calculated amount of carbon black to the mix, to combine with the oxide surface layers: WO2 + 3C = WC + 2CO

(3)

Both methods work, but the second relies on closely controlled and repeatable operating conditions to give virtually the same oxygen content in each run, while the first is far less critical. Either way, the small volume of gas generated should be safely removed, without increasing the amount of porosity in the finish-sintered compact. As with the elimination of oxygen and any pressing lubricant, the removal of other contaminating elements and compounds requires the physical extraction of a gas during the sintering cycle. Such a gas may be the result of volatilization or of a chemical reaction in which the contaminant takes part. There is also the removal of the air or other gas within the pores of the pressed compact to be considered. Although some of these gases diffuse rapidly through the liquid metallic binder or the solid compact, gas transportation is much more rapid and efficient through connected pores. This is one reason for the efficiency and consequent popularity of vacuum sintering, whereby any gases generated or liberated during sintering can be essentially removed. However, if the sintering method is such that surface pores are closed before residual gases are totally removed, any undiffused gas will remain trapped as the compact cools from the sintering temperature and will result in deleterious porosity. Avoiding this eventuality requires minimization of oxidation or adsorbed oxygen and extremely close control of compositional impurities, furnace atmosphere and vacuum, and the time/temperature sintering cycle. Although correct starting materials and sintering techniques can produce an excellent finished product with extremely low porosity, it can be further lowered by HIPing, when pressure is applied through an inert gas (typically argon) at near sintering temperature. Any slight remaining porosity is literally squeezed out, with beneficial effects on such important properties as breaking stress and fracture toughness, through the near-elimination Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

CONSULTANTS' CORNER_ CONSULTANTS' CORNER 1/18/2010 11:35 AM Page 7

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

of crack-initiating pores. HIPing was originally carried out as a separate process, requiring expensive reheating of already sintered components. It has since been found that the pressure previously thought to be required was unnecessarily high, as a result of which a large proportion of hardmetal production is now routinely sintered and then sinter-HIPed in redesigned furnaces capable of both vacuum and high-pressure operation. Cemented carbide manufacturers always aim at, and often reach, near perfection in the quality of their sintered products. Small wonder that hardmetal is regarded as the prima donna of the PM industry.

Q A

Is the cutting-tool industry putting enough emphasis on PM machining ? Let me add a couple of similar questions. Is the cutting-tool industry putting enough emphasis on cast-materials machining? Is the cutting-tool industry putting enough emphasis on wroughtmaterials machining? In either case we would say that the questions were extraordinarily naïve, oversimplistic, or demonstrated a profound ignorance of materials and cutting tools. Just as cast and wrought materials come in a vast variety of compositions and microstructures, and physical and engineering properties, so do PM products. We can no more speak globally of cutting tools and conditions for PM products than we can for cast or wrought entities. In principle, most fully sintered alloys machine in a fashion similar to the same or similar alloys produced by other means. Where, as frequently occurs, there is a distinct difference in composition or properties, it is best for the user rather than the tool manufacturer to establish precise cutting parameters, since other factors (such as the type of machine, power available, vibration, operator skill) may also come into play. Better still is close cooperation between user and tool supplier. But in any case the tool manufacturer should make recommendations and suggest a starting point for tooling optimization. However, what the questioner may have in mind are types of machining specific to the PM industry. An obvious example is green machining or shaping of highly porous blanks, either pressed but unsintered (particles cold-welded to provide modest strength), or pressed and presintered only (sin-

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

tered sufficiently to hold together but not enough to initiate significant shrinkage). Another major instance is of materials that cannot be produced commercially by any other method, such as hardmetals and some types of tungsten-based heavy alloys. In some cases, notably the manufacture of cemented carbides, all of these criteria apply. One cannot say that insufficient emphasis has been given to the machining of hardmetals, whether of pressed, presintered, or fully sintered carbide—or indeed carbonitride, which from this point of view is similar. Before sintering, the material behaves like an extremely abrasive chalk: it can be shaped, easily though crudely, with a thumbnail, but rapidly wears any conventional tool. The hardest grades of carbide can be employed, especially in short-run forming, but nowadays a variety of diamond tools, from polycrystalline diamond (PCD) inserts to diamond-plated bandsaws, are used in this application. Diamond single-point cutting tools also find limited employment in machining high-binder-content sintered carbides for special applications, but are unlikely to displace diamond grinding to any great extent. It is also possible to machine the highestcobalt wear-resistant hardmetals, with perhaps 30 w/o binder (>50 v/o) with the hardest low-cobalt (~3 w/o) grades. As far as other alloys—ferrous or nonferrous— are concerned, there could well be instances where information is lacking on the machining of highporosity sintered compacts, but it is impossible to generalize. With some malleable materials, one difference might be to use tools with a sharper edge or smaller edge radius, in order to reduce the tendency of machining to seal the surface and make the removal of residual porosity more difficult. But there have been a number of useful papers on this subject in recent years, and even the occasional dedicated seminar. I cannot speak for all cutting-tool manufacturers, nor can I know all the problems that beset the PM industry, but my impression is that proper and even increasing emphasis is being given to PM machining by the tooling industry. But, as always, it is up to the PM industry to make its needs clearly known to tool suppliers. ijpm Readers are invited to send in questions for future issues. Submit your questions to: Consultants’ Corner, APMI International, 105 College Road East, Princeton, NJ 08540-6692; Fax (609) 987-8523; E-mail: [email protected]

7

CONSULTANTS' CORNER_ CONSULTANTS' CORNER 1/18/2010 11:36 AM Page 8

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 9

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

HEALTH & ENVIRONMENT

UPDATE ON REACH*, THE CLP** REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY Olivier Coube*** and Peter Brewin****

INTRODUCTION REACH was published on May 29, 2007, in the Official Journal of the European Union (EU) and entered into force on June 1, 2007. At the same time, the new European Chemicals Agency (ECHA)1 was launched, as was the REACH section of the European Powder Metallurgy Association (EPMA).2 After an overview of the REACH regulation and its possible impact on the powder metallurgy (PM) industry in 2007,3 the progress and current status of the REACH regulation is described 2.5 years after its inception and about 1 year before the first registration deadline on November 30, 2010, which concerns most metals. Since January 2009, REACH is not the only regulation that affects industry in the handling of chemicals. After its adoption by the European Parliament, the regulation (EC) No. 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP) entered into force on January 20, 2009. The main aspects of the CLP will also be explained, as they are closely related to REACH.

Since June 2007 the European REACH regulation placed the burden of proof of safety for chemicals (including metals) on the shoulders of industry and no longer on government authorities. Additionally, revision of the health and environmental hazard classification of chemicals, at an international level, along with initiatives similar to REACH in the U.S. and other regions, demonstrated the resolve of governments to compel industry to check and show the safety of their products irrespective of any known hazards. The efforts of European industry to comply with these new laws are of interest to other regions that are likely to face similar legislative requirements in the not-toodistant future.

REACH SINCE ITS INCEPTION The REACH regulation completed the legislative process in Brussels in December 2006 and came into law in all the member states in June 2007. The immediate effect was to place a large bureaucratic burden on manufacturers and importers (M/I) of chemicals in assembling the registration dossiers that are the heart of the regulation. Irrespective of whether a chemical has resulted in a problem in the past, these dossiers must demonstrate that its intrinsic hazards have been quantified, and measures to control human and environmental exposure are communicated right down the supply chain. Different deadlines are set depending on tonnage and danger level, Figure 1. The registration dossier for most metals will have to be com*Registration, Evaluation and Authorization of Chemicals, **Classification, Labeling and Packaging ***EPMA Technical Director, ****Former EPMA Technical Director, European Powder Metallurgy Association, 2nd Floor Talbot House, Market Street, Shrewsbury SY1 1LG United Kingdom; E-mail: oc@ epma.com

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

9

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 10

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

UPDATE ON REACH, THE CLP REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY

Figure 1. Timescales CMR 1,2 = Carcinogenic, mutagenic, or reproductive hazards 1 or 2 R50/53 = Very toxic to aquatic organisms, may cause long-term adverse effects in the environment tpa = mt per year

pleted by December 2010. After this deadline it will be illegal for unregistered suppliers to place chemicals on the market. Since June 1, 2007: ECHA Since June 1, 2007, ECHA, located in Helsinki, Finland, manages the registration, evaluation, authorization, and restriction processes for chemical substances to ensure consistency across the EU. The mission of the ECHA according to Article 77 (tasks of the Agency), is to: • Manage all REACH tasks by carrying out or co-coordinating necessary activities. • Ensure a consistent implementation at the community level. • Provide member states and the European institutions with the best possible scientific advice on questions related to the safety and the socioeconomic aspects of the use of chemicals. June 1, 2008, to December 1, 2008: Pre-Registration The first critical period for the PM industry was Pre-Registration. Companies that have pre-registered their substances will benefit from the staggered registration deadlines (2010, 2013, or 2018) for their substances, as illustrated in Figure 1. Without Pre-Registration, it is illegal for M/Is to place substances on the market without first having registered. The pre-registration period, which started on June 1, 2008, and ended on December 1, 2008,

10

enabled the authority to assess the number of substances to be registered under REACH. During this six-month period, ECHA received about 2.75 million online pre-registrations for ~150,000 substances—about fifteen times more than the number expected. This was caused first by several companies submitting all existing substances and precautionary double pre-registration of the same substance in a supply chain by many companies. Also, if pre-registration covered all the EU “existing substances” (EINECS) they also had to take into account an important list of new substances (ELINCS), of which they were notified. Since then, ECHA has done some tidying up, for example, reconciling the numbers and names of chemicals, putting duplications together, and making deletions where companies have requested them. The current list of substances contains ~143,835, pre-registered by some 65,000 companies. January 2009: Pre-SIEF and SIEF After Pre-Registration, the next step in REACH is the communication stage between the pre-registrants of a substance within a pre-SIEF (Substance Information Exchange Forum). The concept of pre-SIEFs was not foreseen in the REACH regulation, but was introduced with support from industry. The tasks of the pre-SIEF members comprise: • Establishment of the sameness of the substance(s) pre-registered under a specific identifier for the purpose of SIEF formation, in line with the “ECHA guidance document on identification and naming of substance.” • Verification that their substance has not been pre-registered under other identity codes. Subsequently, it is possible to freely merge multiple pre-SIEFs into one and vice versa. • Agreement on the appointment of a designated Lead Registrant (LR). The LR is, among other things, responsible for taking the lead in the SIEF process and the submission of the joint part of the registration file. The decisions taken in the context of the preSIEF and SIEF are the responsibility of industry. ECHA will not intervene in these decisions. Once the decision on the sameness of substance to be covered by the SIEF and the LR has been agreed on, the real activities towards preparation of the joint submission for registration can start. As opposed to the pre-SIEF, the SIEF is legally

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 11

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

UPDATE ON REACH, THE CLP REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY

defined in the REACH regulation in Article 29, but what remains the same is that the management of the SIEF and the tools to be used are up to industry to decide. REACH provides for the formation of a SIEF to share information among M/I of the same “phase-in” substances, as well as allowing participation of downstream users (DU) and other stakeholders to prevent duplicate testing, especially testing on vertebrate animals. In addition, the SIEF may also be a starting point or a suitable platform for participants to organize the mandatory joint submission of data among themselves, as provided for in Article 11 of REACH. This includes, as an option, the exchange of the data needed to perform the Chemical Safety Assessment (CSA), drafting the Chemical Safety Report (CSR), and agreeing on guidance on safe use that may be part of this joint submission. At the end of 2009 only a few percent of the preSIEFs have officially appointed an LR and formed a SIEF. The main preparation activity for the registration dossier is done by the consortia. Since June 1, 2007: REACH Information Technology In order to fulfill the requirements of the REACH regulation (pre-registration, registration dossier, data collection, invoicing, etc.) ECHA has set up an information technology (IT) platform according to Article 111. The aim of REACH-IT is to ensure that the REACH processes in the ECHA, the member states competent authorities (MSCA), industry, and other stakeholders are supported by appropriate IT system(s) and corresponding interfaces. The REACH-IT system is a central system running in ECHA. REACH-IT has three fundamental groups of parties for which it provides different functionalities. Industry Homepage: This is the place where a company can, for example, sign up, pre-register substances, obtain contact details of other companies having pre-registered the same substance, submit registrations, download invoices, and view the status of submitted registrations and payments. In addition, it allows dossier preparation, for example, notification of classification and labeling. Examples of users of the Industry Homepage are: manufacturers, importers, third-party representatives, only representatives (OR) who are EU personnel appointed by non-EU organizations to fulfill their import obligations under REACH, and DUs.

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Agency Workflow: This part of REACH-IT supports the day-to-day work in the regulatory process management of ECHA and in the MSCAs for activities such as registration, evaluation, authorization, restriction and classification, and labeling of substances. Examples of users of the Agency Workflow are: agency staff and MSCA staff. Dissemination Web Site: This part of the REACH-IT is used primarily by staff in the agency and MCSAs. The dissemination Web site will fulfill the requirements laid down in the legislation for dissemination of data. Examples of users of the Dissemination Web site are: general public, consumer and environmental nongovernmental organizations (NGO), and industry. Since June 1, 2008: IUCLID 5 In addition to registration on the REACH-IT platform, and as a requirement of Article 111, industry will have to prepare their technical dossiers in a special format using IUCLID software. IUCLID (International Uniform ChemicaL Information Database) is a software application to capture, store, maintain, and exchange data on intrinsic and hazard properties of chemical substances; it is the essential software for industry to comply with REACH. Without an appropriate IT tool, it would be extremely difficult for industry, especially for small and medium enterprises, to comply with the REACH data requirements. In order to structure these requirements, REACH requires a specific reporting format, namely the IUCLID 5 format. The IUCLID 5 software can be obtained free of charge from the IUCLID server.4 REACTION FROM INDUSTRY: REACH CONSORTIA The huge amount of data led the industry and their substance-based associations to join together to comply with the REACH requirement within the short deadline. This was done by forming socalled REACH consortia. The REACH consortia are private legal entities, launched by the substance-based organizations e.g., the Nickel Institute and all the major metals organizations (copper, iron, manganese, molybdenum, tungsten, etc.), European Chemical Industry Council CEFIC.

11

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 12

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

UPDATE ON REACH, THE CLP REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY

REACH consortia play the role of technical and legal advisers (e.g., by compiling the ca. 9,000 data necessary to fill in the technical dossiers in IUCLID 5 format or by advising on REACH legal text issues). They are, in most cases, assisted by environmental and human-health consulting companies and by academia. However, the legal responsibility remains with the companies regarding the REACH obligations (pre-registration, registration, deadlines). This means that even if they benefit from technical support, companies still need to invest capacity in the form of on-site REACH managers and technicians dealing with the technical and legal aspect of REACH and its implementation in the daily business of the company. In addition to the usual membership of a consortium, a company may need only to buy a so-called Letter of Access or a License to Use. The former gives the company the right to refer to the full study report. This is primarily when the owner of the data provides a Letter of Access to another party that is limited to the use of the data for one or more specific purposes, such as registration under REACH (and/or for other regulatory purposes) but without passing on to that party a copy of the full study report. Second, data can be shared through a license of the right to use the data. Under such a license, the owner of the rights may exert control over the uses to which the data are put by the licensees. This control is achieved through appropriate limitations in the license agreement. Typically, a license to use data will not include rights to transfer the data except possibly under limited, specifically defined circumstances such as a right to include the data as part of the joint submission. REACH AND THE PM INDUSTRY In the PM industry, as in every industry, REACH has divided the supply chain into two groups: the supplier registrants (M/Is) or the ORs on one side, and their DUs on the other side. In a small survey carried out by the EPMA at the beginning of 2009, it appeared that a large majority of the PM M/Is, mainly the powder suppliers, joined the REACH metal consortia. Their customers, in particular the parts makers, remained cautious in their role of DUs. One issue in the PM industry is the multiplicity of substances to follow for the registration process, as shown in Table I. This information is based on

12

a small survey with a few dozen PM M/Is and ORs. Another issue is the multiplicity of substances used by the PM industry, as shown in Table II from the same survey of about 10 DU. Tables I and II show the importance to the PM industry of tracing the substances in their production and to ensuring that their suppliers are REACH compliant and that they are aware of the PM uses of their substances, especially when the substances are not provided by the usual PM supTABLE I. ANSWER TO SURVEY QUESTION: IF YOU ARE AN M/I OR AN OR, WHAT ARE THE PM SUBSTANCES YOU HAVE PRE-REGISTERED AND THE HIGHEST TONNAGE USED? Between 1 and 10 mt

Between 10 and 100 mt

TiO2 Zinc Stearate Glycerine Graphite Mineral Oil FeS Rhenium TaC Arsenic

CuO Ethylene Glycol Tantalum Fused Tungsten Carbide APT AMT Titanium Niobium Bismuth Cadmium

Between 100 and 1,000 mt Cu2O Fe3P Cobalt Cobalt Salts Tungsten Trioxide Tricobalt Tetraoxide Iron Salts Vanadium ZnO CuO Silicon Antimony MnS

>1,000 mt EAF-slag MO3 Tungsten WO3 WC Zinc Lead Iron Copper Molybdenum Carbon Aluminum Tin

TABLE II: ANSWER TO SURVEY QUESTION: IF YOU ARE A DU, WHAT ARE THE PM SUBSTANCES YOU ARE USING AND THE HIGHEST TONNAGE USED? Between 1 and 10 mt

Between 10 and 100 mt

Between 100 and 1,000 mt

Cr3C2 Cr3N2 Mo2C VC ZrC ZrN Magnesium Bismuth Phosphorous TaC Manganese

Silver TiC TiN Zinc Sizing Fluids Cutting Fluids Forging Lubricant Tungsten WC Cobalt Wax Amide Wax Zinc Stearate Aluminum Chromium MnS

Graphite Lubricants Cobalt Press Additives Molybdenum Tin

>1,000 mt Iron Nickel Copper

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 13

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

UPDATE ON REACH, THE CLP REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY

pliers (e.g., powder makers or powder departments). It should be noted that Table I and Table II are certainly not exhaustive. REACH AND PM DOWNSTREAM USES REACH recommends an appropriate communication up and down the supply chain. This includes the M/Is and the DUs of the substances which are effectively their customers and, in turn, the customers of their customers down to the consumers. In fact, according to Article 37, the REACH regulation gives the right to any DU to inform his/her supplier (M/I or DU) about the use(s) of a substance on its own, or in preparation, with the aim of making this an identified use.2 As a minimum, this should take the form of a brief general description of uses on paper or electronically. However, the DU must be aware that, by starting this communication with the supplier of a substance, he/she commits to providing sufficient information (as stated in the REACH regulation) to prepare the part of the registration dossier in which the uses and, for most dossiers, their related exposure scenarios (ES) are described. The ESs comprise an assessment of the expected exposures on human health effects and environmental spheres under the actual or anticipated conditions of use. However, according to Article 37(3), for pre-registered substances the supplier must take note of the request by the DU, provided that it is made 12 months before the registration deadline. Thus for substances which were pre-registered for 1,000 mt per year the request should have been made before December 1, 2009. If a DU does not communicate its uses, he/she may have to prepare the CSR for any use which is not identified by the registrant if the substance meets the criteria for classification. However, there are some exemptions from the obligation for the DU to prepare a CSR: • When the substance does not meet the criteria needed to require a safety data sheet (SDS), e.g., the criteria for classification as dangerous, Article 31 of REACH • When a CSR is not required to be completed by the supplier in accordance with Article 14 of REACH (registration for <10 mt per year, substance does not meet the criteria for classification as dangerous)

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

• When the DU uses the substance or preparation in a total quantity of <1 mt per year • When the DU implements or recommends an exposure scenario which includes, as a minimum, the conditions described in the exposure scenario communicated in the SDS • When the substance is present in a preparation in a concentration lower than any of the concentrations set out in Article 14 of REACH2 (i.e., between 0.1% and 1%, depending on the substance) • When the DU is using the substance for the purposes of product and process-oriented research and development, provided that the risks to human health and the environment are adequately controlled in accordance with the legislative requirements of legislation for the protection of workers and the environment. In order to inform and support PM DUs in their communication task, the EPMA has a dedicated Web site5 and published timely articles.6 REACH AND EXTENDED SAFETY DATA SHEETS Exposure scenarios and information on uses will be linked with the future extended SDS. Thus Section 1 of the e-SDS will cover the identified uses while Section 16 will describe the uses advised against. Coherent language between the REACH CSR and use description will be required and generic use categories will be used to reduce the number of SDSs. Sections 7 and 8 will cover the exposure scenario aspects with a correlation table to be found in Part G, extending the SDS of the Guidance on Information requirements and Chemical Safety Assessment.1 Thus information such as operational conditions (OC) and risk management measures (RMM) will be of critical importance in Section 7.1 (Handling), Section 8.2.1 (Occupational Exposure Controls), and Section 8.2.2 (Environmental Exposure Controls). The eSDS will be one of the practical impacts of REACH in the daily business communication in the PM supply chain and will be one of the first documents to be checked by the national authorities. REACH AND CLP With a view to facilitating worldwide trade, while protecting human health and the environment, harmonized criteria for classification and labeling, together with general principles of their applica-

13

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 14

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

UPDATE ON REACH, THE CLP REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY

tion, have been carefully developed over a period of 12 years within the United Nations (UN) structure. The result was called the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). The objective of the GHS is to harmonize the classification systems of chemicals worldwide. Regulation (EC) No. 1272/2008 on the CLP of substances and mixtures follows various declarations whereby the community confirmed its intention to contribute to the global harmonization of criteria for classification and labeling through incorporating the internationally agreed GHS criteria into community law, such as REACH, since physical, health, and environmental hazard assessments are an important part of the REACH registration process. And, according to the CLP, the powder form of substances may also trigger a stricter classification than in the massive form (e.g., aluminum or nickel). The CLP regulation will have its own obligation to be enforced in member states. It must be noted that not only substances, but also mixtures (e.g., alloys) will have to be classified according to the CLP regulation. The reclassification and labeling of most substances must be completed by December 1, 2010, for substances and June 1, 2015, for mixtures. There will be some transition periods between the CLP regulation and the former directives on CLP of dangerous substances and preparations. INFLUENCE OF REACH IN THE U.S. United States Environmental Protection Agency (EPA) administrator Lisa Jackson announced that its government wants reform of the Toxic Substances Control Act (TSCA) and that the EPA would work with legislators to achieve this goal. She has mandated that the EPA have a sustainable source of adequate funding to enable it to do its job in ensuring the safety of chemicals and that industry should be required to support this cost. Mike Walls, vice president for regulatory and technical affairs, American Chemistry Council (ACC), expects legislation to be introduced this year and sees no reason why it should not be completed in 2010. “Part of the reason we can accelerate is there seems to be a growing agreement on what needs to be done and a willingness all round to learn from REACH,” he adds. Bjorn Hansen, deputy head of chemicals, EU Environment Directorate, says that the principles

14

for reform of TSCA listed by Ms. Jackson “seem to have many commonalities with the objectives and principles established by the European Commission, the Council, and the Parliament leading to REACH.” He welcomes the initiatives set out by the United States to review TSCA and consider new legislation. “We would be very interested to work with the United States during the process of reviewing TSCA and possibly developing new legislation, as was the United States in the development of REACH.” In fact industry, and in particular the chemical industry, in the United States is likely to be a key driver for compatibility—especially those who export to the EU and have started to use the methodology and tools to implement REACH internally. Earlier this month the International Council of Chemical Associations decided to adopt IUCLID, which was originally developed by the European Commission and now standardizes the presentation of REACH and OECD data, as the format on which to build its Global Product Strategy portal. 2010 OUTLOOK 2010 will also be critical for REACH compliance of companies for their large tonnage substances. However, about one year before the first registration deadline only a few thousand companies from ca. 143,000 have informed ECHA about their LR nomination. REACH metal consortia are now in the “home stretch” of filling in the extensive database (ca. 9,000 data in one dossier) via the IUCLID 5 software needed for the registration dossier. Some consortia are planning to register major metal substances from their portfolio early (spring 2010) to remain on the safe side (e.g., nickel). This year should also see an increase in enforcement visits from member states in the M/I companies. Enforcement visits have already started in some member states as part of a REACH enforcement harmonization program. The pre-registration, registration, and compliance of the SDS were inspected for a few substances. Sites visited reflect large companies (e.g., UMICORE in France, Rio Tinto in the Netherlands) and the visits were announced to the companies about one month beforehand in order to allow the REACH manager to be present and to prepare the dossier. The aim was for the inspectors to gather experience by inspecting large, well-prepared companies.

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 15

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

June 27–30 The Westin Diplomat Hollywood (Ft. Lauderdale), Florida

2010 International Conference on Powder Metallurgy & Particulate Materials For complete program and registration information contact: METAL POWDER INDUSTRIES FEDERATION ~ APMI INTERNATIONAL INTERNATIONAL 105 College Road East, Princeton, New Jersey 08540 USA Tel: 609-452-7700 ~ Fax: 609-987-8523 ~ www.mpif.org

Coube.Brewin_Zheng et al 1/18/2010 12:19 PM Page 16

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

UPDATE ON REACH, THE CLP REGULATION, AND THEIR IMPLEMENTATION IN THE EUROPEAN UNION PM INDUSTRY

In 2012 REACH will be revised. Although the main text should remain unchanged regarding the current obligation, new aspects could be included concerning substances having a physical size of <100 nm. Stricter rules are expected for such nanosubstances than for conventional particulate sizes. REFERENCES 1. European Chemical Agency (ECHA), 2009; http:// echa.europa.eu/. 2. EPMA REACH. EPMA Section > REACH Area; http:// www.epma.com/New_non_members/epma-home.htm. 3. P. Brewin, “The New European REACH Regulation: A Major Challenge to Manufacturers and Importers”, Int. J. Powder Metal., 2007, vol. 43, no. 4, pp. 27–32. 4. IUCLID 5. International Uniform ChemicaL Information Database; http://www.iuclid.eu/. 5. DU Communication Tools on PM Uses for REACH, EPMA, 2009; http://www.epma.com/New_non_members/ tools.htm. 6. O. Coube, “REACH: The Importance of Registering PM Applications”, Powder Met., 2009, vol. 52, pp. 192–193. ijpm

16

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:42 AM Page 17

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

RESEARCH & DEVELOPMENT

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING Nicolas Giguere* and Carl Blais** INTRODUCTION Powder metallurgy (PM) is an economical process that enables the mass production of near-net-shape components with complex geometries.1 The automotive industry is the largest consumer of PM components in North America and, in 2008, the average automobile manufactured domestically contained ~19.5 kg (43 lb.) of components produced by the PM process.2 Gears, sprockets, connecting rods, clutch plates, and valve seats are but a few examples of components produced every day for the automotive industry. To sustain its growth, PM must be able to produce components that exceed the most demanding specifications in terms of static and dynamic mechanical properties, at the lowest possible cost. However, to obtain these superior mechanical properties, an optimum microstructure is necessary which, in the case of ferrous PM parts, is generally obtained by heat treatment.3 However, this additional step in the production sequence increases costs and negatively affects the geometrical conformance of the final PM parts. In this context, sinter-hardenable powders show serious potential for the development of high-performance PM components. The approach consists of cooling the parts from the final stage of the sintering cycle at a rate that is high enough to prevent the pearlitic and/or bainitic transformations, resulting in a fully martensitic microstructure. Parts are thus quenched at the end of the sintering cycle without the need for reaustenitizing and quenching in a second heat-treatment sequence. The primary advantages of sinter hardening3 are: no additional heattreatment steps, reduced distortion that is typically generated by the severity of an oil quench, and no cleaning steps. Sinter hardenability is dictated by the chemistry of the alloy, its density, and the cooling profile of the sintering furnace. Prealloyed elements that are used to increase hardenability impede compressibility. Admixed elements decrease compressibility to a lesser extent, although they are not as *Project Manager, **Professor, Powder Metallurgy Laboratory of Université Laval (LAMPOUL) Laval University, Department of Mining, Metallurgical and Materials Engineering, 1718 B Pavillon AdrienPouliot, Québec, Canada G1K 7P4; [email protected]

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

The automotive sector is constantly pressuring the powder metallurgy (PM) industry to produce components with superior mechanical properties at minimum cost. Sinter-hardenable powders are therefore particularly relevant, as they enable the direct quenching of components at the end of the sintering cycle, thus eliminating the extra normally required heattreatment step. This study constitutes the first in a multiphase project aimed at modeling the influence of admixing and/or prealloying elements known to increase hardenability on the optimization of the compressibility and hardenability of sinter-hardenable steel powders. Design of experiments was used to optimize the chemical composition and to study the effects of prealloyed (chromium, manganese, molybdenum, nickel) and admixed (chromium, copper, manganese, nickel) elements on hardenability and compressibility. The volume fraction of martensite after sinter hardening was characterized as well as compressibility, flow rate, apparent and sintered density, green strength, and mechanical properties of the sintered parts. Results show that of all of the elements examined, only prealloyed chromium, molybdenum, and nickel had a significant effect on compressibility and hardenability. Within the range of concentrations examined, the powder exhibiting the optimum sinter hardening had a prealloyed composition of 1.5 w/o Ni, 0.4 w/o Cr and 1.0 w/o Mo.

Presented at PowderMet2009 and published in Advances in Powder Metallurgy & Particulate Materials—2009, Proceedings of the 2009 Conference on Powder Metallurgy & Particulate Materials, which are available from the Publications Department of MPIF (www.mpif.org).

17

Giguere.Blais_Zheng et al 1/18/2010 11:42 AM Page 18

Previous

1-Page View

2-Page View

Table of Contents

Search

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

effective in increasing hardenability, especially in terms of obtaining a homogeneous microstructure. Hence, to fully optimize hardenability and compressibility, a judicious balance must be struck between the prealloyed and admixed elements. The goal of this study was to investigate and model the influence of admixing and prealloying on the optimization of compressibility and hardenability of sinter-hardenable steel powders. Design of experiments was used, coupled with experimental work on small batches of water-atomized prealloyed steel powders. These powders served as the base material from which powder mixes were prepared via the admixing of various fractions of elements known to increase hardenability. Compressibility and hardenability were characterized by measuring the pressure required to achieve a green density of 6.8 g/cm³, and the volume fraction of martensite formed upon sinter hardening. Tensile strength, transverse rupture (TR) strength, apparent hardness, and sintered density were also determined. The results and observations constitute the basis for the second phase of the project in which a more limited family of alloys will be investigated. EXPERIMENTAL PROCEDURE Materials The powders serving as the base materials were water atomized at Université Laval’s Powder Metallurgy Laboratory (LAMPOUL). The atomizing variables (water pressure, jet angle, water flow, melt flow, melt temperature) were maintained constant and were selected to maximize particle morphology in relation to compressibility. Design of experiments (DOE) was used to minimize the number of experiments in order to determine the influence of each variable. Powder mixes were produced according to this design. Four elements were prealloyed and four elements were admixed at two different concentration levels. Two different models were constructed by measuring the compaction pressure required to obtain a green density of 6.8 g/cm³, and the volume fraction of martensite obtained after sinter hardening. Table I cites the different variables and levels involved. The subscripts “p” and “a” refer to prealloyed and admixed powders, respectively. A 28 design was used, meaning that 256 experiments were required for complete resolution. However, a fraction of the design was executed to determine the effect of the 8 variables without hav-

18

TABLE I. DOE VARIABLES AND COMPOSITION (w/o) Variable

Low

Nip Cua Crp Mna Mop Cra Nia Mnp

Level (w/o)

High

0 1 0 0 0 0 1 0

2 3 2 0.5 1 1 3 0.5

TABLE II. CHEMICAL COMPOSITION OF ALLOYS DICTATED BY DOE Experiment 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Chemical Composition (w/o) Prealloyed Elements Admixed Elements Ni Cr Mo Mn Cu Mn Cr Ni 2 2 2 2 2 2 2 2 0 0 0 0 0 0 0 0

2 2 0 0 2 2 0 0 2 2 0 0 2 2 0 0

1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0

0.5 0 0.5 0 0 0.5 0 0.5 0 0.5 0 0.5 0.5 0 0.5 0

3 3 3 3 1 1 1 1 3 3 3 3 1 1 1 1

0.5 0 0.5 0 0.5 0 0.5 0 0.5 0 0.5 0 0.5 0 0.5 0

1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0

3 3 1 1 1 1 3 3 1 1 3 3 3 3 1 1

ing to perform 256 experiments. It was possible to reduce the number of experiments carried out by performing a 16th of the design, called a 28-4IV. With this fraction, the 8 principal effects could then be characterized; however, these effects were convoluted with statistically negligible triple interactions. Details of such a DOE have been given by Box et al.4 By executing a 16th of this design, we were able to perform 16 different experiments, hence 16 different mixes (Table II). Powder Processing and Mix Preparation Following atomization of the powders, hydrogen annealing was performed to lower their oxygen content. The powders were treated in-house in an Abbott 102 mm (4 in.) continuous-belt furnace. Annealing was done in an atmosphere of 80 v/o H2-20 v/o N2 for 60 min at 1,080°C for the

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:42 AM Page 19

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

TABLE III. RECONSTRUCTED PARTICLE-SIZE DISTRIBUTION Class (μm)

Fraction (%)

+ 212 +150 +106 +75 +45 -45

Traces 13 22 25 25 15

TABLE IV. ADMIXED CONSTITUENTS Element

Brand Name

Ni Cr Mn Cu C Lubricant

Inco 123 Acupowder Cr 301 Acupowder Mn 301 Acupowder Cu 165 PM 1651 Atomized Acrawax “C”

chromium-containing powders and at 1,000°C for the powders without chromium. The latter heat treatment resulted in some agglomeration; therefore, a disk pulverizer was used. As this process usually causes strain hardening, the powders were reannealed at 720°C for 1 h in a nitrogen atmosphere. In order to eliminate fluctuations in the size distribution from one batch of atomized powder to another, size distribution reconstruction was performed on each powder. Table III gives the chosen size distribution. The powder blends were prepared in a V-shape mixer. Admixed elements were added to each blend in proportions determined by DOE, Table IV. The concentrations of combined carbon and lubricant were maintained constant at 0.7 w/o and 0.75 w/o, respectively. For the combined carbon, preliminary tests were performed with each base powder to determine the quantity of graphite to be added to obtain 0.7 w/o in each sinter-hardened test specimen. Physical Property Characterization of Mixes The physical properties of each mix were measured. Flow rate and apparent density were also measured according to MPIF Standards 3 and 4, respectively,5,6 and compressibility was characterized according to MPIF Standard 45.7 Green strength was evaluated according to MPIF Standard 15.8 Pressing and Sintering Dog-bone and TR bars were pressed to a green

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

density of 6.8 g/cm³ according to MPIF Standards 10 and 419,10 and sintered in the Abbott continuous-belt furnace at 1,130°C for 30 min in a 90 v/o N2/10 v/o H2 atmosphere. Fan speed in the forced-convection cooling unit (Varicool) was set at 40 Hz. Following sinter hardening, the samples were tempered at 200°C for 1 h in a nitrogen atmosphere. Finally, sintered density and dimensional change were determined following MPIF Standards 42 and 44.11,12 Determination of Static Mechanical Properties Tensile and TR strength were measured according to MPIF Standards 10 and 43.9,13 Apparent hardness was also measured (HRA). Microstructural Characterization Optical microscopy (OM) was used to characterize the microstructure of the sintered steels and to determine the volume fraction of martensite. Scanning electron microscopy (SEM) was used to characterize the morphology of the atomized powders and to identify the phases present. Electron probe microscope analysis (EPMA) was used to determine the chemical composition of the phases present in the microstructures, and to obtain elemental X-ray maps. The composition of the asatomized powder was analyzed using atomic absorption. Carbon content (before and after sintering) was measured using a LECO carbon analyzer (model CS600) and the oxygen content was measured using a LECO analyzer (model TCH600). In terms of nomenclature, the base powder + admixed elements + graphite + wax is referred to as a “mix” prior to sintering. After sintering the material is termed an “alloy.” RESULTS Compressibility A compressibility curve was generated for each of the mixes. The pressure required to obtain a green density of 6.8 g/cm³ was used to quantify the effect of admixing and prealloying on compressibility. Results are presented in Table V. As seen in Table V, the admixed elements had a negligible effect on the compaction pressure required to obtain a green density of 6.8 g/cm³. In turn, this reflected on the mathematical model linking compressibility to the mode of alloying. The model was obtained by performing a least-squares

19

Giguere.Blais_Zheng et al 1/18/2010 11:42 AM Page 20

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

TABLE V. COMPRESSIBILITY OF POWDER MIXES Composition (w/o) Prealloyed Admixed A1 A2 B1 B2 C1 C2 D1 D2 E1 E2 F1 F2 G1 G2 H1 H2

2Ni-2Cr-1Mo-0.5Mn 2Ni-2Cr-1Mo-0.5Mn 2Ni-2Cr 2Ni-2Cr 2Ni-0.5Mn 2Ni-0.5Mn 2Ni-1Mo 2Ni-1Mo 2Cr-1Mo 2Cr-1Mo 2Cr-0.5Mn 2Cr-0.5Mn 1Mo-0.5Mn 1Mo-0.5Mn Pure Fe Pure Fe

Pressure at 6.8 g/cm³ MPa (tsi)

3Cu-0.5Mn-1Cr-3Ni 1Cu-1Ni 3Cu-3Ni 1Cu-0.5Mn-1Cr-1Ni 3Cu-0.5Mn-1Ni 1Cu-1Cr-3Ni 3Cu-1Cr-1Ni 1Cu-0.5Mn-3Ni 3Cu-0.5Mn-1Ni 1Cu-1Cr-3Ni 3Cu-1Cr-1Ni 1Cu-0.5Mn-3Ni 3Cu-3Ni 1Cu-0.5Mn-1Cr-1Ni 3Cu-0.5Mn-1Cr-3Ni 1Cu-1Ni

635 (46) 635 (46) 579 (42) 607 (44) 497 (36) 486 (35) 458 (34) 452 (33) 607 (44) 607 (44) 552 (40) 552 (40) 430 (31) 469 (34) 403 (29) 381 (28)

A B C D E F G H

regression to fit a model on statistical data. ANOVA testing and confidence intervals were calculated to ensure a statistically relevant model. After eliminating the statistically insignificant parameters, a scaled model and an unscaled model were obtained. The scaled model (obtained with reduced and centered values) was used to determine the relative weight of each parameter, while the unscaled model was used to make predictions, as detailed in the discussion. The final scaled and unscaled models determining the effect of alloying elements on compressibility are presented in equations 1 and 2: Ρ @ 6.8 g/cm³ = 521.9 + 22.5 Nip + 77.3 Crp + 15.2 Mop ≡ scaled

(1)

Ρ @ 6.8 g/cm³ = 410.5 + 21.8 Nip + 74.9 Crp + 29.5 Mop ≡ unscaled

(2)

The model indicates that only the prealloyed elements had a significant effect on compressibility. It is important to note that these models apply only for the composition intervals in Table II. Thus, the scaled model predicted that prealloyed chromium had the greatest effect on reducing compressibility, followed by nickel and molybdenum. Table VI gives the flow rate and apparent density of the various prealloyed powders without admixed elements. From Table VI, we determined that the powders

20

TABLE VI. APPARENT DENSITY AND FLOW RATE OF WATER-ATOMIZED PREALLOYED POWDERS Composition (w/o)

Apparent Density (g/cm³)

Flow Rate (s/50 g)

2Ni-2Cr-1Mo-0.5Mn 2Ni-2Cr 2Ni-0.5Mn 2Ni-1Mo 2Cr-1Mo 2Cr-0.5Mn 1Mo-0.5Mn Pure Iron

2.20 2.56 3.16 2.93 2.64 2.74 3.20 2.88

40 33 24 26 30 29 23 26

prealloyed with chromium (i.e., A, B, E, and F) exhibited a lower apparent density and a lower flow rate than the other mixes. Figure 1 presents the green-strength results for the 16 powder mixes cited in Table II. Each specimen was pressed to a green density of 6.8 g/cm³. Again, the chromium-prealloyed mixes (A, B, E, and F) gave different properties compared with the chromium-free mixes. The difference in green strength, flow rate and apparent density can be partially explained by the morphology of the prealloyed powders. Figure 2 shows representative SEMs in the secondary electron image (SEI) mode, highlighting the overall appearance of a prealloyed powder, with and without chromium. As seen in the micrographs in Figure 2, for an identical particle-size distribution, the powder prealloyed with chromium (Figure 2(a)) showed a significant level of particles resulting from the agglomeration of multiple smaller particles and ligaments. Therefore, the particles in the powders prealloyed with chromium were generally more irregular than were those in the chromium-free

Figure 1. Green strength of the 16 mixes in Table II (0.7 w/o C, 0.75 w/o EBS)

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:42 AM Page 21

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

Figure 2. Overall appearance of prealloyed powder, (a) chromium present, and (b) no chromium. SEM/SEI

prealloyed powders. This characteristic explains the significant differences observed for the chromium-bearing powders in terms of apparent density, flow rate, and green strength. It is well known that due to interlocking in loose powders or green compacts, irregular particles display a lower apparent density and flow rate, but a higher green strength. Another significant aspect related to the presence of chromium in low-alloyed steel powders is its high reactivity toward oxygen. Moreover, unlike less stable oxides such as FexOy, NiO, and MoO3, once formed Cr2O3 is extremely difficult to reduce during atmosphere sintering.14 It is therefore not uncommon to have chromium-bearing powders with a residual oxygen concentration significantly higher than that of other PM steels unalloyed with chromium. Table VII presents results for the residual oxygen concentration in hydrogen-annealed prealloyed powders. It can be seen that the presence of chromium in the steel powder had a significant effect on the residual oxygen content. TABLE VII. RESIDUAL OXYGEN CONCENTRATION IN HYDROGEN-ANNEALED PREALLOYED POWDERS Powder

Element (w/o)

Oxygen (w/o)

A B C D E F G H

2Ni-2Cr-1Mo-0.5Mn 2Ni-2Cr 2Ni-0.5Mn 2Ni-1Mo 2Cr-1Mo 2Cr-0.5Mn 1Mo-0.5Mn Pure Fe

0.37 0.38 0.19 0.09 0.49 0.45 0.16 0.07

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Sinter Hardenability After sinter hardening, image analysis was used to determine the volume fraction of martensite present. Figures 3 and 4 show representative microstructures. Figure 3 shows martensite, nickel-rich areas, and porosity in alloy A2. Image analysis in the OM revealed that martensite composed 98% of the microstructure, excluding porosity. In alloy F2 (Figure 4), martensite, bainite, pearlite, nickel-rich areas, and porosity are present. Martensite composed 69% of the pore-free microstructure. Table VIII summarizes the results of image analysis for all 16 mixes obtained by image analysis of at least 20 fields per sample. Using the data in Table VIII, a model was developed by performing a least-squares regression. ANOVA testing and confidence intervals were calculated to ensure a statistically relevant model. Following the elimination of statistically insignificant parameters, the final scaled and unscaled models predicting the influence of alloying elements on hardenability are represented by equations (3) and (4): Martensite (v/o) = 76.0 + 12.6 Nip + 11.2 Crp + 10.8 Mop ≡ scaled

(3)

Martensite (v/o) = 42.5 + 12.2 Nip + 10.8 Crp + 20.8 Mop ≡ unscaled

(4)

According to the scaled model, all of the significant parameters were prealloyed elements (chro-

21

Giguere.Blais_Zheng et al 1/18/2010 11:43 AM Page 22

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

TABLE VIII. MARTENSITE CONTENT

Figure 3. Alloy A2 showing a martensitic (M) microstructure with nickel-rich areas (NRA). OM

Series

(v/o)

A1 A2 B1 B2 C1 C2 D1 D2 E1 E2 F1 F2 G1 G2 H1 H2

82 98 95 94 73 87 90 87 98 84 75 69 95 57 32 0

remaining series were divided into two groups having similar mechanical properties. The first group (B, D, E, and F) shows intermediate mechanical properties, while the second group (C, G, and H)

Figure 4. Alloy F2 showing a martensitic (M) microstructure with bainite (B), pearlite (P) and nickel-rich areas (NRA). OM

Figure 5. TR strength of alloys

mium, nickel, and molybdenum). Arguably, these numbers indicate that prealloyed chromium, nickel, and molybdenum produced similar effects on hardenability. No admixed elements appeared to have a significant effect on sinter hardenability when prealloyed elements were present. Mechanical Properties TR strength, tensile strength, and apparent hardness are shown for each alloy in Figures 5 through 8. As seen in Figures 5 and 6, alloy A2 showed the highest TR strength and tensile strength. The

22

Figure 6. Tensile strength of alloys

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:44 AM Page 23

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

shows the lowest strength values. These properties correlated with apparent hardness, Figure 7. Finally, Figure 8 gives the sintered density of each mix. Mixes were pressed to a green density of 6.8 g/cm³. The mixes with 3 w/o admixed copper experienced more swelling than the others. Most of the alloys had a sintered density of between 6.65 and 6.75 g/cm³. As expected, the powder mixes containing 1 w/o admixed copper (suffix 2) displayed less swelling than did those with 3 w/o admixed copper. DISCUSSION Compressibility The scaled model obtained for compressibility shows that prealloyed chromium, nickel, and molybdenum were the only elements to have a statistically significant effect. The strongest effect was from chromium, followed by nickel and molybdenum. However, Figure 9 shows a decreased compressibility experienced by iron powder alloyed with common transition elements and carbon.1 Figure 9 also indicates that, among the metals group, man-

ganese should have the greatest effect on reducing compressibility, followed by nickel, molybdenum, and chromium; this is not corroborated by the present results. Here, prealloyed 0.5 w/o Mn was the highest concentration used. At this concentration, manganese should have had the same effect as 2 w/o prealloyed nickel. The effect of prealloyed manganese was perhaps not significant, as some of it volatilized. Indeed, upon sintering, the manganese concentration decreased to 0.3 w/o. This concentration may therefore not have been sufficient to significantly affect compressibility. Commercially available powders such as QMP 4201, Höganäs’ Astaloy B, and Hoeganaes’ Ancorsteel 737SH and 2000 have similar manganese concentrations and are reported (by their manufacturers) to have good compressibility. This leads us to believe that there exists a minimum threshold concentration under which manganese has a negligible effect on lowering compressibility. Consequently, the linear behavior for manganese in Figure 9 may not hold true at lower concentrations. As noted previously, chromium appears to have had the most significant effect on compressibility according to our model. This strong effect of chromium may be explained by its marked affinity for oxygen, resulting in the formation of oxide particles during atomization and/or sintering. As presented in Table VII, oxygen content increased significantly with the addition of 2 w/o chromium. A high oxygen content results in an increased volume fraction of oxide particles, which are known to decrease compressibility. Furthermore, we

Figure 7. Apparent hardness of alloys

Figure 8. Sintered density of alloys

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Figure 9. Influence of alloying elements on compressibility of pure iron pressed at 414 MPa1

23

Giguere.Blais_Zheng et al 1/18/2010 11:44 AM Page 24

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

observed differences in particle morphology in the mixes prealloyed with chromium. Thus chromiumbearing melts exhibited decreased fluidity upon atomization, which produced a larger fraction of elongated particles (ligaments) rather than spherical particles (Figure 2(a)). Elongated particles had a significant impact on apparent density (lower), green strength (significantly higher), and flow rate (lower), which are all directly related to particle morphology. Moreover, a lower apparent density requires a higher compaction pressure to obtain a specified green density. These factors explain the important effect of prealloyed chromium on compressibility. Finally, the model found no significant effect of admixed elements on compressibility, in accordance with theory. Sinter Hardenability The scaled model showed that prealloyed nickel had the strongest effect on hardenability, followed closely by prealloyed chromium and molybdenum. However, their scaled values are so close that it is difficult to differentiate between their contributions to hardenability. In carbon steels, the effect of different alloying elements (at a level of 1 w/o) on hardenability can be characterized by the Grossman hardening factor, which measures the enhancement effect on the critical quench diameter.15 Nickel had the lowest effect on hardenability (Grossman hardening factor of 1.4), with chromium and molybdenum displaying factors of 3.1 and 3.7, respectively; however, this does not take into account combined effects, whereas our model does. It is well known that in wrought steels synergetic effects are observed for certain combinations of alloying elements.16 It is likely that such effects took place during our experimentation, thereby modifying the overall effect on sinter hardening, compared with powders to which the alloying elements were added independently, as can be seen in Figure 9. The addition of prealloyed chromium and manganese resulted in the formation of complex chromium and manganese oxides in the sintered parts, as shown in Figure 10 and the energy dispersive X-ray (EDAX) spectrum in Figure 11, which resulted in less free chromium and manganese to benefit hardenability. Furthermore, a typical chromium-free powder has a typical oxygen content of 0.1 w/o, while the level in a powder prealloyed with chromium is close to 0.4 w/o.

24

Considering a powder prealloyed with 2 w/o Cr, and assuming that all of the excess oxygen (0.3 w/o) reacted with the chromium to form Cr2O3, only 1.3 w/o of chromium remained in solid solution. Thus only the non-oxidized fraction of the initial chromium was effective in increasing hardenability. With admixed chromium, it had no significant effect on hardenability due primarily to the fact that the chromium particles did not sinter and were found almost intact, which confirms that limited diffusion took place in the iron matrix, Figure 12. Admixed nickel (1 or 3 w/o additions) was not found to be a significant factor in improving hardenability. This may be due to the fact that admixed nickel rarely diffuses homogeneously under typical sinter-hardening conditions, leading to the formation of nickel-rich areas. When localized in these areas, nickel cannot contribute significantly to hardenability. It was found that admixed 3 w/o Ni produced as much as 15% of nickel-rich areas

Figure 10. Chromium–manganese oxides in prealloyed alloy. SEM/SEI

Figure 11. EDAX spectrum of chromium–manganese oxide (refer to Figure 10)

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:44 AM Page 25

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

um–manganese oxides, and can be correlated with the prealloyed manganese (Figure 13(c)), where the same areas are seen to be rich in manganese. Manganese that did not form oxide inclusions is shown to be uniformly dispersed (dark blue in Figure 13(c)). Interestingly, the admixed manganese (Figure 13(d)) diffused well into the iron matrix, producing very few manganese oxide particles. Prealloyed molybdenum was found to be uniformly dispersed, as shown in Figure 13(e). Finally, as expected, admixed 3 w/o Cu (Figure 13(f)) did not diffuse throughout the iron matrix, resulting in copper-rich areas. Figure 12. Non-sintered admixed chromium particles (arrowed). OM

(NRA) compared with 2%–5% in alloys with admixed 1 w/o Ni. Prealloyed and admixed manganese (up to 0.3 w/o) were also found to have no significant effect on improving hardenability. This result is attributed to their low concentrations, compared with the other alloying elements, combined with the propensity for manganese to vaporize during sintering, resulting in a 20% loss. Elemental Mapping Localization of the prealloyed and admixed elements (chromium, copper, manganese, molybdenum, and nickel) determined by EPMA, are illustrated in Figure 13. A limited nu mber of images sufficed to characterize the distribution of these alloying elements. The prealloyed nickel is uniformly distributed within the matrix, as shown by the dark blue coloration, Figure 13(a). The admixed nickel formed nickel-rich areas which are identified by the green and yellow portions of the map. These areas are surrounded by light-blue areas that indicate that there is a concentration gradient between the admixed nickel particles and the center of the prealloyed nickel particles, thus at least some of the admixed nickel diffused into the matrix. Figure 13(b) shows the elemental mapping of chromium. It was noted previously that admixed chromium did not diffuse (yellow-green areas); however, as can be seen in Figure 13(b), the admixed chromium did in fact diffuse (bright-blue areas around the admixed particles). Prealloyed chromium is dispersed in the iron matrix (dark blue), although some isolated bright-blue spots can be seen. These spots are complex chromi-

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Mechanical Properties The mechanical properties are not those of standard powder mixes, but rather those of the mixes dictated by our DOE. However, with minor differences, these mixes can be compared with materials listed in MPIF Standard 35,17 or to non-standardized commercial powders. Because the admixed chromium diffused marginally during sinter hardening, and thus failed to contribute to hardenability, its effect is not discussed here. If anything, admixed chromium probably had a negative effect on the mechanical properties, as the non-sintered chromium particles may have acted as exogenous inclusions. The following comparisons are based on an equivalent sintered density and combined carbon. Apparent hardness is discussed only for mixes in which a sinter-hardenable equivalent was found, as all of the other mixes were oil quenched. Alloys A1 and A2 may be compared with FLN48108 (+ chromium) or FLNC-4405 (+ chromium).16 It was observed that the addition of admixed 3 w/o Ni resulted in a larger fraction of nickel-rich areas and did not produce as much martensite when compared with admixed 1 w/o Ni. This is reflected in the TR strength and ultimate tensile strength (UTS). The addition of 3 w/o Cu led to a significant swelling in alloy A1, resulting in a lower sintered density and lower mechanical properties. Alloy A2 (TR strength 1,732 MPa and UTS 1,012 MPa) compares favorably with both FLNC-4405 (965 and 430 MPa) and FLC-4808 (930 and 480 MPa).16 Although alloy A2 exhibited one of the lowest compressibility levels, it displayed the best mechanical properties of all the alloys studied. Alloys B1 and B2 have no commercial or MPIF

25

Giguere.Blais_Zheng et al 1/18/2010 11:44 AM Page 26

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

Figure 13. Elemental mapping: (a) prealloyed and admixed nickel in alloy A1, (b) prealloyed and admixed chromium in alloy F1, (c) prealloyed manganese in alloy F1, (d) admixed manganese in alloy H1, (e) prealloyed molybdenum in alloy A1, and (f) admixed copper in alloy A1

equivalents. The presence of admixed 3 w/o Ni resulted in an increase in the number of nickelrich areas in alloy B1. As their standard deviation was significant, no conclusion could be drawn as to which alloy displayed the best mechanical properties. Alloys C1 and C2 may be compared with FN-

26

0208 (with slightly more manganese). The mechanical properties of both these alloys, along with those of mixes G and H, were the lowest of all, although alloy C2 appeared to perform slightly better. Once again, the same conclusion as that for alloys B1 and B2 may be drawn in relation to the amount of admixed copper and nickel on swelling

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:44 AM Page 27

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

and nickel-rich areas. Both C1 and C2 alloys displayed better TR strength (781 and 867 MPa) and UTS (455 and 560 MPa) than did FN-0208 (586 and 310 MPa, respectively). Alloys D1 and D2 may be compared with FLNC4408 (D1) or FLC-4608 (D2), with more manganese and double the level of nickel in the case of alloy D2. In considering their standard deviations, the mechanical properties were essentially identical. Mix D1 had a TR strength (1,300 MPa) and a UTS (635 MPa), superior to those of FLNC-4408 (1,205 and 570 MPa). Alloy D2 had a TR strength (1,140 MPa) and a UTS (700 MPa) superior to those of FLC-4608 (985 and 535 MPa). The apparent hardness of these two alloys (61 HRA/21 HRC) was lower than that of sinter-hardenable FLNC4408 and FLC-4608. The sinter-hardening cooling rates, however, are not given in the standard. The higher nickel content in alloy D2 compared with that in FLC-4608 may, in part, explain the difference in mechanical properties due to the nickelrich areas. Alloys E1 and E2 may be compared with FLC520816 with higher nickel and molybdenum levels. Once again, the mechanical properties of both alloys were essentially identical. Both alloys displayed superior UTS (825 and 750 MPa) and TR strength (1,273 and 1,213 MPa) compared with FLC-5208 (620 and 1,100 MPa), as well as a higher apparent hardness (92 compared with 83 HRB). Alloys F1 and F2 have no commercial or MPIF equivalents. The presence of admixed 3 w/o Cu in alloy F1 induced more swelling, which resulted in a slight decrease in mechanical properties. The higher nickel content in alloy F2 produced more nickel-rich areas and lowered the mechanical properties. The same phenomenon was observed in alloys C, D, and E. One alloy contained 3 w/o Ni and 1 w/o Cu and the other 1 w/o Ni and 3 w/o Cu. The negative swelling effect caused by 3 w/o Cu was counterbalanced by fewer nickel-rich areas when the admixed nickel content was lower (1 w/o). Alloys G1 and G2 may be compared with lowalloy steel FLNC-4408. If we consider the standard deviation, both of these alloys displayed the same tensile strength (510–585 MPa) and TR strength (1,000 MPa). At the same density (6.6 g/cm³), they displayed a higher tensile strength than FLNC4408 (480 MPa) and a slightly lower TR strength (1,100 MPa). Their apparent hardness levels were

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

also similar to that of FLNC-4408. Alloys H1 and H2 may be compared with FN0208. Compared with alloy H2, alloy H1 showed a slightly higher UTS and TR strength. Their respective TR strength levels (988 and 891 MPa) compare favorably with those of FN-0208 (827 MPa), although the tensile strength (557 and 440 MPa) was lower than that of FN-0208 (627 MPa). Optimization of Compressibility and Sinter Hardenability From the compressibility and hardenability models, we are thus able to make predictions as to the optimum sinter-hardenable material. There were three unknown variables (Nip, Crp, and Mop) and only two equations. To solve this system, one of the variables had to be kept constant. Moreover, compressibility and hardenability had to be fixed to solve these equations. Ancorsteel 737SH possesses an excellent combination of compressibility and hardenability.18 From the 737SH data sheet,19 a green density of 6.8 g/cm³ can be attained at a compaction pressure of 500 MPa (36 tsi). The latter criterion was therefore used to determine the most compressible sinter-hardenable powders among those studied. Similarly, sinter-hardening alloys are characterized by their significant hardenability which enables the transformation of austenite into more than 80 v/o martensite using accelerated cooling.20 In this study, the criterion used in terms of hardenability was that a powder should show a minimum of 85 v/o of martensite upon sinter hardening. To solve this system, nickel content (0, 0.5, 1, 1.5, and 2 w/o), compaction pressure (500 and 550 MPa) and martensite content (85, 90, 95, and 100 v/o) were implemented in the system and prealloyed chromium and molybdenum were determined. The model did produce some results that were outside of the chemical compositions initially used in our design of experiment (0 w/o ≤ Crp ≤ 2 w/o, 0 w/o ≤ Mop ≤ 1 w/o), thus rendering them unusable. They are, however, excellent indicators as to what other chemistries should be studied in the next phase of our research. Table IX lists the mixes meeting the cited conditions. As can be seen in Table IX, the alloys with >1 w/o of Cr required a higher compaction pressure to reach a green density of 6.8 g/cm³ (550 MPa) compared with the alloys containing

27

Giguere.Blais_Zheng et al 1/18/2010 11:44 AM Page 28

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

TABLE IX. CHEMICAL COMPOSITION OF MODEL ALLOYS Ni

Cr

Mo

(w/o) 1 2 3 4 5 6 7 8 9

2.0 2.0 2.0 1.5 2.0 1.5 2.0 1.5 1.0

0.95 0.20 1.00 1.10 0.35 0.40 1.20 1.20 1.25

0.85 1.00 0.55 0.85 0.70 1.00 0.25 0.55 0.80

Compaction Pressure at 6.8 g/cm³ (MPa)

Martensitic

550 500 550 550 500 500 550 550 550

95 90 90 90 85 85 85 85 85

(v/o)

<0.4 w/o Cr. The best compromise appears to be mixes 2, 5, and 6, which contained only a small quantity of prealloyed chromium, 1.5 to 2 w/o Ni, and between 0.70 and 1 w/o Mo. These alloys required only 500 MPa to reach a green density of 6.8 g/cm³, yielding up to 85 v/o martensite upon sinter hardening. Of these three alloys, alloy 6 had the lowest total concentration of prealloyed elements and thus constitutes the ideal choice in terms of hardenability, compressibility, and cost. This powder does not match any MPIF standards for structural parts, although its chemistry is similar to that of QMP powder 4701. CONCLUSION 1. Within the concentration range studied, admixed elements known to improve hardenability (chromium, nickel, and molybdenum) had no influence on compressibility. 2. Prealloyed chromium displayed the most significant effect in reducing compressibility, followed by nickel and molybdenum. Chromium had an indirect effect on atomized particle morphology, resulting in lower apparent density and compressibility. The influence of chromium must therefore be further examined in order to eliminate any possible bias due to a significant difference in particle morphology between chromium-bearing powders and those without chromium. 3. Contrary to what is reported in the literature, manganese concentrations in the range of 0.3 to 0.4 w/o have no significant impact on the compressibility or hardenability of sinterhardenable steel powders. 4. Prealloyed chromium, nickel, and molybde-

28

num exhibit a similar effect in improving the hardenability of sinter-hardenable steel powders. 5. The model generated to optimize the hardenability and compressibility of sinter-hardenable powders indicates that the optimum composition is 1.5 w/o Ni, 0.4 w/o Cr, and 1.0 w/o Mo, achieved by prealloying. FUTURE RESEARCH The results constitute the basis of a second phase of experiments aimed at optimizing the compressibility and hardenability of sinter-hardenable powders. We found that the most interesting group of mixes have a prealloyed content of 1.5 to 2 w/o Ni, 0.2 to 0.4 w/o Cr, and ~1 w/o Mo. Therefore, in our next design of experiments, we will focus on this particular family of prealloyed powders, with a prealloyed chromium level between 0.2 and 0.75 w/o, and a prealloyed molybdenum level between 0.5 and 2 w/o, as variables. Prealloyed nickel and admixed copper will be kept constant at 1.5 and 2 w/o, respectively, and carbon will be kept constant at 0.7 w/o. ACKNOWLEDGMENTS This research was funded by the Auto21Network of Centers of Excellence. REFERENCES 1. R.M. German, Powder Metallurgy & Particulate Materials Processing, 1994, Metal Powder Industries Federation, Princeton, NJ. 2. M. Paullin, “State of the North American PM Industry”, Int. Journal Powder Metall., 2008, vol. 44, no. 4, pp. 49–52. 3. G.F. Bocchini, B. Rivolta, G. Silva, E. Poggio, M.R. Pinasco and M.G. Ienco, “Microstructural and Mechanical Characterisation of Some Sinter Hardening Alloys and Comparisons with Heat Treated PM Steels”, Powder Metallurgy, 2004, vol. 47, no. 4, pp. 343–351. 4. G.E.P. Box, W.G. Hunter and J.S. Hunter, Statistics for Experimenters, 1978, John Wiley & Sons, New York, NY. 5. “Standard 3—Method for Determination of Flow Rate of Free-Flowing Metal Powders Using the Hall Apparatus, Standard Test Methods for Metal Powders and Powder Metallurgy Products, 1998, Metal Powder Industries Federation, Princeton, NJ. 6. “Standard 4—Method for Determination of Apparent Density of Free-Flowing Metal Powder Using the Hall Apparatus”, ibid. 7. “Standard 45—Method for Determination of Compressibility of Metal Powders”, ibid. 8. “Standard 15—Method for Determination of Green Strength of Compacted Metal Powder Specimens”, ibid. 9. “Standard 10—Method for Preparing and Evaluating

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Giguere.Blais_Zheng et al 1/18/2010 11:45 AM Page 29

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF COMPRESSIBILITY AND HARDENABILITY BY ADMIXING AND PREALLOYING

Tensile Specimens of Powder Metallurgy Materials”, ibid. 10. “Standard 41—Method for Determination of Transverse Rupture Strength of Powder Metallurgy Materials”, ibid. 11. “Standard 42—Method for Determination of Density of Compacted or Sintered Powder Metallurgy Products”, ibid. 12. “Standard 44—Method for Determination of Dimensional Change from Die Size of Sintered Metal Powder Specimens”, ibid. 13. “Standard 43—Method for Determination of the Apparent Hardness of Powder Metallurgy Products”, ibid. 14. N. Birks and G.H. Meier, Introduction to High Temperature Oxidation of Metals, 1983, Edward Arnold Ltd., London, UK. 15. ASM Handbook, Vol. 7: Powder Metal Technology and Applications, 1998, ASM International, Materials Park, OH, p. 473. 16. G. Krauss, Steels: Processing, Structure and Performance, 2005, ASM International, Materials Park, OH. 17. MPIF Standard 35, Materials Standards for PM Structural Parts, 2007, Metal Powder Industries Federation, Princeton, NJ. 18. B. Lindsley, “Alloy Development of Sinter-Hardenable Compositions”, Proc. Euro PM2007, European Powder Metallurgy Association, Shrewbuty, UK, vol. 1, pp. 107–111. 19. Technical Data, http://www.hoeganaes.com/Product% 20Datasheets/DatasheetsJan2009/Ancorsteel737SH.pdf 20. T. Haberberger, F.G. Hanejko, M.L. Marucci and P. King, “Properties and Applications of High Density SinterHardening Materials,” http://www.hoeganaes.com/nav pages/NewTechbyTopic/TechbyTopicv2/TechPapersv2/12 4.pdf ijpm

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

29

Giguere.Blais_Zheng et al 1/18/2010 11:45 AM Page 30

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Chagnon_Zheng et al 1/18/2010 11:47 AM Page 31

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ENGINEERING & TECHNOLOGY

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTERHARDENED PM STEELS François Chagnon*

INTRODUCTION Sinter hardening is a process in which the martensitic transformation occurs when powder metallurgy (PM) parts are cooled from the sintering temperature. The primary advantage of this process is the elimination of a post-sintering heat treatment. Also, because of the flexibility of this process, the final properties can be tailored via selection of the base powder, mix composition, green density, sintering conditions, and tempering temperature. Many studies have been carried out to evaluate these variables on static properties but only a few have addressed dynamic properties. In terms of static properties, it is generally established that the maximum tensile strength is achieved with carbon concentrations ranging from 0.4 to 0.8 w/o,1–6 depending on the alloy and mix composition as well as the post-sintering cooling rate. When the hardenability of the steel and/or the post-sintering cooling rate increase, the maximum strength shifts toward lower carbon concentrations, consistent with a decrease in the amount of retained austenite. Sinter-hardened parts exhibit a high apparent hardness in the assintered condition and a tempering treatment is often required to modify the mechanical properties. The optimum tempering temperature to maximize tensile strength and impact energy is in the range of 150°C (302°F) to 250°C (482°F), while yield strength is maximized at ~300°C (572°F), the temperature at which the transformation of retained austenite to martensite is essentially complete.7 However, the apparent hardness decreases as the tempering temperature is raised, particularly above 150°C (302°F),7,8 due to softening of the matrix as the martensite loses its tetragonal structure due to the precipitation of carbides.9 Raising the sintering temperature is another way to improve the static properties of sinter-hardened steel parts.10,11 High-temperature sintering increases sintered density, promotes pore rounding, alloy diffusion, and the reduction of oxides, particularly in steels containing chromium and manganese. High-temperature sintering also promotes austenitegrain growth. A large grain size is known to have a beneficial effect on

The effect of sintering temperature and mix composition on the static and dynamic properties of sinter-hardened steels was evaluated in relation to the level of retained austenite. Using a low-alloy steel-base powder, mixes were prepared with 2 w/o Cu and two levels of graphite to attain ~0.7 and 0.5 w/o carbon after sintering, with or without admixed 1 w/o Ni, followed by temperating. Transverse rupture (TR) strength, tensile properties, and plane bending fatigue strength were evaluated. The highest tensile properties are attained at a retained austenite: martensite ratio (γR:M) <0.15. Plane-bending fatigue strength is maximized at a (γR:M) ratio of 0.25 with attendant crack growth primarily through interparticle crack necks. Under cyclic loading, a microstructure consisting of high-carbon plate martensite, compared with low-carbon lath martensite, is preferred.

Presented at PowderMet2009 and published in Advances in Powder Metallurgy & Particulate Materials—2009, Proceedings of the 2009 Conference on Powder Metallurgy & Particulate Materials, which are available from the Publications Department of MPIF (www.mpif.org).

* Principal Scientist, Rio Tinto Metal Powders, P.O. Box 570, Sorel, Québec J3P 5P7, Canada; E-mail: [email protected]

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

31

Chagnon_Zheng et al 1/18/2010 11:47 AM Page 32

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

hardenability because it reduces the number of sites available for the nucleation of pearlite during the phase transformation. However, this is achieved to the detriment of mechanical properties.12,13 In terms of the fatigue performance of sintered PM steels, Saritaş, et al.14 have published a detailed review which confirms that fatigue strength is improved by increasing sintered density and in the presence of small rounded pores. A similar conclusion was drawn by Dalgic, et al.15 in a carbon-free diffusion-bonded steel processed to a density in the range of 6.1 to 7.3 g/cm³ and sintered at either 1,120°C (2,048°F) or 1,280°C (2,336°F). Microstructure is also an important factor affecting fatigue performance. PM steels can be processed in such a way that the final microstructure is either homogeneous or heterogeneous but Saritaş et al.14 do not give a clear indication of which microstructure is preferred in relation to fatigue performance. Subsequently, Saritaş et al.16 reported that high-temperature sintering did not improve the fatigue performance of a prealloyed and two hybrid PM steels with a pearlitic microstructure. Engström et al.17 reported that at a similar sintered density, a heterogeneous microstructure consisting of pearlite, bainite, nickel-rich austenite, and martensite in a 1.5 w/o Mo diffusion-bonded steel (with 4 w/o Ni and 2 w/o Cu and 0.7 w/o C) had a superior fatigue strength to a steel based on 3.5 w/o Cr and 0.5 w/o Mo containing 0.4 w/o C composed primarily of bainite with some martensite. Engström and Bergman18 also reported similar results but when the latter steel was sintered at a high temperature and rapidly cooled to reach an essentially homogeneous martensitic structure, its fatigue strength was superior to that of the steel exhibiting a heterogeneous microstructure. A similar observation was made by Sigl et al.19 who observed improved fatigue performance of the same steels processed to a similar apparent hardness. Marucci et al.20 reported that a heterogeneous microstructure with a higher quantity of a nickel-rich austenite phase between the martensite needles lowered the dynamic performance. Finally, the optimum tempering temperature to maximize the fatigue performance of a sinter-hardened FLNC-4408 steel was reported to be ~150°C (302°F).21 Tempering above 250°C (482°F) resulted in transformation of the retained austenite and a loss in fatigue strength. Based on this literature review, the present study was carried out with the objective of evalu-

32

ating the effect of sintering and tempering temperatures on the static and dynamic performance of sinter-hardened steels, with a particular focus on the effect of retained austenite. EXPERIMENTAL PROCEDURE ATOMET 4701, a low-alloy steel powder (0.45 w/o Mn-0.45 w/o Cr-0.9 w/o Ni-1 w/o Mo), was used in all the experiments. Table I summarizes the three mix compositions and respective identification codes. Nickel was admixed to promote the production of either a nickel-rich phase or retained austenite. All the mixes contained 0.5 w/o ethylene bis-stearamide (EBS) wax as a lubricant. TR and dog-bone specimens were pressed to a green density of 7.00 g/cm³ from each mix and sintered at either 1,120°C (2,048°F) or 1,205°C (2,201°F) for 30 min in a 90 w/o N2/10 w/o H2 atmosphere. The post-sintering cooling rate in the range of 650°C (1,202°F) to 400°C (752°F) was 1.3°C/s for both sintering temperatures. The specimens were tempered at 180°C (356°F) for 60 min. For mix B, a series of specimens was also tempered for 60 min at 220°C (428°F). TR strength, tensile strength, yield strength, and elongation were determined for each test condition. The plane-bending fatigue strength was also evaluated at a load ratio of R=0.1. The fatigue limit at the 50% survival level was determined utilizing the staircase method with a run-out limit of 2.5 × 106 cycles. The values are reported in terms of maximum stress. Microstructures were observed by means of optical microscopy (OM). The amount of retained austenite was evaluated by X-ray diffraction and the other phases were quantified by means of image analysis. The fracture surfaces of the fatigue specimens were characterized by scanning electron microscopy (SEM) in the secondary electron image (SEI) mode. TABLE I. CHEMICAL COMPOSITION OF MIXES (w/o) Identification

Ni

Cu

Graphite

Mix A Mix B Mix C

1 0 0

2 2 2

0.9 0.9 0.7

RESULTS AND DISCUSSION Table II summarizes the results of the study. The higher sintering temperature enhances oxide reduction and, hence, induces larger average carVolume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 33

Previous

1-Page View

2-Page View

Table of Contents

Search

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

bon losses of ~0.06 w/o between the values at 1,205°C (2,201°F) and those at 1,120°C (2,048°F). Figure 1 shows the effect of the processing conditions on apparent hardness of the steels. The highest apparent hardness was reached in steel B tempered at 180°C (356°F). Also, for steels A and B tempered at 180°C (356°F), slightly higher apparent hardness values were observed after sintering at 1,205°C (2,201°F) compared with those after sintering at 1,120°C (2,048°F), even when the car-

bon concentration was modestly lower. These results can be explained by the amount of martensite present in the steels. Figure 2 quantifies the amount of the various phases in the steels as a function of composition and processing conditions. The corresponding microstructures are shown in Figure 3. For a specific steel and processing condition, the largest quantity of martensite is always attained in the specimens sintered at 1,205° (2,201°F). This is related to the larger

TABLE II. SINTERED PROPERTIES OF STEELS AND PROCESSING CONDITIONS Mix A

Mix B

Mix B

Mix C

Sintering Temperature (°C)

1,120

1,205

1,120

1,205

1,120

1,205

1,120

1,205

Tempering Temperature (°C)

180

180

180

180

220

220

180

180

Combined Carbon (w/o)

0.77

0.73

0.77

0.72

0.77

0.72

0.57

0.47

Sintered Density (g/cm3)

6.92

6.94

6.95

6.96

6.96

6.98

6.90

6.93

38

39

40

41

39

38

35

35

Apparent Hardness (HRC) Transverse Rupture Strength, MPa (psi × 103)

1,519 1,683 (220.2) (244.0)

1,566 1,882 (227.1) (272.9)

1,692 1,814 (245.4) (263.1)

1,717 1,904 (248.9) (276.1)

Tensile Strength, MPa (psi × 103)

730 813 (105.8) (117.9)

856 892 (124.1) (129.4)

920 1,048 (133.4) (152.0)

981 1,081 (142.2) (156.8)

Yield Strength, MPa (psi × 103)

648 (94.0)

784 795 (113.7) (115.3)

824 908 (119.5) (131.6)

878 945 (127.3) (137.0)

Elongation (%) Plane-Bending Fatigue Strength (max. stress; 50% survival), MPa (psi × 103) Retained Austenite (v/o) Martensite (v/o) Bainite (v/o)

668 (96.9)

0.3

0.3

0.3

0.3

0.3

0.4

0.4

0.5

448 (65.0)

466 (67.5)

462 (67.0)

474 (68.8)

452 (65.6)

432 (62.7)

402 (58.3)

381 (55.3)

26 71 3

22 77 1

23 71 6

20 79 1

17 73 10

16 82 2

10 67 23

11 81 8

Figure 1. Effect of composition and processing conditions on apparent hardness

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Figure 2. Proportion of phases as a function of composition and processing conditions

33

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 34

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

austenite grains in the steels sintered at this temperature. As noted previously, a larger grain size improves hardenability due to a reduction in the number of nucleation sites for bainite and pearlite.13 It is noted that for steels A and B tempered at 180°C (356°F), a larger quantity of retained austenite is present in the steels sintered at 1,120°C (2,048°F), due to the higher concentration of carbon, which favors the formation of retained austenite. For steel B tempered at 220°C (428°F), a decrease in the amount of retained austenite was observed due to its transformation into bainite, and possibly into martensite. This is clearly evident after sintering at 1,120°C (2,048°F) due to the larger quantity of this phase. Figure 4 shows OMs at a higher magnification of some steels to better understand the effect of mix formulation, sintering and tempering tempera-

tures on the microstructure. At 0.72–0.77 w/o C, the microstructure is composed of plate martensite, retained austenite, some bainite, and nickelrich phases in the case of steel A. Raising the sintering temperature favors the diffusion of nickel and hence an attendant reduction in the number and size of these areas. Nickel-rich phases are not present in steel B, which is free of admixed nickel. Raising the tempering temperature from 180°C (356°F) to 220°C (428°F) lowers the amount of retained austenite, as shown by the microstructure of steel B, and modifies the structure of the martensite, which starts to lose its plate-like structure. For steel C with carbon concentrations of 0.57 and 0.47 w/o, after sintering at 1,120°C (2,048°F), the microstructure is composed of a mixture of lath and plate martensite with a significant amount of bainite. After sintering at 1,205°C

Figure 3. Microstructure of mixes A, B, and C as a function of sintering and tempering temperatures. Nital etch. OM

34

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 35

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

Figure 4. Microstructures of mixes A, B, and C as a function of sintering and tempering temperatures. Nital etch. OMs

(2,201°F), the microstructure is primarily lath martensite, due to the low concentration of carbon (0.47 w/o), and bainite. Some retained austenite can also be observed in both steels. Figure 5 shows the effect of processing conditions on transverse rupture, tensile, yield, and plane-bending strength obtained for the three mixes and the processing conditions. For a given mix and tempering temperature, a higher transverse rupture, tensile, and yield strength are always observed after sintering at 1,205°C (2,201°F) compared with sintering at 1,120°C (2,048°F). On average, the differences are 11%, 9%, and 5%, respectively. The highest values for TR strength (1,904 MPa), tensile strength (1,081 MPa), and yield strength (945 MPa), are achieved with mix C sintered at 1,205°C (2,201°F) and tempered at 180°C (356°F). Mix B sintered at 1,205°C (2,201°F) and tempered at 220°C (428°F) exhibits tensile properties slightly inferior to those of mix C. The lowest tensile properties are observed in mix A sintered at 1,120°C (2,048°F) and tempered at 180°C (356°F). In plane-bending fatigue, a different mode of behavior is observed. The highest fatigue strength is observed for mix A and mix B tempered at 180°C (356°F), with slightly higher values for sintering at 1,205°C (2,201°F) than for sintering at Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

1,120°C (2,048°F), 466 and 448 MPa for mix A, and 474 and 462 MPa for mix B, respectively. The lowest fatigue strength (381 MPa), was observed for mix C sintered at 1,205°C (2,201°F) and tempered at 180°C (356°F). The difference in behavior in static and dynamic loading can only be explained by a modification of the microstructure when the mix formulation, sintering temperature or tempering temperature are changed. To better understand the interactions between the different phases, the ratio of retained austenite:martensite (γR:M) was selected as the primary contributing factor affecting the static and dynamic properties. Figure 6 illustrates the relationship between the concentration of the various phases and this ratio. As expected, the amount of retained austenite increases linearly with this ratio but, for a given ratio, a higher concentration of retained austenite is measured in the mixes sintered at 1,205°C (2,201°F). This can be explained by the larger grain size in these mixes, which promotes hardenability and therefore results in a larger amount of martensite at the expense of bainite. The maximum concentration of martensite is found at a γR:M ratio ~0.15–0.20 for the mixes sintered at 1,205°C (2,201°F) and a ratio of ~0.25–0.30 for those sintered at 1,120°C (2,048°F). At these ratios, the concentration of

35

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 36

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

Figure 5. TR, tensile, yield, and plane-bending fatigue strength as a function of mix and processing conditions

Figure 6. Retained austenite, martensite, and bainite as a function of γR:M ratio for mix B

martensite is ~82% in the mixes sintered at 1,205°C (2,201°F) and 73% for those sintered at 1,120°C (2,048°F) due to a larger concentration of bainite in the latter mixes. Figure 7 illustrates the dependence of TR strength, tensile strength, yield strength, apparent hardness, and plane-bending fatigue strength on the retained γR:M ratio in the various mix formulations sintered at either 1,120°C (2,048°F) or 1,205°C (2,201°F). The data in Figure 7 show how the static and dynamic properties vary with the

36

microstructure, which is dictated by the γR:M ratio. TR, tensile, and yield strength decrease as the ratio increases, with a higher rate of decrease in the mixes sintered at the higher temperatures. It is noted that in relation to tensile properties, higher values are attained in the mixes sintered at the higher temperatures with a ratio ≤0.25. At a ratio >0.25, higher values are observed for the mixes sintered at 1,120°C (2,048°F). This is probably related to the higher level of martensite in the mixes sintered at 1,205°C (2,201°F) compared Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 37

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

Figure 7. Dependence of transverse rupture strength, tensile strength, yield strength, apparent hardness, and plane-bending fatigue strength on the γR:M ratio

with those sintered at 1,120°C (2,048°F) for a low γR:M ratio. Above a ratio of 0.25, the amount of retained austenite becomes excessive and, combined with the large grain size in the mixes sintered at 1,205°C (2,201°F), negatively affects the sintered properties. For apparent hardness and plane-bending fatigue, the effect of sintering temperature becomes almost negligible and both properties increase with the γR:M ratio, reaching a maximum at ~0.27, and then decrease. Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Figure 8 shows the fracture surfaces of the steels from mix B sintered at either 1,120°C (2,048°F) or 1,205°C (2,201°F) and tempered at 180°C (356°F). The fractographs are from the area where the fracture initiates and in the section at the end of the fracture. At 1,120°C (2,048°F), in the area of fracture initiation, the crack grows primarily through the particles, with some areas of interparticle neck fractures. In the area at the end of the fracture, the crack propagates mainly

37

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 38

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

through particle necks (i.e., within the porosity) with a dimpled rupture fracture surface morphology characteristic of a tensile overload. When mix B is sintered at 1,205°C (2,201°F), the fracture mechanism differs significantly from that reported after sintering at 1,120°C (2,048°F). The crack appears to progress through the interparticle necks with some areas of propagation through the particles. At the end of the fracture, the crack propagates mainly through the interparticle necks with a dimpled rupture characteristic of a tensile overload. Figure 9 shows the fracture surfaces of specimens from mix B sintered at either 1,120°C (2,048°F) or 1,205°C (2,201°F) and tempered at 220°C (428°F) at a location in which fracture initiates, and in the section at the end of the fracture. After sintering at 1,120°C (2,048°F), in the area of fracture initiation, the crack grows essentially

through the particles. In the area at the end of the fracture, the dimpled rupture morphology is characteristic of a tensile overload. After sintering at 1,205°C (2,201°F), different fracture characteristics can be observed. There is evidence of crack propagation through the particles, as in the specimens sintered at 1,120°C (2,048°F). In addition, the crack is also observed to propagate through interparticle necks in the presence of fragile intergranular fractures. This could have been caused by the precipitation of carbides at the grain boundaries during tempering at this higher temperature. The morphology at the end of the fracture is typical of a tensile overload. Figure 10 shows representative fracture surfaces of specimens from mixes A and C sintered at 1,120°C (2,048°F) and tempered at 180°C (356°F), in the area in which fracture initiates and in the section at the end of fracture. In the area of fracture ini-

Figure 8. Fracture surfaces of mix B sintered at either 1,120°C (2,048°F) or 1,205°C (2,201°F) and tempered at 180°C (356°F). SEM/SEI

38

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 39

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

tiation, a mix of fracture modes is observed for mix A. The crack appears to grow preferentially through the particles with areas of interparticle neck fractures, but also with some areas showing quasicleavage. For mix C, the crack propagates primarily through the particles with some areas of interparticle neck fractures and a limited amount of quasicleavage. In the other specimens, the end of the fracture surface was typical of a tensile overload. From these results and attendant observations, it is evident that retained austenite is detrimental to static properties but beneficial, up to a certain level, to fatigue strength. To achieve the maximum tensile properties, retained austenite must be minimized at the expense of martensite. In relation to fatigue strength, a certain quantity of retained austenite is required to optimize this property. Sanderow and McPherson22 reported that the optimal concentration of retained austenite in high-

performance case-carburized gears was in the range of 15% to 30%. Two mechanisms are proposed to explain the beneficial effect of retained austenite on fatigue performance. Firstly, during cyclic loading, some retained austenite is transformed to martensite, thus increasing fracture resistance. Secondly, when a crack encounters a region of soft retained austenite, it is diverted and branched or blunted.23 Such mechanisms are also suggested by Unami et al.24 in quenched and tempered 4 w/o Ni-1.5 w/o Cu-0.5 w/o Mo diffusion alloys with 0.6 or 1.0 w/o graphite. These authors also reported improved tensile properties at a low carbon content and enhanced fatigue performance at a high carbon concentration and a retained austenite concentration ~20%. In another study on Fe-4 w/o Ni-1.5 w/o Cu-0.5 w/o Mo diffusion bonded steels, Tremblay and Chagnon25 reported higher tensile properties at 0.5 w/o C than at 1.0

Figure 9. Fracture surfaces of mix B sintered at either 1,120°C (2,048°F) or 1,205°C (2,201°F) and tempered at 220°C (428°F). SEM/SEI

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

39

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 40

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

Figure 10. Fracture surfaces of mixes A and C sintered at 1,120°C (2,048°F) and tempered at 180°C (356°F). SEM/SEI

w/o C. However, for fatigue resistance, the maximum value was reached at ~0.75 w/o C. In contrast, a sub-zero cryogenic treatment to transform the retained austenite resulted in improved fatigue performance at 0.75 w/o C and a lower value at 1 w/o C. It was assumed that when the carbon concentration was raised from 0.5 to 0.75 w/o the improvement in fatigue strength was caused by the formation of a larger quantity of plate martensite in place of lath martensite, since retained austenite is beneficial to fatigue strength only in the presence of plate martensite. In the present study, maximum tensile properties were achieved at a γR:M ratio <0.15, i.e., in a steel devoid of bainite/pearlite, and ≥87% martensite. If, for a similar ratio, some bainite and/or pearlite is present, the tensile properties would be lowered due to the reduction in the martensite level. However, additional work will be required to

40

determine if the tensile strength remains stable or decreases below a γR:M ratio of 0.15. It is also noted that the maximum tensile properties were attained in the mix with 0.47 w/o C sintered at 1,205°C (2,201°F) and tempered at 180°C (356°F). The microstructure consisted of 81% primarily lath martensite, 8% bainite and 11% retained austenite. Plane-bending fatigue strength reaches a maximum (474 MPa) at a γR:M ratio of 0.25, i.e., for a steel devoid of bainite–pearlite, 80% martensite, and 20% retained austenite. This value is in agreement with published data for wrought steels22 and is also reached at the highest apparent hardness value. It is also noted that a microstructure composed primarily of low carbon lath martensite, results in the lowest fatigue performance. This is in agreement with other studies,24,25 which showed that the highest fatigue strength is Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 41

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

reached with high carbon plate martensite containing retained austenite. CONCLUSIONS 1. Mix formulation, and sintering and tempering temperatures significantly affect the static and dynamic properties of sinter-hardened PM steels in different ways, leading to compromises, depending on which property to optimize. 2. The highest tensile properties are reached at a γR:M ratio <0.15. Moreover, optimal values are achieved under processing conditions that maximize the amount of martensite and minimize both pearlite and bainite content. 3. The highest plane-bending fatigue strength is reached at a γR:M ratio of 0.25. For a PM steel devoid of bainite and pearlite, this reflects a structure with 80% martensite and 20% retained austenite. 4. For enhanced fatigue performance, a microstructure consisting of high carbon plate martensite is preferable to one of low carbon lath martensite. 5. For optimal processing conditions that maximize fatigue strength (0.72 w/o C tempered at 180°C (356°F) resulting in 20% retained austenite and 80% martensite, the fatigue crack grows primarily through interparticle necks rather than through particles. Tempering at 220°C (428°F) is detrimental to fatigue strength due to a change in the crackgrowth path from interparticle necks to intergranular, and through particles. REFERENCES 1. F. Chagnon and M. Gagné, “Effect Of Graphite And Copper Concentrations And Post Sintering Cooling Rate On Properties Of Sinter Hardened Materials”, Advances in Powder Metallurgy & Particulate Materials—2000, compiled by H. Ferguson and D.T. Whychell, Sr., Metal Powder Industries Federation, Princeton, NJ, 2000, part 13, pp. 35–45. 2. F. Chagnon and Y. Trudel, “Effect of Copper Additions On Properties of 1.5% Mo Sintered Steels”, Advances in Powder Metallurgy & Particulate Materials—2002, compiled by V. Arnhold, C-L Chu, W.F. Jandeska, Jr. and H.I. Sanderow, Metal Powder Industries Federation, Princeton, NJ, 2002, part 13, pp. 73–82. 3. F. Chagnon, G. Olschewski and S. St-Laurent, “Effects of Product and Process Parameters on Dimensional Stability of Sinter Hardened Materials”, European Powder Metallurgy Association, Shrewsbury, UK, 2001, vol. 4, pp. 230–235. 4. H. Suzuki, M. Satoh, M. Yoshida and Y. Seki, “Sinter

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

5.

6.

7.

8.

9. 10.

11.

12.

13. 14.

15.

16.

17.

Hardening Properties of Pre-Alloyed Powder, 46F3H”, Advances in Powder Metallurgy & Particulate Materials— 2000, compiled by H. Ferguson and D.T. Whychell, Sr., Metal Powder Industries Federation, Princeton, NJ, 2000, part 5, pp. 125–136. H. Suzuki, M. Sato and Y. Seki, “Sinter Hardening Characteristics of Ni-Mo-Mn-Cr Pre-Alloyed Steel Powder”, Advances in Powder Metallurgy & Particulate Materials— 2002, compiled by V. Arnhold, C-L Chu, W.F. Jandeska, Jr. and H.I. Sanderow, Metal Powder Industries Federation, Princeton, NJ, 2002, part 13, pp. 83–95. F. Chagnon and G. Olschewski, “Low Alloy Steel Powders For Sinter Hardening Applications”, Proc. Powder Metallurgy World Congress, edited by K. Kosuge and H. Nagai, Japan Society of Powder and Powder Metallurgy, Kyoto, Japan, 2000, vol. 2, pp. 927–930. F. Chagnon and M. Gagné, “Effect Of Tempering Temperature on Mechanical Properties and Microstructure of Sinter Hardened Materials”, Advances in Powder Metallurgy & Particulate Materials—1999, compiled by C.L. Rose and M.H. Thibodeau, Metal Powder Industries Federation, Princeton, NJ, 1999, vol. 2, part 7, pp. 205–216. M.C. Baran, A.H. Graham, A.B. Davala, R.J. Causton and C. Shade, “A Superior Sinter-Hardenable Material”, ibid., pp. 185–203. S.H. Avner, Introduction to Physical Metallurgy, McGrawHill Book Company, NY, 1974, pp. 305–313. C. Lindberg, “Mechanical Properties of a Water Atomized Fe-Cr-Mo Powder and How to Sinter It”, Advances in Powder Metallurgy & Particulate Materials—1999, compiled by C.L. Rose and M.H. Thibodeau, Metal Powder Industries Federation, Princeton, NJ, 1999, vol. 2, part 7, pp. 229–243. F. Chagnon and Y. Trudel, “Effect of Sintering Parameters on Mechanical Properties of Sinter Hardened Materials”, Advances in Powder Metallurgy & Particulate Materials— 1997, compiled by R.A. McKotch and R. Webb, Metal Powder Industries Federation, Princeton, NJ, 1997, vol. 2, part 14, pp. 97–106. D. Herring, “Grain Size and Its Influence on Materials Properties”, Industrial Heating, 2005, vol. 72, no. 8, pp. 20–22. W.F. Smith, Structure and Properties of Engineering Alloys, McGraw-Hill, New-York, 1981, pp. 122–124. S. Saritaş, W.B. James and A. Lawley, “Fatigue Properties of Sintered Steels: a Critical review”, Euro PM2001 Conference Proceedings, European Powder Metallurgy Association, Shrewsbury, UK, 2001, vol. 1, pp. 272–285. M. Dalgic, S. Lindlohr and P. Beiss, “Bending Fatigue Strength of Distaloy AE”, Euro PM2001 Conference Proceedings, European Powder Metallurgy Association, Shrewsbury, UK, 2001, vol. 2, pp. 292–297. S. Saritaş, R. Causton, W.B. James and A. Lawley, “Effect of Microstructure on Rotating Bending Fatigue Response of a Prealloyed and Two Hybrid P/M Steels”, Advances in Powder Metallurgy & Particulate Materials—2004, compiled by R.A. Chernenkoff and W.B. James, Metal Powder Industries Federation, Princeton, NJ, 2004, vol. 3, part 10, pp. 53–66. U. Engström, K. Lipp and C.M. Sonsino, “Influence of Notches on Fatigue Strength of High Performance PM

41

Chagnon_Zheng et al 1/18/2010 11:48 AM Page 42

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF SINTERING TEMPERATURE ON STATIC AND DYNAMIC PROPERTIES OF SINTER-HARDENED PM STEELS

18.

19.

20.

21.

22.

23. 24.

25.

42

Materials”, Advances in Powder Metallurgy & Particulate Materials—2001, compiled by W.B. Eisen and S. Kassam, Metal Powder Industries Federation, Princeton, NJ, 2001, part 10, pp. 1–9. U. Engström and O. Bergman, “Fatigue Strength of High Performance PM Materials”, Proceedings of the 2003 International Conference on Automotive Fatigue Design & Applications, compiled by R.A. Chernenkoff and W.F. Jandeska, Metal Powder Industries Federation, Princeton, NJ, 2003, pp. 40–48. L.S. Sigl, P. Delarbre, K. Lipp and C.M. Sonsino, “Static and Fatigue Properties of High Strength PM-Steels”, Euro PM2005 Conference Proceedings, European Powder Metallurgy Association, Shrewsbury, UK, 2005, vol. 1, pp. 151–156. M.L. Marucci, K.S. Narasimhan, G. Fillari, N. Chawla and V.V. Ganesh, “Axial Fatigue Properties of Silicon Containing P/M Steels”, Proceedings of the 2003 International Conference on Automotive Fatigue Design & Applications, compiled by R.A. Chernenkoff and W.F. Jandeska, Metal Powder Industries Federation, Princeton, NJ, 2003, pp. 68–76. G. Vachon, R. Angers, T. Vo Van and T. Baazi, “Effect of Processing on the Fatigue Properties of a SinterHardenable PM Steel”, Advances in Powder Metallurgy & Particulate Materials—2006, compiled by W.R. Gasbarre and J.W. von Arx, Metal Powder Industries Federation, Princeton, NJ, 2006, vol. 2, part 10, pp. 65–80. H. Sanderow and D. McPherson, “Role of Heat Treatment on the Fatigue Response of P/M Steels Used in Gear Applications”, Proceedings of the 2003 International Conference on Automotive Fatigue Design & Applications, compiled by R.A. Chernenkoff and W.F. Jandeska, Metal Powder Industries Federation, Princeton, NJ, 2003, pp. 110–126. A. Kumar Sinha, Ferrous Physical Metallurgy, Butterworth Publishers, Boston, MA, 1989, pp 324–325. S. Unami, Y. Ozaki and S. Uenosono, “Effect of Retained Austenite Amounts on the Fatigue Strength of Sintered and Bright-Quenched Steel Compacts with Density of 7.5 g/cm³”, Advances in Powder Metallurgy & Particulate Materials—2003, compiled by R. Lawcock and M. Wright, Metal Powder Industries Federation, Princeton, NJ, 2003, part 7, pp. 288–298. L. Tremblay and F. Chagnon, “Effect of Sintering Temperature and Carbon Content on Static and Dynamic Properties of Diffusion-Bonded Steels”, Advances in Powder Metallurgy & Particulate Materials—2000, compiled by H. Ferguson and D.T. Whychell, Sr., Metal Powder Industries Federation, Princeton, NJ, 2000, part 5, pp. 109–123. ijpm

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 43

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OUTSTANDING TECHNICAL PAPER

INFLUENCE OF CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS Peter K. Sokolowski* and Bruce A. Lindsley**

INTRODUCTION The benefits of sinter-hardening technology to achieve processing efficiency and promote cost-cutting methods are well understood in the PM industry.1 This technology has been supported over the years through advancements in alloy design and improved cooling equipment. With the application of convective cooling systems in modern sintering furnaces, accelerated cooling rates have allowed the use of a broad range of PM alloys for sinter-hardening parts. Traditional sinterhardening alloys are capable of achieving a high level of martensitic transformation under most sintering conditions but, because of their high alloy content, leaner alloy systems have been developed to provide a similar metallurgical response. These leaner alloyed systems, however, require rapid cooling conditions to attain similar microstructural transformations and hence comparable mechanical properties. In order to aid PM parts producers in the selection of suitable alloys for potential sinter-hardening applications with current sintering furnaces, an in-depth study has been undertaken to evaluate hardenability in a range of ferrous PM alloys available to the market. Hardenability is generally accepted as a qualitative measure describing the ease and depth to which an alloy is able to transform to martensite upon cooling from the austenitizing temperature. The hardenability of iron alloys has been exhaustively studied over the years, with the majority of the work performed on wrought alloys.2,3 This body of literature evolved through the inception of innovative test methods, namely, the Grossman and Jominy end-quench tests, to determine the degree to which a material will harden. These proven tests can provide a sound baseline indicator of what to expect from a

The hardenability of powder metallurgy (PM) steels is an important measure of how well alloy systems can be used for sinter hardening. Several options are now available for sinter-hardening applications as new alloys have been developed over the last few years. Alloy composition has been optimized to take advantage of rapid cooling in sinterhardening furnaces while addressing the cost of the alloying elements. One of the most widely used methods for determining hardenability is the Jominy end-quench test in which bar samples are heated into the austenite range and water quenched on one end of the bar, producing a wide range in cooling rate within one sample. The hardenability of different alloy systems was examined utilizing the Jominy test coupled with sintering studies. Austenitizing temperature has an important effect on the measured hardenability of high-molybdenum-containing steels and selection of this process variable for these alloy grades has a profound effect on the predicted hardenability of different alloy systems. Thus, it is recommended that hardenability data in MPIF Standard 35 be re-evaluated at suitable austenitizing temperatures for alloys containing high levels of molybdenum and carbon. The award for this technical paper will be presented at PowderMet2010 in Hollywood, Florida

*Development Engineer, **Manager of Product Development, Hoeganaes Corporation, 1001 Taylors Lane, Cinnaminson, NJ 08077; E-mail: [email protected] Presented at PowderMet2009 and published in Advances in Powder Metallurgy & Particulate Materials—2009, Proceedings of the 2009 Conference on Powder Metallurgy & Particulate Materials, which are available from the Publications Department of MPIF (www.mpif.org).

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

43

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 44

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

given PM alloy in a sinter-hardening route or through standard heat-treat practices. In PM alloys, hardenability depth is reported as the point at which the apparent hardness value drops below 65 HRA; this is referred to as the J Depth,4 and is given in units of 1/16 in. It is well known that the measured apparent hardness of a PM compact is influenced by porosity. Based on apparent hardness, it has been shown that PM materials will exhibit enhanced hardenability at increased sintered densities.5,6 This is also apparent in the J Depth values cited in MPIF Standard 35, where values are stated in relation to sintered density. The caveat to reaching high densities lies in the fact that significant levels of alloying are generally needed to achieve appreciable hardenability and to increase mechanical properties in conventional PM materials. This typically leads to a reduction in compressibility and hence a limitation on sintered density. One approach to circumvent this effect has been through alloying with molybdenum, which has a negligible influence on compressibility. Molybdenum is an attractive alloying element for many reasons. Its introduction in ferrous alloys, even in small amounts, leads to enhanced mechanical properties and markedly improves hardenability.7,8 Additionally, the ease of processing with molybdenum has lead to its industrywide usage as an alloying element to provide high-performance PM materials. While sintered density is a contributing factor in PM hardenability, the primary metallurgical variables that influence alloy hardenability are prior austenite grain size, composition, and chemical homogeneity. Hardenability will increase as the austenite grain size increases due to a reduced total grain-boundary area. Grain boundaries serve as nucleation sites for ferrite and pearlite and, as such, ultimately reduce the effective volume capable of transforming to martensite. 9 Furthermore, the amount and type of elemental alloying can significantly suppress the austenite-to-ferrite and -pearlite transformations. The critical cooling rate, as determined from a continuous-cooling transformation (CCT) diagram, can be modified as the nose of the CCT curve moves to the right as a result of this alloying behavior. Increased alloying permits a slower cooling rate to provide a martensitic transformation in the material. Certain alloying elements, in

44

particular chromium, manganese, molybdenum, and nickel, influence the location of the CCT curves and are thus favorable alloying elements in steels. In alloys that contain both molybdenum and nickel, a synergistic effect is seen between the two elements, increasing their effect on hardenability when the level of nickel is >0.75 w/o. The method of alloying in PM materials significantly influences the hardenability and, perhaps more important, the performance characteristics of the material.1 Whether through admixing, diffusion alloying, prealloying, or a combination thereof, the chemical homogeneity is modified as a result of the alloying method. Ideally, a completely homogeneous microstructure would result in the theoretical or calculated hardenability, based on alloy constituents and levels. Generally speaking, a prealloyed material will exhibit a homogeneous microstructure, depending on cooling rate, which demonstrates the effect of alloying elements in solid solution in austenite. If the austenitizing temperature is below the austenite (γ) singlephase field, some alloying elements will remain in the form of carbides in high-carbon alloys, effectively reducing the alloy content in the matrix. In view of this effect, this paper discusses the hardenability of commercially available ferrous PM alloys and the influence that austenitizing temperature has on the measured J Depth values. PROCEDURE Several commercially available prealloyed steel powders, known to exhibit higher hardenability than admixed copper or nickel steels, were selected for this study, Table I. The powders were produced by water atomization with the alloying elements prealloyed in the melt prior to atomization. Each premix was prepared with 0.75 w/o EBS wax (Acrawax® C) as the lubricant and varying amounts of Asbury type 3203H graphite. Admixed copper was used to produce alloys with 1 w/o Cu and 2 w/o Cu. Large compacts of each mix were pressed to a green density of 7.0 g/cm3, courtesy Powder-Tech Associates. Blanks cut from each compact were pre-sintered at 870°C (1,600°F) to provide sufficient strength for initial machining into oversized cylindrical test bars. The bars were then sintered in a 90/10 (v/o) nitrogen/hydrogen atmosphere at 1,120°C (2,050°F) for 15 min at temperature in a continuous-belt furnace. Depending on the level

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 45

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

TABLE I. NOMINAL COMPOSITION OF BASE PREALLOYS (w/o) Base Iron Ancorsteel® 2000 Ancorsteel 4600V Ancorsteel 721 SH Ancorsteel 737 SH Ancorsteel 150 HP

MPIF Designation

Mo

Ni

Mn

Fe

FL-4200 FL-4600 – FL-4800 FL-4900

0.6 0.55 0.9 1.25 1.5

0.5 1.8 0.5 1.4 –

0.25 0.15 0.4 0.4 0.1

Bal. Bal. Bal. Bal. Bal.

® Ancorsteel is a registered trademark of Hoeganaes Corporation of carbon and copper, sintered density was in the range of 6.9 to 7.0 g/cm3. Finally, the sintered bars were sized to the specified 100 mm (4 in.) length × 25 mm (1 in.) dia., to account for any difference in dimensional change as a result of the sintering process. Hardenability was evaluated by means of the Jominy end-quench method following ASTM Standard A 255 and MPIF Standard 65. 10,11 Samples were austenitized at 900°C (1,650°F) for 30 min at temperature in a 90/10 (v/o) nitrogen/hydrogen atmosphere prior to water end-quenching. In addition, bars of select compositions were evaluated at 845°C (1,550°F) and 955°C (1,750°F) in order to assess hardenability as a function of the austenitizing temperature. Metallographic samples, encompassing the length of each Jominy bar, were prepared by grinding and polishing using standard practices and were etched with 2 v/o nital/4 w/o picral for examination by optical microscopy. Phase analysis was performed using a point-count method at locations coinciding with those of the thermocouples to link the microstructures with the measured cooling rates. An instrumented Jominy method5 was used to determine cooling rates along the length of the Jominy bar. Type-K thermocouples were inserted to a radial depth of approximately 3 mm (0.125 in.) from the surface at distances of 10 mm (6/16 in.), 25 mm (15/16 in.), 45 mm (28/16 in.), and 85 mm (54/16 in.) from the water-quenched end to measure the cooling rates. The average cooling rates reported were measured in the sample between 650°C (1,200°F) and 315°C (600°F). In order to determine the effect of grain size on hardenability as a result of increased austenitizing temperature, grain-size measurements were conducted following ASTM E 112.12 The Abrams Three-Circle intercept method was applied to ten fields of analysis to ensure a statistically viable

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

result. The test was conducted near the quenched end to utilize a fully martensitic microstructure to facilitate the location of the prior austenite grain boundaries. RESULTS Influence of Chemical Composition It is well known that as the alloy content in iron–carbon systems increases (carbon, chromium, copper, manganese, molybdenum, nickel, and silicon), hardenability increases. This behavior is a direct result of the type and amount of interstitial or substitutional alloying within the system. These alloying effects have been studied extensively and are documented in the metallurgical literature.13,14,15,16 Figure 1 displays Jominy curves for a selection of PM alloys providing a range in hardenability, all with additions of 1 w/o Cu-0.7 w/o graphite. The curves for grades FL4200 and FL-4600 drop off in hardness relatively rapidly with J Depths of 6 and 12, respectively. In comparison, the superior sinter-hardening base alloys Ancorsteel 721 SH and FL-4800 have J Depths of 23 and >56, respectively. Interestingly, Ancorsteel 721 SH has nearly 1.3 w/o less nickel than FL-4600, significantly impacting compressibility and potentially alloy cost. Moreover, Ancorsteel 721 SH contains increased levels of molybdenum and manganese compared with FL-4600, but the overall alloy content is reduced, revealing the powerful influence

Figure 1. Hardenability of PM alloys with 1 w/o Cu-0.7 w/o graphite addition austenitized at 900°C (1,650°F)

45

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 46

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

of these two elements, even with small increases. The benefit behind this alloying approach is realized as an improvement in compressibility, a potential reduction in alloy cost (due to appreciably less nickel), and at the same time providing a significant boost in hardenability. If alloying cost is of the least concern, and parts with large cross sections are needed to be sinter hardened, then the heavily alloyed FL-4800 with 1.25 w/o Mo, 1.4 w/o Ni, and 0.4 w/o Mn is a desirable choice. This alloy is capable of through-hardening along the entire length of the Jominy bar, with the implication that this is a reliable alloy under most sintering conditions. There is a substantial improvement in the hardenability of the alloys with the addition of 2 w/o Cu-0.9 w/o graphite, Figure 2. The trend in the contrast in hardenability remains the same for the alloys studied; FL-4600 and Ancorsteel 721 SH are completely through-hardened at these levels of copper and graphite, in addition to FL4800. It is curious, however, that FL-4800 has a lower apparent hardness than Ancorsteel 721 SH at distances far from the water-quenched end. This observation is not fully understood, but is believed to be a result of the influence of retained austenite. While the retained austenite (RA) content has not been examined metallographically in these samples, it has been reported elsewhere17,18 that the heavily alloyed FL-4800 commonly includes considerable levels of RA beyond that of

Figure 2. Hardenability of PM alloys with 2 w/o Cu-0.9 w/o graphite addition austenitized at 900°C (1,650°F)

46

Ancorsteel 721 SH. This thermodynamically unstable phase has a lower hardness than martensite and can potentially lead to adverse effects if allowed to transform. Jominy plots for the base alloys with only graphite additions are not graphically represented, as the J Depth is generally low except for the sinter-hardening alloys Ancorsteel 721 SH and FL-4800. A comprehensive J Depth listing of the alloys evaluated in this study is presented in Table II which serves as a guide in the selection of alloys for sinter-hardening applications. The progression in hardenability of the alloys is clear as the levels of admixed graphite and copper increase. Subsequently, it will be shown, however, that in some cases these results are still underreported as an increased austenitizing temperature can significantly impact the level of hardenability. Influence of Austenitizing Temperature From previous Jominy tests it was recognized that multiple alloys appeared to show significant differences in hardenability when compared with values reported in MPIF Standard 35. One of the differences identified between the current study and the MPIF Standard 35 results was the austenitizing temperature. To understand the effect of this important process parameter7 additional bars of the alloys were austenitized at TABLE II. JOMINY END-QUENCH TESTS RESULTS FOR ALLOYS AUSTENITIZED AT 900°C (1,650°F) Alloy

Graphite (w/o)

Copper (w/o)

J Depth (1/16 in.)

FL-4200

0.6 0.7 0.9

1 2

3 6 21

FL-4600

0.6 0.7 0.9

1 2

5 12 >56

Ancorsteel 721 SH

0.6 0.8 0.7 0.9

1 2

10 18 23 >56

FL-4800

0.8 0.7 0.9

1 2

32 >56 >56

FL-4900

0.6 0.6 0.9

2 2

8 8 14

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 47

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

845°C (1,550°F) and 955°C (1,750°F) and tested to evaluate the influence of austenitizing temperature on hardenability. These temperatures were the same as those used to produce the hardenability data in the MPIF standard. FL-4200 shows no difference in hardenability over this range in temperatures with 1 w/o Cu-0.7 w/o graphite, Figure 3. However, as the level of copper and graphite is increased there is a small measurable improvement with increasing austenitizing temperature. FL-4600, which is noticeably more hardenable than FL-4200,

exhibits a similar response, Figure 4. For the higher copper and graphite addition, the 845°C (1,550°F) austenitizing temperature is insufficient to through-harden the bar. The increase in austenitizing temperature appears to have little effect on these two alloy grades at the lower copper and graphite levels, leading to the conclusion that 845°C (1,550°F) is sufficient to fully austenitize these alloy combinations. In contrast, Figures 5 and 6 reveal that an austenitizing temperature of 845°C (1,550°C) results in significantly lower hardenability in

Figure 3. Effect of austenitizing temperature on the hardenability of FL-4200

Figure 5. Effect of austenitizing temperature on the hardenability of Ancorsteel 721 SH

Figure 4. Effect of austenitizing temperature on the hardenability of FL-4600

Figure 6. Effect of austenitizing temperature on the hardenability of FL-4800

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

47

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 48

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

Ancorsteel 721 SH and FL-4800 with 2 w/o Cu0.9 w/o graphite, compared with 900°C (1,650°F) and 955°C (1,750°F). Given that the alloy did not change (the carbon contents were measured and found to be similar), several possible explanations were considered: austenite grain-size effects, different cooling rates and incomplete austenization due to insufficient time at temperature, or a change in the temperature of the austenite phase field. These possibilities will be elaborated on in the discussion. To better understand the influence of austenitizing temperature on certain alloy systems, particularly alloys with a high-molybdenum– high-carbon content, FL-4800 (1.2 w/o Mo) with 0.8 w/o graphite was investigated. Figure 7 demonstrates the impact of austenitizing temperature on hardenability; the J Depth improves from 11 at 845°C (1,550°F) to 32 at 900°C (1,650°F) and finally to completely through-hardening at 955°C (1,750°F). This result clearly highlights the effect of austenitizing temperature in highly alloyed systems. Metallographic examination along the length of the bars, for which the hardness data are plotted in Figure 7, delineated the corresponding microstructure at four locations, Figure 8. As all the bars have an initial apparent hardness of 74–75 HRA near the quenched end, it is understood that at 10 mm they are fully martensitic. Within 25 mm, however, the microstructure of the

bar austenitized at 845°C (1,550°F) changes to a fine bainitic structure and this is reflected in the associated Jominy curve. At larger distances from the quenched end, where the cooling rate is lower, the microstructure is composed primarily of coarse ferrite/carbide (divorced pearlite/upper bainite) corresponding to an apparent hardness ~50 HRA. In the bar heated to 900°C (1,650°F), the onset of a bainitic/pearlitic transformation is pushed to larger distances from the water-quenched end. This is indicative of the lower cooling rates leading to hardening of the alloy to at least 50 mm (32/16 in.) when the bar is heated to 900°C (1,650°F). Alternatively, when the bar is austenitized at 955°C (1,750°F), the resulting microstructure is predominantly martensitic along the entire length of the bar. The onset of the bainitic transformation is seen in the micrograph at 85 mm from the quenched end and coincides with the small drop in apparent hardness in Figure 7 for the bar austenitized at 955°C (1,750°F). The phase-point count analysis based on the microstructures in Figure 8 is given in Table III and provides a quantitative analysis of the phase content as a result of increasing the austenitizing temperature in FL4800 with 0.8 w/o graphite. To determine if this effect is seen in other highmolybdenum-containing alloys, FL-4900 with 1.5 w/o Mo was tested under the same conditions. In TABLE III. EFFECT OF AUSTENITIZING TEMPERATURE ON METALLICPHASE CONTENT (EXCLUDING PORES) IN FL-4800 WITH 0.8 w/o GRAPHITE Distance from Quenched End mm (in.)

Martensite (w/o)

Bainite* (w/o)

Pearlite** (w/o)

845°C (1,550°F)

10 (6/16) 25 (15/16) 45 (28/16) 85 (54/16)

100 55.2 – –

– 44 – –

– 0.8 99.7 99.8

900°C (1,650°F)

10 (6/16) 25 (15/16) 45 (28/16) 85 (54/16)

100 97.9 77.8 0.3

– 1.8 21.5 –

– 0.3 0.7 99.7

955°C (1,750°F)

10 (6/16) 25 (15/16) 45 (28/16) 85 (54/16)

100 99.5 96.5 76

– 0.5 2.7 23

– – 0.8 1

Austenitizing Temperature

Figure 7. Effect of austenitizing temperature on the hardenability of FL-4800 with 0.8 w/o graphite addition

48

*Includes fine bainite and lower bainite **Includes coarse ferrite-carbide (divorced pearlite)

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 49

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

Figure 8. Microstructures of Jominy bars of FL-4800 with 0.8 w/o graphite at distances of 10 mm (6/16 in.), 25 mm (15/16 in.), 45 mm (28/16 in.), and 85 mm (54/16 in.) from water-quenched end, austenitized at 845°C (1,550°F), 900°C (1,650°F), and 955°C (1,750°F); etched with 2 v/o nital/4 w/o picral. Optical micrographs

Figure 9, FL-4900 with 2 w/o Cu-0.6 w/o graphite appears to exhibit a small improvement in the J Depth, extending from 6 at 845°C (1,550°F) to 8 at 900°C (1,650°F). At 955°C (1,750°F), however, there is significant enhancement in hardenability as the J Depth increases to 20. A similar trend is

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

seen in FL-4900 with 2 w/o Cu-0.9 w/o graphite, Figure 10. The upward shift in the curves to higher apparent hardness values, in comparison with Figure 9, is attributed primarily to the increase in carbon content. The J Depth in this alloy shows a substantial improvement from 8 at 845°C

49

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 50

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

Figure 9. Effect of austenitizing temperature on the hardenability of FL-4900 with 2 w/o Cu-0.6 w/o graphite

Figure 10. Effect of austenitizing temperature on the hardenability of FL-4900 with 2% Cu-0.9 w/o graphite

(1,550°F) to 14 at 900°C (1,650°F) and finally to 30 at 955°C (1,750°F). This increase in hardenability indicates that the lower austenitizing temperatures are insufficient to fully austenitize these alloys. It is unknown at present if further increases in austenitizing temperature beyond 955°C (1,750°F) are necessary in this alloy system to accurately simulate what occurs during cooling from the sintering temperature. Since increased austenitizing temperatures

50

Figure 11. Effect of austenitizing temperature on the hardenability of FLNC-4408

improve the hardenability of prealloyed systems with high levels of molybdenum and carbon, a hybrid sinter-hardening alloy FLNC-4408 was also subjected to the three different austenitizing temperatures. As seen in Figure 11, the hybrid system with a nominal composition 0.85 w/o Mo-2 w/o Ni-1.5 w/o Cu-0.9 w/o graphite illustrates a similar response to increased austenitizing temperatures. The J Depth increases from 10 at 845°C (1,550°F) to 23 at 900°C (1,650°F) and reaches 34 at 955°C (1,750°F). Also, the shape of the curves demonstrates the nature of hybrid alloy systems wherein the microstructure is generally inhomogeneous. The hybrid alloying method leads to the formation of highly alloyed martensitic regions with high hardness adjacent to low-alloy regions with low hardness. This characteristic composite microstructure of hybrid alloy systems results in the retention of a certain level of apparent hardness (>60 HRA), along essentially the entire length of the bar for nearly all austenitizing temperatures. This type of response is not evident in the prealloyed systems previously discussed. DISCUSSION The objective in this study was to provide PM parts producers with up-to-date information on the hardenability of several commercially available ferrous alloys capable of sinter hardening. In doing so, it was realized that the measured J Depth values were not the same for comparable alloys as

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 51

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

those reported in MPIF Standard 35. Through additional testing it was found that the measured hardenability was significantly influenced by the austenitizing temperature for alloy systems containing high levels of molybdenum (>0.5 w/o) in combination with admixed graphite. Several possible explanations for the increased hardenability values of these systems were considered. The first possibility is that a change in the sintered carbon level with austenitizing temperature was responsible for the variation in hardenability. Sintered carbon measurements were made on the Jominy bars and the values were typically within 0.04 w/o for the three austenitizing temperatures in each alloy system, with the lowest values measured for 955°C (1,750°F). Given that the sintered carbon was not responsible for the change in hardenability, other possibilities were explored: prior austenite grain size, differences in cooling rates, and incomplete austenization due to insufficient time at temperature or a change in the temperature of the austenite phase field. Also, the initial microstructure could potentially influence these results as the Jominy test was performed on as-sintered bars without a normalizing treatment prior to austenitizing. We now address these possibilities and suggest changes in the methodology pertaining to hardenability data cited in MPIF Standard 35. In the present study, prior austenite grain size was not expected to influence hardenability to any great extent over the austenitizing temperature range evaluated, particularly since pores are known to pin grain boundaries, preventing excessive grain growth. However, due to potential grain-boundary pinning effects as a result of undissolved carbides (at an austenitizing temperature of 845°C (1,550°F) and not at 955°C (1,750°F)) and differences in grain-growth rate as a function of temperature, a grain-size difference was observed. To reveal prior austenite grain boundaries, samples were austenitized at 845°C (1,550°F) and 955°C (1,750°F) then slow cooled to 745°C (1,375°F) to form proeutectoid carbide at the grain boundaries and finally quenched to transform the austenite to martensite. This procedure resulted in a clear delineation of the grain boundaries. The grain size, as measured using ASTM E 112, of the bars austenitized at 845°C (1,550°F) is estimated to be ~8 µm, whereas the grain size at 955°C (1,750°F) is estimated to be

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

~19 µm. Approximations of the ideal diameter, based on grain-size factors and composition, show an increase in hardenability ~10%. However, the change in grain size as a result of the different austenitizing temperatures is not sufficient to account for the widely different behavior seen in Figure 7. Also, if grain size was an overwhelming factor in these hardenability results, then the effect should have been similar for all the compositions, not just for the highmolybdenum-containing alloys. Therefore, the grain-size variations observed are expected to play only a minor role in the measured hardenability of the alloy systems evaluated. As a critical factor in determining which transformation products are formed during cooling, the cooling rate was measured at multiple locations along the length of the Jominy bar utilizing an instrumented method. The bar was austenitized under the same conditions as previously described for the typical Jominy tests. The test was conducted at 845°C (1,550°F), 900°C (1,650°F), and 955°C (1,750°F), to resolve if increased temperatures result in a difference in cooling rates. If the rates are noticeably higher at the elevated austenitizing temperatures, this could lead to an increase in the measured hardenability for certain alloy systems. It should be noted, however, that the cooling rate measured is an average rate and applicable only to the Jominy test performed during this study. These results do not necessarily correlate with cooling rates seen in PM parts exiting a typical sintering furnace. Hence the associated hardness level in the Jominy bar does not imply that the hardness of a PM component will be the same. What can be understood from these results is whether or not the cooling rates, at different austenitizing temperatures, could be a source of increased hardenability. The cooling rates measured in this manner, reported in Table IV, are equivalent between TABLE IV. AVERAGE JOMINY BAR COOLING RATES Distance from Quenched End mm (in.) 10 (6/16) 25 (15/16) 45 (28/16) 85 (54/16)

Average Cooling Rate (°C/s) 845°C 900°C 955°C (1,550°F) (1,650°F) (1,750°F) 10.4 3.1 1.6 1.2

10.2 3.1 1.6 1.1

11.6 3.2 1.7 1.2

51

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 52

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

845°C (1,550°F) and 900°C (1,650°F) at all locations along the bar. At 955°C (1,750°F), the rates are similar to those experienced at the lower temperatures, though at 10 mm from the waterquenched end a moderate increase in cooling rate of nominally 1°C/s was found. While 1°C/s can potentially be sufficient to promote a difference in microstructure, it is seen only close to the quenched end. Regardless, the rate nearest the quenched end for all bars is rapid enough to immediately form martensite upon cooling from all the austenitizing temperatures for all alloy systems tested. This was evident in the microstructural analysis, as seen in Figure 8. For that reason it can be concluded that the austenitizing temperature, within the range studied, has no measurable impact on the cooling rate at critical distances from the quenched end since the cooling rates are identical. This does not imply, however, that austenitizing temperature does not affect the hardenability for particular alloy systems. Traditionally, wrought Jominy bars undergo a normalizing heat treatment prior to austenitizing as specified in ASTM A 255. This is done to ensure that specimens have a uniform microstructure prior to heat treatment. In the case of PM, it is believed that the sintering stage provides the appropriate starting microstructural conditions to fulfill this requirement. To test this hypothesis, two bars of FL-4900 with 0.6 w/o graphite were first sintered at 1,120°C (2,050°F) then normalized for 1 h at 925°C (1,700°F) and allowed to cool slowly in a protective atmosphere to prevent decarburization. The bars were subsequently austenitized at 845°C (1,550°F) and 955°C (1,750°F), respectively, for 30 min at temperature. The hardenability was unaffected by the additional normalizing treatment when compared with the same alloy tested without normalizing; the J Depths were 4 at 845°C (1,550°F) and 11 at 955°C (1,750°F) under both conditions. Consequently, it can be concluded that the sintering stage for PM components, and PM Jominy bars, serves as the normalizing treatment to provide acceptable starting microstructural conditions. Furthermore, a separate bar of FL-4900 with 0.6 w/o graphite was austenitized at 900°C (1,650°F) for 1 h at temperature to determine the effect of time at temperature. Since all hardenability results presented thus far pertain to samples austenitized for 30 min at temperature, a longer

52

period of time was used to determine the influence of time. While it is known diffusional processes are time and temperature dependent, time at temperature has not been addressed as of yet as a significant factor in the data. The stipulated 30 min is generally sufficient if the temperature is high enough and this likely holds true in most cases. The result of holding at temperature for 1 h indicates that only a minor improvement is seen in hardenability as the J Depth increases from 8 to 9. Thus higher temperatures may perhaps reveal the true potential of the alloy instead of longer times. Another consideration is that a change in the austenite phase field, due to alloying, affected the amount of austenite transformed and the level of the alloying elements dissolved at a prescribed austenitizing temperature. Considering that molybdenum and carbon are influential alloying elements in determining hardenability, any potential loss of molybdenum and/or carbon in solution in the austenite prior to quenching can drastically influence the outcome. It is believed that a significant amount of molybdenum and carbon remain tied up in carbide formation, a highly favorable state, at the lower austenitizing temperatures. This leads to a significantly lower alloy content in the matrix with substantial carbide content remaining largely undissolved and in which the carbides have a passive role in determining hardenability. This reduced alloying at lower austenitizing temperatures appears evident in the high-molybdenum-containing alloys Ancorsteel 721 SH, FL-4800, and FL-4900. Therefore, the term austenitizing temperature is loosely applied in this study in reference to the heat-treatment temperature. It is believed that due to the level of alloying in particular alloy grades, the austenitizing temperature is more than likely located within the γ-α or γ-M3C twophase region, depending on carbon content. Bain and Paxton clearly demonstrated the effect of molybdenum content on carbon solubility in austenite.19 As seen in Figure 12, the addition of molybdenum to steel shifts the eutectoid composition to lower carbon contents, and contracts the austenite phase field. Perhaps more important, in the context of this work, the ACM boundary is substantially raised to higher temperatures for a given carbon content. Thus in order to completely dissolve the MoxC-type carbides, and to make full

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 53

Previous

1-Page View

2-Page View

Table of Contents

Search

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

Figure 13. FL-4900 with 2 w/o Cu-0.9 w/o graphite, heat treated at 720°C (1,325°F), and austenitized at 845°C (1,550°F) for 30 min, revealing undissolved carbides (arrows); etched with 2 v/o nital/4 w/o picral. Optical micrograph

Figure 12. Effect of molybdenum content on carbon solubility in austenite19

use of alloying, higher austenitizing temperatures should be used to correctly identify the hardenability of high-molybdenum-containing PM alloys. Furthermore, as has been demonstrated with elevated austenitizing temperatures, an increase in hardenability in FL-4800 and other alloy systems can be achieved. This is believed to be primarily a result of an increase in iron/molybdenum-type carbides going into solution in austenite. To confirm this assessment, heat-treatment studies were performed to exaggerate the size of the carbides as the carbides in the Jominy bar samples appear to be below optical resolution. A sample of FL-4900 with 2 w/o Cu-0.9 w/o graphite was compacted to 7.0 g/cm3 and sintered at 1,120°C (2,050°F) for 15 min at temperature. The sample was subsequently aged at 720°C (1,325°F) to coarsen the carbide structure for ease of viewing. After slow cooling to room temperature, the sample was re-heated to 845°C (1,550°F) for 30 min and water quenched to simulate the

Jominy test. While the relation to the Jominy bar microstructures is not totally equivalent, Figure 13 reveals the presence of undissolved carbides dispersed throughout the martensitic matrix, thereby effectively reducing the alloy content in solution. As a corollary to this study, the measured range in J Depths of sinter-hardening grades is listed in Table V in comparison with values reported in MPIF Standard 35. Though the densities are not equivalent for every comparison, it does reveal that the J Depth is perhaps underreported in the standard when compared with the hardenability achieved in samples austenitized at higher temperatures. It is also probable that in the case of FLC-4908, containing 1.5 w/o Mo, the full potential of the measured hardenability was not reached at 955°C (1,750°F) and may require an even higher temperature. Therefore, it is a recommendation of this study that hardenability data in MPIF Standard 35 be re-evaluated at suit-

TABLE V. COMPARISON OF HARDENABILITY RESULTS WITH MPIF STANDARD 35 VALUES Material Designation

845°C (1,550°F)

FLNC-4408 FLC-4608 FLC-4805 FLC2-4808 FLC-4908

10 43 19 28 8

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Current Study, J Depth 900°C 955°C Sintered Density (1,650°F) (1,750°F) (g/cm3) 23 >56 >56 >56 14

34 >56 >56 >56 30

7.00 7.00 7.00 7.00 7.00

MPIF Standard 35, J Depth 845°C Sintered Density (1,550°F) (g/cm3) 11 32 35 52 9.5

7.06 6.92 7.25 7.00 7.08

53

Outstanding Tech Paper_Zheng et al 1/18/2010 11:50 AM Page 54

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

INFLUENCE ON CHEMICAL COMPOSITION AND AUSTENITIZING TEMPERATURE ON HARDENABILITY OF PM STEELS

able austenitizing temperatures for sinter-hardening alloys containing high levels of molybdenum and carbon. CONCLUSIONS The hardenability of PM steels, capable of providing sinter-hardening characteristics, has been re-examined by means of the Jominy end-quench test. The intent of the study was to aid PM parts producers in the selection of appropriate alloy systems for sinter-hardening applications. These hardenability results conflict with those for comparable alloys reported in MPIF Standard 35. In an effort to understand these differences, hardenability was studied over a range of austenitizing temperatures to determine the effect of this parameter on reported values, thereby influencing the J Depth value that various alloys have been given. It was found that an austenitizing temperature of 845°C (1,550°F), applied to alloy systems with a high molybdenum content (>0.5 w/o) was insufficient to completely austenitize the samples. It is therefore recommended that hardenability data in MPIF Standard 35 be re-evaluated at suitable austenitizing temperatures for alloys containing high levels of molybdenum and carbon. ACKNOWLEDGEMENTS The authors are grateful to Gerard Golin and Tom Murphy for providing metallographic analysis, photomicrographs, and insightful discussions pertinent to this work. REFERENCES 1. W.B. James, “What is Sinter Hardening?”, 1998, Hoeganaes Technical Data, Hoeganaes Corporation, Cinnaminson, NJ. 2. C.F. Jatczak, “Hardenability of Carbon and Alloys Steels”, ASM Metals Handbook, Properties and Selection: Iron and Steels, Ninth Edition, American Society for Metals, Metals Park, OH, 1978, vol. 1, pp. 471–497. 3. Hardenability Concepts with Applications to Steel, edited by D.V. Doane and J.S. Kirkaldy, TMS, The Metallurgical Society, Warrendale, PA, 1978. 4. MPIF Standard 35, Materials Standards for PM Structural Parts, 2007, Metal Powder Industries Federation, Princeton, NJ. 5. S. Saritaş, R.D. Doherty and A. Lawley, “Effect of Porosity on the Hardenability of P/M Steels”, Advances in Powder Metallurgy & Particulate Materials—2001, compiled by W.B. Eisen and S. Kassam, Metal Powder Industries Federation, Princeton, NJ, 2001, part 10, pp. 112–130.

54

6. R.M. German, Powder Metallurgy & Particulate Materials Processing, 2005, Metal Powder Industries Federation, Princeton, NJ. 7. F.J. Semel, “Cooling Rate Effects on the Metallurgical Response of a Recently Developed Sinter-Hardening Grade”, Advances in Powder Metallurgy & Particulate Materials—2002, compiled by V. Arnhold, C. Chu, W.F. Jandeska, Jr. and H.I. Sanderow, Metal Powder Industries Federation, Princeton, NJ, 2002, part 13, pp. 102–117. 8. B. Lindsley and H. Rutz, “Effect of Molybdenum Content in PM Steels”, Advances in Powder Metallurgy & Particulate Materials—2008, compiled by R. Lawcock, A. Lawley and P. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, part 7, pp. 26–34. 9. R.V. Fostini and F.J. Schoen, “Effects of Carbon and Austenitic Grain Size on the Hardenability of Molybdenum Steels”, Transformation and Hardenability in Steels Symposium, Climax Molybdenum Company of Michigan, Ann Arbor, Michigan, 1967, pp. 195–209. 10. ASTM International Standard A 255-2007, Standard Test Method for Determining Hardenability of Steel, Am. Soc. Testing & Materials, Conshohocken, PA. 11. MPIF Standard 65, Sample Preparation and Determination of the Hardenability of PM Steels, Standard Test Methods for Metal Powders and Powder Metallurgy Products, 2008, Metal Powder Industries Federation, Princeton, NJ. 12. ASTM International Standard E 112-96 (2004), Standard Test Method for Determining Average Grain Size, Am. Soc. Testing & Materials, Conshohocken, PA. 13. M.A. Grossman, “Hardenability Calculated from Chemical Composition”, Trans. TMS-AIME, 1942, vol. 150, pp. 227–259. 14. C.F. Jatczak, “Hardenability in High Carbon Steels”, Metallurgical and Materials Transactions B, 1973, vol. 4, no. 10, pp. 2,267–2,277. 15. W.W. Cias and D.V. Doane, “Phase Transformational Kinetics and Hardenability of Alloyed Medium-Carbon Steels”, Metallurgical and Materials Transactions B, 1973, vol. 4, no. 10, pp. 2,257–2,266. 16. R.A. Grange, “Estimating the Hardenability of Carbon Steels”, Metallurgical and Materials Transactions B, 1973, vol. 4, no. 10, pp. 2,231–2,244. 17. B. Lindsley, G. Fillari and T. Murphy, “Effect of Composition and Cooling Rate on Physical Properties and Microstructure of Prealloyed P/M Steels”, Advances in Powder Metallurgy & Particulate Materials—2005, compiled by C. Ruas and T.A. Tomlin, Metal Powder Industries Federation, Princeton, NJ, 2005, part 10, p. 353–366. 18. P. Sokolowski, B. Lindsley and F. Hanejko, “Introduction of a New Sinter-Hardening PM Steel”, Advances in Powder Metallurgy & Particulate Materials—2008, compiled by R. Lawcock, A. Lawley and P. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, part 7, p. 43–51. 19. E.C. Bain and H.W. Paxton, Alloying Elements in Steel, Second Edition, 1966, American Society for Metals, Metals Park, Ohio. ijpm

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 55

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

PM INDUSTRY NEWS IN REVIEW The following items have appeared in PM Newsbytes since the previous issue of the Journal. To read a fuller treatment of any of these items, go to www.apmiinternational.org, login to the “Members Only” section, and click on “Expanded Stories from PM Newsbytes.”

New Unit Advances Interaction between PM Industry and End Users Höganäs AB, Sweden, has opened the Power of Powder Centre to create more business opportunities by providing a faster and more efficient way to advance the development of innovative solutions in powder technology. The new unit will bring together PM parts makers, end users, and Höganäs for closer, more cost-effective cooperation to encourage new PM parts applications.

Federation will launch the Isostatic Pressing Association on January 1, 2010. Representing the international hot and cold isostatic (HIP & CIP) pressing community, the new association will include captive and tollprocessing parts makers, equipment manufacturers, universities and R&D organizations, and end users of HIP and CIP products.

Tungsten Company Adds Funds North American Tungsten Corporation Ltd., Vancouver, B.C., Canada, has completed a private placement financing issuing 20,433,333 common shares at a price of Can$0.15. The West’s largest producer of tungsten concentrate will use the proceeds of Can$3,065,000 for working capital.

MIBA’s Sales and Earnings Slide Facing a worldwide decline in core automotive markets, Miba AG, Laarkirchen, Austria, experienced a decline of 23.4 percent in sales for the first three quarters of its 2009–10 fiscal year, down to 228.3 million euros (about $334 million). Group-wide earnings before interest and taxes fell sharply to 5.4 million euros (about $7.9 million), down from 32.4 million euros (about $47 million) in the same period the previous year.

New Materials for Laser Sintering EOS GmbH, Krailling, Germany, has introduced a nickel-based superalloy IN718 and aluminumcasting alloy AlSi10Mg for direct metal laser sintering. The company is a leading supplier of laser sintering systems, including the EOSINT M 270 which produces parts by fusing metal powder into solid parts by melting via a focused laser beam.

Materials Process Lab Expansion Thermal Technology, Santa Rosa, Calif., has expanded its materials process laboratory, which provides process development and verification, toll processing, and pilot production. The lab is equipped with three high-temperature furnaces, crystal-growth capabilities, sparksintering system, glove box, and a nanomaterials preparation area.

MPIF to Launch Isostatic Pressing Association The Metal Powder Industries

GKN Markets Improving GKN plc, London, UK, reports that demand in major markets has been

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

better than anticipated and fourthquarter sales are up compared to the third quarter. Its automotive business, including powder metallurgy, has benefited from government incentive programs supporting sales of smaller light vehicles and improved production demand. Award-Winning Engines Are Heavy PM Users Ward’s Automotive Group editors have selected their annual list of 10 best auto engines for 2010, with several containing many PM parts. The Ford 3.5L EcoBoost Turbocharged DOHC V-6 topped the list, with 81 PM parts weighing a total of 21 pounds. Positive Signs for 2010 “The PM industry faces a slow recovery,” says Michael E. Lutheran, newly elected president of the Metal Powder Industries Federationand vice president of United States Metal Powders Inc. “But I expect 2010 will be better than last year.” He sees 2010 light-vehicle production in North America increasing to about 10 million vehicles and recovering to 12 to 14 million vehicles in the 2011–13 timeframe. He believes that the powder metallurgy industry must devote more attention to working with transplant-automaker technical people. “We need to continue efforts to encourage more conversions to PM parts in transplant vehicles,” he says.

55

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 56

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY EQUIPMENT MANUFACTURERS ABBOTT FURNACE COMPANY www.abbottfurnace.com Abbott Furnace Company specializes in continuous furnace technology for sintering, steam treating, heat treating, annealing, tempering and brazing. Technical innovations include Ceramic Muffles and Belts, Advanced VariCool System, Quality Delube Process and Computerized Controls. Abbott also offers custom fabrication of replacement parts, a full line of spare parts and repair and calibration service. ABTEX CORPORATION www.abtex.com Abtex Corporation manufactures application-specific abrasive filament deburring brushes and automated systems to apply them. Abtex Systems Group designs/builds machinery for deburring both green and ground/machined sintered parts. Planetary head systems are employed for flat parts and rotary indexing systems for more complex part geometries. 30 years of applications experience combined with custom brushes and machines ensures the most effective and efficient deburring solution. ALLEGHENY COATINGS www.alleghenycoatings.com Allegheny Coatings, located in Ridgway, PA, is an ISO 9001 registered applicator of coatings and platings for use on powder metals. These applications provide for lubricity, as well as corrosion, heat, and wear resistance. Resin and inorganic impregnation are also available. In addition, Allegheny Coatings offers unique coating services such as part masking, cyclical corrosion testing, and a variety of chrome-free coatings. Web site: www.alleghenycoatings.com. ALLOY ENGINEERING COMPANY www.alloyengineering.com Since 1943, The Alloy Engineering Company has been recognized as the premier designer and manufacturer of high-quality, alloy equipment for furnace and high-temperature corrosive industrial applications. Our heritage of design and manufacturing innovation is as important as our commitment to sharing our application expertise with customers and providing responsive technical support of products throughout their operational life. We believe that customers satisfaction defines quality. And delivering, or surpassing, expected performance and life is the essence of customer satisfaction.

56

ARBURG GmbH + Co KG www.arburg.com ARBURG is one of the world’s leading manufacturers of injection molding machines with clamping forces from 125 to 5,000 kN. The product range is completed by robotic systems, complex projects and other peripherals. ARBURG holds a leading position in the PIM sector for decades. The PIM range includes ALLROUNDER injection molding machines, which are especially equipped for the processing of powder materials, comprehensive customer support and training courses. AUTOMATED CELLS & EQUIPMENT www.autocells.com Automated Cells & Equipment, Inc. Founded in 1996 by its president, Jim Morris, Automated Cells & Equipment (ACE) designs robotic and flexible automation solutions for manufacturers. ACE designs systems to perform press takeout, furnace and sizing press load/unload palletizing and deburring operations. Cost-effective, innovative manufacturing solutions have been designed, produced and installed at multiple powder metal facilities throughout North America. Based in upstate New York, ACE has developed several long-term relationships with manufacturers by emphasizing personalized, customized service. Training is provided for all ACE systems, as well as technical support 24 hours a day, 7 days a week. BRONSON & BRATTON INC. www.brons.com We are designers and fabricators of PM Tooling Design: your part, your press, our finished design Engineering: our experience, our CAD, equals totally integrated tooling Technology: our computer database with design variations will conform to your equipment requirements Processing: our CAM system integrates the engineering and machine data required for quality tools Quality: has been a tradition at Bronson & Bratton since 1948. We are ISO 9001:2000 Certified CAD + CAM = CIT (Computer Integrated Tooling) C.I. HAYES, a Gasbarre Products Company www.cihayes.com For the past 103 years, C.I. Hayes has manufactured industrial furnaces and generators for many industrial applications. The furnace line includes hightemperature pusher furnaces, single-chamber and continuous vacuum furnaces with air or oil quench capabili-

ties, tube strip furnaces, and conventional continuous-mesh-belt furnaces for sintering, steam treating, delubing. Endothermic, exothermic, and dissociated ammonia generators are manufactured in various sizes. Custom-designed furnaces are manufactured for specific parts and processes. CENTORR VACUUM INDUSTRIES INC. www.centorr.com CVI is a 50-year-old manufacturer of custom high-temperature vacuum and controlled-atmosphere heat-treat and sintering furnaces for the Metals and Ceramics industries. Applications include heat treating, brazing, sintering, hot pressing, diffusion bonding, and injection molding of metals or ceramics. Furnaces are available with either refractory metal or graphite hot zones in sizes from 1 cu. in. to several cu. meters, from 1,000°C to 3,000°C. CHECKER INDUSTRIES www.1800checker.com Checker Industries, a Precision Finishing Inc. company, supplies costeffective solutions for metal finishing and conditioning. Our long-term relationships with the best known manufactures in the industry assure you the latest finishing technologies. We operate our own tumbling and blast cleaning contract shops and formulate and manufacture CHEMTROL® vibratory, washing, and floor-cleaning compounds. Whether your problem entrails deburring, burnishing, blast cleaning, washing or waste treatment, we have the experience to assist you. CIECO, INC. www.ciecocontrols.com CIECO offers five levels of press controls for the powder metal industry. From low-cost PPC1100R to the Automator II controller. Our dual microprocessor controls eliminate the high cost of dual plc packages and comply with OSHA, ANSI and CSA safety standards. Visit our Web site at www.ciecocontrols.com to view these controls. For an Internet Webinar demonstration on the Automator II controller, call our customer service department at 412-262-5581. CM FURNACES, INC. www.cmfurnaces.com Furnaces & Equipment: Furnaces operating at temperatures from 1,200°F to 4,000°F. Batch and continuous pusher furnaces from lab scales to fully automated production units. All electric with high-efficiency insulation packages. Atmospheres: Furnaces available to operate in hydrogen, nitrogen, inert or air atmospheres. Continuous dew point

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 57

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

and oxygen-level monitoring and control are offered. Other Products/Services: Inline delube and debind ovens with air, inert and/or reducing atmospheres. Debind ovens for BASF binder system. Toll firing and process development. DORST AMERICA, INC. www.dorst.de Dorst offers the highest precision compacting and calibrating presses available with excellent productivity and maximum energy efficiency—all with removable die sets. Options available include automatic die-set change, self programming and optimization for the most demanding applications. Also available are part-handling automation, existingpress remanufacturing, customized preventative maintenance programs, as well as operation, set-up, maintenance and tool-design training. EDGETEK www.ptg-machines.com Edgetek, a Precision Technology Group company, is a builder of production grinding machines for the manufacture of a wide variety of components from the automotive, aerospace and other manufacturing sectors. For the PM industry, Edgetek’s line of Superabrasive Machines has been proven extremely effective in interrupted cuts and high metal-removal rates in difficult-tomachine materials such as sinter-hardened powder metals. Substantial increases in tool life over conventional machining methods will result in lower cost per part. ELMCO ENGINEERING, INC. www.elmco-press.com ELMCO Engineering Inc. is a leading manufacturer of new and rebuilt PM equipment. We service all makes of presses, provide control and feeder upgrades, and have an extensive parts inventory at three locations. We offer our own new ELMCO multi-motion mechanical presses, and standard molding mechanical presses, hydraulic specialty presses, plus inclined and upright mechanical sizing presses. As Yoshizuka’s North American representative, we offer a full line of compacting presses, including state-of-the-art CNC hydraulic servo models. GASBARRE PRODUCTS, INC. www.gasbarre.com Provides full-service design, manufacturing and marketing of capital equipment for the particulate materials and thermal processing industries. Featuring Gasbarre Mechanical Presses, Best Hydraulic Presses, PTX-Pentronix HighSpeed Presses and Part Loaders, SIMAC

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Isostatic Presses, Sinterite Furnaces, C.I. Hayes Furnaces, McKee Carbide Tooling and related services. Gasbarre supplies all processing equipment for the PM industry, from atmosphere generators to powder-handling equipment, presses, sintering & annealing furnaces, sizing presses and oil-impregnation equipment. GENERAL CARBIDE CORPORATION www.generalcarbide.com General Carbide is a major supplier of carbide tooling to the Powder Metal (PM) Industry. Our grades display high wear resistance and high fracture toughness. Wire EDM grades are formulated to withstand Wire & Ram EDM and are guaranteed not to crack. Our premium grade selection of GC-813CT, GC411CT, GC-613CT, GC-618T demonstrate enhanced performance, due to the unique crystal structure and additives that provide increased toughness, corrosion resistance and anti-galling characteristics. HENKEL TECHNOLOGIES www.henkel.com/auto Henkel, a recognized and valued supplier of engineered adhesives and sealants, has developed the Loctite® Impregnation Systems (LIS) of Loctite® high-performance impregnation technology for sealing powder metal components. Henkel maintains an Impregnation Process Engineering Laboratory in Madison Heights, MI, to evaluate and test customer parts and optimize the choice of impregnation resin and equipment. Please send specific questions to: [email protected]. HERNON MANUFACTURING INC. www.hernonmfg.com Since 1978, Hernon Manufacturing has produced high-performance impregnation resins and processing equipment. Hernon Impregnation Resin (HPS™) offers a breakthrough in sealing leaking porous metals such as powder metal castings and sintered metal parts. HPS™ also offers other benefits such as increased lubricity, which lowers tool wear, and resistance to degradation by hydrocarbon solvents such as gasoline, motor oil, and transmission fluid. Hernon Manufacturing provides complete impregnation systems including design and installation. LABORATORY TESTING INC. www.labtesting.com LTI is an independent testing laboratory providing certified test reports since 1984. The lab specializes in Nadcapaccredited mechanical, chemical, metallurgical, dimensional and nonde-

structive testing. Our chemists are highly experienced with classical and instrumental wet chemistry and spectroscopy. They process a wide range of samples including metals, powder metals, ores, ferroalloys, composites and ceramics. Laboratory Testing Inc. also provides NIST-traceable calibration services, test-specimen machining and failure analysis. LINDE AG, LINDE GASES DIVISION www.linde-gas.com With its innovative solutions, Linde Gas is playing a pioneering role in the global market. As a technology leader, it is our task to constantly raise the bar. We want to offer more than just high-quality gases to our customers in the PM Industry. No matter what kind of process is your daily business, from the automatization, hot isostatic pressing, or to the actual sintering—our experts always have the right solution. Linde Gas—ideas become solutions. Please contact us at [email protected] LITTLE LAKES MACHINE & TOOL CO. LTD. www.llmt.com Builders of quality PM tooling and also maintenance of tooling (recuts). Your design or we will fully design & 3-d model and machine to those models. Quality has been a tradition at Little Lakes since 1960. We are ISO 9001:2000 Certified. One of our specialties is using advanced technology to maintain tight tolerances and supply “press ready” tools right off the machine. Sink EDM with additive, WEDM, CNC Form grinding, CNC O.D., I.D. grinding, jig grinding. Let us recut your tools on our high-speed hardmilling automation (robot) cell. NSL ANALYTICAL SERVICES www.nslanalytical.com NSL Analytical Services is an ISO/IEC 17025 and Nadcap-certified Independent Commercial Testing Laboratory providing reliable materials testing to powder metallurgy customers throughout the United States and around the world. Our staff of chemists, metallurgists and technicians is experienced in metal and alloys testing. Our elemental chemical analysis and metals testing capabilities are used for failure analysis, product evaluation, and materials verification to help our customers achieve the highest standards of product quality.

57

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 58

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

OSTERWALDER, INC. www.osterwalder.com OSTERWALDER AG develops and manufactures state-of-the-art hydraulic, mechanical-hydraulic and electrical powder compacting presses, in Lyss, Switzerland. The wide product range offers system solutions for pressing iron, ceramic, tungsten carbide powders and other special materials into small precision parts or sophisticated structural parts of first-class quality. OSTERWALDER AG provides user-oriented press technology and customer support exceeding today’s requirements. QUALA-DIE, INC. www.quala-die.com Quala-Die, Inc., is the leader in powder metal tooling and precision machining. From design through production QualaDie can provide you with superior service and quality. RESCO PRODUCTS, INC. www.rescoproducts.com Resco is a supplier of cordierite, alumina, and silicon carbide products to the powder metal industry. This includes standard plates, rings, pusher slabs, and special shapes in cordierite and high alumina as well as muffles, support slabs and beams in silicon carbide. Please contact us to determine the product required for your application. SHAPE-MASTER TOOL COMPANY www.shapemastertool.com Shape-Master Tool manufactures polycrystalline cubic boron nitride (PCBN) cutting tools for PM machining. With a metallurgical engineer on staff, ShapeMaster understands PM and the nuances of PM machining optimization. We don’t offer a single solution for all PM alloys because it’s simply not possible. Shape-Master utilizes over eight different PCBN grades for PM due to the differences between iron–carbon, Fe-Cu, Fe-Ni, low-alloy, as-sintered, copperinfiltrated, steam-treated, hardened, sinter-hardened, and powder-forged components. SINTER-PACIFIC (a Div. of International Sintered Components Pty Ltd) www.sinter-pacific.com Sinter-Pacific was established in October 1993 with a focus on providing our Asia Pacific customers with costeffective design solutions using powder metal technology from the world’s best. Diversification has now provided PM products, specialty dry bearing technology, PM processing machinery & equipment along with NDT solutions for our customers.

58

SMS MEER GmbH www.sms-meer.com SMS Meer GmbH is part of the SMS group and is located at Mönchengladbach, Germany. The hydraulic-press division offers forging and powder-compaction presses. We are for over 50 years a competent partner for the metal powder, ceramics and tungsten carbide industry and have sold more than 1,800 pf powder presses. Range of powder presses and adapters: - Hydraulic CNC presses from 600 up to 20,000 kN - Hybrid CNC up to 2,500 kN - High-speed mechanical presses from 30 up to 450 kN - Controlled punch adapters (CPA) with up to eight integrated CNC press axes SURFACE COMBUSTION, INC. www.surfacecombustion.com Surface Combustion offers a diverse product offering for batch and continuous furnace designs for atmosphere, non-atmosphere, or vacuum processing of ferrous and/or nonferrous components/materials. Surface also produces the industry’s most popular endothermic and exothermic gas atmosphere generators. THE P/M EXPERIENCE INC. www.lauffer.de The P/M Experience Inc. provides consulting assistance in the manufacturing of PM parts. We are also the North American agent for Lauffer presses. LAUFFER Pressen is a leading manufacturer of hydraulic presses for the PM industry. The product range comprises closed-loop controlled powder-compacting presses from 12 to 1,200 tons, and calibrating presses from 63 to 1,250 tons, presses for special applications, as well as automation systems for presses. VIRTO/ELCAN INC. www.virto-elcan.com Virto/Elcan Inc. works with customers to provide high-performance screening solutions for their advanced powder metal products. Our technology offers significant advantages over any other screening machines. These performance advantages can be demonstrated on production-sized equipment in our full-scale testing/tolling facility. At our facility in Mamaroneck, NY, we provide production solutions for many leading powder metals companies. Come see why we have the best screening machines!

METAL POWDER PRODUCERS ACUPOWDER INTERNATIONAL, LLC www.acupowder.com ACuPowder, with plants in NJ & TN, is a major U.S. producer of metal powders. Products include: antimony, bismuth, brass, bronze, bronze premixes, chromium, copper, copper oxide, copper premixes, diluted bronze premixes, graphite, high-strength bronze, infiltrant, manganese, MnS+, nickel, phos copper, silicon, silver, tin, tin alloys and PM lubricants. New products include powders for MIM, thermal management. “Green Bullets,” lead-free solders, copper brazing, plastic fillers and cold casting. ADVANTAGE METAL POWDERS www.advantagempi.com Advantage Metal Powders provides a full product line of magnetic and non-magnetic powders including, but not limited to, iron, prealloyed, sinter-hardening and soft magnetic materials. In addition to virgin powder blends, Advantage offers remill powder and remill/virgin composite blends that meet MPIF’s Std. 35 specification. Advantage also purchases green scrap and will process customer-supplied green scrap. They have a state-of-the-art laboratory with testing and R&D services available. AMETEK SPECIALTY METAL PRODUCTS www.ametekmetals.com Major producer of stainless steel and high-alloy powders for PM, filtration, MIM, and thermal spray. Fully dense consolidation capability via proprietary pneumatic isostatic forging (PIF) process to make bars, rods, and specialty shapes from a wide variety of alloys. Full range of thermal-management products like AlSiC, copper–tungsten, copper– molybdenum, and copper clad–copper/ molybdenum copper heat sink for telecommunication, advanced radar systems, and other high-heat-dissipation requirements. U. S. manufacturer of CP Ti and Ti 6/4 powders through our Reading Alloys operation. ARC METALS CORP. www.arcmetals.com ARC Metals is the industry leader in the production of remill materials. ARC Metals also offers custom blending and full metallography with in-house technical support. ASBURY GRAPHITE MILLS, INC. www.asbury.com Asbury Graphite Mills, Inc., and its Southwestern Graphite Division, contin-

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 59

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

ue to be the world leader in supply of quality and consistency of graphite and carbon powders for admix applications. Since the inception of the powder metal industry, Asbury has been providing both natural and synthetic graphite products for every application. Asbury also offers graphite-based lubricants and sintering trays to the industry. For strength and dimensional stability, choose Asbury. ATI POWDER METALS www.alleghenytechnologies.com ATI Powder Metals is a manufacturer of high-quality, spherical prealloyed metal powders including titanium, titanium– boron, titanium aluminide, nickel, nickel-base superalloy, cobalt, and iron-base wear- and corrosion-resistant alloys. The firm provides fully dense HIP components and toll HIP services. They provide technical expertise and partnership in programs from new alloy development through powder production and component manufacturing. ECKA GRANULES OF AMERICA L.P. www.ecka-granules.com ECKA Granules is the leading manufacturer for nonferrous metal powders. The product range includes aluminum, magnesium, copper, calcium, tin, lead, zinc, silicon and their alloys, as well as readyto-press blends. Production techniques include milling and grinding, electrodeposition, air, water, and gas atomization, granulation for melting and recycling processing. HENGYUAN METAL & ALLOY POWDERS LTD. www.hengyuanpowders.com Hengyuan Metal & Alloy Powders Limited supplies a variety of fine metal and alloy powders for PM and MIM applications. Ferroalloy powders such as Ferro-molybdenum, low-carbon ferro-manganese, high-carbon ferro-manganese, low-carbon ferro-chromium, high-carbon ferro chromium, ferro-phosphorus, ferro-tungsten, ferro-boron, ferro-titanium, chromium metal powder, copper and copperalloy powders, stainless steel powders. Contact [email protected]. Phone 416-997-8780. HOEGANAES CORPORATION www.hoeganaes.com Hoeganaes Corporation, world leader in ferrous powder production, has been a driving force within the PM industry for 55 years. The company has seven manufacturing facilities in the USA and Europe to meet customers' needs worldwide. It continues to invest in manufacturing capacity to support industry growth while providing design, process

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

and material system education worldwide. Hoeganaes holds these certifications: ISO 14001, ISO/TS 16949, and ISO 9001, QS 9000. HORSEHEAD CORPORATION www.horsehead.net Horsehead, formerly New Jersey Zinc Co., makes air-atomized powders. Located in Palmerton, Pa., Horsehead is a major supplier of zinc and brass powders as well as copper, bronze, infiltrants, phos-copper, and nickel silver powders. Contact info: Paul Wagar/ General Manager–Metal Powder Sales [email protected] INTERNATIONAL TITANIUM POWDER (ITP) www.itponline.com International Titanium Powder (ITP) was formed in 1997 to develop and commercialize the Armstrong Process™—a patented and proprietary technology to produce high-purity metal and alloy powders with emphasis on titanium. Armstrong Process™ technology is intended to lower the production cost of powders suitable for non-melt direct consolidation of titanium to enable lowcost manufacturing of titanium products and to reduce the environmental impact of titanium production. MAGNESIUM ELEKTRON POWDERS www.magnesium-elektron.com Magnesium Elektron Powders, a world leader in the manufacture of magnesium particulates and specialty niche alloy powders. At our three facilities in North America, we manufacture atomized and ground particulates in a wide range of shapes and sizes: chips, granules, coarse powders and fine powders. Our products are used for a variety of applications & markets including: military, steel desulphurization, chemical synthesis, welding, powder metallurgy, specialty pyrotechnics, and flameless ration-heaters. METALPÓ INDÚSTRIA E COMÉRCIO LTDA. www.metalpo.com.br Since 1967, Metalpó focuses its activities on powder metallurgy as a nonferrous powders and sintered-parts producer. Typical Metalpó powder metallurgy products are self-lubricating bearings (Bronze and Iron), structural parts (Iron, Stainless Steel, Bronze and Brass) and metal powders (Copper, Premix Bronze, Prealloyed Bronze, Brass and Tin). Metalpó has achieved recognition for the highest level of quality with quality assurance management system ISO 9001/2000 and ISO TS 16949 assessments.

NORTH AMERICAN HÖGANÄS, INC. www.nah.com North American Höganäs, Inc., a subsidiary of Höganäs AB, is a supplier of iron-based metal powders and stainless steel powders designed for a broad spectrum of applications, including components, friction, welding, brazing, thermal coating, soft magnetic composites, electro photographic and numerous chem/ met applications. Production takes place in four strategic locations: Stony Creek Plant, located in Hollsopple, PA, is the world’s most integrated production resource for atomized iron and steel powders. St. Marys Plant, located in St. Marys, PA, is a mixing facility which is capable of producing small to truckloadsize custom mixes. Niagara Falls Plant, located in Niagara Falls, NY, produces a comprehensive range of products ranging from friction materials, powder metallurgy and soft magnetics, to food additives and general chemical use. Johnstown Plant, located in Johnstown, PA, produces a broad range of products including stainless steel powders, ironalloy powders, nickel-alloy powders, electrolytic iron powders and chips, manganese and silicon powders, and GLIDCOP® dispersion-strengthened copper products. OM GROUP (OMG) www.omgi.com OM Group, Inc. (OMG) is a diversified global developer, producer and marketer of value-added specialty chemicals and advanced materials that are essential to complex chemical and industrial processes. With more than 30 years of experience in cobalt powders, OMG powders serve the needs of many industries including but not limited to hardmetals, diamond tools, PM, thermal spray and magnets. Other key technology-based end-use applications include affordable energy, portable power, clean air, clean water, and proprietary products and services for the microelectronics industry. Headquartered in Cleveland, Ohio, OM Group operates manufacturing facilities in the Americas, Europe, Asia and Africa. For more information, visit the company’s Web site at http://www.omgi.com. PREMIER METAL & RECYCLING, INC. www.premiermetaland recycling.com Premier Metal & Recycling, Inc., is a complete scrap-metal recycling company. Our staff brings over 20 years experience in the scrap-metal industry. We purchase all powder metal scrap including sintered parts, belts, muffles, floor sweepings, green parts and powders. Premier Metal also sells remill nonferrous powders. Our company offers very

59

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 60

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

competitive pricing. Please contact us at 814-834-1239 or by e-mail at: [email protected] QMP AMERICA www.qmp-powders.com QMP, registered to ISO 9001, ISO 14001, and ISO/TS 16949, provides a full product line of iron and steel powders in the Americas, Europe, and Asia. ATOMET standard grades and prealloys, binder-treated FLOMET™ mixes, diffusion-bonded ATOMET DB powders, machinable (sulphur-free) grades, sinter-hardening grades, and soft magnetic composite materials are available to customers worldwide. SCM METAL PRODUCTS, INC. www.scmmetals.com With manufacturing facilities in the U.S. and China, SCM Metal Products is a global, technological leader in the manufacturing and distribution of copper powders, pastes, flakes, alloys and oxides, as well as the North American sales and marketing arm for AMTIX ferrous and nonferrous MIM powders. SCM’s products serve a wide array of applications including powder metallurgy, MIM, brazing, electronics, chemicals (silanes) and numerous industrial applications. Visit us at www.scmmetals.com. SUPERIOR GRAPHITE www.superiorgraphite.com Superior Graphite specializes in thermal purification, advanced sizing, blending, and coating technologies, providing value-added graphite and carbon-based solutions globally. Combining 90 years of experience and advanced technologies into every facet of the organization, a wide range of markets are served, such as agriculture, battery/fuel cells, ceramic armor, carbon parts, ferrous/nonferrous metallurgy, friction management, hot metal forming, polymer/composites, powder metals, lubricity, and performance drilling additives. TIMCAL GRAPHITE & CARBON www.timcal.com TIMCAL Graphite & Carbon is committed to produce highly specialized graphite and carbon materials for today’s and tomorrow’s powder metallurgy industries. TIMCAL Graphite & Carbon is a global leader in realizing customer solutions in graphite and carbon applications and is a member of IMERYS, a world leader in adding value to minerals. UMICORE www.umicore.com Umicore Tool Materials is a business line of Umicore, serving the markets of diamond tools and hardmetal applica-

60

tions. We offer a wide range of cobalt powders, nickel powders and prealloyed alternatives (from our Cobalite range). Being a worldwide market leader, we see successful use of our products in tools for stone-cutting and construction, as well as hardmetal or cemented carbide applications. Our products provide the perfect solution to create bonds with other constituents like diamonds or tungsten carbide. Due to our extensive application know-how and R&D facilities, we can provide you with the necessary technical support.

MIM/PIM ADVANCED METALWORKING PRACTICES, LLC www.advancedmetalworking.com Producer of high-quality feedstock for MIM since 1988—longer than any other supplier. ADVAMET® feedstocks are available for many steels and stainless steels and some nonferrous compositions. We can customize feedstocks for different target shrinkages. On-time shipments of feedstocks in tonnage quantities. Test lots for new customers or new applications. Visit our Web site for more information about the consistent quality of our feedstocks, discussion of dimensional precision, and background. ARBURG GmbH + Co KG www.arburg.com ARBURG is one of the world’s leading manufacturers of injection molding machines with clamping forces from 125 to 5,000 kN. The product range is completed by robotic systems, complex projects and other peripherals. ARBURG holds a leading position in the PIM sector for decades. The PIM range includes ALLROUNDER injection molding machines, which are especially equipped for the processing of powder materials, comprehensive customer support and training courses. BASF CORPORATION www.basf.com/catamold BASF Catamold® is a ready-to-mold feedstock for MIM and CIM. Our material portfolio includes various low-alloy steels, stainless steels, tool steel, soft magnetic alloys, super alloys, special alloys (Ti, W, others) and oxide ceramics. New grades will be developed as needed for our customers. Catamold® incorporates catalytic debinding and offers high green strength and dimensional stability. It is well suited for both batch and continuous PIM operations. www.basf.com/catamold.

FloMet LLC www.flomet.com FloMet is an ISO 9000:2000 registered custom manufacturer of precision, highvolume metal components with extremely difficult tolerance requirements, through the metal injection molding (MIM) process, producing custom components for various manufacturing markets, including Medical/Surgical/ Orthopedic, Dental/Orthodontic, Health/Hearing, Aerospace/Defense, Electrical, Telecommunications and Industrial. FloMet specializes in customblended feedstocks made of stainless steel, cobalt and nickel-based alloys, providing low-carbon and high-density components, which provide superior properties of strength and versatility. INTERNATIONAL SPECIALTY PRODUCTS www.ispcorp.com ISP is the sole U.S. producer of over 20 grades of high-purity carbonyl iron powder (CIP) products that have unique properties and applications ranging from electronics, radar-absorbing materials, EMI/RFI shielding, metal injection molding, vitamin and food iron supplements as well as catalysts for various chemical processes. ISP has over 50 years of CIP manufacturing experience, yielding high-quality and consistent products. Please visit our Web site at www.ispcorp.com for further details. KINETICS CLIMAX, INC. A Division of Freeport-McMoRan Company www.kinetics.com Kinetics Climax, Inc. Metal injection molding has been Kinetics specialty since 1982. Kinetics’ Design Engineering and Technology Development staff has a highly successful track record of providing creative application solutions including the consolidation of multiple parts, reduced assembly operations, reduced costs and performance-specific engineered materials. With its inherent design flexibility, MIM is capable of producing highly complex geometries in many different alloys, ranging from stainless steels, alloy steels, refractory metals, thermal-management and soft magnetic materials to controlled-expansion alloys (low CTE) and custom-engineered materials. NETSHAPE TECNOLOGIES, INC. www.netshapetech.com A manufacturer of engineered, complex, high-strength components using powder metallurgy and metal injection molding, focused on industrial markets. NetShape is a Lean-focused, global supplier with 3 PM and 1 MIM operations worldwide, Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 61

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

including a facility in Suzhou, China. Industry-leading technologies include high-performance materials, unmatched shape complexity, tolerances and part size. Our innovative Conversioneering® process and strong engineering support offer unmatched value and support for converting parts to PM. PARMATECH CORPORATION www.parmatech.com Since 1972, Parmatech Corporation has been a leading provider of custom manufactured Metal Injection Molding (MIM) components and services. Through proprietary process and materials technology, Parmatech provides a robust set of solutions to meet the challenges of their customers around the world. Developed from over thirty-five years of operational experience, Parmatech’s unique set of tools provide solutions to even the most demanding MIM applications. Parmatech Corporation is part of the ATW family of companies. REMINGTON ARMS COMPANY, INC., Powder Metal Products Division www.remingtonpmpd.com The Powder Metal Products Division has been a MIM parts producer since the mid-1980s and continues to supply Remington and a number of commercial customers with high-quality MIM parts, in medium-to-high volumes. We offer low-alloy steels, stainless steels, and soft magnetic materials for the firearm and ordnance markets. Please visit our Web site at www.remingtonpmpd.com to learn more about MIM technology and our MIM product offering. RYER, INC. www.ryerinc.com Ryer, Inc., is a manufacturer, developer and supplier of custom and standard feedstocks for the metal injection molding industry. We offer the widest range of particle sizes, material types and debinding methods in the MIM industry. As a custom compounder, Ryer can match your current material shrink specifications and flow characteristics. Ryer Feedstocks are inspected, tested and documented to assure you receive consistent, predictable results with “batch to batch” repeatability. SELEE CORPORATION www.selee.com SELEE Corporation, a member of the Porvair Group, manufactures high-temperature, low-mass kiln furniture in seven different ceramic compositions to meet your application’s specific needs. We make both open-cell foam kiln furniture as well as micro-porous kiln furniture. We are also a distributor for Ferro

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

Process Temperature Control Rings. Our manufacturing facility is located in the beautiful Blue Ridge Mountains in Hendersonville, North Carolina, U.S.A. Certified ISO 9001:2000 and ISO 4001:2004. SUNROCK CERAMICS COMPANY Sunrock Ceramics Company in Broadview, IL (outside Chicago) is an industrial ceramics manufacturer focused on specialty alumina products such as pusher plates, setter tiles and hot-face furnace linings for the sintering needs of the high-temperature powder metallurgy market, including producers of MIM and CIM parts. Sunrock’s pusher plates, pressed with HPA-CG material, are used in some of the most demanding cycles in the industry such as the sintering of stainless steel and tungsten carbide parts in high-temperature hydrogen atmosphere. High-purity alumina refractory brick made with HPA-99, a 99.5% alumina formulation, are designed for hot-face lining in reducing atmosphere.

OTHER ULTRA INFILTRANT www.ultra-infiltrant.com The patented Ultra Infiltrant Copper Infiltration Technology System exceeds MPIF Standard 35 in metallurgical and mechanical response. Ultra Infiltrant eliminates all the non-value-added process, cost and waste associated with pressing powder copper infiltrants. Ultra Infiltrant leaves no residue or erosion and is available in multiple wire diameters and cross sections to accommodate virtually any preform geometry. Ultra Infiltrant is the world leader in copper infiltration technology…A Solid Line of Thinking.

HIP/CIP AVURE TECHNOLOGIES Avure Technologies is the largest, most trusted supplier of hot and cold isostatic presses to the global powder metal industry. Formerly ASEA/ABB, the company produces isostatic presses ranging from laboratory scale to greater-thanmeters in working diameter using Avure’s own QUINTUS® wire-winding technology. Avure is held in high regard for its isostatic application expertise, project management experience in building and delivering complex systems and global service and support team.

CARPENTER POWDER PRODUCTS www.cartech.com Provides prealloyed powders that are tailored to meet customer requirements for thermal surfacing processes, metal injection molding, near-net-shape hot consolidation technologies, and mill form products (billet, bar, wire, plate, sheet, and strip). Our manufacturing versatility and technical knowledge enable us to provide you with consistent high-quality products. ERASTEEL SAS www.erasteel.com Erasteel is the world leading producer of steel powders by gas atomization. With two atomization units, Dvalin™ and Flexiplant™, located in Söderfors, Sweden, and service centers in America, Asia and Europe, Erasteel can supply a wide range of powders and steels with a high level of cleanliness. Tool steels, high-speed steels, stainless steels, lowalloyed steels and other specialty alloys under customer specification are available for many applications: hot isostatic pressing, thermal spraying, centrifugal casting, etc. KITTYHAWK PRODUCTS www.kittyhawkinc.com Kittyhawk Products—qualified experts in the field of hot isostatic processing. HIP is an affordable process of unique benefit in solving complex design problems while increasing the strength of properties. Together with our sister company, Synertech P/M Inc., we offer unmatched net-shape capabilities with powder metal parts design and manufacture.

PM PRODUCTS OR PARTS PRODUCERS ACE IRON & METAL CO., INC. Ace Iron & Metal is a full-service metal recycling company in business since 1945. We purchase all types of powder metal scrap inclusive of green, sinter, floor sweeps, and all maintenance scrap, along with furnace scrap. We can be contacted via our e-mail address [email protected] or our toll-free number. ALLIED SINTERINGS, INC. www.alliedsinterings.com Allied Sinterings is a manufacture of custom-engineered powder metal products for small applications, including small gears and miniature components for planetary drives, automotive and industrial sub-assemblies, electronics and, in particular, small components and assemblies for medical devices.

61

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 62

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

Specialties include gearing with up to 120 DP, Stainless Steel, and customized materials including precious metals. ALLREAD PRODUCTS LLC www.allreadproducts.com Allread Products is a very versatile company that will manufacture large or small volumes of parts. Our pressing capabilities range from 4-ton presses up to 100-ton presses. We process multitudes of materials including ferrous and ferrous alloys, most nonferrous, stainless steel, aluminum, and Teflon. Our secondary department is quite extensive including 6 CNC machines and a number of small automatic machines for special applications. Along with these capabilities we also do assembly of various parts. ASCO SINTERING CO. www.ascosintering.com Manufacturer of precision complex multilevel structural powder metal parts & assemblies. Experienced sintered metal engineering & metallurgical staff. Serving the automotive, lock, hardware, lawn & garden, irrigation, medical, hand tools, computer & cutlery industries. Capabilities include tool design, tooling, metallurgy, warm compaction, high-temperature sintering, sinter hardening, heat treat, resin impregnation, deburring, secondary machining, assembly & plating. Materials include low-alloy, diffused, copper, carbon & infiltrated steels, 300 & 400 stainless steels, brass, nickel silver, Monel®, soft magnetics, copper & bronze. ATLAS PRESSED METALS www.atlaspressed.com Atlas Pressed Metals has been a producer of powdered metal components since 1976. Atlas specializes in production of high-performance bearings, structural and gear components using iron, iron alloys, soft magnetic alloys, stainless steel, bronze, brass and custom materials. BODYCOTE HIP www.bodycote.com Bodycote is the world’s leading provider of metallurgical services. Hot Isostatic Pressing (HIP) of PM components is just one of the many services that Bodycote provides, from the design and fabrication of the PM container to the powder filling, evacuation, sealing and HIP. CAPSTAN Capstan is a leader in sintered metal manufacturing. Gears, multi-level structural components and filters are just a few of our specialties. Demonstrating a serious commitment to leading edge

62

technologies, Capstan finds solutions to the most demanding applications. Manufacturing locations are strategically located California, Tennessee, Mexico and Massachusetts. Fifty years of experience gives Capstan a definitive edge in materials and manufacturing technologies. FMS CORPORATION www.fmscorporation.com FMS Corporation is a precision manufacturer of high-performance sintered metal components, serving the off-road vehicle, aerospace, computer and home appliance industries, among others. Material capabilities include high-performance, high-density steels, stainless steel, soft magnetic materials, and many nonferrous alloys. Production capabilities include in-house tool design and manufacture, conventional and wire EDM, compaction from 2 to 1,100 tons, high-temperature vacuum sintering, CNC machining, grinding, lapping, resin and oil impregnation. KEYSTONE POWDERED METAL COMPANY www.keystonepm.com Keystone Powdered Metal Company is a leading powder metal parts supplier to the automotive OEMs, automotive Tier I and Tier II manufacturers. Keystone provides its customers with highly engineered products which utilize the industry’s most advanced technologies and material systems. Primary products include planetary carriers, pinion gears, parking gears, transmission sprockets, engine timing sprockets and assembled one-way clutches for use in automotive powertrain applications. METAL POWDER PRODUCTS COMPANY www.metalpowderproducts.com Metal Powder Products Company is an international provider of custom-engineered powder metallurgy product solutions to customers in a variety of industries. MPP has developed a number of innovations in material formulation, sintering, densification, powder metallurgy joining techniques, and value-added secondary operations. MPP is the largest manufacturer of powder metal aluminum structural parts in North America. METALPÓ INDÚSTRIA E COMÉRCIO LTDA. www.metalpo.com.br Since 1967, Metalpó focuses its activities on powder metallurgy as a nonferrous powders and sintered-parts producer. Typical Metalpó powder metallurgy products are self-lubricating

bearings (Bronze and Iron), structural parts (Iron, Stainless Steel, Bronze and Brass) and metal powders (Copper, Premix Bronze, Prealloyed Bronze, Brass and Tin). Metalpó has achieved recognition for the highest level of quality with quality assurance management system ISO 9001/2000 and ISO TS 16949 assessments. METCO INDUSTRIES www.metcopm.com Metco Industries, Inc., has molding capabilities up to 400 ton including multi-action for ferrous and nonferrous applications. Advanced secondary machining facility on site for quicker response to customer demands. Celebrating 25 years of PM excellence in the automotive, lawn & garden, recreational vehicle, healthcare and commercial markets. MI-TECH METALS, INC. www.mi-techmetals.com Mi-Tech Metals, Inc., located in Indianapolis, Indiana, produces tungsten heavy alloy and copper and silver tungsten composite materials. Additional materials include tungsten carbide and pure molybdenum and tungsten. Mi-Tech maintains inventory to meet immediate requirements and our extensive machine shop manufactures parts to print. MOTT CORPORATION www.mottcorp.com Mott Corporation has been providing unique solutions in the development and application of porous metal media since 1959. Mott partners with customers in many industries to engineer and design porous metal products with very specific tolerances and attributes. Mott is ISO 9001:2008 Certified and also maintains Class 100 and Class 10,000 clean room environments. Visit our Web site www.mottcorp.com for our complete line of porous metal capabilities and products. NETSHAPE TECHNOLOGIES, INC. www.netshapetech.com A manufacturer of engineered, complex, high-strength components using powder metallurgy and metal injection molding, focused on industrial markets. NetShape is a Lean-focused, global supplier with 3 PM and 1 MIM operations worldwide, including a facility in Suzhou, China. Industry-leading technologies include high-performance materials, unmatched shape complexity, tolerances and part size. Our innovative Conversioneering® process and strong engineering support offer unmatched value and support for converting parts to PM.

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 63

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2010 WEB SITE DIRECTORY

PLANSEE SE www.plansee-group.com With the four divisions PLANSEE HPM, GTP, CERATIZIT and PMG, the Plansee Group worldwide delivers excellence in powder metallurgy. The Group has 33 production sites across three continents and the global sales network spans 49 countries. In the 2008/09 fiscal year the Group generated sales of 1.1 billion euros and employed a workforce of 6,350 employees. Powders and powdermetallurgically manufactured semifinished products, tools and ready-toinstall components from high-performance materials of Plansee are used in many high-tech products of everyday life. Amongst others, Plansee supplies the automotive, electronics and construction industry and develops solutions for mechanical and powder engineering as well as lighting and medical technology. PMG www.pmgsinter.com PMG – The global Powder Metal Group. What we stand for: • Unsurpassed powder metal components for engine, transmission, chassis, and electrical applications. • Development of innovative components and systems for the automobile of the future. • Worldwide close connection to our customers with our technical sales organization and our local production sites in Austria, China, Germany, Spain, and the United States. PMG puts precision in powder metallurgy. PSM INDUSTRIES, INC. www.psmindustries.com Six divisions offer highly engineered, technology-driven solutions which provide optimum performance at the lowest cost. Material experts—technologies include PM, MIM, tungsten carbide, steel-bonded titanium carbide (a metal matrix composite) and fully dense tool steels. Small parts to large. Low and high volume. High-temperature sintering. Completed assemblies. Experienced new product development including prototypes and cost reducing existing components. Serving all markets including automotive. www.psmindustries.com.

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

SELEE CORPORATION www.selee.com SELEE Corporation, a member of the Porvair Group, manufactures high-temperature, low-mass kiln furniture in seven different ceramic compositions to meet your application’s specific needs. We make both open-cell foam kiln furniture as well as micro-porous kiln furniture. We are also a distributor for Ferro Process Temperature Control Rings. Our manufacturing facility is located in the beautiful Blue Ridge Mountains in Hendersonville, North Carolina, U.S.A. Certified ISO 9001:2000 and ISO 4001:2004. SMC POWDER METALLURGY www.smcpowdermetallurgy.com SMC Powder Metallurgy is a 60-yearyoung PM manufacturer, diverse in the materials supplied, the business markets served, and the parts manufactured. SMC Powder Metallurgy manufactures in a modern 112,000 sq. ft. facility located in Galeton, Pennsylvania, dedicated solely to the manufacturing of powder metal components. SMC Powder Metallurgy is TS16949 certified company. For additional detail, please visit our Web site at www.smcpowdermetallurgy.com.

VOLUNTEER SINTERED PRODUCTS, INC. www.volunteersintered.com Established 1981, family owned/operated Press Range 20-200 Ton Materials include iron, prealloyed steels, brass, bronze, stainless Parts include gears, bearings, structurals, cams, etc. Secondary operations—copper infiltrating, brazing, coining, burnishing, drilling, tapping, turning, oil impregnation, deburring Inspections/QC ISO 9001 certified, Rockwell hardness, gear tester, optical comparator, surface finish, crush tester Specialties complex, close-tolerance parts, short lead times for tooling and production WESTERN SINTERING CO. INC. www.westernsintering.com Manufacturer of custom powder metal parts. Presses to 300 tons. Steel, stainless steel, and copper-base materials. Complete secondary facilities and heat treat in-house. ijpm

STERLING SINTERED TECHNOLOGIES www.sterlingsintered.com Sterling Sintered Technologies, an ISO 9001-2000 company, is an innovative leader in the manufacture of powder metal components. The Sterling team works with customers to concurrently design parts and processes for them. This approach has allowed Sterling Sintered and its customers to develop new applications and push PM technology to the forefront of our industry. Let Sterling Sintered do this for you. For additional information explore our Web site at www.sterlingsintered.com

63

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:51 AM Page 64

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ADVERTISERS’ INDEX

ADVERTISER

FAX

WEB SITE

PAGE

ACE IRON & METAL CO. INC._________(269) 342-0185 ______________________________________________________5 ACUPOWDER INTERNATIONAL, LLC ___(908) 851-4597 ________www.acupowder.com ___________________________42 ELNIK SYSTEMS ____________________(973) 239-6066 _________www.elnik.com __________________________________29 EPMA ___________________________44 01743 362968 _______www.epma.com _______________________________16 GLOBAL TITANIUM _________________(313) 366-5305 ________www.globaltitanium.com ________________________30 HOEGANAES CORPORATION _________(856) 786-2574 ________www.hoeganaes.com ___________INSIDE FRONT COVER NORTH AMERICAN HÖGANÄS INC. ____(814) 479 2003 ________www.nah.com __________________________________3 QMP ____________________________(734) 953-0082 ________www.qmp-powders.com ________________BACK COVER SCM METAL PRODUCTS, INC. ________(919) 544-7996 ________www.scmmetals.com ____________INSIDE BACK COVER SURFACE COMBUSTION_____________(419) 891-7151 ________www.surfacecombustion.com _____________________8

ADVERTISER’S REQUEST FOR INFORMATION FAX FORM Need more information on products or services seen in this issue?

Complete the form below and fax to the advertiser(s) of your choice. Fax numbers are listed in the advertisers’ index above.

To:___________________________________ Fax #: ______________________________________ Company: _________________________________________________________________________ Please send me more information on:_____________________________________________________ _________________________________________________________________________________ as advertised in the __________ issue of the International Journal of Powder Metallurgy. Please send information to: Name: Title: ________________________________________________________________________ Company: _________________________________________________________________________ Address:___________________________________________________________________________ City:____________________________ State:_______________ Postal Code: ___________________ Country:___________________________________________________________________________ Phone:___________________ Fax:___________________ E-Mail: ___________________________

64

Volume 46, Issue 1, 2010 International Journal of Powder Metallurgy

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:54 AM Page 65

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

56-64,C3,C4_MEETINGS_CONFERENCES 1/18/2010 11:54 AM Page 66

Previous

1-Page View

2-Page View

Search

Table of Contents