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JULY.AUG.2010.IJPM cover_July_August IJPM cover 7/22/2010 10:29 AM Page 1
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SHOW ISSUE
July/August 2010
46/4 2010 PM Design Excellence Awards The PM Industry in North America—2010 Heat Treatment of a MIM CoCrMo Alloy Industrial Sintering of Hybrid Cr-Mo-Mn Steels
FRONT MATTER_ FRONT MATTER 7/22/2010 10:45 AM Page 15
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FRONT MATTER_ FRONT MATTER 7/22/2010 10:45 AM Page 1
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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) G.F. Bocchini (Italy) F. Chagnon (Canada) C-L Chu (Taiwan) O. Coube (Europe) H. Danninger, FAPMI (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]
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46/4 July/August 2010
Editor’s Note PMT Spotlight On …Jason R. Forster 2010 APMI Fellow Awards An Appreciation—Alan Lawley Consultants’ Corner Pierre W. Taubenblat 2010 Poster Awards 2010 PM Design Excellence Awards Competition Winners PM World Congress in Florence Axel Madsen/CPMT Scholar Reports
ENGINEERING & TECHNOLOGY 25 State of the PM Industry in North America—2010 M.E. Lutheran
29 Industrial Sintering of Hybrid Low-Carbon 3Cr-0.5Mo-xMn Steels M. Selecká and A. Šalak
RESEARCH & DEVELOPMENT 43 Solution Annealing and Aging of a MIM CoCrMo Alloy P.V. Muterlle, I. Lonardelli, M. Perina, M. Zendron, R. Bardini and A. Molinari
DEPARTMENTS 53 PM Industry News in Review 55 Meetings and Conferences 56 Advertisers’ Index Cover: Grand Prize–winning parts from MPIF’s 2010 Design Excellence Awards competition. 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 7/22/2010 10:45 AM Page 2
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EDITOR’S NOTE
P
owderMet2010, a successful milestone for the PM and particulate materials industry, is now a part of history. In this post-show issue of the Journal, the text of the “State of the PM Industry in North America— 2010” address by MPIF President Mike Lutheran is included. In addition, Peter Johnson profiles the 2010 PM Design Excellence Awards Competition. The winning Grand Prize parts are displayed on the front cover. In keeping with tradition, this issue publishes the four reports prepared by the Axel Madsen/CPMT scholars. Based on their experiences at PowderMet2010, each report clearly identifies the many tangible and indirect benefits derived from their first exposure to the PM industry. In a very positive way the grant program serves to encourage worthy students to consider pursuing a professional career in our industry. A frequent contributor to the “Consultants’ Corner,” Pierre Taubenblat responds to readers’ questions in two diverse areas. A rationale is given for renewed interest in electrolytic copper powder, and the potential of infiltration to improve the properties of clutch hubs for automatic transmissions is assessed. Congratulations to Mike Jaffe and Herbert Danninger, the 2010 APMI Fellow Award recipients. Mike can claim over five decades of service to the PM industry, focusing on process and product development, design, manufacturing, and production. Herbert’s distinguished career in PM embraces academe, R&D, and proactive involvement in APMI and EPMA. In the “Engineering & Technology” section, Selecká and Šalak examine the effect of manganese additions and the type of manganese carrier on the microstructure and properties of a prealloyed hybrid low-carbon steels sintered under industrial conditions. The study confirms the reduction/self-cleaning effect of manganese vapor in the sintering atmosphere, resulting in attractive strength levels. Muterlle et al. detail the effects of solution annealing and aging on the properties of a CoCrMo alloy fabricated by MIM. By optimizing the solutionannealing temperature, attractive combinations of strength and ductility can be achieved. This is attributed to a high strain-hardening rate arising from the strain-induced transformation of austenite to martensite.
Alan Lawley Editor-in-Chief
In the course of my professional career I have, on occasion, attempted to differentiate unambiguously between engineering and science—and in turn to understand the differences between (and similarities of) engineers and scientists. The distinction is somewhat blurred since frequently engineers practice science and scientists do engineering. In this context, I found a recent article in “The Bent of Tau Beta Pi” (2010, vol. C1, no. 3, pp. 22–26) by Henry Petroski (Vesic professor of civil engineering and professor of history, Duke University) to be enlightening. He notes that engineers frequently invoke Dr. Theodor von Kármán’s oft-quoted distinction between scientists and engineers, namely, scientists seek to understand what is, whereas engineers seek to create what never was! It follows that science studies what is; engineering creates what never was. To quote Professor Petroski, “It is engineering and not science that has a direct influence on our daily lives, on our comfort, and on our standard of living.” I feel fortunate to have majored in engineering!
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
FRONT MATTER_ FRONT MATTER 7/22/2010 10:45 AM Page 3
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SPOTLIGHT ON-LEFT PG_ SPOTLIGHT ON 7/22/2010 10:47 AM Page 4
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SPOTLIGHT ON ...
JASON R. FORSTER, PMT Education: Associate Degree, Materials Engineering Technology, Penn State University—Dubois Campus, 2000
related issues. Since joining GKN, I have completed set-up of the metallurgical laboratory, worked on customer issues, and helped to develop new applications.
Why did you study powder metallurgy/particulate materials? In high school (St. Marys, Pennsylvania) we had a small compaction press, sintering furnace, sizing press, and metallurgical laboratory. I spent most of my senior year working in the laboratory making PM parts. I was fascinated by how you could take a powder and make it into a solid part.
What gives you the most satisfaction in your career? It’s very satisfying to work with the new materials that have been developed over the past few years. Some of these new materials are helping achieve new properties, especially density levels, that were never thought possible. These new materials will help grow the PM industry.
When did your interest in engineering/science begin? It started when I was young. I was always interested in knowing how things were made. Then when I was in high school and working in the metallurgical laboratory, my interest grew. It was amazing to me how you could tell which material and processing method were used to make a PM part by cutting it and looking at the inside with a microscope. What was your first job in PM? What did you do? My first job in PM was as a co-op high school student. I worked in the machine shop at Elco Sintered Alloys, Kersey, Pennsylvania. I also spent my first two summers during high school tumbling parts. Describe your career path, companies worked for, and responsibilities. After graduation I started working for Allegheny Powder Metallurgy (now NetShape Technologies), Falls Creek, Pennsylvania, as a laboratory technician checking parts for cracks and performing failure analysis for customers. I spent the next eight years working my way up to the rank of materials engineer, eventually taking on laboratory management responsibilities. In this capacity, I worked with engineers in developing different materials and properties, and on customer-
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List your MPIF/APMI activities. I am a member of the West Penn chapter of APMI and frequently attend their monthly meetings. What major changes/trend(s) in the PM industry have you seen? Customers are looking for improved properties and characteristics in their parts, such as high density and tighter tolerances. These changes are making engineers rethink conventional materials and manufacturing methods. Why did you choose to pursue PMT certification? I wanted to further my knowledge of the PM industry, and PMT certification was an effective way to achieve that goal. There are many different aspects of the particulate materials industry in which the PMT certification has been beneficial—in particular, an increased knowledge of the technology.
Metallurgist GKN Sinter Metals–St. Marys 104 Fairview Road Kersey, Pennsylvania 15846 Phone: 814-781-4804 Fax: 814-834-7156 E-mail:
[email protected]
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
SPOTLIGHT ON-LEFT PG_ SPOTLIGHT ON 7/22/2010 10:47 AM Page 5
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SPOTLIGHT ON ...JASON R. FORSTER, PMT
How have you benefited from PMT certification in your career? Gaining PMT I certification has helped to broaden my knowledge of the PM and particulate materials industry.
What are your current interests, hobbies, and activities outside of work? I am a member of the local fire company. Spending time with my family is a major part of my “outside of work” life. ijpm
Would you like to be featured here? Have you been PMT Certified for more than 2 years? Contact Dora Schember (
[email protected]) for more information.
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Award Recipients_ CONSULTANTS' CORNER 7/22/2010 10:48 AM Page 6
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2010 FELLOW AWARD RECIPIENTS
A prestigious lifetime award recognizing APMI International members for their significant contributions to the society and their high level of expertise in the science, technology, practice, or business of the PM industry
MYRON I. JAFFE Better known as Mike, he has made important contributions and is widely recognized for his consulting work in research, process & product development, design, manufacturing, and production. With over 57 years of dedicated service to the PM industry, he is well recognized as the “man with the popcorn press,” a demonstration press that dramatically illustrates particulate compaction. With nearly 50 years of APMI membership, he has parlayed his strong engineering background (BSEE from Northeastern University) with business savvy (MBA from Harvard Business School) to assist in technology transfer through technical marketing, education/teaching, and many other technical industrial-advancement programs. A major emphasis of his professional career has been to educate potential end users about the advantages of powder metallurgy. Presently with Brewer Hill Designs, LLC, Mike supports his consulting by his strong academic achievements and the experience that he gained in the PM industry while working for 36 years in various positions at Sintered Metals, Inc. He has organized several seminars and has presented at every MPIF Basic PM Short Course since its inception 45 years ago. Mike is a past president of MPIF and the Powder Metallurgy Parts Association. He is a recipient of the MPIF Distinguished Service to Powder Metallurgy Award. He wrote “Improving Dimensional Tolerance” for the ASM Handbook, Vol. 7, Powder Metallurgy Technologies and Applications.
HERBERT DANNINGER Herbert has distinguished himself as a leader in PM for nearly 30 years. He is internationally known for his analysis of issues based on sound technical and scientific principles. As Full Professor for Chemical Technology of Inorganic Materials, Vienna University of Technology, he has worked as an efficient bridge between Eastern and Western Europe.His current teaching is supported by his strong academic achievements, Dipl.-Ing. in Technical Chemistry and PhD in Technical Science from Vienna University of Technology, and the experience that he gained while collaborating with the PM industry. A member of APMI International for over 20 years, Herbert is an active member of the APMI International Liaison Committee. He is currently Chairman of the “Gemeinschaftsausschuss Pulvermetallurgie” (the PM association of the German speaking countries), the Chairman of the Powder Metallurgy Group (Austrian Society for Metallurgy), a member of the EPMA Research and Training Group, and an annual lecturer at the EPMA training course. He has participated on many technical program committees for EPMA and MPIF conferences. Herbert has authored/co-authored over 300 PM-related publications in journals and conference proceedings, and supervised 39 PhD students on PM. He is a recipient of the Dr. Ernst Fehrer Prize of Vienna University of Technology and was honored as Skaupy lecturer at the Hagen PM symposium in 2006.
The 2010 APMI Fellow Awards were presented at PowderMet2010, Hollywood, Florida
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
Lawley Appreciation_Zheng et al 7/22/2010 10:49 AM Page 7
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AN APPRECIATION
ALAN LAWLEY— 25 YEARS AS EDITOR OF THE INTERNATIONAL JOURNAL OF POWDER METALLURGY Peter K. Johnson*
C
elebrating 25 years as editor-in-chief, Alan Lawley has enjoyed a long and distinguished career as an educator, researcher, consultant, and author. He took over leadership of the Journal from Founding Editor Henry H. Hausner in 1985, and has presided over numerous changes and improvements to the Journal, supporting its position as the leading authoritative publication for the international PM industry. Some of these changes have included a new title, a new format and frequency, an emphasis on quality, and a balance between theory, analysis, and practice. Kempton H. Roll, founding publisher and former executive director of MPIF and APMI says, “Alan had strong opinions and presented them in a friendly way. He brought an overseas connection to the Journal. His good sense of humor continues to be reflected in his editorial columns.” Alan was introduced to PM in 1967 as a new faculty member at Drexel University, through a major U.S. government–sponsored Themis research program on PM. “They needed a project director and I was chosen,” he recalls. “I could barely spell powder metallurgy at the time.” After receiving a PhD in metallurgy from the University of Birmingham in England he received an appointment in 1958 as a post-doctoral fellow at the University of Pennsylvania. He spent two years at Penn before joining the Franklin Institute as a laboratory manager, a post he held for six years. Alan helped develop Drexel’s noteworthy PM academic and research programs, concentrating on atomization, triaxial compaction, sintering, new ferrous alloys, and powder forging. He became a full professor in 1969 and retired from Drexel as the Grosvenor Professor of Metallurgy in 2006, when he achieved emeritus rank. He has advised
*Contributing Editor, International Journal of Powder Metallurgy, APMI International, 105 College Road East, Princeton, New Jersey 08540-6692, USA; E-mail:
[email protected]
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Lawley Appreciation_Zheng et al 7/22/2010 10:49 AM Page 8
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ALAN LAWLEY—25 YEARS AS EDITOR OF THE INTERNATIONAL JOURNAL OF POWDER METALLURGY
25 doctoral students and 25 master students, most of whom are still working in the PM industry. He has authored or co-authored more than 300 technical publications. He received the MPIF Distinguished Service to PM award in 1991 and was named an APMI Fellow in 1998, in addition to election to the prestigious National Academy of Engineering. As a strict grammarian and serious upholder of the King’s English, he admits to failing students for their wordsmithing deficiencies and never accepting split infinitives from Journal authors. Pierre Taubenblat, chairman of the Editorial Review Committee says, “Alan has a unique style
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in approaching authors and is always responsive to their needs and gives constructive feedback. By combining theory and practice, he has made the Journal into a seamless entity and a much respected publication.” Reflecting on his long editorial tenure, Alan is most pleased at building a wider bridge between industry and the academic community. “I also tried to provide more continuity between basic and applied research topics and PM manufacturing,” he says. “And I am particularly pleased at the success of our focus issues covering leading-edge technologies in PM and particulate materials.” ijpm
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
CONSULTANTS' CORNER_ CONSULTANTS' CORNER 7/22/2010 10:50 AM Page 9
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CONSULTANTS’ CORNER
PIERRE W. TAUBENBLAT, FAPMI, FASM* Q
There appears to be renewed interest in electrolytic copper powder. Why is this and what are the advantages and major applications? There are currently no domestic electrolytic copper powder (ECuP) producers selling to customers. However, one company in this country produces ECuP for their internal needs. The majority of ECuP is currently made in China, Europe, Japan, and Russia. The last major domestic producer of ECuP was AMAX which exited the market in the 1980s, having captured about a 25% global-market share. In theory, and on a small laboratory scale, it is easy to make ECuP in limited quantities. All that is needed is a large beaker, copper and stainless steel wires, copper sulfate and sulphuric acid electrolytes, and a DC power supply. A simple setup for producing ECuP is shown in Figure 1. Once the circuit is closed, copper powder begins to precipitate out on the cathode and then falls to the bottom of the cell where it is collected. It is then washed, dried, and classified. The final ECuP product is characterized by high purity, a unique dendritic shape (with particles forming tree- and needle-like growth branches), and excellent green
strength. A representative illustration of the morphology of ECuP is shown in Figure 2. By changing the electrolyte composition, current density, cell potential, and bath temperature, ECuP with apparent densities between 1 and 4 g/cm3 can be made by hammer milling, screening, and blending the as-produced powders. More specialized ECuP with an apparent density as low as 0.5 g/cm3 and an exceptionally high green strength (>34 MPa (5,000 psi)) can be produced when the precipitated powder is handled carefully so that the original dendritic structure of the powder is preserved. Major applications for ECuP are friction components, and electrical and thermal conductors. Other applications include sintered parts such as bearings, blends with iron powders, and thinwalled green components such as frangible bullets.
Figure 1. Production of electrolytic cooper powder—schematic
Figure 2. Optical micrograph showing morphology of ECuP
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*President, Promet Associates, 358 North 4th Avenue, Highland Park, NJ 08904, USA; Phone: 732-545-9775; Mobile: 848-248-8473; E-mail: pierreGersey@ aol.com
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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CONSULTANTS' CORNER_ CONSULTANTS' CORNER 7/22/2010 10:50 AM Page 10
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CONSULTANTS’ CORNER
Q
We are producing clutch hubs for automatic transmissions and would like to improve density, hardness, and strength. Would infiltration be a good alternative to using higher compacting pressures, higher sintering temperature, a longer sintering time, and/or coining? Infiltration is one of powder metallurgy’s (PM) most versatile and complex processes. It is used to enhance density, strength, and hardness, to seal porosity, and to improve machinability. Infiltration has a long history of success in achieving property enhancement and has been an integral process in solving multiple problems for over 50 years. There are six main types of infiltrants that have evolved during this time: (1) The earliest infiltration processes are still an option today and use pure copper slugs placed on the top or the bottom of the part to be strengthened. When the melting temperature of copper, 1,083°C (1,981°F), is reached capillary forces allow the liquid copper to be absorbed into the structure. This infiltration method is simple and relatively easy to implement but often erodes the surface of the parts. (2) The next generation of infiltrants uses a blend of copper powders containing iron, graphite, manganese, and sometimes zinc. The product has good green strength but generally produces a loose residue which needs to be removed from the parts. (3) In the early 1970s new infiltrants were developed that essentially eliminated erosion and produced a hard non-sticking residue that was easily removed from the parts. These infiltrants are made by atomization and contain combinations of aluminum, iron, manganese, and nickel (<10 w/o total). (4) Parallel to development (3), a non-residue infiltrant was created that contained cobalt as the main ingredient. The infiltrant is produced by atomization and the relatively expensive cobalt additive results in no residue and no erosion. The infiltrant products cited above require a compaction step to form a slug which is then placed on the top, bottom, or on both surfaces of the compact prior to sintering. Two newer types of infiltrants are also available, (5) one that can be delivered in the form of a paste that is squeezed out on the part via a delivery sys-
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tem, and (6) a product that is available in wire form and other configurations. All six of these products can be selected and used today. Most copper powder producers make infiltrants in powder form and one company makes it in wire and other shapes. After sintering the parts, all infiltrants enhance density, hardness, tensile strength, and corrosion resistance. They also improve the machinabilty and impact strength of sintered parts. At the sintering temperature, the infiltrant is absorbed into the pores by capillary action, producing a composite material. Infiltration is still an art rather then an exact science because results produced by the same infiltrant are affected by furnace conditions, the most critical being temperature, time, and atmosphere. A conservative approach would be to select more than one infiltrant and to evaluate and compare infiltrant costs and the cost of the additional steps required to achieve the desired properties. For example, with 12.5 w/o of an atomized infiltrant compacted to 7.2 g/cm3, typical mechanical properties after infiltration are cited in Table I. The part consisted of an Fe-0.8 w/o graphite steel matrix after one-step infiltration/sintering at 1,121°C (2,050°F) for 1 h. TABLE I. PROPERTIES OF INFILTRATED STEEL Green Density Infiltrated Density Apparent Hardness Impact Strength Transverse Rupture Strength Tensile Strength Elongation
6.7 g/cm3 7.7 g/cm3 91 HRB 13 J (10 ft.·lb.) 1,286 MPa (186,000 psi) 794 MPa (115,000 psi) 2%
In this example, the increase in density from 6.7 to 7.7 g/cm3 and the new composite microstructure produced by the infiltrant are the primary reasons for the excellent mechanical properties developed. 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 085406692; Fax (609) 987-8523; E-mail:
[email protected]
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
Outstanding Poster Award_ CONSULTANTS' CORNER 7/22/2010 10:51 AM Page 11
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OUTSTANDING POSTER AWARD
SURFACE CHARACTERIZATION OF SHOT PEENED ALUMINUM POWDER METALLURGY ALLOYS Matthew D. Harding, D. Paul Bishop, Dalhousie University & Ian W. Donaldson, GKN Sinter Metals
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Outstanding Poster Award_ CONSULTANTS' CORNER 7/22/2010 10:52 AM Page 12
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OUTSTANDING POSTER AWARD
The International Journal of Powder Metallurgy would also like to recognize the Posters of Merit from PowderMet2010: Development of a WC-Ni-Si-Al-Based Cemented Carbide for Engineering Applications Edmilson O. Correa, Julio N. Santos, Universidade Federal de Itajubá, Itajubá, Minas Gerais, Brazil & Aloisio N. Klein, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil Diffusion Analysis in Iron Powder Metal Matrix Composites Steven R. Spurgeon, Joseph C. Hsieh, Mitra L. Taheri, Drexel University, Philadelphia, Pennsylvania, USA Bridging the Research-to-Commercialization Gap: Industrial Scalability of Low-Cost Oxide Dispersion-Strengthened (ODS) Ni-Based Alloy Precursor Powders John L. Meyer, Joel R. Rieken, Iowa State University & Iver E. Anderson, David J. Byrd, Ames Laboratory, Ames, Iowa, USA
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
design excellence award winners_Zheng et al 7/22/2010 10:52 AM Page 13
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DESIGN EXCELLENCE AWARDS
2010 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS Peter K. Johnson*
GRAND PRIZE AWARDS The four parts selected as the Grand Prize winners are shown in Figure 1. GKN Sinter Metals, Auburn Hills, Michigan, won the Grand Prize in the automotive—transmission category for a fully integrated planetary carrier and rocker-style one-way clutch assembly (Figure 2), an industry first. Designed and made for Ford Motor Company, Dearborn, Mich., the clutch assembly is used in the Ford Super Duty truck 5R110 five-speed automatic transmission for both diesel and gasoline engines. The application is a three-piece sinter-brazed planetary carrier consisting of both PM copper-steel and sinter-hardened materials, assembled
Figure 1. Grand Prize winners
Winners of the 2010 Powder Metallurgy Design Excellence Awards Competition, sponsored by the Metal Powder Industries Federation, were announced at PowderMet2010, the 2010 International Conference on Powder Metallurgy & Particulate Materials. Receiving grand prizes and awards of distinction, the winning parts are outstanding examples of powder metallurgy’s (PM) precision, performance, complexity, economy, and innovative design advantages. Competing against manufacturing processes like die casting, hobbing cast iron, weldments, machining, and investment casting, the winning PM parts offer high strength, remarkable performance under demanding conditions, precision, and cost savings. End-use markets include automotive, industrial machinery, sporting goods, defense, firearms, and high-security locks. PM’s sustainability or “green” benefits are readily apparent in many of the winning parts. For example, the process eliminates harmful cutting fluids and volatile organics, reduces scrap and waste, cuts energy and fuel consumption, and contributes to recycling.
The awards were presented at PowderMet2010 in Hollywood, Florida.
*Contributing Editor, International Journal of Powder Metallurgy, APMI International, 105 College Road East, Princeton, New Jersey 08540-6692, USA; E-mail:
[email protected]
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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design excellence award winners_Zheng et al 7/22/2010 10:53 AM Page 14
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2010 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
with a single-pressed cam plate, which is also sinter-hardened. The application consists of four parts (cam plate, spider, clutch hub, and rocker plate) that are combined with 12 steel rocker struts and springs, a retainer plate, and snap ring to form the one-way clutch planetary carrier assembly. Providing a cost savings of more than 25%, the PM assembly replaced a two-piece riveted planetary carrier attached by the spline interface with a full one-way clutch assembly. GKN achieved a density of 7.25 g/cm3 in the single-pressed complex sinterhardened cam form without warm compaction and high-temperature sintering. Secondary operations are limited to machining the bearing journals, oil holes, and pinion holes. Smith Metal Products, Lindstrom, Minnesota, received the Grand Prize in the hand tools/recreation category for a 17-4 PH stainless steel hunting arrow tip—called a shuttle T-lock broadhead— made by metal injection molding (MIM) for Trophy Taker, Inc., Plains, Mont. Figure 3. Formed to a
final density of 7.6 g/cm3, the unusual shape extends the design engineering advances of the MIM process. The mold design for the ferrule was challenging because of the long aspect ratio of the t-slot cores running parallel to the length of the part. Other manufacturing processes were considered but could not provide the necessary geometry for commercial production, and the prototypes cost many times more than MIM. The broadhead has a yield strength of 945 MPa (137,000 psi) and a tensile strength of 1,096 MPa (159,000 psi). The ferrule hardness is 36 HRC and the blade hardness is 38 HRC. Secondary operations are limited to final grinding of a razor sharp edge on the tip of the ferrule and the leading edge of the blade. FloMet LLC, DeLand, Florida, won the Grand Prize in the aerospace/military category for a safe and arm rotor (Figure 4) used in an explosive device for a Department of Defense application. Produced by the MIM process, the 316L stainless steel part is formed to a density of >7.6 g/cm3. Its significant properties include an ultimate tensile strength of 517 MPa (75,000 psi), yield strength of 172 MPa (25,000 psi), 50% elongation, 190 J (140 ft.·lbf) impact strength and 67 HRB hardness. The complex shape features numerous outside radii and angular surfaces. At least 12 functional features and surfaces are geometrically controlled by concentricity, profile, and true position tolerances. No secondary operations are performed. The part is assembled into a housing to provide the two-stage safety for the explosive device. It replaced a zinc die casting whose mechanical properties were ultimately not consistent enough to pass validation testing. The MIM process is highly sustainable when compared with competitive processes such as machining and EDM. The process is customized from for-
Figure 3. Shuttle T-lock broadhead
Figure 4. Safe and arm rotor
Figure 2. Clutch and carrier assembly
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
design excellence award winners_Zheng et al 7/22/2010 10:54 AM Page 15
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2010 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
mulating the feedstock and recycling through manufacturing. For example, the proprietary debinding furnaces feature a scrubber system that processes all chemistry internally, removing any potential for the exit of gases into the atmosphere. Materials taken from the scrubbers (waxes, oils, waste) are recycled and used in a road paving product. Advanced Materials Technologies Pte Ltd, Singapore, won the Grand Prize in the industrial motors/controls & hydraulics category for four complex 316L stainless steel MIM parts—lock cover, lock barrel pin, lock barrel boss, and lock barrel square, Figure 5. The parts are assembled into a locking device for heavy machinery operating in harsh environments. Choosing the MIM process over casting provided a superior surface finish that did not require polishing, enhanced corrosion resistance, as well as a 30% cost savings. The parts are formed to a density of >7.5 g/cm3 and feature a tensile strength of 517 MPa (75,000 psi), a yield strength of 172 MPa (25,000 psi), 50% elongation, and a 67 HRB hardness. They must undergo cyclical rotational testing of more than 300,000 cycles and a 48 h salt-spray test. Secondary operations are limited to coining the cover and barrel and glass beading the four parts to provide a uniform color.
Figure 6. Award of Distinction winners
AWARDS OF DISTINCTION Eight parts were selected for Awards of Distinction, Figure 6. PMG Füssen GmbH, Füssen, Germany, won the Award of Distinction in the automotive—engine category for a multi-level PM steel crankshaft sprocket (Figure 7) used in a V-6 engine. Made for iwis motorsysteme GmbH & Co. KG, Munich, Germany, the multi-level part has a density of 7.0 g/cm3, a yield strength of 310 MPa (45,000 psi), and a tensile strength of 372 MPa (54,000 psi). It
Figure 5. Lock cover and barrels
Figure 7. V-6 crankshaft sprocket Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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design excellence award winners_Zheng et al 7/22/2010 10:55 AM Page 16
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2010 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
Figure 9. Dead-locking lever
Figure 8. One-way clutch outer race
features an inner ring diameter that is pressed and machined after sintering to achieve high-precision tolerances. Even with secondary operations—sizing, machining, induction hardening, steam treating, and final grinding on the lower hub—PM still provided significant cost savings for the customer. PMG Indiana Corporation, Columbus, Indiana, received the Award of Distinction in the automotive—transmission category for a one-way clutch outer race (Figure 8) made for EXEDY Globalparts Corporation, Belleville, Mich. Used in a torqueconverter stator, the heavily loaded part transmits more than 274 Nm (202 ft.·lbf) of torque amounting to extremely high Hertzian contact stresses on the cam surface and high tensile stresses in the hoop area. A proprietary surface densification process forms the inner surface of the race to a minimum density of 7.7 g/cm3. The process provides improved durability over a fully dense hotforged part. The PM part was converted from conventional steel using sprag elements with a cam profile into a design incorporating the cam profile in the inner diameter. ASCO Sintering Company, Commerce, California, won an Award of Distinction in the hardware/appliances category for a high-strength sinter-hardened PM steel dead-locking lever (Figure 9) made for a 40H series high-security mortise lock made by Stanley Security Solutions, Inc., Indianapolis, Ind. Warm compacted and sintered to a density of 7.0 g/cm3, the part has a 1,000 MPa (145,000 psi) ultimate tensile strength, a 12.9 J (9.5 ft.·lbf) impact strength, a 276 MPa (40,000 psi) fatigue strength, and a 30 HRC hardness. The part undergoes resin impregnation, deburring, zinc plating, and chromating.
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By eliminating a milling operation, which uses cutting fluids that may contain harmful chemical agents that ultimately contribute to the “greenhouse effect,” PM not only provided a 40% cost savings but clearly demonstrated PM’s “sustainability” advantage. Capstan Atlantic, Wrentham, Massachusetts, won another Award of Distinction in this category for a high-density transfixed pinion gear and sector used in a high-volume printing application, Figure 10. Formed to a density of 7.3 g/cm3, the parts have a 1,345 MPa (195,000 psi) tensile strength, 1,276 (185,000 psi) yield strength, a 517 MPa (75,000 psi) fatigue limit and a 60 HRC hardness. The pinion gear, which meets the AGMA Q9 precision level, is selectively roll-densified and crowned for bending-fatigue resistance and rolling-contact-fatigue resistance. Both parts are hardened for wear resistance. Capstan’s proprietary high-strength PM process and gear-crowning design provided parts with twice the “in-service” life of those made via the previous manufacturing process and eliminated field failures due to tooth breakage experienced by those previous components. The crowning process increased the gear life from 2,000,000 cycles to 4,000,000 cycles. Burgess-Norton Mfg. Co., Geneva, Illinois, won the first Award of Distinction in the hand tools/recreation category for a final belt-drive
Figure 10. Transfixed gear and sector Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
design excellence award winners_Zheng et al 7/22/2010 10:56 AM Page 17
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Figure 11. Motorcycle drive sprocket
sprocket (Figure 11) which transmits torque from the transmission to the rear wheel on a large motorcycle. Replacing a sprocket made from hobbed cast iron, the high-volume PM steel part is produced on a 700 mt (770 st) CNC hydraulic compacting press, which forms the outside-diameter flange on the top and a center web on the bottom, a combination of features not possible with conventional compacting technology. The part has a 345 MPa (50,000 psi) minimum tensile strength, HRB 80 minimum apparent hardness with a steam-oxide surface treatment that has a 50 HRC hardness. PM provided a cost savings of up to 30%, while improving reliability, quality, and wear and corrosion resistance over the wrought part. PM demonstrates its sustainability benefits by eliminating machining scrap and harmful coolants from the waste stream, while improving the end product’s fuel economy with a stronger, yet lighter, component. Megamet Solid Metals, Inc., Earth City, Missouri, won the other Award of Distinction in this category for an upswept grip safety (Figure 12) used in the 1911-style 45-caliber pistol made by Colt’s Manufacturing Company, LLC, West Hartford, Connecticut. The complex 17-4 PH stainless steel part is produced by the MIM process to a density of 7.6 g/cm3. It has an as-sintered yield strength of 662 MPa (96,000 psi) and a tensile strength of 952 MPa (138,000 psi). The upswept design of the grip safety part, which was traditionally investment cast, would previously require extensive secondary machining. Switching to the MIM process reduced customer lead times and provided exceptional cost savings, in addition to Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
increasing production rates and producing a more uniform part. The upswept grip safety performs several functions: it blocks the trigger from firing, shields the hammer from impacting or injuring the shooter’s hand when the pistol cycles, and interacts with the shooter’s palm for comfort. Colt performed a 10,000-cycle test to qualify the part. Lovejoy Sintered Solutions LLC, Downers Grove, Illinois, won two Awards of Distinction in the industrial motors/controls & hydraulics category. The first award is for a rotating machine counterweight (Figure 13) used in a scroll compressor for refrigerated trucks and trailers. The counterweight balances the vibration of the orbiting scroll that compresses the gas. Formed to a density range of 6.7 to 7.0 g/cm3, the PM steel part has a tensile strength of 324 MPa (47,000 psi) and 57–60 HRB hardness. It provided a 42 percent cost savings over the two-piece design it replaced, which required machining the bolt and threaded holes in addition to separate tooling and presses for both parts. The customer conducted fatigue
Figure 12. Upswept grip safety
Figure 13. Counterweight
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design excellence award winners_Zheng et al 7/22/2010 10:57 AM Page 18
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2010 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
and vibration testing and reports double the fatigue performance compared with the previous two-piece version. In addition, assembly of the two pieces required the use of thread-locking fluid, which contains volatile organics; eliminating this fluid through the one-piece design is an obvious sustainability benefit of PM. Lovejoy Sintered Solutions LLC and its customer Rosta AG, Hunzenschwil, Switzerland, received the final Award of Distinction in this category for a PM steel tensioner assembly used in a belt- or chain-drive system, Figure 14. Made to a density range of 6.2 to 6.9 g/cm3, the parts have an ultimate tensile strength of 297 MPa (43,000 psi), a yield strength of 269 MPa (39,000 psi), and a 70 HRB hardness. The housing must withstand 373 N-m (275 ft.·lbf) torque between the column and flange and the arm must survive 421 N-m (310 ft.·lbf). The application was originally an assembly of weldments of a steel tube and plate requiring sawing and stamping; PM eliminated the material loss associated with these operations. Pressing the protractor into the arm eliminated the labor-intensive operation of roll printing an angle scale on the housing. Choosing the PM process provided a cost savings of 26% over the previously made version. Tapping a mounting hole in the housing flange and powder coating are the only secondary operations. Past winners of the MPIF PM Design Excellence Awards Competition can be viewed by visiting www.mpif.org/designcenter/designcenter.asp? linkid=11. ijpm
Figure 14. Tensioner assembly
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
PM World Congress_ CONSULTANTS' CORNER 7/22/2010 10:58 AM Page 19
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AMETEK
AMETEK
AMETEK’s
AMETEK
WWWAMETEKMETALSCOM
Visit V isit us at BOOTH # 77 77
Fortezza da Basso Centre, Florence
www.ametekmetals.com
PM World Congress_ CONSULTANTS' CORNER 7/22/2010 10:59 AM Page 20
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WORLD CONGRESS
PM2010 IN ITALY The 2010 Powder Metallurgy World Congress and Exhibition (PM2010), October 10 to 14, in Florence, Italy, will showcase the technology within, and the capability of, the global powder metallurgy industry. Sponsored by the European Powder Metallurgy Association, in cooperation with key members from the PM community in Italy, the World Congress features a four-day technical program including some 600 technical papers on powder metallurgy and particulate materials providing insight into current R&D and recent industry developments and trends. The World PM Exhibition will showcase the latest developments from the global PM supply chain. Keynote speakers will cover PM industry trends in Asia, Europe, and North America. In addition, Sefano Maggi, Fiat Group Automotive, will address “Automotive Challenges for the Next Future. Fiat Answers and Material Trends.” For further information visit http://www.epma.com/pm_2010/home2.htm
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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EXHIBITORS
PM2010 IN ITALY
Air Products Europe Alvier AG PM-Technology Ametek Speciality Metals/Reading Alloys Asbury Carbons Atect Corporation ATLASpress Manfred Pscherer GmbH Atomising Systems Ltd Arburg GmbH + Co KG Avure Technologies BASF SE B.M. di Belluzzo S.r.l Bodycote Heiss-Isostatisches Pressen GmbH Burkard Metallpulver Vertrieb & Hofer Werkstoff-Marketing Beratung Carpenter Powder Products GmbH Chang Sung Corporation Cremer Thermoprozessanlagen GmbH Cuccolini S.r.l Diamante A&T Magazine Dieffenbacher GmbH + Co. KG Dorst Technologies Ecka Granulate GmbH & Co. KG EISENMANN Anlagenbau GmbH & Co. KG Elino Industrie – Ofenbau GmbH Elnik Systems EPSI, FREY & Co GmbH & FCT Systeme Epson Atmix Corporation Erasteel Kloster AB Erowa AG Ltd Eurotungstene Metal Powders Fette GmbH/Roboworker Automation GmbH Fraunhofer Institut – IFAM Fraunhofer Institut – IKTS The Furnace Belt Company Graphit Kropfmühl A G Hoeganaes Corporation Hoganäs AB
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
Institut Dr. Foerster & Co. KG Italian Showcase Japan Powder Metallurgy Association Kohsei Co., Ltd Lauffer Pressen GmbH Linbraze S.A.S LINDE AG, LINDE Gases Division Linn High Therm GmbH LMI GmbH Mahler GmbH Maney Publishing Masria for Metallurgical Powder Industry MEDAV GmbH Metal Powder Industries Federation & APMI Metal Powder Report MUT Advanced Heating GmbH Nabertherm GmbH NMD New Materials Development GmbH Osterwalder AG Phoenix Scientific Industries Ltd (PSI) PolyMIM GmbH Pometon SpA Powder Injection Moulding International Proment – Project Management Ltd Rio Tinto Metal Powders Sacmi Imola S.C. Sandvik Osprey Ltd – Powder Group SCM Metal Products Inc. Sentes-BIR A.S. Shenzen Gem High-Tech Co., Ltd SMS Meer GmbH Steuler Industrieller Korrosionsschutz GmbH Sumca SAS Timcal Graphite & Carbon UDDEHOLM Yuelong Superfine Metal Co., Ltd
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axel madsen_Zheng et al 7/22/2010 11:25 AM Page 22
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PERSONAL INSIGHTS
AXEL MADSEN/CPMT SCHOLAR REPORTS
MATTHEW HARDING Dalhousie University Halifax, Nova Scotia Canada I have been involved in powder metallurgy (PM) for the last year. The opportunity that the Scholarship and Grant Committee of the Center for Powder Metallurgy Technology (CPMT) gave me (through the Axel Madsen Conference Grant Program) to attend PowderMet2010 provided a unique experience to not only see new developments and gain a better understanding of the PM industry, but also to take advantage of the networking opportunity it presented. Virtually all sectors of the industry were represented at the conference and exhibition, from powder producers to parts manufacturers and the R&D community. Even with the large number of attendees, there was a sense that this was a tightly knit group. Inclusion of the social events in the registration package for the grant recipients provided an experience that otherwise would not have been possible. All the social events, from the opening night reception, to the industry recognition and design luncheons and the conference dinner were well organized and the food was outstanding. Along with the finances provided by the grant, recognition from individuals within the PM industry that came with the grant was most rewarding. I quickly met a number of individuals who received the grant in past years, some who have since spent 20+ years in the industry. Even during my paper presentation, I felt as though being a grant recipient increased interest in listening to my presentation—a rewarding experience. The technical sessions were interesting and it was good to see that everyone was sharing knowledge
gained through research with the industry. It was particularly enlightening to listen to the informal discussions that took place after the sessions, with people coming together, sharing thoughts, and providing feedback and suggestions on future R&D to complement the results of studies that were presented. This was the first professional conference I have attended and I was somewhat nervous about presenting my work, but after sitting through a number of sessions that feeling quickly passed after seeing the friendly and constructive attitude of everyone present. I would like to thank the CPMT Scholarship and Grants Committee for this opportunity. It was an incredible experience that definitely broadened my understanding of the PM industry and built on my interest in the technology. I would also like to thank my supervisor, Dr. Paul Bishop, and Ian Donaldson for their continued support and help in preparing for the conference, without which my research would not have been possible.
MIKE LEFLER University of Utah Salt Lake City, Utah PowderMet2010 was a great experience for me. Although this was not my first international conference, I enjoyed the time in Florida more than at my previous conference. I would like to thank the Scholarship and Grants Committee of the Center for Powder Metallurgy Technology (CPMT) for selecting me as a recipient of an Axel Madsen/CPMT Conference Grant. Hollywood, Florida, is a beautiful city set in a stunning beachfront location. I tried to take advantage of the beach as well as the outdoor facilities at the
Axel Madsen/CPMT Conference Grants are awarded to deserving students with a serious interest in PM. The recipients were recognized at the Industry Recognition Luncheon during PowderMet2010.
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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AXEL MADSEN/CPMT SCHOLAR REPORTS
Westin Diplomat Hotel as much as possible. Whenever the conference was not is session I spent my time swimming in the ocean and the pools and enjoying the beach. Florida beaches are wonderful with their open access where one can go for miles without obstruction. Two things about the conference particularly impressed me. First, the powder metallurgy (PM) community appears to be a very close-knit group. The people whom I met were friendly and helpful, and while they were there for their own reasons, they appeared to be working together toward a common goal. Several of the presentations that I attended focused on the problems and opportunities that the entire industry is facing. This attitude of working together to create opportunities and solve common problems impressed me. I would like to especially thank Professor Zak Fang for his mentoring and help as well as for nominating me. In conclusion, I would again like to say that PowderMet2010 was a great learning experience that encouraged me to continue to pursue PM as a research topic and as a future professional career.
JOHN L. MEYER Iowa State University Ames, Iowa PowderMet2010, Ft. Lauderdale/Hollywood, Florida, was a wonderful opportunity to expand my understanding of powder metallurgy (PM), make excellent networking connections and visit a new location. On Sunday afternoon I arrived and found that The Westin Diplomat provided excellent accommodations and a perfect backdrop for the conference. Located directly on the beach it allowed me and other landlocked Midwesterners an opportunity to enjoy the beauty of the ocean. After becoming acquainted with the hotel it was time for the opening night reception. Hors d’oeuvres and beverages were available, providing a casual opportunity to meet new faces and hear about different viewpoints within the PM field. Having made over a dozen new contacts from various locales, I turned in for the evening. Monday provided the first day of technical sessions and the Industry Recognition Luncheon. Grant recipients were seated with industry representatives who provided excellent opportunities for dialogue. It was Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
certainly an honor to be recognized along with the authors of the Outstanding Technical Paper, the Excellence in Metallography awardee, and the APMI Fellow inductees. On Monday evening I ordered food to go, went through my presentation and caught some sleep. Tuesday was the day with many topics scheduled in my area of interest. There were several interesting talks in my session on atomization and I enjoyed giving a presentation on my work. It led to further discussions with industry personnel well after the presentation, which I was grateful for. After the Design Excellence Awards luncheon the grant recipients manned their posters. All the grant recipients were asked to prepare a poster covering their research and, after going through the process of creating a poster and knowing the hard work that went into all of the posters, I wish that more conference attendees would have stopped by during the poster session. I am most grateful for the positive interaction I had with those who did visit. After a long day it was time to unwind and the social events provided with the conference were a perfect fit. Following a water-taxi ride on the Intracoastal Waterway we arrived at the China Grill. The social hour and dinner exceeded my expectations and resulted in an enjoyable evening. Wednesday provided one last opportunity to attend technical sessions before the conference concluded. Overall, I was pleased with the technical sessions, as it was rewarding to be able to receive observations from an industrial point of view and to note the complexities and needs of the PM industry. South Florida provided a beautiful setting for the conference. The accommodations were excellent and the social events provided an environment conducive to learning and networking. Thank you to the Scholarship and Grants Committee of the Center for Powder Metallurgy Technology (CPMT) for providing me with an opportunity I would not have been able to afford on my own.
STEVEN SPURGEON Department of Materials Science & Engineering Drexel University Philadelphia, Pennsylvania I was thrilled to have been given the opportunity to attend PowderMet2010 in Hollywood, Florida. Each year the conference brings together the brightest and
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axel madsen_Zheng et al 7/22/2010 11:26 AM Page 24
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AXEL MADSEN/CPMT SCHOLAR REPORTS
most talented people in the powder metallurgy (PM) community. Not only was I able to learn from the best in the field, I also had the chance to develop connections with peers and leaders in the industry. None of this would have been possible without the financial support of the Center for Powder Metallurgy Technology (CPMT) through their Axel Madsen Scholarships and Grants program. Upon arrival at the beautiful Westin Diplomat Hotel, I was surprised at how conveniently located the exhibition hall and technical sessions were. The conference organizers clearly made an effort to ensure that all the conference venues were close and accessible to attendees. This allowed me to spend less time worrying about where to go; instead I could meet colleagues, share the results of my work, and attend technical sessions. I particularly enjoyed the Opening General Session and the Industry Recognition Luncheon. The first event featured an honest and insightful discussion of environmental responsibility and energy efficiency. I found that this session touched on many pertinent engineering issues and that it was particularly welltimed in light of the Gulf oil crisis. The Industry
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Recognition Luncheon also gave me a chance to discuss current affairs with students and practicing engineers. All the attendees were gracious, offering suggestions for my PhD project and sharing stories about their own experiences in graduate school. The other student grant awardees were equally as kind and, over the course of lunch, we became fast friends. As part of the conference program I was given the chance to present a talk on some of my early research. The audience was packed and I was nervous, but there was no reason to worry. The audience was supportive and genuinely interested in my work. They asked thoughtful and constructive questions and pointed out avenues for future study. Several individuals even gave me their contact information so I could follow up with them later. I am grateful and honored to have been awarded an Axel Madsen/CPMT grant. Without their financial support I would not have been able to attend this prestigious conference. I would also not have had the chance to network with other scientists and engineers from whom I received many ideas and suggestions. I look forward to next year’s event and to serving the PM industry in the coming years. ijpm
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
State of the Industry_Zheng et al 7/22/2010 11:01 AM Page 25
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ENGINEERING & TECHNOLOGY
STATE OF THE PM INDUSTRY IN NORTH AMERICA—2010 Michael E. Lutheran*
REVIEWING 2009 In 2009 the industry slowly began turning the corner, with a 28% rebound in iron powder shipments in the second half of the year. However, for the year total iron powder shipments declined 25% from 2008 to 222,118 mt (244,839 st), levels not seen since 1992, Figure 1. Essentially, the industry hit bottom in 2009, marking five years of dwindling powder demand. Copper and copper-base powder shipments have declined as well, with 2009 shipments declining 24% to 12,010 mt (13,239 st), Figure 2. But 2009 ended on a positive note, especially during the final quar-
Without a doubt the North American powder metallurgy (PM) Industry has endured the worst period of declining production and sales in all sectors (metal powders, equipment and parts) in its history. We have suffered along with many manufacturing and raw materials industries. But PM is still alive and well and has landed back on its feet despite the many naysayers. We are all survivors. That spirit of PM entrepreneurship, determination and resiliency born years ago in the hills and valleys of Western Pennsylvania and now evident in PM parts plants throughout our country, has seen this industry through again.
Figure 1. North American iron powder shipments (1 st = 0.9072 mt)
Figure 2. North American copper and copper-base powder shipments (1 st = 0.9072 mt)
Presented at PowderMet2010 in Hollywood, Florida
*President, Metal Powder Industries Federation
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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State of the Industry_Zheng et al 7/22/2010 11:01 AM Page 26
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STATE OF THE PM INDUSTRY IN NORTH AMERICA—2010
ter. The turnaround predicted by many industry executives at the June 2009 Las Vegas conference certainly came true. 2010 OUTLOOK The strong rebound of last year’s fourth quarter has continued into the first quarter of 2010 when iron powder shipments soared 64% above the same period in 2009 to 80,206 mt (88,410 st), Figure 3. The first quarter’s average monthly shipments of 26,935 mt (29,470 st) project into annual shipments exceeding 317,520 mt (350,000 st). However, it would be more realistic to forecast shipments in the 290,304 to 299,376 mt (320,000 to 330,000 st) range. First quarter 2010 copper and copper-base powder shipments rose 36% to3608 mt (3,977 st), Figure 4. The turnaround for our industry has not been without challenges. The nickel-powder supply shortage has wreaked havoc on our industry. The prolonged Vale Inco strike in Canada, exacerbated by rising demand, has created severe issues for our industry throughout the supply chain. American Metal Market reported that nickel-powder consumers in the United States were in a panic mode at the end of May 2010. MPIF has
Figure 3. 2009–10 North American quarterly iron powder shipments (1 st = 0.9072 mt)
Figure 4. 2009–10 North American quarterly copper and copper-base powder shipments (1 st = 0.9072 mt)
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communicated to Vale Inco the impact on our industry and continues to closely monitor and report on this situation. A most recent development is Vale Inco’s sale of Novamet Specialty Products Corp. in New Jersey. Vale has reported that it will continue to supply Novamet with nickel products from its Sudbury, Canada, and Clydach, Wales, nickel refineries. THE AUTOMOTIVE MARKET Whether we like it or not, the light-vehicle market remains the dominant force impacting the PM industry’s financial health and future growth. The industry’s OEM structure and product mix have changed dramatically as well as geographically. It is no longer just North America, but Europe, Asia, and South America. Survival demands that we think and act globally. For example, IHS Global Insight forecasts the total world light-vehicle sales to reach 79.6 million units in 2012, including U.S. sales of 15.6 million. And if you need more positive statistics, according to Automotive News an official in China reported that China’s annual market for cars, trucks, and buses will reach 30 million sometime in the not-too-distant future. While both forecasts may be overly optimistic, especially China’s, the industry needs more hopeful news like this. With the unquestioned quality and innovation of North American PM products, exporting systems is a definite, positive option. Speaking of forecasts, it appears that North American light-vehicle production this year could top 11.5 million units. With that output the automotive industry will consume an estimated 208,656 mt (230,000 st) of PM parts. It is also estimated that PM parts content in the average-size vehicle will end up at 18.6 kg (41 lb.), about the same as in 2009. This is based on typical Detroit 3 usage and on overseas brands such as Toyota, Honda, and Hyundai-Kia actually increasing their PM content. The U.S. number continues to compare favorably with the European PM average parts content in 2009, 7.2 kg (15.8 lb.) as reported by the European Powder Metallurgy Association, and with that of Japan, 8.6 kg (18.9 lb.), as reported by the Japan Powder Metallurgy Association. GM’s use of PM parts continues to be very strong at an average of about 21.8 kg (48 lb.) per vehicle. Ford is next at 20.5 kg (45 lb.), Chrysler at 19.5 kg (43 lb.), followed by the Asian brands at 17.3 kg (38 lb.). However, some European SUVs and light trucks contain as much as 19.1 kg (42 lb.) of PM parts. Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
State of the Industry_Zheng et al 7/22/2010 11:01 AM Page 27
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STATE OF THE PM INDUSTRY IN NORTH AMERICA—2010
There is more good news about the automotive market. The new six-speed transmissions introduced by GM and Ford have a high PM content, in the 13.6 kg (30 lb.) range. Several of Ward’s 2010 Best Engine choices have high PM contents as well. Ford’s 3.5L EcoBoost Turbocharged V-6 engine has 81 PM parts weighing a total of 9.5 kg (21 lb.). The engine contains PM valve guides and valve seat inserts, connecting rods, oil pump, sensor ring, cam caps, VVT assemblies, camshaft sprocket, and crankshaft sprocket and hub. The MPIF Technical Board continues to update the PM Automotive Parts Catalog launched last year. Aimed at automotive design engineers and materials specifiers, the catalog identifies up to 1,000 PM parts representing 325 applications in a typical vehicle. The applications are in the engine, transmission, and chassis. In addition to North America, the catalog also covers Europe, Japan, and Korea. And there are some new high-profile PM stars to showcase. The heralded Tata Nano model contains PM parts in the valve train, as well as in the timing, hydraulic, and suspension systems. On the other end of the price range, luxury models like the Ferrari California and 456 Italia, and the Mercedes AMG SLS, all use advanced PM hydraulic-pump parts that are assembled into a double-clutch transmission. However, there are still challenges ahead, especially in 2016. That’s when the recently approved government Corporate Average Fuel Economy (CAFE) regulation of 35.5 mpg kicks in. It is a dramatic increase from the current 27.5 mpg regulation, and a far cry from the original CAFE 1978 standard of 18 mpg. The new 2016 standard will open the door for smaller engines—four- and even three-cylinder engines—and more hybrid/electric vehicles, as well as the next generation of transmissions. New smaller engines are being designed now for production in 2014 and 2015. They will usher in a new era of more demanding performance requirements that will put a serious strain on current PM technology. Selling PM’s benefits to the overseas OEMs is another challenge that is vital to our survival. Foreign vehicle manufacturers need to be educated about PM’s capabilities and how to apply the technology. The industry must maintain an ongoing concerted effort to reach transplant decision makers in North America but also in design centers in Europe and Asia. International relationVolume 46, Issue 4, 2010 International Journal of Powder Metallurgy
ships must be cultivated through a sustained overseas sales and marketing effort, but that takes a large investment to fund. So perhaps more consolidations are in order. On the other hand, industry-sponsored trade missions could open up new doors to reach decision makers in Tokyo, Seoul, Mumbai, and Shanghai. INDUSTRY TRANSITIONS Although seriously impacted by the economic downturn, the PM industry has experienced relatively few corporate changes since 2008. A private equity firm purchased Engineered Sinterings & Plastics (now called Wakefield Solutions) in 2008. Last year Capstan purchased the assets of MPP Anaheim and SSI purchased certain assets of Hazen Powder Parts, with both plants now being out of business. So far in 2010, Melling Engine Parts purchased Rush Metals from Cloyes Gear & Products, and Alpha Sintered Metals purchased the assets of Maxtech (Quebec). However, in the past two years eight PM parts plants have closed, with three more shutdowns expected by the end of the year. Several multiplant companies have rationalized production and closed inefficient facilities. On the other hand, a leading European PM parts maker recently announced the opening of a new greenfield plant in Ohio. The industry will struggle with overcapacity for at least several more years. Despite this, many companies have learned to operate in a leaner way and have improved productivity with reduced workforces. Bottom lines have clearly strengthened. MIM AND HIP TRENDS Bucking the negative PM marketplace trend last year, the U.S. metal injection molding (MIM) business performed fairly well, supported by the growing firearms and medical markets. In a survey conducted by the Metal Injection Molding Association (MIMA), 77% of the responding companies expect increasing sales in 2010. The three most significant business challenges faced by the MIM industry are global competition, raw materials costs, and meeting customer requirements. The top manufacturing challenges are new material development, continuous improvement, and maintaining and improving quality. The MIM business will continue growing by replacing complex CNC-machined parts and investment castings. The annual U.S. MIM market
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State of the Industry_Zheng et al 7/22/2010 11:01 AM Page 28
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STATE OF THE PM INDUSTRY IN NORTH AMERICA—2010
is estimated at $170–$200 million, about the same as in Europe. The current market in Asia, which includes Japan, Taiwan, Singapore, Korea, and China, is estimated at $300 million. Europe’s dominant MIM end-markets are automotive and highend jewelry, while Asia focuses on electronics and consumer products. The total annual worldwide MIM market is estimated at $640 to $700 million. The future of hot isostatic pressing (HIP) is bright, supported by growing sectors such as casting densification, MIM parts densification, aerospace and energy, near-net-shape powder parts, diffusion-bonded parts, cladding, and metal powder billets. New near-net PM applications in oil and gas exploration and land-based turbines are growth markets. HIPed PM tool steels, titanium, and more exotic alloys are growing as well, along with diffusion bonding for nuclear applications. For example, pilot projects involve diffusion bonding of the first wall of a reactor. In the electronics sector, sputtering targets made from metal powders represent the leading application. HIPed parts can range in size from tiny dental brackets to massive billets weighing more than 4,545 kg (10,000 lb.). Recognizing the growing influence and importance of isostatic pressing technology, this past year MPIF formed its newest association, the Isostatic Pressing Association. TECHNOLOGY DEVELOPMENTS Our industry’s future will undoubtedly depend on new technology. Metal powder producers, equipment makers, and PM parts and products makers are all busy investing in new materials and process improvements. We must never write off the creative resiliency of the PM industry to overcome obstacles. Metal powder companies are studying new materials and processes to advance PM’s dynamic properties and competitiveness. New materials include lean diffusion-bonded alloys for heat treating and new materials for warm compacting and sinter hardening. Equipment builders are developing new electronically controlled compacting presses, rapid-tooling-change systems and highertemperature and higher-efficiency furnaces. The MPIF Technical Board is assessing technology issues that will impact PM’s future growth. Its programs include single-press-to-full-density, an update on MIM trends, and evaluating the potential threats of competitive and disruptive technologies and processes. The Technical Board is also studying potential PM applications in green energy
28
and power. The Center for Powder Metallurgy Technology (CPMT) is conducting programs aimed at generating a path to higher density via new tooling concepts and higher-tonnage presses capable of compaction pressures above 827 MPa (60 tsi). Final densities of more than 7.45 g/cm3 have been achieved on complex parts. The center is also developing data for establishing machinability guidelines and life-cycle-fatigue data. In all, CPMT is investing $150,000 in programs in 2010. Recognizing the shortage of trained PM engineers, CPMT continues to provide annual scholarships through the Clayton Family Foundation and the Howard I. Sanderow endowment. Educating design engineers and the end-user industrial public has always been a focus and steady theme woven into many MPIF programs. To this end, MPIF released a new 13-minute video, “PM Touches Your Life,” illustrating why PM is the preferred metal-forming solution. The video has already attracted more than 1,200 viewings on YouTube. Standards development is another important industry program. In 2009 MPIF published a new edition of Standard 35, Materials Standards for PM Structural Parts. We also published new editions of Standard Test Methods for Metal Powders and Powder Metallurgy Products, and Standard 35, Materials Standards for PM Self-Lubricating Bearings. The new information contained in these standards is vital in educating design engineers, purchasing agents, and other specifiers of materials. In addition, the Global PM Property Database continues to grow in content and serve global needs for information about PM products and materials. With the launch of MPIF’s sustainability initiative at the PowderMet2010 conference, PM’s advantages as “a recognized green technology” are receiving prominent attention. More than a buzz word, PM’s sustainable value comes from its netshape capabilities and its very high materials-utilization advantage. We are an energy-efficient and green technology that must be promoted as such. We have a very positive message to tell. Let us view 2010 as a transition year leading us to a new era of opportunity in the global marketplace. The industry has been challenged and shaken, yet the future is still positive. Again, never underestimate the creative resiliency of this industry to overcome and rise again to new heights. Competitive technologies that do, do so at their peril! ijpm Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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ENGINEERING & TECHNOLOGY
INDUSTRIAL SINTERING OF HYBRID LOW-CARBON 3Cr-0.5 Mo-xMn STEELS Marcela Selecká* and Andrej Šalak**
INTRODUCTION The manufacture of precision ferrous PM parts, in particular for automotive applications including engines and transmissions components, is the focus of extensive R&D. In addition to porosity, the metal matrix can be modified to improve mechanical properties. Traditionally, sintered steels containing copper, molybdenum, and nickel are used, the choice of these alloying elements reflecting a reduction of the respective oxides in almost any low-purity sintering atmosphere.1 The drawbacks to nickel are its potential allergenic and carcinogenic effects and its high price. As base alloying elements in wrought steels, chromium and manganese are the cheapest and exhibit a high hardening effect. These elements, individually or collectively, plus a small addition of molybdenum, increase hardenability. Chromium and molybdenum are strong carbide formers. Thus, multiple combinations of these elements at lower alloying levels compared with copper and nickel constitute a group of new sintered highperformance steels. Manganese and nickel exhibit similar properties; they increase the width of the γ-region and decrease the transformation temperatures. Nickel increases hardness and strength to a lesser extent than manganese, but increases toughness. The effect of chromium as an efficient alloying element in PM steels has been considered in detail elsewhere.2,3 Based on thermodynamics, the reduction of chromium and manganese oxides requires a sintering atmosphere with an extremely low oxygen potential.4–7 In an industrial sintering atmosphere it is virtually impossible to achieve an oxygen partial pressure which, given the limits of the chromium and manganese lines in the Richardson–Ellingham oxygen potential diagram,8 will result in a reduction of the respective oxides. Due to the high vapor pressure of manganese, sublimation permits the sintering of iron–manganese steels in commercial-purity atmospheres.9,10 The successful sintering of iron–manganese steels in impure atmospheres has been explained by the “self-cleaning/protection-reduction process” in which gaseous manganese in the sintering atmosphere attains equilibrium conditions for manganese-oxygen.5,6,8 The introduction of commercial prealloyed iron–chromium–molybdenum–(vanadium) steel powder grades has allowed for the manufacture of sintered hybrid high-strength steels with a manganese addition. This was
The object of this investigation was to examine the effect of a 1–3 w/o manganese addition and of three manganese carriers on the microstructure and mechanical properties of a prealloyed Fe-3 w/o Cr-0.5 w/o Mo-0.24 w/o C steel sintered under industrial conditions in a pusher furnace. The powder metallurgy (PM) alloys were sintered at 1,180°C (2,156°F) in a 70 v/o N2/ 30 v/o H2 atmosphere with a dew point of -50°C (-58°F). Tensile and bend strength and impact energy were determined and attendant microstructures and fracture morphologies characterized. The highest values of tensile (806 MPa) and bend (1,175 MPa) strength were obtained with 2 w/o manganese added via a medium-carbon ferromanganese. A marked decrease in the strength with 3 w/o Mn was observed. Heterogeneous microstructures containing martensite, bainite, and fine pearlite were formed with continuous cooling.
*Senior Scientific Worker, **Chief Scientific Worker, Institute of Materials Research of Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovak Republic; e-mail:
[email protected]
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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INDUSTRIAL SINTERING OF HYBRID LOW-CARBON 3Cr-0.5 Mo-xMn STEELS
confirmed by determining the properties of hybrid Fe-1.3 w/o Cr-0.3 w/o Mn-0.3 w/o Mo-0.3 w/o V0.24 w/o C steels sintered for 1 h at 1,120°C (2,048°F) in cracked ammonia with a dew point of 30°C (-22°F) and for 1 h at 1,200°C (2,192°F) in hydrogen.11-13 The hybrid Fe-3 w/o Cr-0.5 w/o Mox w/o Mn-0.24 w/o C alloys were sintered under laboratory conditions for 30 min at 1,250°C (2,282°F) in dissociated ammonia (dew point -30°C) and sinter hardened.14 These positive results were obtained with manganese-containing steels sintered primarily under laboratory conditions.15 Sintering under industrial conditions has confirmed problems with manganese and chromium (the latter without a carbon addition) as alloying elements. This was demonstrated by the mechanical properties of sintered specimens corresponding to those attained under laboratory conditions.16 Tensile and impact bars for evaluating the mechanical and tribological properties, and parts (conveyor rollers) from Fe-2.4 w/o Mn-0.1–0.4 w/o C steels were sintered in a pusher furnace for 40 min at 1,180°C (2,156°F) in a 75 v/o N2/25 v/o H2 atmosphere. Spur gears for a drilling machine and spur pinion gears for a mixer prepared from mixed Fe-2.8 w/o Mn-0.6 w/o C powders were sintered in a mesh-belt furnace for 20 min at 1,150°C (2,102°F) under cracked ammonia in a semi-closed container.18 Oil-pump-rotor parts produced from Fe-1.5 w/o Mn-0.8 w/o C steel were sintered in a belt furnace using standard sintering conditions.19 High-temperature industrial sintering of hybrid Fe-1.5 w/o Cr1.5 w/o Mn-x w/o C steel was also performed.20 The objective of the present work was to investigate the effect of manganese additions, and of manganese carrier grades, on the mechanical properties, microstructures, and fracture response of hybrid Fe3 w/o Cr-0.5 w/o Mo-x w/o Mn-0.24 w/o C steels sintered under common industrial conditions, and to confirm the effect of manganese in vapor form on the sintering process. EXPERIMENTAL PROCEDURE Specimens were prepared from Fe-3 w/o Cr-0.5 w/o Mo prealloyed Astaloy CrM (coded CrM) with additions of manganese of 1, 2, and 3 w/o as: (a) Electrolytic manganese (nominal purity 99.8%; 0.37 w/o O2; particle size <20 μm); coded EMn; (b) Medium-carbon ferromanganese (80 w/o Mn1.1 w/o C-0.98 w/o Si; particle size <45 μm, 0.67 w/o O2); coded FeMn;
30
Figure 1. Schematic of pusher sintering furnace and corresponding temperature profile: 1— box with FeCrMnMo samples, 2—boxes in front of and behind box 1 containing FeNiCuMo components, 3—thermocouples
(c) High-carbon ferromanganese (76 w/o Mn-6.6 w/o C-1.0 w/o Si, balance Fe; particle size <45 μm, 0.77 w/o O2), coded FeMnC. Both ferromanganese grades were milled in a laboratory ball mill in air. The surface of the as-milled manganese carrier powders was covered by an adhesive dark grey film, a product of wear between the milled manganese carrier and the cast milling balls. X-ray analysis confirmed the presence of unstable MnO2 on the surface of the ferromanganese particles. The graphite addition was adjusted in mixes EMn and FeMn and in the CrM powder to account for the combined carbon content in the 3 w/o Mn mix when added as FeMnC; a green carbon content of 0.24 w/o was obtained. Lubricant (HWC, Hoechst microwax c) was added to a level of 0.7 w/o. Standard tensile (ISO 2740), bend (ISO 3325, 10 × 5 × 55 mm) and impact-energy test bars (ISO 5754, 10 × 10 × 55 mm) were compacted to 10 v/o porosity (green density 7.0 g/cm3). The samples (~1,200 g) were sintered in the same steel box (330 × 330 × 80 mm) for 40 min at 1,180°C (2,156°F) in 75 v/o N2/25 v/o H2 atmosphere with an inlet dew point of -50°C (-58°F) in a pusher furnace at a heating rate of ~15°C/min (~59°F/min), and a cooling rate of ~10°C/min (~50°F/min). The heating and cooling rates were calculated on the basis of time and the length of the furnace zones. A schematic of the furnace with the temperature profile is shown in Figure 1. RESULTS Basic Characteristics The sintered density, carbon, and manganese Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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INDUSTRIAL SINTERING OF HYBRID LOW-CARBON 3Cr-0.5 Mo-xMn STEELS
TABLE I. SINTERED DENSITY, COMBINED CARBON AND MANGANESE CONTENT, AND DIMENSIONAL CHANGE Mn Carrier
No
Mn Added (w/o)
0
1
2
3
1
2
3
1
2
3
ρ (g/cm3)*
7.05
7.04
7.00
6.97
7.04
7.01
6.98
7.04
7.03
7.02
Cc (w/o)
0.20
0.20
0.23
0.25
0.21
0.23
0.24
0.21
0.24
0.24
Mn Sintered (w/o)
0.25
0.88
2.04
3.09
1.14
2.06
3.11
1.09
2.15
3.05
Δl/l (%)
-0.40 -0.51 -0.60
-0.30 -0.24 -0.50
-0.16 -0.13 -0.30
0.00 -0.10 -0.20
-0.25 -0.30 -0.40
-0.10 -0.25 -0.30
0.00 -0.04 -0.20
-0.20 -0.30 -0.50
-0.10 -0.10 -0.30
+0.10 -0.10 -0.10
Rm TRS KC
EMn
FeMn
FeMnC
Note: Carbon and manganese levels determined from chips from three tensile bars. Rm = tensile bars; TRS = transverse rupture bars; KC = impact energy bars *Tensile bars contents and dimensional changes of the sample bars are given in Table I. A small sintered-density decrease was observed with increasing manganese additions due to the lower density of manganese compared with that of the base CrM powder. The carbon and manganese contents of all the steels showed relatively small differences (±), in relation to their starting levels, i.e., no decarburization or demanganization. In contrast, in the samples without manganese additions, an increase in the manganese content to a mean value of 0.25 w/o was determined. The linear-length changes of the bars became smaller with increasing manganese content with a tendency to zero change at the highest manganese content (3 w/o) and without any effect of the manganese carrier grade. The observed differences in dimensional changes between the individual test bars were caused by their differing geometry and mass. Inasmuch as the manganese loss in the samples was not observed, these data can be used for the dimensional characterization of the steels. In contrast, a significant demanganization of the Fe-(2,3,4 w/o) Mn samples was observed in dilatometer tests in a 75 v/o H2/25 v/o N2 atmosphere for 30 min at 1,150°C (2,102°F) due to small dimensions, high porosity (16 v/o), and the processing of individual samples.21 This cannot occur under common sintering conditions with a batch of larger specimens/parts in a laboratory or industrial furnace. Mechanical Properties The dependence of the tensile and bend strength on the manganese addition and the grade of manganese carrier is shown in Figures 2 and 3. The dependence of apparent hardness and impact energy on the level of manganese and on the grade of the Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
Figure 2. Dependence of tensile strength (UTS) of hybrid Fe-3 w/o Cr-xMn-0.5 w/o Mo-0.24 w/o C steels on manganese content and manganese carrier grade
Figure 3. Dependence of transverse rupture strength (TRS) of hybrid Fe-3 w/o Cr-xMn-0.5 w/o Mo-0.24 w/o C steels on manganese content and manganese carrier grade
manganese carrier is shown in Figures 4 and 5. The highest tensile strength (806 MPa) and bend strength (1,175 MPa) were obtained with 2 w/o Mn, added as FeMn. This made it possible to increase the tensile strength by 131 MPa/1 w/o Mn and the bend strength by 174 MPa/1 w/o Mn in comparison with
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INDUSTRIAL SINTERING OF HYBRID LOW-CARBON 3Cr-0.5 Mo-xMn STEELS
Impact-energy values were in the range of 13.8 J (for a manganese-free steel) to 7.9 J (for a 3 w/o Mn steel), with relatively minor differences in relation to the manganese carrier grade.
Figure 4. Dependence of apparent hardness (HV 10) of hybrid Fe-3 w/o Cr-xMn-0.5 w/o Mo-0.24 w/o C steels on manganese content and manganese carrier grade
Figure 5. Dependence of impact energy of hybrid Fe-3 w/o Cr-xMn0.5 w/o Mo-0.24 w/o C steels on manganese content and manganese carrier grade
the tensile strength of a manganese-free steel. The highest relative increase in both strength properties was obtained with a 1 w/o Mn addition, as demonstrated by the tensile strength of 745 MPa (manganese added as FeMn), and bend strength of 1,150 MPa (manganese added as FeMnC). A marked decrease in both strength properties was observed in the 3 w/o Mn steels, especially those alloyed with manganese in the form of either ferromanganese grades. The effect of the manganese carrier grade was observed primarily in relation to the strength properties of the steels with manganese contents >1 w/o. The lowest strength was attained in the steels with the manganese addition in the form of electrolytic manganese. The apparent hardness (up to 318 HV 10) increased linearly with increasing manganese additions; smaller increases in apparent hardness were observed at 2 and 3 w/o Mn, added as electrolytic manganese. The impact energy of the steels decreased with increasing manganese content.
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Microstructures Figure 6 shows characteristic microstructures of the PM steels with the highest tensile strength (manganese added as FeMn). These steels exhibited a relatively homogeneous microstruture, characteristic of hybrid manganese-containing steels, and a significantly higher level of homogeneity than is characteristic of other mixed alloy PM steels. The microindentation hardness values of the microconstituents are shown in Figure 7 as minimal and maximal values (black). These hardness data were used to characterize the phases in each steel in more detail than is possible from the micrographs in Figure 6. The microindentation hardness values confirm that the microstructures contained fine pearlite, upper and lower bainite, and martensite. The manganization of the manganese-free steel to 0.25 w/o Mn observable in Figure 6(a), and determined by microindentation hardness values in the range of 185 to 327 HV 0.025, was the result of the effect of manganese vapor formed by sublimation from manganese carriers in manganese-containing steels. The manganese vapor fills the interconnected pores and condenses on the surfaces of the powder particles in the compact resulting in gas-phase alloying. As shown in Figure 7, the microindentation hardness of the martensitic islands increased in the range of 503 to 659 HV 0.025 with an increase in the manganese content. This also applies to the minimum microindentation hardness values which increased from 228 to 343 HV 0.025, corresponding to fine pearlite and upper bainite, depending on the manganese content. The effect of the manganese carrier grade is demonstrated by these microindentation hardness ranges. The martensitic islands (590 HV 0.025) were observed in a steel with 1 w/o Mn in which manganese was added as FeMnC. Increasing minimum and maximum microindentation hardness values with increasing manganese additions reflect the increasing proportion of harder phases in the microstructures. It can be assumed that some optimum ratio of softer phases (pearlite, bainite) and martensite at 2 w/o Mn (Figures 2 and 3) resulted in the highest strength properties. In contrast, in the 3 w/o Mn steels a relatively high proportion of brittle martenVolume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Figure 6. Representative microstructures in core of hybrid Fe-3 w/o Cr-0.5 w/o Mo-xMn-xCc steel with the highest strength (manganese added as FeMn). (a) 0 Mn (0.25 w/o Mn-0.20 w/o Cc, UTS = 506 MPa), (b) 1 Mn (1.14 w/o Mn-0.21 w/o Cc, UTS = 756 MPa), (c) 2 Mn (2.06 w/o Mn-0.23 w/o Cc, UTS = 806 MPa), (d) 3 Mn (3.11 w/o Mn-0.24 w/o Cc, UTS = 663 MPa). Optical micrographs/nital etch
site to that of bainite showed a marked decrease in the strength properties. The increasing microindentation hardness of all the phases with increasing manganese additions was reflected in a continuous increase in apparent hardness and decreasing impact energy, Figure 5. The effect of the manganese carrier on the microstructure of the steels, confirmed by the microindentation hardness values, is reflected in the strength properties shown in Figures 2 and 3.
Figure 7. Microindentation hardness (HV 0.025) of microconstituents in hybrid Fe-3 w/o Cr-0.5 w/o Mo-xMn-0.24 w/o C steels (50 indentations in each constituent). CrM—base prealloyed carbon-free powder. Microindentation hardness of CrM particles of different size was in the range 77 to 103 HV 0.025. Measured HV 0.025 values of phases: fine pearlite ~185–281, upper bainite ~312–343, lower bainite ~459–492, martensite (M) ~503–659 Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
Fracture Figure 8 shows representative fracture surfaces of the 1 Mn, 2 Mn, and 3 Mn specimens of maximum tensile strength (manganese added as FeMn), and of 3 w/o Mn (manganese added as FeMnC). The fracture surface of the 1 Mn steel exhibited a ductile dimpled rupture morphology and small transgranular cleavage facets, Figure 8(a). The fracture surface of the manganese-free steel exhibited a smaller fraction of ductile dimpled rupture, and is comparable
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Figure 8. Fracture surfaces of hybrid Fe-3 w/o Cr-0.5 w/o Mo-(1, 2,3) Mn steel tensile bars (a), (b), (c) (manganese added as FeMn) and (d) 3 Mn steel (manganese added as FeMnC). (a) 1 Mn (1.14 w/o Mn-0.21 w/o Cc, UTS = 756 MPa, 214 HV 10), (b) 2 Mn (2.06 w/o Mn-0.23 w/o Cc, UTS = 806 MPa, 286 HV 10), (c) 3 Mn (3.11 w/o Mn-0.24 w/o Cc, UTS = 663 MPa, 318 HV 10), (d) 3 Mn (3.05 w/o Mn-0.24 w/o Cc, UTS = 586 MPa, 316 HV 10). Scanning electron micrographs/secondary electron images
with that of the 1 Mn steel. The fracture surface of the 2 Mn steel exhibited a mixed morphology, Figure 8(b), with primarily large transgranular ductile rupture and a small number of transgranular and intergranular cleavage facets. In contrast, the fracture surface of the lower strength 3 Mn steel exhibited mainly transgranular and intergranular cleavage, smooth intergranular decohesion and a small number of dimpled facets,22 Figure 8(c). The fracture surface shown in Figure 8(d) (manganese added as FeMnC) is characterized primarily by intergranular smooth decohesion facets and, to a minor extent, by transgranular cleavage facets and scattered dimples. No non-metallic inclusions were found in the dimples on the fracture surfaces. DISCUSSION The results obtained on the hybrid steels (mixtures of CrM prealloyed Fe-3 w/o Cr-0.5 w/o Mo and three low-carbon additives containing manganese) confirm that under industrial sintering conditions manganese results in several effects due to its high vapor pressure. Manganese exhibits a markedly
34
higher vapor pressure compared with that of other common alloying elements used in PM steels, for example, copper, chromium, nickel, and molybdenum, as illustrated in Table II. The thermodynamic requirements cited for the purity of the protective atmosphere in the sintering of manganese-containing steels are so high that it is not possible to achieve these conditions in practice. The high affinity of manganese for oxygen, and consequently the difficulty in reducing the oxides, are recognized as a problem in sintering manganesecontaining steels because hydrogen-containing atmospheres should have a dew point lower than that given in Table II to prevent oxidation of manganese or to result in the reduction of MnO. This fact notwithstanding, from 1948 to the present time manganese-containing steels have been successfully sintered under conditions that do not fulfill the thermodynamic requirements.15 The sintering and alloying of manganese-containing steels take place as a result of the high vapor pressure of manganese via the formation of vapor by sublimation of the manganese carrier in the compact. The sublimation Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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INDUSTRIAL SINTERING OF HYBRID LOW-CARBON 3Cr-0.5 Mo-xMn STEELS
TABLE II. CALCULATED EQUILIBRIUM DATA FOR Mn/MnO IN O2 AND VAPOR PRESSURE OF MANGANESE, COPPER, CHROMIUM, NICKEL, AND MOLYBDENUM6,8,10 AS A FUNCTION OF TEMPERATURE Temperature (°C/°F) PO2 (Pa) Dew Point (°C/°F) Vapor Pressure (Pa)
Mn Cu Cr Ni Mo
600/1,112
700/1,292
800/1,472
900/1,652
1,000/1,832
1,100/2,012
1,200/2,192
10-38
10-34
10-30
10-28
10-24
10-22
10-20
-102/-152
-90/-130
-80/-112
-74/-101
-60/-76
-54/-65
-40/-40
2.9·10-5
1.3·10-3
-
-
2.9·10-2 -
0.38 4.23·10-4 1.08·10-5 3.95·10-6 2.03·10-17
3.23 6.10·10-3 2.36·10-4 1.17·10-5 4.07·10-15
19.90 5.94·10-2 3.26·10-3 2.11·10-4 3.73·10-13
99.00 4.23·10-3 3.13·10-2 2.68·10-3 1.85·10-11
rate depends on the temperature; manganese begins to sublime in the preheating stage of the sintering process and its vapor, which fills the pores within the compact and reacts with the oxygen in the atmosphere to form MnO. This reaction has a selfcleaning/protective-reducing effect on the sintering atmosphere, dictated by the equation: Mn(g) + H2O = H2 + MnO
(1)
Volatile MnO is transported away by the atmosphere. By this reaction, oxidation of the manganese powder particles in the compact is prevented during sintering in an atmosphere that does not meet the thermodynamic criteria. When the oxygen potential of the dynamic atmosphere exceeds the equilibrium values for oxidation of most reactive metals such as chromium and manganese, the excess oxygen reacts with gaseous manganese, escaping from the compacts through the interconnected pores. This process decreases the oxygen content in the atmosphere and thus reduces the oxygen potential to the equilibrium value given by the Mn/MnO line for the sintering atmosphere in the Richardson diagram.6,8,10,23 This reaction is, in reality, the effect of the high affinity of manganese for oxygen in the active gaseous form. As a consequence, some gaseous manganese is oxidized to MnO in the form of a fine green powder which is transported away by the flowing atmosphere. However, the solid surface of the sintered powder, in this case CrM + Mn, is also protected from oxidation.24 This holds true for chromium as its affinity for oxygen is slightly lower than that of manganese and its chemical potential is significantly lower than that of pure chromium due to its lower concentration in the CrM powder. This also holds for manganese in solid solution in iron since, in some masVolume 46, Issue 4, 2010 International Journal of Powder Metallurgy
ter alloys used as manganese carriers, its chemical potential is significantly lower than that of pure manganese in gaseous form.8,9,11 For box sintering of many compacts, whether in the laboratory or under industrial conditions, each compact loses a small fraction of manganese into the atmosphere via the space between and surrounding the compacts. This results in a “cloud” of manganese enveloping the compact (the total batch of the specimens/ parts), even those that are manganese-free or with a lower manganese content compared with the main batch. This leads to a manganese-concentration compensation between the compacts and to partial manganization of the manganese-free specimens that were added to the manganese steel specimens for experimental purposes only. This proves that no demanganization occurs when sintering a batch of specimens/parts, consistent with the data in Table I. As a result, a small amount of manganese is lost by oxidation to MnO which has no adverse effect on the surface concentration of manganese on the specimens containing manganese sintered in one box.5,6 The microstructures of the surface layers of a hybrid Fe-Cr-Mn steel and of a Fe-Mn steel also confirm the absence of demanganization, Figure 9. Industrial sintering conditions in continuous furnaces differ from laboratory sintering conditions. During industrial sintering, boxes containing the specimens/parts move through the furnace from the entrance to the exit and the atmosphere is in a counterflow direction, i.e., it moves in a direction opposite to that of the movement of the boxes, Figure 1. Normally, with decreasing temperature, the atmosphere flowing through the sintering and preheating zones is increasingly contaminated by H2O and CO2, the products of prior reduction processes.
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Figure 9. Representative microstructures of surface of: (a) hybrid Fe-3 w/o Cr-0.5 w/o Mo-3 w/o Mn-0.24 w/o C tensile bar (manganese added as FeMnC), (b) Fe-3 w/o Mn-0.5 w/o C steel roller part. Tensile bar and roller, sintered independently in same pusher furnace for 40 min at 1,180°C (2,156°F) in 70 v/o N2/30 v/o H2 atmosphere. Optical micrographs/nital etch
It is necessary to pay special attention to the atmosphere in the dewaxing zone, considering the strict thermodynamic requirements for the oxygen partial pressure in the sintering atmosphere for manganese steels. As the parts in this zone heat up, the lubricant melts, evaporates and breaks down into smaller complex molecules (for example, methane, ethane, butane, propane, carbon monoxide, carbon dioxide, water). This decomposition starts at temperatures as low as 150°C (302°F), peaks near 450°C (842°F), and is usually completed at 550°C (1,022°F). The atmosphere plays a role in polymer burnout since it can provide reaction species to help break apart the polymer molecules. To ensure burnout of the lubricants in air, the atmosphere in this zone, including the controlled base atmosphere, must be strongly oxidizing with a dew point up to +20°C (+68°F). The use of atmospheres with oxidants is restricted to 650°C (1,202°F) to ensure entry of the compacts into the preheat sintering zone with a higher temperature and an atmosphere of markedly higher purity.25-27 The dew point of the sintering atmosphere at the boundary of the dewaxing–preheat zone at 650°C (1,202°F) should be <-90°C (<-130°F) based on thermodynamics. However, this criterion was not fulfilled (Table II) and the specimens in the box were exposed within 60 min to the effect of an oxidizing atmosphere (manganese starts to oxidize in air at ~400°C (~752°F)) as they moved through the dewaxing zone. These results prove that there was no oxidation of the manganese carrier particles in the compacts in this zone and that the oxide films on the surface of the CrM particles in the compacts, if they existed,
36
were removed (reduced). If not, the formation of interparticle necks in the compact at ~700°C (~1,292°F), as well as the diffusion of manganese into the interior of the base-powder particles from the condensed surface layer at the same temperature (observed by optical microscopy of Fe-Mn compacts), would not occur.6 Sublimation of the mannganese and alloying of the iron matrix at ~600°C (~1,112°F) was confirmed by means of dilatometer tests monitoring dimensional expansion of Fe-Mn steel samples compared with those of iron.21 Inasmuch as at least 3 w/o Cr steel exhibits a protective action against oxidation, particularly at low temperatures, a coherent film of Cr2O3 usually forms as a subscale or a spinel such as FeCr2O4 at the metal/scale interface.28 The surface of the Fe-3 w/o Cr-0.5 w/o Mo particles may be covered with this oxide or spinel. Based on differential thermal analysis (DTA) of sintering of Fe-3 w/o Cr-0.5 w/o Mo powder with the addition of carbon in hydrogen, degassing occurred at a temperature >1,000°C (>1,832°F) due to the higher thermodynamic stability of chromium oxides.29,30 In contrast, alloying of an Fe-3 w/o Cr0.3 w/o Mo-0.3 w/o V compact with a 3 w/o Mn addition was clearly demonstrated by the dilatometer results. Dimensional changes, especially at the α–γ phase transformation temperature (increased swelling and decreased transformation temperature caused by manganese) compared with those in the absence of manganese, Figure 10.21 Based on our results, the potential existence of chromium oxide or a spinel on the surface of the CrM powder particles did not adversely affect the sintering and alloying of Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Figure 10. Dilatometric traces of Fe-3 w/o Cr-0.3 w/o Mo-0.3 w/o V (KIP 30CRV prealloyed powder) and hybrid Fe-3 w/o Cr-0.3 w/o Mo-0.3 w/o V-3 w/o Mn-0.25 w/o C steel samples. Isothermally sintered for 30 min at 1,150°C (2,102°F), 75 v/o H2/25 v/o N2 atmosphere, dew point -30°C (-22°F). Manganese added as EMn and carbon as graphite
the hybrid steels. In the presence of Cr2O its reaction with manganese vapor should be considered as favorable and will control the sintering process at useful reaction rates.31 Thus, the sublimation of manganese occurred in the early stages in the preheat zone; the corresponding sintering process, including alloying of the Fe-3 w/o Cr-0.5 w/o Mo matrix by manganese, occurred under the selfreduction effect of the manganese vapor in the 70 v/o N2/30 v/o H2 atmosphere. This phenomenon indicates that components alloyed with manganese (mixed or hybrid) can be sintered under industrial conditions in boxes in continuously operating furnaces equipped with a dewaxing zone and in an atmosphere that does not meet the requirements for the purity of the atmosphere, based on the Richardson diagram, Table I. This fact also facilitates the practical sintering of steels containing elements such as chromium and manganese to increase strength and hardenability. In addition to its proven scavenging effect, gaseous manganese fills the pores and simultaneously condenses on the surfaces of the base CrM particles in the compact, forming a layer with a high manganese concentration. This is the beginning of solid-phase (powder)–gas-phase (manganese vapor) alloying of sintered manganese-containing steels.6,8 Alloying of the iron matrix by manganese during preheating was confirmed by the strength properties of iron–manganese samples.24 Manganese is then transferred from sites of high concentration (surface layers) to sites of lower or zero concentration into the interior of the base particles by solid-state diffusion. Diffusion rates depend on the temperature and on Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
the diffusion mechanism (volume diffusion, grain boundary, and pipe diffusion along dislocations). It can also be invoked that diffusion-induced grainboundary migration (DIGM) of the original boundaries also takes place, together with the nucleation of new grains. These phenomena play an important role in the diffusion of manganese via vapor transport into the CrM particles, as reported for iron–manganese steels.32-34 This diffusion is controlled by several factors that are also related to the properties of the base powder and which are reflected in the as-sintered properties of the compacts.35 In affecting manganese alloying by diffusion, the primary characteristics of the CrM powder compacts are: • lattice defects in the solute compared with those in the pure iron lattice and an increase caused by the addition of alloying elements (chromium and molybdenum); high cooling rates in wateratomized particles of different sizes, which can be related to the microindentation hardness of the original CrM particles (ranging from 77 to 103 HV 0.025, Figure 7), reflecting inhomogeneity in the microstructure as a further factor affecting the diffusion mechanism of manganese • shape of the powder particles: those possessing a large specific surface area alloy more rapidly than spherical particles characterized by a relatively small specific surface area • particle size distribution: smaller particles form by alloying sooner than do larger particles (shorter diffusion distances), and as austenite grains of various sizes are formed • work hardening: cold-compacted contact areas between particles increase the dislocation density. The result of the complex interactions between the manganese-diffusion mechanisms and the characteristics of the powder particles is the formation of heterogeneous sintered microstructures. A clear demonstration of this are the differences in the microindentation hardness values of the individual steels, Figure 7, notwithstanding the observation that the microstructures appear to be relatively homogeneous, Figure 6. This proves that the heterogeneity of the microstructure caused by these factors is also retained, to some extent, in the austenite. This means that individual microvolumes in the microstructure, not equal in size, were alloyed by variable concentrations of manganese and carbon.36 The consequence of this is that the products of
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the austenite transformation in different grains, and even in the same grain-microvolumes, can differ. In this case, the manganese-alloying effect due to chemical heterogeneity resulted in heterogeneous microstructures in the sintered steels. This resulted in the transformation of austenite to microstructures (with several phases corresponding to austenite grain-microvolumes with manganese and carbon concentrations), namely, fine pearlite, bainites, and martensite with an initial content of 0.24 w/o C. The formation of martensite in these steels is the consequence of the diffusionless transformation of austenite to martensite at slow cooling rates, similar to that in air in wrought steels containing 5–6 w/o Mn.37,38 This also occurs in continuous industrial sintering, similar to the martensitic transformation in iron–carbon steels. The microstructure of this transformation is a supersaturated α-solid solution with a concentration corresponding to that of the γsolution, i.e., manganese martensite without the formation of the tetragonal lattice. The formation of the martensite causes self-phase strengthening. Furthermore, as a rule, in wrought steels with ≥1.5 w/o Cr, the martensite is formed when the manganese content reaches ~2.5 w/o.37,38 This explains the formation of martensite in the steels with a 1 w/o Mn addition. Similarly, bainite forms in wrought iron–manganese–carbon steels containing ~0.2 w/o Mn,39 and with chromium, since we can assume that an even lower manganese content is needed for the formation of bainite. These factors support the diffusionless transformation in hybrid sintered Fe-3 w/o Cr-0.5 w/o MoxMn-0.24 w/o C steels in grain-microvolumes containing a minimum 2.5 w/o Mn to martensite, and to bainite in steels containing <2 w/o Mn,37 i.e., steels with 1 w/o Mn, Figure 7. It can be concluded that in the austenite formed from the CrM powder with a manganese addition, primarily martensite and bainite are formed in the grains and in their microvolumes with heterogeneous manganese concentrations at slow cooling rates at the phase transformation. This is in comparison with manganese-free CrM powder. The transformation of austenite in the sintered iron–manganese–carbon steels, usually with 2–5 w/o Mn and 0.5–0.9 w/o C occurs primarily by the same process and also at slow laboratory furnace cooling rates. This is proven by the formation of martensite, bainite, and pearlite in the microstructures with characteristics of the iron powder grades. The properties of these steels were affected by the
38
manganese addition and partly by the manganese carrier grade. It was shown in Figures 2 and 3 that the effect of manganese at low carbon contents markedly affects the strength properties. The highest strengthening effect was with 1 w/o Mn addition and decreased with increasing manganese additions. The strengthening effect of manganese in wrought steels, in which the carbon content is lower (up to 0.4–0.5 w/o C is regarded as optimum) is higher. The effect of manganese on strength at 0.7 to 0.9 w/o C is marginal.37,38 The highest tensile and bend strengths attained with 2 w/o Mn are the consequence of the formation of a bainitic structure in some grain-microvolumes and in others of a martensitic structure with corresponding manganese and carbon concentrations. Regarding the chromium content, with 2 w/o Mn added, some “optimal” ratio of softer bainite and brittle martensite can be attained. This explains the formation of more uniform “heterogeneous” microstructures compared, with iron–manganese– carbon steels at the same manganese content. Thus the synergistic effect of chromium and manganese on the austenite transformation at this relatively low manganese addition was clearly demonstrated. The microindentation hardness measurements show convincingly that in sintered multi-phase structures it is necessary to study the bainite in more detail,40 Figure 7. Under isothermal transformation conditions bainite, the main constituent in the microstructures (Figure 6), is classified as upper bainite (slow cooling rates) and lower bainite (lath bainite, high cooling rates). The transformation of austenite in wrought steels containing carbon and some alloying elements progresses in a complex manner under continuous cooling conditions and, therefore, the phases are difficult to define.36 This is the case in PM because continuous cooling is intrinsic to sintering performed in the laboratory, under industrial sintering conditions, and in sinter hardening. The microstructures are heterogeneous and formed by grain-microvolumes with various manganese and carbon concentrations, as found in a relatively wide range of bainite microindentation hardness levels. This applies to all sintered steels, whether mixed, hybrid, or prealloyed. When evaluating the dependence on cooling rate41 of the formation of the various bainite morphologies in Fe-(3,4) w/o Mn-0.8 w/o C steels, it is necessary to consider the effect of alloying elements on the kinetics of the bainite transformation. The strongest effect is exhibited by manganese followed Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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by chromium, nickel, and molybdenum.36,38 Based on the characteristics of the austenite transformation to bainite under conditions of continuous cooling, it can be assumed that bainite forms with various morphologies. The form with the granular feature frequently forms only with continuous cooling in some wrought steels.36 This must be taken into account for all slowly/continuously cooled PM alloyed steels. The characteristic feature of granular bainite formation is the existence of dispersed martensite– austenite aggregates (islands of martensite and austenite (M-A)) in the highly dislocated ferritic matrix. This constituent exhibits strain capacity in the ductile-fracture temperature range. In the brittle-fracture temperature range the M-A constituent can contribute to the reinitiation of cleavage fracture. The structural unit is, however, less clearly defined by optical microscopy and requires transmission electron microscopy (TEM). This phase adversely affects the strength and toughness of the steels through coarsening of the primary grains under slow cooling and/or through the high hardness of the M-A component.42–44 The characteristic bainitic structures of a mixed sintered steel cooled from 900°C (1,652°F) in nitrogen are shown in Figure 11. It can be assumed that the marked decrease in the strength of the 3 Mn steels under slow cooling rates is caused by a larger fraction of martensite and granular bainite in the microstructures. Lower bainite can be excluded because the carbides that are formed within the laths are more effective barriers to crack propagation than are the carbides localized at the interfaces in upper bainite.42 As shown in Figure
8(c), the fracture of a 3 Mn steel (alloying via FeMn) is mixed and is formed by transgranular and intergranular cleavage facets, and to a lesser extent by a ductile dimpled morphology. The transgranular microcracks are localized in the large martensitic plates, and intergranular rupture is the result of boundary brittleness in martensitic structures caused by acicular martensite and/or by other factors.42 The fracture surface of a 3 Mn steel (alloying via FeMnC) shown in Figure 8(d) is mixed, formed mostly by smooth intergranular rupture—grain boundary decohesion22 along the former austenitic grain boundaries, due to embrittlement. This can also be caused by zones with different structures (ferrite/austenite and/or martensite layers) in austenite matrices in the vicinity of grain boundaries, as can be the case with granular bainite. The proportion of the intergranular zones may be large. Figure 12 shows the fracture surfaces of 3 Mn steels alloyed via FeMn and FeMnC at a higher magnification. The region with the possible presence of granular bainite becomes hard and brittle and contributes to rupture by grain boundary decohesion.43,44 In the case of alloying with FeMnC of lower chemical purity than FeMn, it might be possible for impurity segregation at the grain boundaries to promote brittleness, causing a significant decrease in strength. The formation of a relatively large fraction of martensite and granular bainite in the Fe-3 w/o Cr3 w/o Mn steel under normal sintering conditions is predicted from a physical metallurgy perspective and the decrease in strength limits its utility. A similar brittleness in Fe-4 w/o Mn-C steels has been established.3,45
Figure 11. Bainite structures in sintered mixed Fe-1.4 w/o Mn-0.5 w/o Cr-0.5 w/o Mo-0.6 w/o Cu-0.07 w/o C steel; porosity 7 v/o at a sintered density of 7.28 g/cm3. (a) lath bainite and ferrite. (b) gold shadowed carbon replica.40 TEM Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Figure 12. Representative highmagnification fractographs of 3 Mn steels (a) from Figure 8(c), (b) from Figure 8(d).
The type of manganese carrier resulted in a range of strength levels of the steels, without marked effects on hardness and impact energy. A similar effect of the same manganese carrier on the strength of sintered iron–manganese–carbon steels in relation to the iron powder grades was recorded.46 Electrolytic manganese has a high purity whereas both ferromanganese grades are ternary, multicomponent high manganese–iron–carbon alloys. These alloys differ in chemical activity because of differences in composition; electrolytic manganese exhibits the highest manganese sublimation rate. A difference between electrolytic manganese and the ferromanganese grades used in this study also exists with respect to the particle-size distribution; electrolytic manganese has a particle size <20 μm and for the ferromanganese grades it is <45 μm. This larger range in the particle-size distribution is reflected in the prolonged sublimation time of the manganese and condensation during the preheat stage (larger particles). Manganese-diffusion alloying from the surface layer into the interior of the base particles in the compact is advantageous compared with fine-particle electrolytic manganese (sublimation for a shorter time at lower temperatures). The adverse effect of high-carbon ferromanganese on the 2 Mn and the 3 Mn steels probably relects the higher fraction of a complex iron–manganese carbide (Mn,Fe)7C3 of high hardness in the microstructures,47 Figure 7. The complex concurrent diffusion of three elements from one source (carbon, manganese, silicon),48 and the lower chemical purity compared with medium-carbon ferromanganese are other factors influencing the role of manganese. The residual “microparticles” of ferromanganese (those remaining after manganese sublimation) at the interparticle contacts (~4 μm in size) in Fe~(2,3,4)Mn) can contribute to the growth of interpar-
40
ticle necks during sintering and hence increase density and strength and become part of the austenite. As shown from the fractographs, no metallic inclusions were found in the dimples, Figure 8. Based on our results, commercial medium-carbon ferromanganese was lowest in cost and the optimum manganese carrier for alloying sintered steels. CONCLUSIONS 1. The properties of the hybrid system Fe-3 w/o Cr-0.5 w/o Mo-(1-3) w/o Mn-0.24 w/o C reflect successful sintering in an industrial pusher furnace at 1,180°C (2,156°F) in 70 v/o N2/30 v/o H2, notwithstanding the high affinity of manganese and chromium for oxygen. This is due to the reduction/self-cleaning effect of the manganese vapor in the sintering atmosphere, including the oxidizing atmosphere in the dewaxing zone of the furnace, caused by its high vapor pressure. The reaction of gaseous manganese and oxygen producing MnO decreased the oxygen potential in the atmosphere to the equilibrium value given by the Mn/MnO ratio, and by the Cr/Cr2O3 line in the Richardson–Ellingham oxygen potential diagram. 2. The highest as-sintered tensile strength (806 MPa) and bend strength (1,175 MPa) was achieved when 2 w/o Mn was added in the form of medium-carbon ferromanganese. Markedly lower values of strength were obtained by adding 3 w/o Mn. Impact energy decreased essentially linearly to 7.9 J and the apparent hardness increased up to 318 HV10 by increasing the level of the manganese addition. The effect of the manganese carrier grade was observed primarily on strength. These properties resulted from solution strengthenVolume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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3.
4.
5.
6.
ing of the base iron–chromium–molybdenum prealloyed powder in the compacts by manganese through solid-phase–gas-phase alloying. Demanganization or decarburization of the sintered hybrid iron–chromium–manganese steels did not occur. Heterogeneous microstructures, formed as a result of slow cooling, consisted of martensite, lower and upper bainite, and fine pearlite. The proportions of these constituents depended on the amount of manganese added and on the microconcentrations of manganese and carbon in grain-microvolumes formed in heterogeneous austenite. The properties depended on the level of the manganese addition. Heterogeneity is related to non-uniform alloying of manganese in the prealloyed Fe-3 w/o Cr-0.5 w/o Mo powder in the compacts. Martensite forms with slow furnace cooling in the microvolumes in steels containing 4–5 w/o Mn. Interaction with chromium also occurs in the microvolumes in ~2 w/o Mn steels and at a low total-carbon content; the latter is heterogeneously distributed in the microstructure. Different ferromanganese grades affected strength; in particular there was a significant decrease in these properties in the 3 Mn steels. The combination of a 3 w/o Cr steel with 3 w/o Mn adversely affected the strength. The lowest strengths were achieved when manganese was added in the form of electrolytic manganese. The results confirm the synergistic hardening effect of chromium, manganese, and molybdenum, at a low carbon level, on the mechanical properties of Fe-3 w/o Cr-0.5 w/o Mo-(1,2,3) w/o Mn-0.24 w/o C steels sintered under standard industrial conditions. Except for the 3 Mn steels, with modifications of the carbon content up to ~0.5 w/o and cooling rates, the hybrid system can be attractive in the production of cost-effective high-performance PM parts, without the addition of other elements to enhance hardenability, and as a substitute for nickel.
ACKNOWLEDGEMENT The work was performed within the framework of the Scientific Grant Agency of ME SR and SAS, Slovak Republic (Grant No. 2/0103/09).
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
REFERENCES 1. H. Danninger, R. Pöttschacher, S. Bradac, A. Šalak and J. Seyrkammer, “Comparison of Mn, Cr, and Mo Alloyed Sintered Steels from Elemental Powders”, Powder Metallurgy, 2005, vol. 48, no. 1, pp. 23–32. 2. A. Šalak, “Sublimation and Condensation of Manganese”, Hutnické listy, 1980, vol. XXXV, no. 2, pp. 724–727 (in Slovak). 3. A. Šalak, Ferrous Powder Metallurgy, 1995, Cambridge International Science Publishing, Cambridge, UK. 4. A. Šalak, M. Selecká and R. Bureš, “Manganese in Ferrous Powder Metallurgy”, Powder Metallurgy Progress, 2001, vol. 1, no. 1, pp. 41–57. 5. M. Jalilizyaeian, C. Gierl and H. Danninger, “Manganese Evaporation during Sintering of Fe-Mn-Cr Compacts from Prealloyed Iron Powder”, Advances in Powder Metallurgy & Particulate Materials—2008, compiled by R. Lawcock, A. Lawley and P.J. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, vol. 2, part 5, pp. 72–78. 6. A. Šalak, “Manganese Vapor-Protection of Premixed Manganese Steels against Oxidation during Sintering”, Powder Metallurgy International, 1986, vol. 18, no. 4, pp. 266–270. 7. S. Kremel, H. Danninger and Y. Yu, “Effect of Sintering Conditions on Particle Contacts and Mechanical Properties of PM Steels Prepared from 3% Cr Prealloyed Powder”, Powder Metallurgy Progress, 2002, vol. 2, no. 4, pp. 211–221. 8. J.M. Torralba and M. Campos, “Low Alloyed Cr-Mo Sintered Steels—Update”, Powder Metallurgy Progress, 2002, vol. 2, no. 3, pp. 177–187. 9. A. Šalak and J. Ďurišin, “Evaporation of Manganese in Solid State and its Effect on Sintering of Manganese Alloyed Steels”, Pokroky práškové metalurgie VÚPM, 1979, no. 2–3, pp. 29–40 (in Slovak). 10. A. Šalak, “Sintered Manganese Steels, Part II: Manganese Evaporation during Sintering”, Powder Metallurgy International, 1980, vol. 12, no. 2, pp. 72–75. 11. A. Šalak, M. Selecká, R. Keresti and Ľ. Parilák, “Mechanical Properties of Sintered Fe-Mn-Cr-Mo-V Steels”, Proc. 2000 Powder Metallurgy World Congress & Exhibition, edited by K. Kosuge and H. Nagai, Japan Powder Metallurgy Assocation, Tokyo, 2000, part 2, pp. 9–12. 12. A. Šalak, M. Selecká and Ľ. Parilák, “Properties of Hybrid Fe-Mn-Cr-C Sintered Steel”, Proc. EURO PM2001, European Powder Metalurgy Association, Shrewsbury, UK, 2001, vol. 1, pp. 251–256. 13. M. Selecká and A. Šalak, “Fracture of Hybrid Sintered FeCr-Mn-C Steel”, Proc. Int. Conf. Fractography 2003, Stará Lesná, Institute of Materials Research of Slovak Academy of Sciences, Košice, Slovakia, 2003, pp. 116–121. 14. A. Šalak and M. Selecká, “Effect of Manganese Content and Manganese Carrier on Properties of Sintered and Sinter Hardened Hybrid Fe-3Cr-0.5Mo-xMn-0.24C Steel”, Powder Metallurgy, 2008, vol. 51, no. 4, pp. 327–339. 15. A. Šalak and M. Selecká, “Sinter-Aloying and Properties of Manganese Steels—State of the Art”, Powder Metallurgy Research Trends, NOVA, Hauppauge, NJ (in press). 16. E. Dudrová, M. Kabátová, R. Bidulský and A.S. Wronski, “Industrial Processing, Microstructure and Mechanical Properties of Fe-(2-4)Mn-0.85Mo-(0.3-0.7)C Sintered Steels”, Powder Metallurgy, 2004, vol. 47, no. 2, pp. 181–190.
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17. A. Šalak, M. Selecká, A. Čajka and Š. Franek, “Tribological Properties of Sintered Manganese Steel”, Proc. Int. Conf. DF PM 2002, Stará Lesná, Institute of Materials Research of Slovak Academy of Sciences, Košice, Slovakia, 2002, vol.1, pp. 285–293. 18. A. Cias, “Processing and Mechanical Properties of Sintered Manganese Steel Gears”, Powder Metallurgy Progress, 2005, vol. 5, no. 3, pp. 147–163. 19. M.J. Dougan and J. Moratò, “New Robust Mn-Based PM Steels”, Advances in Powder Metallurgy and Particulate Materials—2008, compiled by R. Lawcock, A. Lawley and P.J. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, vol. 2, part 6, pp. 46–58. 20. R. Shivanath, P.K. Jones and R. Lawcock, “On the Synergies of High Temperature Sintering and Alloy Development for High Endurance P/M Powertrain Components”, Advances in Powder Metallurgy and Particulate Materials—1996, compiled by T.M. Cadle and K.S. Narasimhan, Metal Powder Industries Federation, Princeton, NJ, 1996, vol. 4, part 13, pp. 427–437. 21. M. Selecká and A. Šalak, “Gas-phase Alloying of Sintered Manganese Containing Steels Analysed by Dilatometry: Effect of Carbon and Base Powders”, Powder Metallurgy Progress, 2008, vol. 8, no. 1, pp. 35–47. 22. V. Karel, “Systematization of Base Microfractographical Terms”, Proc. Fractography ‘87, 9th conference, Tatranské Matliare, Institute of Materials Research of Slovak Academy of Sciences, Košice, Slovakia, 1987, part 1, pp. 119–145 (in Slovak). 23. E. Navara, “Alloying of Sintered Steels with Manganese”, Proc. 6th Powder Metallurgy Conference in Czechoslovakia, Brno, VUPM Šumperk (Institute of Materials Research of Slovak Academy of Sciences, Košice, Slovakia), 1982, vol. 1, pp. 143–147. 24. A. Šalak, “Effect of Extreme Sintering Conditions upon Properties of Sintered Managanese Steels”, Powder Metallurgy International, 1984, vol. 16, no. 6, pp. 260–263. 25. L.F. Pease, III and W.G. West, Fundamentals of Powder Metallurgy, 2002, Metal Powder Industries Federation, Princeton, NJ. 26. R.M. German, Powder Metallurgy of Iron and Steel, 1998, John Wiley and Sons, Inc., New York, NY. 27. D. Whittaker, “Practical Issues in the Sintering of Ferrous Parts”, Metal Powder Report, 1984, vol. 39, no.1 , pp. 26–30. 28. J. Kučera and M. Hajduga, High-temperature and Long-time Oxidation of Iron and Steels, 1998, Wydawnictvwo PL Filia w Bialsko-Bialej, Poland. 29. H. Danninger and C. Gierl, “New Alloying Systems for Ferrous Powder Metallurgy Precision Parts”, Science of Sintering, 2008, vol. 40, pp. 33–46. 30. H. Danninger, C. Gierl, S. Kremel, G. Leitner, K. JaenickeRoessler and Y. Yu, “Degassing and Deoxidation Processes during Sintering of Unalloyed and Alloyed PM Steels”, Powder Metallurgy Progress, 2002, vol. 2, no. 3, pp. 125–140. 31. S.C. Mitchell and A. Cias, “Carbothermic Reduction of Oxides during Nitrogen Sintering of Manganese and Chromium Steels”, Powder Metallurgy Progress, 2004, vol.
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4, no.3, pp. 132–142. 32. A. Šalak, “Manganese Sublimation and Carbon Ferromanganese Liquid Phase Formation During Sintering of Premixed Manganese Steels”, Int. J. Powder Metal. & Powder Tech., 1980, vol. 16, no. 4, pp. 369–386. 33. A. Šalak, “Diffusion Induced Grain Boundary Migration in Alloying of Iron Powder with Manganese Vapor”, Kovové Materiály (Metallic Materials), 1989, vol. 27, vol. 2, pp. 159–169 (in Slovak). 34. A. Šalak, “Activated Alloying of Fe-Mn Powder Systems by Manganese Vapor”, Science of Sintering, 1989, vol. 21, no. 3, pp. 145–154. 35. Höganäs Iron and Steel Powders for Sintered Components, 2002, Höganäs AB, Höganäs, Sweden. 36. M.E. Blanter, Phase Transformations at Thermal Treatment, 1962, Metallurgizdat, Moscow (in Russian). 37. E. Houdremont, Handbuch der Sonderstahlkunde (Special Steel Science), 1956, vol. 1, Springer Verlag, Berlin (in German). 38. I.E. Kontorovich, Heat Treatment of Steels and Cast Iron, Book II, Alloyed Steels, 1950, Metallurgizdat, Moscow (in Russian). 39. N.A. McPherson and T.N. Baker, “The Microstructure and Properties of Some Low-Carbon 4% Manganese Steels Containing Niobium and Vanadium”, Metal Science, 1976, vol. 10, no. 4, pp. 140–144. 40. A. Šalak, “Properties of Low Carbon Low Alloyed Sintered Steel with Bainitic Structure”, Strojírenství, 1976, vol. 26, no. 10, pp. 619–623 (in Slovak). 41. M. Sulowski and A. Cias, “The Effect of Cooling Rate on the Structure and Mechanical Properties of Sinter Hardened Fe(3-4)Mn-0.8C Steels”, Proc. EURO PM2003, European Powder Metallurgy Association, Shrewsbury, UK, 2003, vol. 1, pp. 453–458. 42. G. Henry and D. Horstmann, DE FERRI METALLOGRAPHIA V Fractography and Microfractography, 1979, Verlag Stahleisen, Düsseldorf, Germany. 43. I. Hrivňák, “Granular Bainite in High Strength Steel Welds”, Kovové Materiály (Metallic Materials), 1995, vol. 33, no. 1, pp. 31–42 (in Slovak). 44. E. Mazancová, P. Wyslych and K. Mazanec, “Physical Metallurgy of Granular Bainite”, Kovové Materiály (Metallic Materials), 1995, vol. 33, no. 2, pp. 94–104 (in Czech). 45. E. Dudrová, M. Kabátová, R. Bureš, R. Bidulský and A.S. Wronski, “Processing, Microstructure and Properties of 24% Mn and 0.3/0.7% C Sintered Steels”, Kovové Materiály (Metallic Materials), 2005, vol. 43, pp. 404–421. 46. V. Sinka, M. Selecká and A. Šalak, “The Influence of Iron Powder Grade and Manganese Carrier on the Homogeneity Modulus of Sintered Mn Steels”, Materials Science Forums, 2003, vols. 416–418, pp. 455–460. 47. D.N. Gasik, V.S. Ignatyev and M.I. Gasik, Structure and Quality of Industrial Ferroalloys and of Alloying Elements, Technika, Kiew, 1975 (in Russian). 48. M.A. Krishtal, Diffusion Processes in Ferrous Alloys, 1963, Gos. Nauchno-techn. Izd. Lit. po chernoy i tsvetnoy metallurghiyi, Moscow (in Russian). ijpm
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RESEARCH & DEVELOPMENT
SOLUTION ANNEALING AND AGING OF A MIM CoCrMo ALLOY Palloma V. Muterlle*, Ivan Lonardelli*, Matteo Perina***, Marianna Zendron***, Rudj Bardini***, and Alberto Molinari**
INTRODUCTION The mechanical properties and wear characteristics of biocompatible Co-Cr-Mo alloys are strongly influenced by their microstructure, in particular by carbide precipitation in the metallic matrix. Carbides increase hardness and yield strength but decrease ductility, particularly when they are segregated at grain boundaries and in interdendritic regions.1,2 In wear tests against UHMWPE, carbides may abrade the polymer. This phenomenon is minimized by lubrication and depends on the carbide morphology; in particular, dispersed and localized particles are more abrasive than homogeneously distributed carbides in the eutectic cells.3 To modify the microstructure with the aim of increasing ductility, a solution-annealing treatment is carried out, which essentially dissolves the carbide particles. The improved ductility is, however, accomplished by a decrease in strength. An aging treatment may then be carried out to reprecipitate the carbides homogeneously within the metallic matrix and to increase the amount of the hcp phase.1,4–5 The constitution of the metallic matrix evolves with heat treatment but the major effect on properties is attributed to the change in the distribution and amount of carbides. The microstructural transformations occurring on heat treatment have been investigated by Vander Sande et al.6 and Weeton and Signorelli.2 Cobalt-base biomedical prostheses can be successfully produced by the MIM prealloyed powders.7–10 Powders with a carbon content between 0.05 w/o and 0.35 w/o are commercially available. A low carbon level results in an essentially carbide-free sintered microstructure, with an attendant positive effect on ductility. In contrast, a high carbon content activates sintering because of the formation of a eutectic liquid at 1,240°C–1,270°C. The sintering temperature to obtain the pore-free density is lower than that of the low-carbon alloys,10 but ductility is depressed. However, alloys with a higher carbon content may be of practical interest since they exhibit superior wear behavior against UHMWPE and a higher strength than medium- and low-carbon alloys.3 In the present work the heat treatment of a Co-29 w/o Cr-6 w/o Mo0.35 w/o C alloy produced by MIM was investigated. MIM produces an
The effect of solutionannealing temperature over the range 1,200°C–1,250°C on the microstructure, microindentation hardness, and hardness of a Co-Cr-Mo 0.35 w/o C alloy produced by the metal injection molding (MIM) of prealloyed powders was investigated. An optimal compromise between carbide solution and grain growth was attained at 1,220°C. Aging promoted intragranular Widmastätten precipitation of carbides, and the formation of fine lamellar hexagonal close packed (hcp) phases at the grain boundaries. After solution annealing at 1,220°C, the tensile properties were attractive, in particular ductility. After subsequent aging the alloy was brittle. The strain-hardening behavior of the alloy was examined and rationalized in terms of the straininduced transformation of austenite to martensite.
*PhD Student, **Professor, University of Trento, Dipartimento di Ingegneria dei Materiali e Tecnologia Industriali, Università di Trento, Mesiano 77, 38100, Trento, Italy; E-mail:
[email protected], ***Engineer, MIMEST spa, Viale Dante 300, 38057, Pergine Valsugana, Trento, Italy
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as-sintered microstructure significantly different from that of cast alloys of similar composition. In particular, as-cast microstructures are relatively coarse with both dendritic and interdendritic carbides resulting from microsegregation (coring) on solidification. In contrast, sintered microstructures exhibit large eutectic cells, and the carbides distribution is not as homogeneous. Even with a similar chemical composition, the transformations during heat treatment can be influenced by the distribution and composition of the carbides. The alloy was then solution annealed in the temperature range 1,200°C–1,250°C to investigate the effect on the dissolution of carbides, and on the transformations on aging at 750°C for 3 h and 20 h. The effect of the solution-annealing temperature and of the aging time on the microstructural transformations was studied by thermal analysis. Microstructural characterization utilized light optical microscopy (LOM), scanning electron microscopy (SEM), and X-ray diffractometry (XRD), and hardness and microindentation hardness were also measured. The tensile properties of the alloy were determined after solution annealing at selected temperatures and after aging.
solution-annealing temperature was performed under an 8 bar nitrogen flux. Specimens were air cooled after aging. Phase transformations on heating were examined by means of differential scanning calorimetry (DSC). Analyses were carried out under an argon–hydrogen (150 ml) atmosphere, by heating specimens at 20°C/min up to 1,300°C. Microstructures were characterized by LOM and SEM after electrolytic etching (94 ml distilled water, 4.5 ml HNO3, 1.5 ml H2O2 solution, at 3V for 4 s). To resolve the different carbides, a coloretching method was adopted; this uses an etchant (one part 20 v/o KMnO4 + 80 v/o water and one part 8 v/o NaOH + 92 v/o water), after the electrolytic etch. The carbides exhibit different colors: Cr27C6 brown, Cr7C3 bright yellow, and M6C blue. The constitution of the metallic matrix was investigated by XRD using CuKa radiation with a monochromator on the diffracted beam. Microindentation hardness (HV0.05) and hardness (HV30) were measured by making ten indentations on each specimen. Tensile tests were carried out on an Instron machine at a strain rate of 0.1s-1.
EXPERIMENTAL PROCEDURE Specimens were produced from a gas-atomized prealloyed F75 alloy (Co-29 w/o Cr-6 w/o Mo) containing 0.35 w/o C. Particle size was 80 w/o <22 µm with an apparent density of 5.55 g/cm3. The powder was blended with a proprietary polyolefin-base binder to produce the MIM feedstock. After injection molding the binder was removed by a two-step debinding process, namely, by immersion in water and then thermally to remove the residual 20 w/o binder. The brown parts were then sintered in a graphitic vacuum furnace (TAV Spa, Caravaggio, Italy) at 10-2 bar under the following conditions: 1,300°C, 1 h holding time, nitrogen backfilling, and cooling at 1 bar of nitrogen flux (~15°C/min). The sintered density was >99% of the pore-free value. Solution annealing and aging treatments were carried out in the same vacuum furnace, utilizing the conditions cited in Table I. Cooling from the
RESULTS AND DISCUSSION Figure 1 shows a representative microstructure of the sintered CoCrMo alloy. It contains predominantly eutectic cells and grain-boundary precipitates. Three types of carbides were identified by the color metallographic etching: • M23C6: the main constituent of the eutectic cells (lamellar) • M6C and M7C3: present in the eutectic cells and along grain boundaries The SEM micrograph in Figure 2 shows the morphology of the carbides (M23C6 in the center, M6C and M7C3 on the right). In addition, the small and fragmented precipitates at the grain boundaries are the sigma phase. The formation of this constituent was detected in conjunction with, or subsequent to, M23C6 precipitation.2 The microstructure is relatively coarse with a grain size 115 ± 12 µm, a result of the high sintering temperature. Following Koster and Sperner11 and Sahm12,13
TABLE I. PROCESSING AND HEAT TREATING PARAMETERS Thermal Debinding in Nitrogen and Sintering at 1,300°C/1 h
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Solution Annealing at 1,200°C/4 h (1) Solution Annealing at 1,220°C/4 h (2) Solution Annealing at 1,240°C/4 h (3)
Aging at 750°C for 3 h and 20 h
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Figure 3. Quasiternary phase diagram of the Co-Cr-Mo-C system14
Figure 1. Representative as-sintered microstrcuture of Co-Cr-Mo-0.35 w/o C alloy. LOM
Figure 4. DSC curve of the as-sintered alloy
Figure 2. As-sintered microstructure of Co-Cr-Mo-0.35 w/o C alloy. SEM
the projection of the monovariant solidification lines in the ternary Co-Cr-C system can be represented as shown in Figure 3. Koster11 has reported two ternary eutectics in the Co-Cr-C system: (i) ET1 between sigma phase, M23C6, and a cobalt-rich solid solution (plus liquid) which melts at 1,335°C, and: (ii) ET2 between graphite, M7C3, and cobalt which melts at 1,230°C. In light of the complete mutual solid solubility of chromium and molybdenum at high temperatures, it is reasonable to include chromium and molybdenum in combination, to obtain the chromium equivalent (molybdenum:chromium ratios up to 1:4). Kilner14 found that the two eutectics are close Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
to each other, to the extent that the F75 alloy with 0.27 w/o C exhibits only one single eutectic transformation at 1,235 ± 5°C. This transformation involves M7C3, M23C6, sigma phase, and a facecentered cubic (fcc) cobalt-rich phase close to the eutectic composition. DSC analysis was carried out for the purpose of identifying the eutectic transformations leading to the formation of the liquid phase. Figure 4 shows the DSC curve of the as-sintered alloy. Two endothermic peaks are evident, with the maxima at ~1,245°C and ~1,265°C which correspond to two eutectic reactions involving the eutectic cells containing M23C6 (1,245°C) and M7C3 carbide (1,265°C). M6C can precipitate directly from the fcc solid solution and also form as a product of the transformation on heating M23C6.2,19 On the basis of these results, three temperatures were selected for the solution-annealing treatment, namely, 1,200°C, 1,220°C, and
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1,250°C. The first two temperatures are lower than the eutectic temperature and the third is between the two eutectic temperatures. Solution Annealing at 1,200°C Figure 5(a) shows the microstructure of the alloy solution annealed at 1,200°C. Figures 5(b) and 5(c) show the microstructure of the alloy after aging at 750°C for 3 h and 20 h, respectively. Solution annealing at 1,200°C results in partial dissolution of the eutectic cells and fragmentation of the grainboundary precipitates. The grain size of the metallic matrix (115 ± 12 µm) does not change with heat treatment. Aging promotes Widmastätten precipitation within the grains, and the formation of the hcp phase at the grain boundaries. On increasing the aging time, both phenomena are enhanced, as expected. In relation to the hexagonal phase, it is well known5,15,16 that a transition from hcp 1 to hcp 2 occurs on prolonging aging. The latter
occurs by the precipitation of fine carbides between the hexagonal lamellae. Solution Annealing at 1,220°C Figure 6(a) shows the microstructure of the alloy solution annealed at 1,220°C and Figures 6(b) and 6(c) show the microstructure after aging at 750°C for 3 h and 20 h, respectively. Solution annealing at 1,220°C results in complete dissolution of the carbides in the eutectic cells. M23C6 and some of the M7C3 carbide particles remain at the grain boundaries. The sigma phase also remains and the grain size of the metallic matrix does not change from that in the sintered condition (115 ± 12 µm). Kilner14 found that prolonged solution treatment (<24 h) at temperatures close to, but below, the melting point of the interdendritic constituent resulted in the appearance of M23C6 carbides as the only interdendritic phase; the M23C6 carbides dissolve resulting in a homogeneous alloy. On aging, the same transformations previously
Figure 5. Representative microstructures of sintered alloy. (a) solution annealed at 1,200°C, (b) and (c) aged at 750°C for 3 h and 20 h, respectively. LOM
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Figure 6. Representative microstructures of sintered alloy (a) solution annealed at 1,220°C, (b) and (c) aged at 750°C for 3 h and 20 h, respectively. (a), (b), and (c) LOM, (d) SEM
described occur. These transformations involve intragranular Widmastätten precipitation and grain-boundary precipitation of the hexagonal constituents. The detailed microstructure of the alloy after aging for 20 h is shown in the SEM micrograph of Figure 6(d). Since the Widmanstätten precipitates are M23C6 carbides,2,5,15,16 solution annealing and aging are effective in promoting the formation of a homogeneous dispersion of carbides in the metallic matrix. This is in contrast to the highly segregated microstructure of the as-sintered alloy. Weeton and Signorelli2 have shown that Cr7C3 undergoes decomposition upon aging: Cr7C3 Cr23C6 + Free Carbon (1) Free Carbon + Chromium Additional Cr23C6 (2) Solution Annealing at 1,250°C Figure 7(a) shows a representative LOM microstructure of the alloy solution annealed at Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
1,250°C. The eutectic cells are completely dissolved, as are most of the other carbides. Only a few M23C6, M6C and M7C3 carbides are visible but with a modified morphology. In particular, analysis by SEM (Figure 7(b)) identifies globular particles of M23C6/M7C3 and eutectic M6C with a low dihedral angle. The grain size of the metallic matrix is increased slightly from 140 ± 23 µm, because of dissolution of the carbides. Solution annealing above the eutectic reaction temperature was studied by Kilner14 who observed a serrated appearance of the boundaries between the interdendritic constituent and the matrix. This has been described as a “starlike” phase. In addition to this phase, grain-boundary melting takes place, as observed in the present study. After aging (Figures 8(a) and 8(b)), both the intragranular Widmastätten precipitates and the grain boundary hexagonal constituents are evident, the former in a lesser amount than in the previous alloys.
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Figure 7. Representative microstructure of sintered alloy after solution annealing at 1,250°C. (a) LOM, (b) SEM
Figure 8. Representative microstructure after aging at 750°C (a) 3 h, (b) 20 h. LOM
Mechanical Properties The mechanical properties of the cobalt alloy depend on the constitution of the metallic matrix.17 An important property of this alloy is its high strain hardenability, which is due to the low stacking-fault energy of the fcc and hcp phases, coupled with the strain-induced transformation of austenite to martensite.10 Table II cites the results of the quantitative XRD analysis of the constitution of the matrix on alloys solution annealed at 1,220°C and 1,250°C. The alloy solution annealed at 1,200°C was excluded since it did not represent a microstructural condition of practical interest. The as-atomized powder is completely fcc since all the alloying elements are dissolved in the metallic matrix and carbide precipitation is suppressed by the high degree of undercooling during solidification following atomization. On sintering, carbides precipitate and austenite transforms to martensite
48
on cooling so that the as-sintered alloy is then fully martensitic. Solution annealing dissolves the carbon in the matrix, thereby increasing the stability of the austenite, which transforms partially into martensite on cooling. On aging, the amount of martensite increases because of the formation of hexagonal phases at the grain boundaries. TABLE II. CONSTITUTION OF METALLIC MATRIX Material and Condition Powder 0.35 w/o C Sintered at 1,300°C Solution Annealed at 1,220°C Solution Annealed at 1,220°C and Aged at 750°C 3 h Solution Annealed at 1,220°C and Aged at 750°C 20 h Solution Annealed at 1,250°C Solution Annealed at 1,250°C and Aged at 750°C 3 h Solution Annealed at 1,250°C and Aged at 750°C 20 h
fcc (v/o)
hcp (v/o)
100 62 78.3 61.7 70 53.7 53.9
100 38 21.7 38.3 30 46.3 46.1
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Figure 9. Matrix hardness and microindentation hardness
Figure 9 shows the matrix microindentation hardness and the hardness of the alloys investigated. Solution annealing causes an increase in the microindentation hardness because of solution hardening by carbon and the alloying elements, with a small decrease with increasing temperature. On aging, microindentation hardness increases, particularly after 20 h, because of intragranular precipitation. Hardness decreases after solution annealing, since this property is influenced by the carbides and by the grain size; this also rationalizes the further decrease with increase in the solution annealing temperature. On the basis of the results of the microstructural characterization, analysis of the constituents of the alloy, the microindentation hardness and hardness tests, a solution annealing temperature of 1,220°C was selected for the tensile tests. The lower temperature (1,200°C) does not significantly reduce the amount of carbides, whereas the higher temperature (1,250°C) results in dissolution of the carbides but at the expense of hardness due to grain growth. The alloy solution annealed at 1,220°C is expected to exhibit enhanced ductility compared with the alloy solution annealed at 1,200°C, and a higher strength than that of the alloy solution annealed at 1,250°C. Figure 10 shows the results of the tensile tests on a yield strength–percent elongation map (average data for five tests in each condition).10 Solution annealing results in a significant increase in ductility, accompanied by only a small decrease in yield strength. On aging, the strength further increases, but the decrease in ductility is pronounced because of the negative effect of the grain-boundary hexagonal constituent.18 In particular, the alloy aged for 20 h, which could be Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
attractive commercially in tribological applications (due to its high hardness provided by the fine precipitation of carbides), does not exhibit sufficient ductility. A unique characteristic of these alloys is their high level of strain hardening. Figure 11 shows an example of the stress-strain curve of a solutionannealed alloy; the increase in proof stress in the plastic region is pronounced, indicative of a high resistance to plastic deformation.19 This property is of importance in enhancing the resistance of the alloy to overloading. The microstructure of the solution-annealed alloy is primarily austenitic (Table II). However, XRD analyses of the fractured tensile specimens show that the amount of austenite close to the fracture surface is negligible. Strain hardening is therefore due to the strain-induced transformation
Figure 10. Yield strength and elongation at fracture for alloys sintered at 1,300°C, and solution annealed at 1,220°C for 4 h followed by aging
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TABLE III. PLASTIC FIELD PARAMETERS Alloy Condition Solution Annealed at 1,220°C
K
M
N
R2
1,120
1.35
0.13
0.9992
ear relationships can be assumed between the strain hardening coefficient n and true strain, and Kim and Lim17 invoked the relation: n = d lnσt / d lnεt = Mεt + N
(4)
where M and N are temperature-dependent constants. Upon integration of equation (4), a flow equation is obtained: Figure 11. Tensile stress-strain curve of alloy solution annealed at 1,220°C for 4 h
of austenite to martensite. The strain-hardening coefficient cannot be calculated from the classical Ludwick-Hollomon model, since the log-log diagram of true stress vs. true strain does not exhibit a linear relation; it shows a continuous increase in slope, as demonstrated in Figure 12. This is characteristic of the behavior of metastable austenite in steels, and can be modeled following Kim and Lim.20 The correlation between true stress and true strain, assumed to be quadratic, is: lnσt = a(ln ε t ) 2 + b(ln ε t ) + c
(3)
where a, b, and c are experimentally determined constants. Based on the experimental data, a lin-
Figure 12. True-stress/true-strain curve for alloy solution annealed at 1,220°C for 4h
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σt = KεtN exp(Mεt)
(5)
where K is a constant depending on the alloy, and M describes how the flow stress increases with plastic strain because of the strain-induced transformation of austenite to martensite. K, N, and M are given in Table III, and the strain-hardening rate is shown in Figure 13 as a function of strain. It increases from 0.13 at strain zero up to 0.33 at the UTS, due to the strain induced transformation. SUMMARY AND CONCLUSIONS The effect of the solution-annealing temperature on the microstructure, microindentation hardness, and hardness of a Co-Cr-Mo-0.35 w/o C alloy produced by MIM of prealloyed powder was investigated. Temperature was varied between 1,200°C and 1,250°C. The as-sintered microstructure contains a high level of carbides: M23C6, M6C,
Figure 13. Strain-hardening coefficient vs. true strain for alloy solution annealed at 1,220°C for 4 h Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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SOLUTION ANNEALING AND AGING OF A MIM CoCrMo ALLOY
and M7C3, and sigma phase precipitated at the grain boundaries. Solution annealing at 1,200°C does not change the microstructure significantly. At 1,220°C the dissolution of the eutectic cell carbides, partial dissolution of sigma phase, and the evolution of M23C6 and M7C3 carbides with a globular morphology are observed. At 1,250°C carbides and sigma phase are completely dissolved, but a liquid phase and both globular M23C6 and M7C3 carbides and eutectic M6C carbides are formed. Aging promotes the intragranular Widmastätten precipitation of carbides, and the formation of fine lamellar hcp phases at the grain boundaries. The optimal solution-annealing temperature was 1,220°C, notwithstanding the presence of some residual carbides at the grain boundaries. Tensile properties after solution annealing at this temperature were attractive, since ductility increases significantly without an excessive decrease in tensile strength, in comparison with the alloy in the as-sintered condition. After aging, the alloy was brittle because of the negative effect of the hexagonal phase at grain boundaries. The strain-hardening rate of the solution annealed alloy was high, due to the strain-induced transformation of austenite to martensite. The characteristic could provide a positive contribution to plasticity and compensate for the negative effect of the residual grain-boundary precipitates, which can cause brittleness. Work is in progress to evaluate the effect of solution annealing on fatigue resistance. REFERENCES 1. H.S. Dobbs and J.L.M. Robertson, “Heat Treatment of Cast Co-Cr-Mo for Orthopaedic Implant Use”, J. Mater. Sci., 1983, vol. 18, pp. 391–401. 2. J.W. Weeton and R.A. Signorelli, “Effect of Heat Treatment Upon Microstructures, Microconstituents, and Hardness of a Wrought Cobalt Base Alloy”, Trans. Amer. Soc. Met., 1955, vol. 47, pp. 815–852. 3. P.V. Muterlle, M. Zendron, C. Zanella, M. Perina, R. Bardini and A. Molinari, “Effect of Microstructure on the Properties of a Biomedical Co-Cr-Mo Alloy Produced by MIM”, Advances in Powder Metallurgy & Particulate Materials—2009, compiled by T.J. Jesberger and S.J. Mashl, Metal Powder Industries Federation, Princeton, NJ, 2009, vol. 1, part 4, pp. 60–69. 4. A.J. Saldivar Garcia and H.F. Lopez, “Microstructural Effects on the Wear Resistance of Wrought and As-Cast Co-Cr-Mo-C Implant Alloys”, J. Biomed. Mater. Res., 2005, vol. 74A, pp. 269–274. 5. R.N.J. Taylor and R.B. Waterhouse, “A Study of the Aging Behaviour of a Cobalt Based Implant Alloy”, J. Mater. Sci., 1983, vol. 18, pp. 3,265–3,280.
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
6. J.B. Vander Sande, J.R. Coke and J. Wulff, “A Transmission Electron Microscopy Study of the Mechanisms of Strengthening in Heat-Treated Co-Cr-MoC Alloy”, Met. Trans., 1976, vol. 7A, pp. 389–397. 7. J.A. Sago, M.W. Broadley and J.K. Eckert, “Development of CoCr MIM Alloys Suitable for Medical Device Applications”, Advances in Powder Metallurgy & Particulate Materials—2009, compiled by T.J. Jesberger and S.J. Mashl, Metal Powder Industries Federation, Princeton, NJ, 2009, vol. 1, part 4, pp. 111–117. 8. R. Tandon, “Net-Shaping of Co-Cr-Mo (F-75) via Metal Injection Molding”, Cobalt-Base Alloys for Biomedical Applications, ASTM STP 1365, edited by J.A. Disegi, R.L. Kennedy, R. Pilliar, ASTM, West Conshohocken, PA, 1999, pp. 3–10. 9. P.V. Muterlle, M. Perina, M. Mantovani, L. Girardini and A. Molinari, “ Microstructure and Mechanical Properties of a C Alloyed Co-Cr-Mo Produced by MIM”, Proceedings EURO PM2007, EPMA, Shrewsbury, UK, 2007, vol. 2, pp. 215–220. 10. P.V. Muterlle, M. D’Incau, M. Perina, R. Bardini and A. Molinari, “Effect of Heat Treatment on Microstructure and Properties of Co-Cr-Mo Alloy Produced by MIM”, Advances in Powder Metallurgy & Particulate Materials—2008, compiled by R. Lawcock, A. Lawley and P.J. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, vol. 2, part 4, pp. 183–190. 11. V.W. Koster and F. Sperner “Das Dreistoffsystem KobaltChrom-Kohlenstoff. Arch Eisenhuttenwesen”, 1955, vol. 26, pp. 555–559. 12. P.R. Sahm and D.Y. Watt, “The Monovariant Eutectic Co 1−x Cr x -Cr 7−x , Co x C 3 ”, Metallurgical and Materials Transactions B, 1971, vol. 2, pp. 1260–1261. 13. P.R. Sahm, M. Lorenz, W. Hugi and V. Frühauf, “The Monovariant Eutectic Co, Cr-Cr7-xCoxC3”, Metallurgical and Materials Transactions B, 1972, vol. 3, pp. 1,022–1,025. 14. T. Kilner, R.M. Pilliar, G.C. Weatherly and C. Allibert, “Phase Identification and Incipient Melting in a Cast CoCr Surgical Implant Alloy”, J. Biomed. Mater. Res., 1982, vol. 16, pp. 63–79. 15. K. Rajan, “Phase Transformations in a Wrought Co-CrMo-C Alloy”, Met. Trans., 1982, vol. 13A, pp. 1,161–1,166. 16. K. Rajan, “Nucleation of Recrystallization in a Co-Cr-Mo Alloy”, Met. Trans., 1984, vol. 15A, pp. 1,335-1,338. 17. A. Salinas-Rodriguez and J.L. Rodriguez-Galicia, “Deformation Behavior of Low-Carbon Co-Cr-Mo Alloys for Low-Friction Implant Applications”, J. Biomed. Mater. Res., 1996, vol. 31, pp. 409–419. 18. P.V. Muterlle, M. Zendron, M. Perina, R. Bardini and A. Molinari, “Effect of Sintering Temperature and Heat Treatment on Microstructure and Tensile Properties of Co-Cr-Mo Alloy with 0.23%C Produced by MIM,” J. Mat. Science, in press 19. H. Mancha, M. Gómez, M. Castro, M. Méndez, J. Méndez and J. Juárez, “Effect of Heat Treatment on the Mechanical Properties of an As-Cast ASTM F-75 Implant Alloy”, J. Mater. Synth Process, 1996, vol. 4, no. 4, pp. 217–226. 20. Y.G. Kim and C.Y. Lim, “The Flow Equation and Its Necking Criterion in Austenitic Cryogenic Fe-Mn-Al-X Steels”, Met. Trans., 1988, vol. 19A, pp. 1,625–1,626. ijpm
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MUTERRLE et al_Zheng et al 7/22/2010 11:03 AM Page 52
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2011 International Conference on Powder Metallurgy & Particulate Materials May 18–21 • Marriott Marquis • San Francisco, California NEW DATES & LOCATION
For complete program and registration information contact:
METAL POWDER INDUSTRIES FEDERATION APMI INTERNATIONAL 105 College Road East, Princeton, New Jersey 08540 USA Tel: 609-452-7700 ~ Fax: 609-987-8523 ~ www.mpif.org
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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.”
Carbide Firm Expands Yillik Precision Carbides, division of PSM Industries, Inc., has moved to a new 13,000 sq. ft. building near its former location in Ontario, Calif. The larger plant supports the company’s recent growth into new miniature carbide products for oilfield-equipment, medical, and sporting-goods industries. Canadian Government Loans Funds for Tungsten Project The Ministry of Economic Development and Trade, Ontario, Canada, is providing a Can$4.14 million loan to H.C. Starck Canada to modernize the company’s tungsten powder plant in Sarnia, Ontario. The loan is funded by the province’s Advanced Manufacturing Investment Strategy repayable loan program, which encourages companies to invest in leading-edge technologies and processes. Graphite Maker Achieves Certifications The Bodio, Switzerland, plant of TIMCAL Graphite & Carbon has achieved ISO 14001 (environmental management system) and OHSAS 18001 (occupational health and safety management system) certifications from the Swiss Association for Quality and Management Systems SQS. The plant produces graphite and other carbon products, silicon graphite and lubrication technologies for hot metal forming. Powder Maker Reports Strong Gains Höganäs AB, Sweden, reports a 69 percent increase in first quarter Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
sales over the same period in 2009 to MSEK 1,548 (about $215 million). Overall production soared, especially in Asia and South America where it more than doubled. Miba Completes Takeover of Coatings Firm Miba AG, Laakirchen, Austria, has completed the takeover of Teer Coatings Ltd., Droitwich, UK, a supplier of polymer coatings, electroplated overlays, and PVD coatings. Miba acquired a 24.9 percent interest in Teer in 2009. Powder Maker Designs NewGeneration Electric Motor for Bicycles Höganäs AB, Sweden, is introducing a new electric-motor design for bicycles featuring a PM stator in the Swedish pavilion at the World Expo in Shanghai, China. Located on 1,304 acres in Shanghai’s Pudong district, the expo is expected to draw 60 to 70 million visitors during the next six months. Union Process Expands in China Requiring more manufacturing space to meet growing demand, Union Process, Inc., Akron, Ohio, has moved its joint-venture operation, Qingdao Union Process Precision Machinery Co., Ltd., to a larger facility in downtown Qingdao, China. The company makes wet and dry grinding mills and dispersing equipment. PM Companies Signal Positive Outlook Three major European-headquartered PM companies are viewing
present conditions and future prospects in a positive light. Miba AG, Laarkirchen, Austria, despite reporting a 16.8 percent sales decline to €311.8 million (about $395 million) for fiscal year 2009–10, had a strong start in the 2010–11 business year. GKN plc, London, UK, reports encouraging market conditions in the first quarter of 2010 for its major businesses. And Tomkins plc, London, UK, reports a positive outlook for its automotive products used in the aftermarket and OEM segments. New High-Temperature PM Materials Federal-Mogul Corporation, Southfield, Mich., is extending its materials range for powder metallurgy bushings and guides designed for high-temperature applications in turbochargers and exhaust gas recirculation systems. The company will offer new materials to meet the very tough durability targets imposed by the increasingly severe exhaust-gas conditions up to about 1,050°C (1,922°F) in the new generation of downsized, low-CO2 engines. PM Trends in Italy Production of iron and copper-base PM parts in Italy declined 27.8 percent in 2009 to 24,400 short tons, reports ASSINTER, the Italian PM Association. Automotive applications accounted for 59 percent of PM parts production, instruments and mechanical devices for 19.9 percent, power tools for 13.5 percent, and appliances, 7.6 percent.
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PM INDUSTRY NEWS IN REVIEW
New Micro-Injection Molding Module Arburg GmbH + Co KG, Lossburg, Germany, offers a new micro-injection module for powder injection molding (PIM) miniature components. Designed for electric Allrounder A machines with a size 70 injection unit, the module can be changed rapidly and used on different machines. MIM Web Site in Four Languages Kinetics Climax, Inc., Wilsonville, Ore., has opened a new Web site (www.kinetics.com) on metal injection molding (MIM) technology presented in four languages: English, simplified Chinese, German, and Spanish. An online design guide provides best practices for designing MIM
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parts for improved quality and performance. Materials Supplier Certified for Sustainable Energy Management H.C. Starck, GmbH, a supplier of refractory metals, technical ceramics, and conductive polymers, has achieved certification for sustainable energy management at its Goslar, Germany, production site. The certification, validated by the GUTcert organization, complies with DIN EN 16001 which recognizes the company’s continuous improvement of energy efficiency and systematic optimization of energy flows. High-Pressure-Sintering Furnace Line Reengineered Centorr Vacuum Industries,
Nashua, N.H., has expanded the temperature range and pressure capabilities of its Sinterbar line of high-pressure sintering furnaces first introduced in 1982. An engineering team has improved the furnace’s thermal performance, safety, durability and cost-effectiveness, the company reports. Isostatic Technology Showcased at PM Conference Dieffenbacher GmbH & Co. KG, Eppingen, Germany, will showcase its cold (CIP) and hot isostatic pressing (HIP) technology at the PowderMet2010 Conference in Hollywood (Fort Lauderdale), Florida. It will display the ISOMAT and ISOPLANT CIP presses. ijpm
Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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MEETINGS AND CONFERENCES
2010
2011
2013
ILASS 2010 23RD ANNUAL CONFERENCE ON LIQUID ATOMIZATION AND SPRAY SYSTEMS September 6–8 Brno, Czech Republic www.ilasseurope2010.org
(NOTE: NEW DATES & LOCATION) PowderMet2011: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS May 18–21 San Francisco, CA MPIF*
PowderMet2013: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 23–26 Chicago, IL MPIF*
ICM11 THE 11TH INTERNATIONAL CONFERENCE ON THE MECHANICAL BEHAVIOR OF MATERIALS June 5–8 Lake Como, Italy www.icm11.org
2014
TSS COLD SPRAY CONFERENCE September 27–28 Akron, OH www.asminternational.org TITANIUM 2010 October 3–5 Orlando, FL www.titanium.org PM2010 WORLD CONGRESS October 10–14 Florence, Italy www.epma.com/pm2010
INTERNATIONAL CONFERENCE ON SINTERING 2011 August 28–September 1 Jeju Island, Korea www.sintering2011.org
7TH INTERNATIONAL SYMPOSIUM ON SUPERALLOY 718 & DERIVATIVES October 10–13 Pittsburgh, PA www.tms.org
2012
PM + ACE 2010 2ND INTERNATIONAL POWDER METALLURGY & ADVANCED CERAMICS EXHIBITION & CONFERENCE October 18–20 Shanghai, China www.China-PM-ACE.com/en FORGING, SHEET METAL FORMING & POWDER METALLURGY – LINKING INDUSTRY & TECHNOLOGY October 20–22 Porto Alegre, Brazil www.senafor.com.br PM SINTERING SEMINAR December TBA MPIF* Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
PM2014 WORLD CONGRESS May 18–22 Lake Buena Vista (Orlando), FL MPIF*
PowderMet2012: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 10–13 Nashville, TN MPIF* SUPERALLOYS 2012: TWELFTH INTERNATIONAL SYMPOSIUM ON SUPERALLOYS September 9–13 Champion, PA
*Metal Powder Industries Federation 105 College Road East, Princeton, New Jersey 08540-6692 USA (609) 452-7700 Fax (609) 987-8523 Visit www.mpif.org for updates and registration. Dates and locations may change
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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 ________________________________18 Ametek specialty metal products ____________(724) 225-6622 __________www.ametekmetals.com ______________________________19 Global Titanium __________________________(313) 366-5305 __________www.globaltitanium.com ______________________________54 Hoeganaes Corporation ___________________(856) 786-2574 __________www.hoeganaes.com ___________________Inside Front Cover Magnaquench ___________________________(65) 6415 0670 __________www.mqitechnology.com_______________________________8 North American Höganäs Inc. ______________(814) 479-2003 __________www.nah.com _______________________________________3 Rio Tinto Metal Powders/ Quebec Metal Powders Limited ____________(734) 953-0082 __________www.qmp-powders.com _______________________Back Cover SCM Metal Products, Inc. __________________(919) 544-7996 __________www.scmmetals.com ____________________Inside Back Cover TIMCAL ________________________________+41-91-873-2009 _________www.timcal.com ____________________________________24
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: ___________________________
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Volume 46, Issue 4, 2010 International Journal of Powder Metallurgy
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Metal Powders
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