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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 H.I. Sanderow, FAPMI D.W. Smith, FAPMI R. Tandon T.A. Tomlin D.T. Whychell, Sr., FAPMI M. Wright, PMT A. Zavaliangos INTERNATIONAL LIAISON COMMITTEE D. Whittaker (UK) Chairman V. Arnhold (Germany) E.C. Barba (Mexico) P. Beiss, FAPMI (Germany) C. Blais (Canada) P. Blanchard (France) G.F. Bocchini (Italy) F. Chagnon (Canada) C-L Chu (Taiwan) O. Coube (Europe) H. Danninger (Austria) U. Engström (Sweden) O. Grinder (Sweden) S. Guo (China) F-L Han (China) K.S. Hwang (Taiwan) Y.D. Kim (Korea) G. L’Espérance, FAPMI (Canada) H. Miura (Japan) C.B. Molins (Spain) R.L. Orban (Romania) T.L. Pecanha (Brazil) F. Petzoldt (Germany) S. Saritas (Turkey) 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] President of APMI International Nicholas T. Mares
[email protected] Executive Director/CEO, APMI International C. James Trombino, CAE
[email protected]
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powder metallurgy Contents 2 5 9 11 15 18
44/5 September/October 2008
Editor's Note Newsmaker Joseph Tunick Strauss PM Industry News in Review PMT Spotlight On …Christopher Hammond Consultants’ Corner Myron I. Jaffe 2008 POSTER AWARDS K. Songsiri, A. Manonukul, P. Chalermkarnnon, H. Nakayama and M. Fujiwara M.N. Chikhradze and G.S. Oniashvili
23 Axel Madsen/CPMT Scholar Reports M. Boisvert; E.M. Byrne; J. Martz; and N. Oster
FOCUS: Hot Isostatic Pressing 27 Hot Isostatic Pressing: More than a Niche Technology S.J. Mashl
33 Diversification of Hot Isostatic Pressing Equipment Technology K. Watanabe, K. Suzuki, S. Kofune, N. Nakai, M. Yoneda, Y. Manabe and T. Fujikawa
41 Applications for Large-Scale Prealloyed Hot Isostatically Pressed Powder Metallurgy Materials B. McTiernan
49 Cladding of Briquetting Tools by Hot Isostatic Pressing for Wear Resistance C. Broeckmann, A. Höfter and A. Packeisen
57 Hot Isostatic Pressing Simulation for Titanium Alloys T. Teraoku
DEPARTMENTS 62 Meetings and Conferences 63 APMI Membership Application 64 Advertisers’ Index Cover: Welding of HIPing container. Photo courtesy Crucible Materials Corporation, Pittsburgh, Pennsylvania. 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 © 2008 by APMI International. Subscription rates to non-members; USA, Canada and Mexico: $95.00 individuals, $220.00 institutions; overseas: additional $40.00 postage; single issues $50.00. Printed in USA by Cadmus Communications Corporation, P.O. Box 27367, Richmond, Virginia 23261-7367. 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 INTERNATIONAL 105 College Road East, Princeton, New Jersey 08540-6692 USA Tel: (609) 452-7700 • Fax: (609) 987-8523 • E-mail:
[email protected]
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EDITOR’S NOTE
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n a society driven by technological advances, nine years is a long time frame. Witness and compare the current state-of-the-art of hot isostatic pressing with that existing in 1999—when the Journal last focused on this materials-processing technology. Coordinated by Steve Mashl, the content of this Focus Issue provides a comprehensive overview of the state and direction of the hot isostatic pressing industry, now clearly more than a “niche” processing technology. As one yardstick, Avure Technologies is building a dedicated hot isostatic press for PM stainless steel components with a capacity for processing up to 10,000 mt annually. With a heated work zone 2 m dia. × 2.6 m in height, it will accommodate large parts, subassemblies and large batches of small parts. In the “Newsmaker” section, Peter Johnson profiles Joe Strauss, a successful consultant and practitioner specializing in the atomization of conventional and unusual materials. I think that after reading the profile you will agree that “unconventional tinker and metal powder entrepreneur” is an apt description of this active member of MPIF and the PM community. In the “Consultants’ Corner,” Mike Jaffe (assisted by his son Sandy) again demonstrates his expertise as a hands-on PM practitioner. Readers’ questions considered embrace: maintenance procedures for sintering furnaces; balancing atmosphere flow in a sintering furnace; selection and lubricant amounts to avoid galling in core rods; and the effects of coining and repressing on porosity and the properties of compacts. As in previous years, the Axel Madsen/CPMT Scholar reports provide interesting and important insights from potential next-generation PM industry leaders. Each of the four student recipients derived both tangible and indirect benefits from his experiences while attending the PM 2008 World Congress. This program is clearly a “must” for continuation by the PM industry.
Alan Lawley Editor-in-Chief
In a recent article in The Bent of Tau Beta Pi (vol. XCIX, no. 3, pp 16–21), Jeff Wadsworth, executive vice president, global laboratory operations, Battelle Memorial Institute, and a metallurgist educated in the UK, provides an incisive perspective on the role of materials and materials processing on three current major global concerns: energy production and use; the environment and climate change; and national/global security. The attendant materials challenges include: specialized metals and alloys; materials for clean energy; ultrascale computing technology; electronic and photonic materials, sensors and actuators; small weapons and light armor; and portable energy sources. While currently involved in updating the MPIF Industry Roadmap, I am struck by the many potential opportunities for the PM industry to be a leading participant in tackling these major global concerns.
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Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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NEWSMAKER
JOSEPH TUNICK STRAUSS By Peter K. Johnson* Joe Strauss, founder and president of HJE Company, Inc., Queensbury, New York, is an unconventional tinker and metal powder entrepreneur. He breathes new life into old beat-up cars, designs highly sophisticated metal-atomizing units, is a powder maker of “last resort” for unusual materials, as well as providing field service for metal powder producers. “I’m also a doorto-door atomizer repair guy,” he says. His powder metallurgy (PM) journey began at the age of seven running a lathe in his stepfather’s machine shop in Peekskill, New York, “I worked weekends and summers through high school and college days,” he says. The shop pressed and sintered industrial diamond tools. Partial to mathematics and science in high school, he enrolled at Rensselaer Polytechnic Institute (RPI), Troy, New York, in 1973. He earned a BS in materials engineering in 1977, studying physical metallurgy, specifically welding metallurgy, as PM was not being taught there at the time. He considered a master’s degree program before accepting a job as a welding engineer with Electric Boat Corporation, in Groton, Connecticut. “I was not a stellar student,” he admits. “I was more of a hands-on person.” Professor Fritz V. Lenel, a PM pioneer still on the RPI faculty then, did not encourage Strauss. Lenel told him, “I’m 72 years old and tired of babysitting people.” Strauss stayed at Electric Boat for one year before switching to National Diamond Laboratories in California. While there he developed a highspeed PM process for making diamond tools that reduced cycle times from 30 minutes to one *Contributing editor
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
minute per piece. Still hankering for PM experience, he enrolled at Michigan Technological University in 1979. Before finishing his MS course work he joined the R&D group at Valenite Tools in Detroit. For a time his love of manufacturing overcame academics, but not for long. While visiting RPI in 1984 he met his former advisor who suggested, “You should return for a PhD degree.” He wrestled with the idea and decided that he needed to enhance his powder skills. Professor Randall German was his faculty advisor (and Fritz Lenel was on his thesis committee!). Pursuing a doctorate stretched out to seven years because of numerous consulting projects and developing and building atomizers. “Rand was very generous in hiring students to help with consulting contracts,” he recalls. Finding his niche, he became proficient in atomization technology, including induction melting and nozzle design. Leveraging that success he built other prototype units and spoke at an atomization workshop organized by the Massachusetts Institute of Technology (MIT) in 1987, quite an honor for a graduate student. As he gained expertise in atomization technology, he met many of the major players in the atomization community and the PM industry. “I realized that no one else was designing and building atomizer parts and units,” he says. Soon after receiving his PhD in Materials Engineering in 1991, he rented industrial space nearby and began making atomizers for dental alloys and jewelry solders. As the business prospered he moved into larger quarters in Glens Falls in 1995. In 2004 he purchased a 1,400 sq. m (15,000 sq. ft.) building on 12,000 sq. m (~3 acres) in Queensbury, New York. With ijpm
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NEWSMAKER: JOSEPH TUNICK STRAUSS
five employees, he builds gas- and water-atomizing units, offers contract R&D, as well as providing toll atomizing services for unusual or nontraditional alloys and materials, for example, metals, plastics and glass. He has a complete PM laboratory for testing and prototyping nontraditional materials and applications. There are more than 20 HJE atomizers operating internationally. Most have capacities of less than 20 kg (44 lb.). The largest unit built has a capacity of 22.7 kg (50 lb.) per min. As a scale reference, Strauss reports that 90 percent of dental amalgams made in North America are produced from one HJE atomizing system. Along the way, Strauss has honed his mechanical engineering skills rehabbing old cars, a serious hobby hatched during his high school days. He currently owns 30 cars in various conditions,
including a barnful of rusting Buicks and Opels. Casting frugality aside, he purchased his first new vehicle ever, a pickup truck, in 2001. Another, more recent, hobby is collecting old PM textbooks. “The technology in those older books is still relevant,” he says. “Call me if you want to get rid of old PM books,” he offers. When not at home with his wife Stephanie, a French teacher, and their six-year-old daughter, Lison, he pursues another hobby—searching for new diners. His favorite eatery is Poopies Diner in Glens Falls, known for its fresh ingredients and local color. An unassuming but high-tech entrepreneur, Joe Strauss loves his work and believes there is an unlimited future for nontraditional powders and processes. Calling his company a “PM playground,” he says “it’s fun playing in my place.” ijpm
PURCHASER & PROCESSOR
Powder Metal Scrap (800) 313-9672 Since 1946
Ferrous & Non-Ferrous Metals Green, Sintered, Floor Sweeps, Furnace & Maintenance Scrap
1403 Fourth St. • Kalamazoo, MI 49048 • Tel: 269-342-0183 • Fax: 269-342-0185 Robert Lando E-mail:
[email protected]
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Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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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.”
Kobelco Metal Powder Acquired Höganäs AB, Sweden, has acquired the business of Kobelco Metal Powder of America, Inc. (KOMPA), Seymour, Ind., through its subsidiary North American Höganäs, Inc. (NAH), Hollsopple, Pa. Established in 1987, KOMPA is a subsidiary of Kobe Steel, Ltd., Japan. Federal-Mogul Opens Powertrain Components Plant in Brazil Federal-Mogul Corp., Southfield, Mich., recently began producing pistons from a state-of-the-art manufacturing line at its new Powertrain Energy business segment’s 110,000 sq. ft. plant in Araras, Brazil. The facility has 338 employees and makes pistons, camshafts, valve seats, PM valve seat inserts, and PM valve guides for several leading vehicle manufacturers. Improving First Half for Swedish Powder Maker Höganäs AB, Sweden, reported growth in sales and shipments of metal powders during the first half of 2008. The company forecasts a highly uncertain immediate future, especially a weaker market in North America and somewhat slower growth in Europe and South America. Supplier Inflation Sharply rising raw materials costs are overwhelming auto parts suppliers, reports Automotive News, resulting in a new round of price increases for new vehicles. Suppliers predict the start of an inflationary spiral. Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
New PM Parts Plant in China The PMG Group, a joint venture of Plansee Group and Mitsubishi Materials Corp., is building a 54,000 sq. ft. automotive PM parts manufacturing plant in Shanghai, China. The initial investment is 12 million euros (about $19 million).
received six contracts from several automakers, reportedly worth more than $50 million, to produce powderforged (PF) connecting rods for fourand six-cylinder engines used globally in 2009 and 2010 vehicles. The vehicles are scheduled for launching in Asia, Europe, and North America.
PM Growing in Italy Italy’s PM parts industry grew 12 percent in 2007, with production reaching 35,770 short tons, according to the Italian PM association ASSINTER. Production of iron-base parts increased to 33,557 short tons, while production of copper-base parts declined slightly to 2,213 short tons.
PM Sales Rise GKN’s Powder Metallurgy sales, including those of Sinter Metals and Hoeganaes, rose almost eight percent to £333 million (about $621 million) for the first six months of 2008. However, trading profits for the same period declined from £15 million (about $28 million) in 2007 to £11 million (about $20.5 million).
New PM Parts Plant Miba AG, Laarkirchen, Austria, announced plans to build a new PM parts plant in McConnelsville, Ohio. The groundbreaking ceremony is scheduled for later this year and production is expected to begin around mid-2009.
ALTANA Group Agrees to Buy U.S. Bronze Pigments Business The specialty chemicals Group of ALTANA AG, Wesel, Germany, has signed an agreement to acquire the non-aluminum pigments business of United States Bronze Powders, Inc. (USBP), Flemington, N.J. The USBP pigments business generated approximately $8 million in sales in 2007.
Grant Fuels Low-Cost Titanium Powder Process Phoenix Scientific Industries Ltd. (PSI), UK, has received a £1 million (about $1.92 million) grant to develop a commercial production process for spherical, low-oxygen, ceramicfree titanium powder. PSI claims the process will produce titanium powder at a fraction of current costs. Connecting Rod Contracts Awarded Metaldyne, Plymouth, Mich., has
Promising Titanium Alloy Applications Dynamet Technology, Inc., Burlington, Mass., has received four Small Business Innovation Research (SBIR) contracts during 2008 to develop PM materials and processes for biomedical and defense applications. The National Institutes of Health (NIH), Department of Defense (DOD), and the National Science ijpm
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PM INDUSTRY NEWS IN REVIEW
Foundation (NSF) awarded the contracts. Titanium Powder Sale Cristal US, Inc., a wholly owned subsidiary of Cristal Global, Saudi Arabia, announced an agreement to purchase International Titanium Powder, LLC (ITP), Woodridge, Ill., from Titanium Company of America, LLC. Established in 1997, ITP operates a research & development facility and a pilot plant in Lockport, Ill. PM Conference in India The 5th International Conference and Exhibition on High Performance Materials Through Powder Metallurgy will take place February 16–18, 2009, in Goa, India. Sponsored by the Powder Metallurgy Association of India (PMAI), the conference program will cover new
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materials for the automotive and engineering field, innovative processes, new developments, advanced PM through ultrafine and nanomaterials, and progress in the automotive industry. New Variable Cam Timing Technology Utilizes PM BorgWarner, Auburn Hills, Mich., reports it will supply cam torque actuated (CTA) variable cam timing technology for the upgraded Ford Duratec 3.0-liter V-6 engine in the 2009 Ford Escape. The new CTA system contains up to four PM parts, a BorgWarner spokesman reports. Lab Grinding Mill Union Process, Inc., Akron, Ohio, offers the Q-03 bench-top laboratory circulation grinding mill. The smaller circulation attritor is
designed for lab trials that use much smaller samples, from a 1/2 gallon to one gallon. Miba Sales Rise Miba AG Laarkirchen, Austria, reported first-half fiscal-year sales of 199.7 million euros (about $283 million), a two percent increase. However, after adjustment for the sales loss due to disposal of its PM parts plant in Spain, sales grew by 14 percent. PM Applications in Food Processing Food and beverage suppliers use porous metal spargers made from metal powders by Mott Corporation, Farmington, Conn. Applications include oxygen stripping, nitrogen injection, carbon dioxide injection, carbonation, and steam sparging. ijpm
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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SPOTLIGHT ON ...
CHRISTOPHER HAMMOND, PMT Education: BS Mechanical Engineering (Automotive Specialty), Kettering University, 1996 Why did you study powder metallurgy/particulate materials? I had limited exposure to powder metallurgy (PM) in college. I made a PM bulldog by cold isostatic pressing (CIP) in a materials science class. I acquired my initial real experience in PM with my first job at Mascotech, North Vernon, Indiana, making powder-forged connecting rods. When did your interest in engineering/ science begin? I have been interested in engineering as long as I can remember. I grew up working on cars, engines, equipment, and houses with my father. I disassembled anything I could find. It was later in life that I figured out how to put things back together! What was your first job in PM? What did you do? My first PM job was at Mascotech where I started out as a manufacturing engineer working in the secondary operations area doing equipment improvements and introducing automation. I learned a tremendous amount and was given complete freedom to try new things. Describe your career path and companies worked for, and responsibilities. I started my career at Eaton Corporation, Marshall, Michigan, as a co-op student. I worked in various departments and started getting more PM exposure in the metallurgical laboratory by cutting up PM valve guides and valve seats. After college, I started at Mascotech (Metaldyne) as a manufacturing engineer. I moved to product engineering after about year and became more involved with customers, tool design, and prototyping. In 2000, I went to work for GKN Sinter
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
Metals, Zeeland, Michigan, where I functioned as a product applications engineer developing new PM parts with customers. This was interesting to me because I was able to see many new technologies long before they went into actual production. I was promoted to business unit manager for the low-tonnage area and then became engineering manager until the plant closed in 2006. We had a good team at Zeeland and I am very proud of the accomplishments we were able to achieve. After GKN, I went to work for a forging company in Detroit as an engineer responsible for production. In 2007, after a layoff, I accepted the position of manufacturing development manager at Sintering Technologies Inc., Greensburg, Indiana. What gives you the most satisfaction in your career? Having a job that challenges me every day is most satisfying. In my opinion, there is nothing worse than a job you are bored with. List your MPIF/APMI activities. I attended PM2TEC2005 in Montreal, and the MPIF seminar “Advances in High Density.” What major changes/trend(s) in the PM industry have you seen? I have seen numerous company consolidations, closures, and overseas resourcing, which is depressing. The complexity of the PM parts produced today is amazing. I am encouraged by the amount of automation that exists in the PM industry now. I think this will be one of the keys to making the technology more competitive. Manufacturing Development Manager Sintering Technologies Inc. 1024 Barachel Lane Greensburg, Indiana 47240 Phone: 616-218-8515 E-mail:
[email protected]
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SPOTLIGHT ON ...CHRISTOPHER HAMMOND, PMT
Why did you choose to pursue PMT certification? I had thought about pursuing certification for several years, but never took the time. A former boss encouraged me to take the test and I am glad he did. How have you benefited from PMT certification in your career? I think that having PMT certification gives additional credibility when working with customers. I
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feel that it has introduced me to a broader range of information and technology in PM. What are your current interests, hobbies, and activities outside of work? I enjoy spending time with my family, woodworking, building houses, working on cars, and finding my golf balls in various ponds and wooded areas—when time permits. ijpm
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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CONSULTANTS’ CORNER
M.I. “Mike” JAFFE* AND SAMUEL M. “Sandy” JAFFE
Q
What maintenance procedures are recommended for low-temperature (belt) and high-temperature (pusher, walking beam) furnaces? 1. Frequent checks of the atmosphere (dew point) and temperature profiles across the belt and through the furnace can detect small changes that could be indicative of problems that may be starting. The furnace should operate in a predictable and consistent manner. 2. Maintain a database of when the furnace is producing quality parts. This should include temperature profiles, dew points, belt color and appearance, sintered part color, physical properties and microstructure, position of internal doors and curtains, atmosphere flows, and appearance. 3. The use of “standard” pieces as an ongoing check can be valuable. An iron–carbon–copper material is sensitive to most furnace conditions. A simple part such as a ring 25.4 mm (1 in.) OD × 12.7 mm (0.5 in.) ID × 6.35 mm (0.25 in.) thick has been used as it is easy to test for hardness, size change, appearance, microstructure, and crushing strength. These parts should be accurately made for composition, size, and weight and kept in airtight containers. If these are run through the furnace (several across the belt) on a scheduled basis, unexpected changes in results indicate a potential problem. 4. Temperature controls should be checked for accuracy on a routine basis. Thermocouples such as type K should be replaced on a schedule; do not wait for a failure. If control temperature and over-temperature thermocouples
A
5. 6. 7.
8.
9. 10. 11. 12.
13.
are mounted close together they can be used as a periodic check of each other. (See FORD standard W-HTX 12, “Ther mocouple Checking and Replacement Procedures.”) Make sure the flow meters are clean and responsive. Verify that the belt speed agrees with the setting. Verify that the gas burn-off on both ends is correct. The front end should be carrying the burnt-out lubricant and the back end should be discharging a clean protective atmosphere and clean parts. Lubricant build-up and stray materials in the furnace should be cleaned as they can affect the atmosphere and/or damage the belt. A worn, distorted and/or broken belt should be replaced. The belt-drive tension system should be checked. Gas safety valves should be checked per NFPA regulations. If the atmosphere appears to be a problem, all pipe connections should be checked for tightness since air can enter through extremely small holes, even when the pipe has a positive gas pressure. Muffles should be checked for holes. All of the procedures cited, except for belt-specific items, can apply to walking beam or pusher furnaces. The manufacturer’s procedures should be followed for maintaining walking beam or pusher mechanisms.
*M. I. (Mike) Jaffe, Box 240, 144 Brewer Hill, Mill River, Massachusetts 01244-0240, USA; Phone: 413-229-3134; E-mail:
[email protected]
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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CONSULTANTS’ CORNER
Q A
What is the best way to balance the atmosphere flow in a sintering furnace without trial and error? There are intelligent approaches to setting up a furnace but it is our opinion that there will always be a certain amount of trial and error. The aim is to keep the error to a minimum. The function of a furnace atmosphere is to have the gas flow thoroughly “wash” the lubricant out of the parts in the preheat or burn-off zone and carry it out through the front door. The atmosphere should then provide deoxidizing and cleansing conditions for sintering, a suitable carbon restoration zone at the start of cooling for steel parts, and then an oxygen-free atmosphere for cooling. Since all of these actions are influenced by the parts themselves—how they are stacked, their height, weight per unit length, the lubricant and the alloy, the atmosphere and attendant flow rates, how the flow is directed if this is a controlled attribute, and the ambient conditions—it is unlikely that one set of conditions will apply. To start, observation of the gases exiting the front and rear of the furnace should show most gas exiting from the front end, less gas from the back end, but with a sufficient flow that, at both ends of the furnace, there is little or no indication of gas burning inside the furnace itself. The condition in the furnace can be checked by dew point and oxygen analyzers and the exiting gas can be checked with an explosimeter to verify that there is hydrogen present. The parts themselves should be checked for appearance (soot, oxidation), hardness, size, microstructure, etc. Samples should be taken from locations across the belt, from the edges as well as from the center. Observation of stainless steel shim stock pieces across the belt will indicate possible air leaks, if they become discolored. The position of all valves and adjustable inlets, as well as flow rates, should be recorded and marked as needed. Ambient conditions such as open doors and windows and the placement of fans should be noted as these can affect the furnace atmosphere. (See A. Richardson, S. Srinivasan and P. Stratton, “Atmosphere Composition in Tunnel Fur naces: Ef fects of Draughts”, Heat Treating Progress, vol. 8, no. 4, 2008, pp. 36–39). With typical parts being run, you would expect
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to see the gases emitted from front door burning with a yellow flame. It is preferable that the flame front does not enter the furnace; this is controlled by the door height, a gas curtain (if used), and the level of the gas flow. The burn-out at the rear end of the furnace should be clear with little or no flame front re-entering the furnace. If spots of black soot are present on the parts, lubricant burn-out is not complete due to incorrect time and temperature and/or an improper atmosphere. Observation of raw copper in low-copper alloys and/or little or no rounding of pores would indicate insufficient time and/or temperature in sintering. Decarburization would indicate a high dew point and grain boundary carbides would indicate a high-carbon potential atmosphere or a dirty furnace. An experienced powder metallurgist can derive important information about sintering conditions by examining metallurgical mounts of the parts. What are the best types and amounts of lubricant in order to avoid galling in the core rods of compacting tools? Is it possible to reduce the amount of lubricant if graphite is added to the mix? Any lubricant that is able to prevent or minimize die-wall and punch wear should also work for core rods. Small core rods are generally more fragile than dies and punches and can be subjected to high tensile and flexural stresses. In an example part, a 2.54 mm ( 0.1 in) dia. rod is subject to twice the tensile stress of a 5.08 mm (0.2 in.) dia. rod. Also, wear on a core rod in the area of compaction can produce an “hourglass” profile which will increase the tensile load during ejection. Historically, zinc and other metallic stearates were the basic lubricants but now there are a number of proprietary materials based on bisstearamides that have no metallic component; these are in general use and are considered more acceptable. The use of extra lubricant may reduce wear but can create problems in sintering and can result in an increase in stack emissions. There are numerous surface treatments for cores to enhance wear resistance such as chrome plating, titanium nitriding, and ion implantation. Carbide-tipped or solid-carbide rods can be used in many cases. There are now many PM tool steels that may fill the gap between steels and carbides. The original
Q A
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CONSULTANTS’ CORNER
finish of the cores is important, a mirror finish being desirable. An extra advantage of most wearresistant coatings is that when the coating wears it can usually be stripped and recoated if the underlying rod is not worn. (See H. Scanlon, “Lubricants in Ferrous Powder Metallurgy”, Hoeganaes Corp., and R. Beimel, “Tooling For PM”, J.I.T. Tool & Die Inc.; both presentations were given at the MPIF Basic Short Course, July 21–23, 2008). The graphite added to ferrous powder blends is for the purpose of introducing carbon into the iron to produce steel; its lubricant effect is minimal. If the sintered part contains more than 0.8 w/o C, it tends to precipitate out in the grain boundaries creating a weak and brittle part.
Q
What effects do coining or repressing have on the porosity of a component? Compare single and double pressing to arrive at the same density and compare hardness levels after heat treatment. Re-pressing can accomplish many things. Sizing can improve dimensional tolerances while coining can alter the surface configuration. Re-pressing can increase density and may be referred to as forging or just “re-pressing.” Repressing may do all three things concurrently. For example, if we target a ferrous part at a density of 7.3 g/cm3 we could do this by single pressing, double pressing (press, sinter, re-press, and possibly resinter) and now also warm compacting. Let us look at each operation: Single pressing: For most ferrous materials this would require a compaction pressure of ~828 MPa (120,000 psi). If the powder contains 1 w/o lubricant, the ultimate density would be 7.35 g/cm3 regardless of the compaction pressure as the compressed lubricant has a density ~1 g/cm 3 . Pressing at 828 MPa (120,000 psi) for simple or rugged shapes may be suitable but it can result in a tool-maintenance problem with complex parts. It also makes the delubricating process more difficult as the tighter pore structure restricts the removal of lubricant during sintering. Double pressing: If the part is first pressed to a medium density of 6.6–6.8 g/cm3, the tools will last longer. If the powder has more than a minimal carbon content, it may be best to presinter at a temperature below that which allows the carbon to alloy with the iron so that it will not harden. If this is done at ~816°C (1,500°F) the graphite will not
A
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
form pearlite and the copper and nickel, if present, will not alloy. The lubricant can burn off at this temperature and the cold work in the powder resulting from compaction will be relieved. After this presinter, it can be surface lubricated and then re-pressed at reasonable tonnages to achieve a high density. This should be followed by a full sinter to develop physical and mechanical properties, but keep in mind that during the full sinter, size changes can occur. If the part is pure iron, such as a magnetic pole piece, the first sinter can be at full temperature, preferably in a decarburizing atmosphere. The second pressing will increase the density and work the material so that the resintered part will be tougher and stronger than a single-pressed part at the same density. Warm compacting: By heating the iron powder to ~150°C (302°F) before compaction, higher densities at lower compaction pressures can be achieved. The press must have the capacity to heat the powder, and the tools should be designed to operate at the elevated temperature. Since comparative data for heat-treated singlepress and double-press parts are not readily found, L. Pease, Powder-Tech Associates, kindly offered to run tests on FN-0205. The parts were heat treated at Pennsylvania Industrial Heat Treaters. Parts “A” were single pressed to 7.35 g/cm3 and sintered in dissociated ammonia (DA) at 1,120°C (2,050°F) for 30 min. Parts “B” were pressed to 7.1 g/cm 3 , presintered at 843°C (1,550°F) in DA, then re-pressed to 7.3 g/cm3 and fully sintered in DA at 1,120°C (2,050°F) for 30 min. The results in the two cases were similar. The average as-sintered hardness of parts “A” was 77.9 HRB and of parts “B” was 78.9. The average asheat-treated hardness for parts “A” was 43.6 HRC and for parts “B” was 45.2 HRC. More samples would have to be run to establish any clear differences. Note that the powder contained 0.75 w/o lubricant and parts “A” required a compaction pressure of 828 MPa (120,000 psi) to achieve 7.35 g/cm3. Parts “A” also showed evidence of microlaminations which could affect their strength. The single-press approach would not be our recommendation. ijpm Readers are invited to send in questions for future issues. Submit your questions to: Consultants’ Corner, APMI International, 105 College Road East, Princeton, NJ 08540-6692; Fax (609) 987-8523; E-mail:
[email protected]
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2009 International Conference on Powder Metallurgy & Particulate Materials June 28–July 1, The Mirage Hotel, Las Vegas
• International Technical Program • Worldwide Trade Exhibition • Special Events
For complete program and registration information contact: INTERNATIONAL
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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PERSONAL INSIGHTS
AXEL MADSEN/CPMT SCHOLAR REPORTS MATHIEU BOISVERT École Polytechnique de Montréal Montréal, QC, Canada First, I would like to thank the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology (CPMT) for a CPMT/Axel Madsen Conference Grant, as well as my supervising professor, Gilles L’Espérance, for his constant support and invaluable advice on the poster preparation. The PM2008 World Congress, held in Washington, D.C., was the first major conference I attended and the fact that it was truly international made me a little more anxious than I expected. I recently started my graduate studies in PM so I was under pressure to generate results in a short time prior to the conference. However, being at the conference made me realize that the extra hours expended were worthwhile! I landed in Washington, D.C., on June 8th in the afternoon, a beautiful (but hot) day to visit the city. It was amazing to see the White House other than in movies. In the evening, as every good student would do, my friends and I visited some of the taverns in Old Town and had a great time. The presentations started on Monday morning and I soon discovered that there were interesting concurrent sessions. Unfortunately, as I cannot be in two places at the same time, my coworkers and I had to coordinate our schedules to be present at most of the presentations. In general, the presentations were interesting and some of them gave me ideas for my research project. I also had the opportunity to hear the presentation by Professor Henein on impulse atomization of Al-Fe alloys, a project I worked on in the summer of 2007. During the Industry Recognition Luncheon, I
had the privilege of talking with leaders of the powder metallurgy (PM) industry, as well as to the two new APMI Fellows. Moreover, I enjoyed conversing with the other CPMT/Axel Madsen Conference Grant recipients. In conclusion, the PM2008 World Congress was an outstanding event, giving me unique opportunities to improve my knowledge of PM as well as getting new ideas for my research project. Furthermore, creating new network relationships and consolidating existing ones were important. Listening to the presentations made me strive to be in a position to present my own results next year; I cannot wait for PowderMet2009 in Las Vegas! ERIK M. BYRNE Pennsylvania State University University Park, Pennsylvania Driving under the hotel unloading area after the long drive to D.C., I was ready to park my car and begin my first experience at a professional conference. I was impressed with both the National Harbor and the Gaylord National Resort. The newly built hotel was as impressive as it was comfortable, and it was staffed with helpful employees. I was equally impressed with my room and shortly after waking up, my Monday morning began with the first round of technical sessions. All the technical presenters were engaging and easily conveyed key concepts of their research to the audience. The presentations were interesting, but I was not prepared for the amount of information that was presented in each session. I told myself that I must remember to bring a notebook for the afternoon sessions, and then left for lunch.
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 the PM2008 World Congress.
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Lunch offered a time to thank and introduce myself to some of the individuals who made my attendance possible through the Scholarships and Grant Committee of the Center for Powder Metallurgy Technology. It was also an opportune time to meet my fellow grant recipients. Lunch was great and was a welcome departure from my typical college diet. The food was excellent, and I greatly enjoyed the time spent getting to know those at my table. Aside from eating and enjoying the technical sessions, I was also able to gain experience as a presenter. During the poster session, I was concerned that my work on the electrical conductivity measurements of hardmetals would not attract much interest. Concer n was unnecessary, because during the session many people expressed interest in the topic. The poster session gave me the confidence I needed for my Thursday morning presentation. Many people that I met during the conference attended and this helped put my nerves at ease during the presentation. I was fortunate that this event was a World Congress. The event drew an impressive international audience. I also enjoyed the industry exhibits which allowed me to see the variety of business opportunities available within the PM industry. Everyone that I met during the World Congress was warm and sincere. The PM community, though close-knit, is an extremely welcoming group. They helped make my first conference to be a memorable one. Overall, I had a fulfilling conference experience. I was able to present my research, meet many individuals within the PM industry, and attend informative technical sessions. Aside from two absent authors at the technical sessions, the conference was flawless. I was particularly impressed with the variety of sessions dedicated to tungsten carbide. These sessions were helpful to me as I complete my Master’s thesis. I am most grateful to those who support the Center for Powder Metallurgy Technology. The CPMT/Axel Madsen Conference Grant allowed for my attendance and the memorable experience. JAMES MARTZ Pennsylvania State University DuBois, Pennsylvania Just over one year ago, I was offered a workstudy position by Dr. Steven Johnson to help around his laboratory. Soon after starting, I had
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become knowledgeable about much of the equipment, and it was not long before I was given the opportunity to begin research on aluminum powders. I was new to PM research and was impressed by observing everything that can be created using closed die compaction. Dr. Johnson taught me numerous things as we moved through research, from the characterization of the powders and compaction methods to delubrication and sintering. Dr. Johnson asked if he could nominate me for a CPMT/Axel Madsen Conference Grant and, after a little study on the creation of research posters, I accepted. Eventually, the news came that I had been awarded a grant! I was really excited, having never before attended a conference of this magnitude and found the creation of the poster to be a considerable challenge. All of my research had to be displayed in an attractive, coherent, and detailed manner, and kept within the boundaries of the specified poster size. After more research on understanding the organization and information flow of a poster, I finally had a detailed outline of what the poster was going to look like. As research continued, I managed to keep the poster as up to date as possible. It was not long before I printed out a final copy, and prepared for the PM2008 World Congress! After making the drive from DuBois, I arrived at the Gaylord National Resort with enough time to take a shower and set up my poster. A quick walk through the hotel confirmed that it was essentially an indoor city. The atrium provided an amazing view of the Potomac River, while maintaining a comfortable indoor climate. After setting up my poster, I went back to the room for a quick nap. It was not until I woke up that I realized I had forgotten to set the alarm clock. I was late for the opening dinner! I got everything I needed, and made my way to the dining area to find that timing was not strict. A buffet style dinner left an open environment for me, and others who may have been late. For the first time in my life, I was able to have dinner at the same table as people from five different countries. This was an experience I enjoyed, and which would continue throughout the conference. Having never before attended a technical conference, I was unsure I would be able to keep up with everything that was taking place. However, after my first technical session I got the hang of things. I attended multiple technical sessions, primarily on aluminum alloys (which I have been Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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researching) and nanoparticles (which I have an interest in). When technical sessions were not taking place, I enjoyed walking through the exhibits, and seeing all the interesting displays. Near the end of the conference, I was informed that I was the recipient of an Outstanding Poster Award which was far beyond my expectations. Being able to attend the PM2008 World Congress was an amazing and unforgettable experience! Attending this conference changed my view of the PM industry, and the science which drives it. I was able to attend many technical sessions in which I learned many things beyond the current textbooks. I would like to thank Dr. Steven Johnson for nominating me, and the Grants Committee of the Center for Powder Metallurgy Technology for selecting me to receive a CPMT/Axel Madsen Conference Grant in order to experience the conference first hand!
NATHANIEL OSTER Iowa State University Ames, Iowa Attending the PM2008 World Congress was a wonderful experience for me. Five days were spent learning about PM, making connections with members of the PM community, and forming new ideas for future research. The conference started off with a wonderful dinner. It was the first chance I really had to see all those attending the conference. I was amazed by the number of people I was introduced to and the camaraderie of the group. Being an international conference, the diversity of people attending was amazing. My suggestion for improving this aspect of the conference is to include the dinner as part of the student registration. It proved to be a valuable networking tool, which benefits the PM industry as a whole.
AMERICAN ISOSTATIC PRESSES, INC. HOT & COLD ISOSTATIC PRESSES
1205 S. Columbus Airport Rd. Columbus, Ohio USA 43207 614-497-3148 1-800-375-7108 sales @aiphip.com www.aiphip.com
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
AIP AIP 25
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Throughout the week, the technical sessions were filled with an impressive number of topics. I learned about everything from stainless steel alloy design to novel atomization techniques to electric discharge compaction. Research in these areas exhibited elements of basic science with a focus on applied science. Presentations were informative to those with doctoral degrees in metallurgy but were still understandable by students like me, just starting their education in PM. In the evening, I attended the hospitality suites of two companies. These also proved to be excellent networking events. I walked away from the suites with a wallet full of business cards. In addition to the poster that I presented as a requirement for the CPMT/Axel Madsen
Conference Grant, I presented a technical paper. Both publications offered valuable experience. It forced me to write, speak in public, answer difficult questions, and graphically display and organize information. These are skills that I will need throughout my career. The conference ended with a fantastic gala at the National Portrait Gallery. A great meal, wonderful entertainment, and spending the final night with those that I met throughout the week was a finale worthy of the conference. Receiving a CPMT/Axel Madsen Conference Grant was a great way for me to experience all that I did. I certainly hope that the program continues. ijpm
Entwicklungs-GmbH
RESIDUR® – Briquetting Tools: The Solution for Your Wear Problem When using RESIDUR® tires, operating costs for briquetting rolls will be lowered substantially. The extremely wear resistant surface leads to long lasting lifetimes accompanied by a constant high quality of the briquettes produced. RESIDUR® characteristics can be suitably adjusted for extreme requirements. The high thickness of the layer additionally improves the economical benefits of HIP-clad rolls by allowing refurbishment. Köppern Entwicklungs-GmbH Königsteiner Straße 2 fon: +49 (0) 2324 207 – 305 fax: +49 (0) 2324 207 – 301 e-mail:
[email protected] www.koeppern-research.com
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HOT ISOSTATIC PRESSING
HOT ISOSTATIC PRESSING: MORE THAN A NICHE TECHNOLOGY Stephen J. Mashl*
Within the world of materials processing, hot isostatic pressing (HIPing) is considered a “niche” technology. One reason for this lies in the versatility of the process. The main applications of HIPing can be classified into three groups: elimination of porosity in castings; consolidation of powder metallurgy (PM) materials to pore-free levels; and the diffusion bonding of materials. It is also possible to accomplish more than one of these tasks concurrently. An example is the consolidation of a powder while bonding it to a substrate (a common practice) and, if the substrate is a cast material and the process parameters are chosen correctly, internal shrinkage pores within the cast substrate will collapse and heal. Within the casting industry HIPing is generally seen as a mandatory, post-casting process used to minimize scatter in mechanical properties and to improve fatigue resistance and impact toughness in life-critical components such as turbine blades and vanes used in jet-aircraft engines. In less critical applications, HIPing is seen as either, an option employed when a customer’s application requires mechanical property levels that are not achievable with an as-cast microstructure, or as a process that might save a batch of castings with a level of internal porosity that precluded passing a nondestructive test criterion. In diffusion bonding, HIPing competes with processes such as furnace brazing and hot pressing, processes that can either offer continuous throughput in comparison with HIPing batch operations or be implemented at considerably less expense from a capital equipment standpoint. With solid-state bonding, however, the hydrostatic pressure acting on the bond surface serves to clamp the surfaces together during processing and also prevents the formation of Kirkendall porosity that often results when the net flux of diffusing atoms is not equal across the bond interface. The result can be an exceptionally strong bond. The PM industry is generally considered to be dominated by parts produced by die compaction followed by sintering (conventional PM). While die compaction and sintering provide a closer-to-net shape than is possible in all but the most advanced and expensive HIPing processes, the small levels of porosity present in conventional PM parts limit their use in fatigue-critical applications and in situations where
*Global Director, Research & Development, Bodycote International PLC, 155 River Street, Andover, Massachusetts 01810, USA; E-mail:
[email protected]
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mechanical property requirements normally specify a wrought material. By producing a pore-free PM product, HIP can compete with forgings. Further, given the absence of die-wall friction (present in conventional PM processing), the size of a HIPed part is limited only by the size of the HIP vessel and the volume that the capsule or component occupies prior to HIPing. The HIPing of very large PM parts, with mass measured in tens of tons, is common. So, when HIPing is considered with respect to its role within either the casting, bonding, or PM industries, its role within these specific industries is relatively small; when viewed in entirety, however, the HIPing industry is impressive. It is a process capable of producing parts having exceptional mechanical properties that can be used in a wide variety of applications. The International HIP Committee (IHC) comprises people from within the international HIPing community whose primary task is to bring the global HIPing community together once every three years for a process-specific conference. This event is the one opportunity to attend a meeting
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in which the sole focus is HIPing. In May 2008, the conference was held in Huntington Beach, California, and included 43 technical presentations, given over a period of 2-1/2 days. The talks, posters, and exhibits were all of a high quality, maintaining the standards set at previous meetings in Paris in 2005, Moscow in 2002, and all of the previous IHC HIP conferences. The editorial staff of the Inter national Jour nal of Powder Metallurgy and this author selected contributions that focused on PM processing and also provided a broad overview of the HIPing industry. While identifying four papers out of 43 for publication in the Journal was not a trivial task, I believe that these papers provide an excellent overview and perspective of the current state of HIPing in relation to PM technology. The paper written by McTiernan provides a comprehensive overview of the PM products that can be produced via HIPing. A common theme in HIP PM cladding operations is that of producing a part that uses expensive corrosion- or wear resistant materials only on the surfaces where
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they are needed. McTiernan provides excellent examples of the processing routes employed when implementing this concept during the production of clad steel mill rolls, extrusion barrels, and screws. Tool steels made from atomized powder are among the highest grade of these materials available. One reason for this is that the uniform dispersion of fine carbides present in HIPed PM tool steels is absent in wrought or cast grades. The micrographs in the McTiernan paper provide graphic evidence of this difference. McTiernan also shows the encapsulate/HIP/extrude sequence that Crucible uses to consolidate atomized metal powders into bulk nickel-base superalloy billets used to fabricate rotating components in aircraft engines. The next time you converse with an engineer who says “PM parts are inherently weak,” make a note of this, especially if the conversation takes place on an airplane! Finally, McTiernan describes the production of a Ti-6Al-4V alloy with 1 w/o boron addition, a modification that improves strength and Young’s modulus compared with Ti-6Al-4V. McTiernan notes that the powder -production method involves induction skull melting/inert-gas atomization and cites the continuous stirring action resulting from the inductive current. Given the low density of the TiB precipitates that endow the alloy with exceptional strength-to-weight properties, it is probably safe to assume that this is yet another alloy that could not be produced with the same desirable microstructure through any route other than PM. Broeckmann et al. provide additional insight into issues related to HIP cladding operations in describing Köppern Entwicklungs’ approach to the fabrication of wear-resistant rolls for the briquetting compaction of abrasive particulate materials. Broeckmann provides an in-depth analysis of the mode and mechanisms of wear when processing a variety of materials. Their solution is to clad layers, up to 35 mm thick, of selected wearresistant carbide-rich PM materials. It should be noted that cladding a surface with a layer of material this thick is impossible with other cladding techniques such as thermal spray or vapor deposition. In the Köppern application, the thickness of the clad layer is significant in that it allows the rolls to be resurfaced at least once before they have to be taken out of service. Broeckmann et al. also address the two main Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
obstacles encountered when producing or processing HIP clad materials, namely, internal stresses that result from the differences in thermal expansion of the substrate and the clad layer, and undesirable phase transformations occurring, in part, at the interdiffusion layer between the clad and the base material. The authors describe how finite element analysis (FEA) can be used to avoid problematic combinations and to devise solutions. FEA is being used with increasing frequency to predict the densification and dimensional change that take place when consolidating loose powder in a capsule of complex shape. The paper by Teraoku discusses the production of complex HIPed PM near -net shapes, produced using advanced capsule fabrication techniques combined with FEA. There are multiple theoretical models that serve as the foundation for finite element software (Teraoku uses the porous plasticity model developed by Shima and Oyane) and each model requires specific parameters as inputs to determine the starting conditions thereby allowing the accurate prediction of the properties and characteristics of the materials being processed. Teraoku gives the reader valuable insight into the modeling process by showing how, samples are produced which delineate the necessary modeling inputs for FEA. The Teraoku paper is also significant in that it describes a novel approach to complex PM part fabrication by HIPing. When high levels of dimensional control are required on specific surfaces of a part, consumable solid cores are employed. Common practice is to machine these cores from wrought billet material, a practice that is both expensive and time consuming. Teraoku and his colleagues employ an alternative approach, namely, using another advanced PM technique, selective laser sintering (SLS), to fabricate the cores. The paper does not address the economic differences of machined vs. SLS cores but the approach is intriguing. None of this interesting work could be performed without the availability of high-quality HIP equipment. The fourth paper, authored by Watanabe et al., describes recent advances in HIP equipment. The concepts presented include approaches to reduce cycle time and to extend the capabilities of a HIPing unit so that the process can go beyond basic consolidation or pore closure and be used to explore combined HIPing and heat-treating processes. Another area of equip-
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ment innovation described by Watanabe et al. is the use of non-typical atmospheres within a HIPing environment. This is done to allow the processing of materials that are not stable in a conventional HIPing/argon environment. For example, some oxide ceramics can be reduced if exposed to a pure argon atmosphere for long times at a high temperature, i.e., under conventional HIPing conditions. Having a partial pressure of oxygen in the HIPing atmosphere is a potential solution. However, most high-temperature HIPing units possess furnaces and heat shields made from molybdenum or graphite. Furnaces constructed from these materials will degrade rapidly when exposed to oxygen under working conditions. The authors describe approaches to this problem, as well as to other challenges to HIPing equipment manufacturers. Hydrogen-fuel-cell technology is under study as an alternative fuel source for transportation. Some fuel cells operate at pressures in the range 35–70 MPa (6,000–11,000 psi) and hydrogen is known to embrittle many materials. Testing candidate materials for use in fuel cells is critical. How does one build test equipment capable of testing these materials under aggressive operating environments without the equipment itself being subject to hydrogen embrittlement? Watanabe et al. comment on these and other challenges. Innovations coming from the equipment suppliers will certainly serve to expand applications for HIPing in the future. In closing, let me say that, individually, the papers in this edition of the Journal describe particular aspects of the HIPing-PM industry in detail. Taken together, this collection of papers provides a comprehensive overview of the entire state and direction of the HIPing industry, now clearly more than a “niche” technology. These articles cover trends and advances in equipment, the use of computer modeling, and improvements in processing techniques and products. I hope and trust that you will find each contribution enlightening. ijpm
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HOT ISOSTATIC PROCESSING SERVICES FOR PRODUCTION AND RESEARCH PROGRAMS ISO 9001, AS9100 REGISTERED
• CASTING DENSIFICATION • Improved Properties • Reduced Rejection Rate • Reduced Scrape Rate
• POWDER CONSOLIDATION • PRESSURE BRAZING • DIFFUSION BONDING • CERAMICS
KITTYHAWK PRODUCTS
11651 MONARCH ST. • GARDEN GROVE, CA 92841 Tel. (714) 895-5024 Fax (714) 893-8709 www.kittyhawkinc.com E-mail:
[email protected]
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HOT ISOSTATIC PRESSING
DIVERSIFICATION OF HOT ISOSTATIC PRESSING EQUIPMENT TECHNOLOGY Katsumi Watanabe*, Kazuya Suzuki**, Shigeo Kofune**, Noriyuki Nakai**, Makoto Yoneda**, Yasuo Manabe** and Takao Fujikawa**
INTRODUCTION Over half a century has passed since HIPing was invented in the United States in the mid-1950s. Early in the 1970s some Japanese cemented carbide manufacturers began to use HIPing to eliminate the pores left in sintered cemented carbide components. Since then, efforts have been made to improve the productivity of the HIPing process and to reduce its cost. Engineers in Japan have focused on the elimination of residual pores in sintered ceramics, PM materials, and castings. In the HIPing of some oxide ceramics, atmosphere control, specifically oxygen partial pressure, has been a focus of R&D, in an attempt to avoid undesirable side effects, such as degradation of electrical resistance and color. Thus, HIPing equipment or furnace components used for these applications have to be designed to satisfy the need for controlling oxygen partial pressure. In the 1980s it was found that some nitride ceramics such as silicon nitride need to be HIPed in a nitrogen atmosphere. To this end, HIPing equipment with a graphite furnace that can be operated in a nitrogen atmosphere was developed. Some of the topical events related to HIPing technology that took place in Japan from the 1970s through the 1990s are summarized in Table I. TABLE I: CHRONOLOGY OF HIP DEVELOPMENTS IN JAPAN * Small R&D high-pressure gas equipment * Production HIPing for cemented carbide parts * Production HIPing for high-speed tool-steel billets * Production HIPing for soft ferrites * 2,000°C medium-size R&D HIPing unit * Modular HIPing system for soft ferrite production * Oxygen HIPing unit for R&D of ceramics * 3,000°C ultra-high temperature HIPing unit for production * Ultra-clean HIPing unit for silicon wafer interconnects
1964 1971 1977 1978 1981 1982 1986 1991 1998
Entering the 21st century, pressure to reduce carbon dioxide emissions, which are deemed to be the main cause of global warming,
Technology developments on hot isostatic pressing (HIPing) equipment in the last 15 years are reviewed in three areas: rapid cooling for large HIPing units, high-productivity HIPing systems for aluminum castings, and atmospherecontrol functions for special purposes. In particular the development of atmospherecontrol technology is described in detail, since this technology appears promising in future applications that focus on the production of functional materials. HIPing equipment that can control oxygen partial pressure at the ppm level was developed to process superconducting ceramic cables. More recently, equipment to measure mechanical properties under high pressure in pure hydrogen has been developed, exemplified by the fatigue testing of stainless steels or aluminum alloys for compressed-hydrogen station components. In the processing of metals and ceramics, the use of hydrogen is also promising, because frequently it drastically changes the mechanical properties of metals. The most critical issue in designing equipment for high-pressure hydrogen is safety so that a priority is placed on safety considerations in design.
Presented at HIP ‘08, the 9th International Conference on Hot Isostatic Pressing, organized by IHC, the International HIP Committee, May 2008, Huntington Beach, California
*Design Engineer, **Engineering Manager, Kobe Steel, Ltd. Machinery Co., Heavy Machinery Department, 2-3-1, Shinhama, Arai-Cho, Takasago-shi, Hyogo-Ken 676-8670, Japan; E-mail:
[email protected]
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DIVERSIFICATION OF HOT ISOSTATIC PRESSING EQUIPMENT TECHNOLOGY
intensified and R&D of hydrogen fuel cell vehicles (FCV) became the focus of major governmental projects in Japan. The problem here was that the hydrogen source and compressed hydrogen (as high as 35 MPa or 70 MPa) contained in a gas cylinder was the easiest way to design a feasible FCV system, because high-pressure methane was already used as a fuel for some vehicles. One of the technological problems was that there were insufficient data on mechanical property changes under a high-pressure hydrogen atmosphere from the safety point of view. It was known that hydrogen often renders some steels and other alloys brittle and causes sudden failure. Kobe Steel has been involved in this project to develop equipment for mechanical property measurements, especially fatigue properties under high-pressure hydrogen. On the other hand, hydrogen is an interesting element vis-à-vis metals or alloys because it can change mechanical properties by for ming hydrides or by diffusing into the solid. In this paper, the development of HIPing equipment technology in Japan is described with a focus on HIPing atmosphere-control functions. RAPID COOLING FOR LARGE HIPing UNITS One of the weaknesses of HIPing as a commercial process is its long cycle time, in particular its long cooling time. In recent years, the size of HIPing units has increased and the problem associated with long cycle time is becoming more serious than ever. Presently, from the viewpoint of processing time, shortening the long cooling times to a level equal to the heating time is easily achieved by introducing a gas convection circuit inside the pressure vessel, with or without cooling fans. The use of fans to create high-pressure gas circulation inside the processing chamber was also found to be effective in shortening the holding time and also to achieve temperature uniformity inside the processing chamber. Gas circulation promotes heat transfer from the high-temperature gas medium to the work pieces and also improves temperature uniformity inside the chamber. This type of HIPing equipment, with an inner diameter >1 m, will become standard for the processing of metals, particularly castings, in the next decade. HIGH-PRODUCTIVITY HIPing SYSTEMS Preheating HIPing and Modular HIPing Systems In the 1970s, reduction of the cycle time in
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HIPing was one of the goals in the manufacture of high-speed tool-steel (HSS) billets at a reasonable cost. In the case of HSS, the powder is contained in a mild steel capsule, and the heated capsules are transferred to the HIPing vessel under atmosphere, if the HIPing furnace is constructed from oxidation-resistant materials. Thus, the preheating HIPing system was developed and has been used for the commercial production of HSS billets. Figure 1 illustrates removal of a 400 kg, 320 mm dia. HSS billet, from the preheating furnace before transfer to the HIPing vessel after preheating to >1,000°C. In contrast, when the material being processed or the furnace materials are not oxidation resistant, the inside of the furnace and the charge cannot be exposed to the atmosphere. In such cases, another approach must to be introduced to reduce cycle time. For example, soft ferrite sintered compacts for magnetic recording heads have been HIPed at ~1,250°C in a molybdenum furnace. Reduction of HIPing vessel residence time has been achieved by the use of a modular-furnace concept, in which the material charge and molybdenum furnace are removed from the HIPing vessel and the temperature inside the furnace is kept at ~600°C. This concept is also ideal for soft ferrite materials because they are sensitive to oxygen partial pressure and are usually HIPed in ceramic containers with embedding powder to avoid compositional change during processing, including HIPing, and long-time cooling after HIPing. The
Figure 1. Removal of preheated HSS billet capsule from preheating furnace at ~1,100°C
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modular-furnace system with multiple sets of furnaces has been used in order to achieve the longtime cooling outside the HIPing vessel and to concurrently shorten the vessel residence time. Thus, these modular-type HIPing systems have been standard for the production of soft ferrites for magnetic recording-head materials. The modular-system concept is also attractive when multiple sets of furnaces with different types of heaters (such as molybdenum and graphite) are used. In the Kobe Steel modular system, these furnaces are bottom loading and designed with a plug-in configuration. They can be exchanged in the same pressure vessel and can be handled by a specially designed manipulator. HIPing System for Aluminum Castings It is well known that HIPing is widely accepted in the casting industry due to its capability for eliminating casting defects such as gas porosity and shrink voids. In the aerospace industry HIPing is specified in the manufacture of critical components such as jet-engine-turbine blades and some rotating components cast from nickelbase superalloys. This is also the case for aluminum castings; however, commercial application has been limited to expensive aerospace compo-
nents and sports-car engine components because of the high processing cost. The automotive industry is now becoming aggressive in reducing vehicle weight to meet the requirements of better fuel consumption and lower emissions. The ratio of aluminum weight to total weight per vehicle is rapidly increasing and a combined process of sand casting and HIPing is attracting attention as a promising approach to the manufacture of complex-shape components. In order to commercialize such combined processes in the production of aluminum castings for automobiles, the cost of HIPing has to be reduced and several studies focused on this goal are now under way. Lower HIPing pressure, shorter cycle time and integration of HIP treatment with solution heat treatment are central to these studies. In terms of HIPing pressure, the authors carried out a series of HIPing tests using permanent mold-cast specimens and evaluated the effect of pressure. Some of the results have been presented at the International HIP Conference in 2005. Here it was shown that, even at 25 MPa (only one-fourth of the normal HIPing pressure), an improvement in tensile strength can be achieved. Also, for fatigue integrity, the recommended pressure is in the 40–50 MPa range,
Figure 2. HIPing/T6 heat-treatment system, in which the heat shields of the HIPing furnace are used for solution heat treatment to avoid a temperature drop during transfer from the HIPing station to the solution heat-treatment station—schematic SHT = Solution heat treatment, WQ = Water quench
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which is low compared with the conventional HIPing pressure. Thus, equipment cost is expected to become much lower.1 With a view to improving productivity and reducing the processing cost, integration of HIPing with solutioning treatment using the same HIPing furnace designed with the modular concept has been proposed.2 The advantages of this approach over conventional processes are: (1) Total processing time, including the time needed to transfer the charge from a HIPing shop to a heat-treatment shop, can be minimized, with attendant shorter delivery times; (2) yield and quality of castings can be maintained consistently; (3) thermal-energy consumption by reheating for solution treatment can be reduced; and (4) total processing cost can be reduced. Figure 2 illustrates the concept of specially designed HIPing equipment for aluminum castings. The thermal insulating hood (heat shield) can also be used as a part of the solution heattreatment furnace. In this system, temperature uniformity inside the furnace is achieved by forced-gas convection driven by an electric fan. In addition, temperature drop of the charge during transfer from the HIPing unit to the solution heattreatment furnace can be avoided and thus consistent quality can be achieved. The cost of HIPing and heat treatment is <1 USD/kg and the system has the potential to achieve this goal. It is conjectured that the HIPing treatment of aluminum cast automobile compo-
nents for some premium cars is now at the stage of commercial production trials in Europe. ATMOSPHERE-CONTROL TECHNOLOGY UNDER HIGH PRESSURE Oxygen Some oxide ceramics are sensitive to oxygen partial pressure at high temperatures. For example, the soft ferrite Mn-Zn, which has a spinel-type crystal structure, decomposes to for m FeO (wustite) under low oxygen partial pressure at high temperatures. It transfor ms to Fe 2 O 3 (gamma-hematite) if the oxygen partial pressure is too high. Thus, the atmosphere surrounding the furnace charge has to be controlled to avoid compositional change. Conventionally, atmosphere conditioning was achieved by embedding the charge in a powder bed containing ferrite powder of the same composition. The use of embedding powders, however, led to other problems in commercial production. One is that the embedding powders were often scattered inside the furnace during pressurization or depressurization and deposited on the electric insulators of the heating devices. Another limitation is that the powder causes an undesirable temperature distribution inside the powder bed and degrades compositional and residual strain quality. In the case of superconducting ceramics such as the YBaCuO system, the stability of the superconducting phase is strongly influenced by the oxygen partial pressure at high temperatures; a high oxygen pressure pro-
Figure 3. HIPing unit for oxygen partial pressure control—schematic
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motes formation of the desired phase. To achieve the ideal HIPing treatment for these oxide ceramics, it is necessary that HIPing be performed under an atmosphere with the desired partial pressure of oxygen. In designing HIPing equipment for oxygen HIPing, the pressure-vessel material is oxidation-resistant stainless steel and the material for the heating element is a platinum alloy. The choice is an oxidation-resistant ironbase alloy for commercial production. In R&D, temperatures as high as 2,000°C are sometimes required, in which case a zirconia heating element is used. In this case, because the electrical resistance of zirconia is high at temperatures <1,100°C, preheating via a platinum heater is employed until the temperature reaches ~1,300°C. In 2003, a large high-pressure-gas sintering unit for the production of bismuth–strontium superconducting cables was installed at one of the Japanese electric cable manufacturing companies. The specifications of this unit are 1.2 m dia. × 1.2 m height; maximum temperature 950°C, and maximum operation pressure 30 MPa. Wound-cable materials were sintered in an atmosphere of argon at several hundreds ppm of oxygen. The cables manufactured using this unit are now used for ground testing in a power-generation system in Albany, New York. The configuration of this high-pressure-gas sintering unit is shown in Figure 3. High-pressure oxidation of metals or semiconductor materials using similar equipment is being assessed as another application for HIPing technology. Nitrogen Some nitride ceramics such as silicon nitride decompose at high temperatures. In the case of silicon, nitride sintering is usually carried out at ~1,750°C, in a nitrogen atmosphere (0.1–0.2 MPa) to suppress the decomposition. In order to obtain pore-free density, HIPing of sintered compacts under high-pressure nitrogen was found to be effective and was utilized in commercial production in the early 1980s. So-called pore-free silicon nitride components such as ball bearings are now manufactured by this process. High-pressure nitrogen can also be used to synthesize nitrides of various metals or by reaction sintering of silicon with nitrogen gas. The high pressure promotes diffusion of the nitrogen into the nitride, so that the nitridation time can be Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
shortened or the synthesizing temperature can be lowered. The first attempt at high-pressure reaction sintering of silicon nitride was carried out at Kobe Steel in 1980 and some experimental results were reported.3 In recent years some sialon compounds were found to exhibit photoluminescence and are expected to be an excellent light-emitting material for flat-panel displays. This reaction is exothermic with a considerable amount of heat generated, so the temperature of raw material rises excessively during nitridation which causes melting. Effective removal of the heat of reaction, and concurrent enhancement of the nitridation rate, can be realized by the simultaneous control of nitrogen pressure and temperature. Carbonaceous Gas Atmosphere Carbon fiber/carbon composites (C/C composites) exhibit attractive mechanical properties at high temperatures under inert atmospheres. However, the conventional manufacturing process is complicated and time consuming. The conventional process consists of impregnation of molten tar/pitch into the pores of carbon/fiber precursors and carbonization by heating under an inert atmosphere. Further, a single cycle using this procedure was not sufficient to achieve dense C/C composites, and repeated cycles (8–10) were necessary. By using high-pressure impregnation and carbonization under a high-pressure-gas atmosphere it is possible to realize a higher densification level per cycle, and to shorten the processing cycles or time. In this process, special HIPing units have been used with a chamber inside the heating devices to protect furnace components from carburization by the carbonaceous gas generated from tar/pitch. Recently large HIPing equipment for this purpose have been manufactured. The inner diameter and the height of the protection chamber are 1.2 m and 2 m, respectively, and this unit is now operated commercially at 650°C–850°C/100 MPa to produce nozzle-throat parts for the solid motors used in H2 and H2A rockets. Hydrogen Hydrogen is deemed a dangerous gas because of its flammability and its propensity to cause hydrogen embrittlement in body-centered-cubic (BCC) metals, including ferritic steels. However, in recent years hydrogen is attracting attention as a future energy source from the viewpoint of a clean fuel with no carbon dioxide emission, the primary
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Figure 4. Configuration of fatigue evaluation equipment under high-pressure hydrogen
Figure 5. Appearance of fatigue-evaluation equipment under high-pressure hydrogen
cause of global warming. Fuel cells using highpressure hydrogen (35 MPa or 70 MPa) as a fuel are currently the most practical power source for vehicles. Numerous fuel-cell vehicles of this type are now at the stage of actual road testing, but there are several problems to be solved before commercial utilization. One problem is the lack of sufficient data to design components that are exposed to high-pressure hydrogen (>35 MPa). In Japan there has been an increasing demand
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for evaluation of the mechanical properties of materials to be used for such components. Fatigue strength and toughness are of the most importance in terms of safety over long service life. However, even the design of fatigue evaluation test equipment faces problems in terms of safety. The concept of equipment for property evaluation should be similar to that for HIPing equipment in relation to a pressure level of >>10 MPa. Thus, design criteria for HIPing equipment were applied to fatigue-evaluation equipment and the first unit, with a maximum pressure of 45 MPa of pure hydrogen, was developed in 2004. This unit is illustrated in Figures 4 and 5. The frame-type pressure-vessel configuration was chosen to insure safety with little stress concentration, combined with a hydraulically driven fatigue-test apparatus. The pressure vessel with press frames TABLE II. SPECIFICATIONS OF FATIGUE-EVALUATION EQUIPMENT UNDER HIGH-PRESSURE HYDROGEN Component
Tensile Strength, Fatigue Strength, KIC, JIC
Vessel
Double-plate press frame Bottom-closure-penetrating pull rod with O-ring seal Hydraulic (oil) 45 MPa (pure hydrogen) -50°C to 100°C -100 kN to 100 kN 0.01 mm/min to 60 mm/min
Loading Mode Maximum Pressure Temperature Range Maximum Load Load Velocity
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is placed in a thermostatic chamber to control the temperature from -50°C to 100°C; specifications of this unit are summarized in Table II. The most critical issue in the design of the unit was to ensure the safety of the total system. In designing the high-pressure vessel, A286 was selected; this material is not sensitive to hydrogen embrittlement. SUS316L, an austenitic stainless, was used for the piping. The press-frame-type vessel was immersed in a flow of nitrogen inside the thermostatic chamber and a hydrogen-gas sensor was located along the outlet of the gas-flow pipeline to detect any hydrogen leaks. When a hydrogen leak was detected, the alert system was activated and an interlocking system operated to stop the operation. Three similar units with a pressure capacity of 100 MPa were manufactured and are now used to accumulate fatigue data for austenite-type stainless steels and some aluminum alloys. Hydrogen also has interesting characteristics other than being a clean fuel. Most of the pertinent phenomena related to hydrogen are attributed to the small radius of the hydrogen atom. The atomic radius is sufficiently small that hydrogen atoms can diffuse readily into some metals. Sometimes hydrides are formed which drastically change the metals’ mechanical properties. In this context hydrogen is of interest as a processing medium and has often been used as a processing gas. For example, hydride formation under a hydrogen pressure of 0.2 to 0.4 MPa is used to produce permanent magnet iron–neodymium–boron powder. Fine powders are produced by dehydrogenation after grinding the brittle hydride powder. Also a fine grain size can be developed in some titanium alloys by heat treatment under pressurized pure hydrogen after HIPing. Mechanical properties such as low-cycle fatigue strength are thought to be improved. However, these hydride-forming reactions require high temperatures, so more attention has to be given to the design, manufacture and operation of the equipment. So far, at pressures of 100 MPa the maximum temperature is <100°C, but operational experience with these units will lead to the realization of higher operating temperatures. It is anticipated that this area of application will expand markedly in the near future. SUPER CLEAN HIPing UNIT FOR SILICON WAFERS4 In the field of ultra-large-scale integratedVolume 44, Issue 5, 2008 International Journal of Powder Metallurgy
circuits (ULSIs), the requirement for higher device-packing density and increased reliability is becoming more and more important. Also in order to meet the requirement of higher operating frequencies where the impedance delay problem is critical, wiring materials are changing from conventional aluminum to copper. The diameter of the holes that connect the upper wiring layer and lower wiring layer is becoming smaller. Therefore, filling the holes with the wires and insuring the reliability of the connections is becoming increasingly difficult. HIPing is a suitable process to achieve complete filling of these holes with copper layers and to enhance the reliability of the interconnection. HIPing equipment for ULSI wafers is unique in terms of particle-free construction and short cycle time with automated wafer -handling systems. Figure 6 shows the appearance of representative HIPing equipment designed for this purpose. This application is expected to play an important role in improving reliability and the yield of ULSIs when the design criteria for ULSI become smaller, for example, <30–50 nm in the coming years. SUPERCRITICAL FLUID (CARBON DIOXIDE) A supercritical fluid is not a gas but has similar characteristics to high-pressure gas. In particular, carbon dioxide has been used as the pressure medium for extracting various organic ingredients for food- or health-related substances from natural products. Decaffeinated coffee and cigarettes
Figure 6. Clean HIPing unit for silicon wafer processing (200 mm wafer; 50 pieces/batch): 400°C/150MPa/1.5–2.0 h/cycle
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with controlled nicotine levels are examples. In the case of carbon dioxide, the critical point is 31°C and 7 MPa and the supercritical fluid state is formed in the region of much lower pressures and temperatures than in HIPing. Thus, temperature control is normally carried out primarily by heating the pressure medium en route to the pressure vessel by a heat exchanger, and keeping it at a constant temperature by heating externally with a jacketed structure using the flow of a heattransmitting medium. In recent years the application area for supercritical carbon dioxide has expanded into cleaning or drying of silicon wafers. These operations are performed after etching, organic material film deposition, chemical decoration of various kinds of organic polymers or metal particles, and pasteurization of food. Except for the case of extraction from liquid raw material, the material processed is normally in a solid state, so the process becomes a batchtype operation. Accordingly, the high-pressure vessel has to be opened each time, when the raw material is put in the vessel and when the resultant products are taken out of the vessel. Because of this, the closure/opening operation needs to be simple and safe and hence a press-frame configuration similar to that in HIPing equipment is often used. A representative unit for nicotine extraction is shown in Figure 7. Supercritical fluids other
than carbon dioxide which have a higher critical temperature and pressure will also become important as a solvent for extraction and chemical decoration of polymers or metal powders. FUTURE PROSPECTS In the commercial application of HIPing, large units with an inner diameter >1 m will become standard. The primary application is in defect healing of castings made of nickel-base superalloys and aluminum alloys. Some diffusion-bonded components for industrial machines and nuclear components will also be manufactured by large HIPing equipment. In the areas of new materials R&D, atmosphere control in processing oxide or nitride ceramics will become increasingly important. Further, the oxidation or nitridation of metals to produce new oxides or nitrides with special functions will be one of the ways to explore new materials. The high-pressure-gas equipment technologies for the design and the manufacture of HIPing equipment accumulated in the past 50 years will be applied to create new processes, or in the manufacture of equipment for the evaluation of materials. Materials for the automotive and medical fields and some electronic or optical materials are candidates for future HIPing or highpressure-gas processing. Collaboration between equipment manufacturers and end users will become more important in expanding HIPing technology, and to realize new material developments. REFERENCES
Figure 7. Supercritical carbon dioxide extraction equipment for cigarettes with controlled nicotine levels3
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1. Y. Manabe and T. Fujikawa, “HIP Treatment of Al Castings for Automobile Applications”, Proc. Int. Conf. on Hot Isostatic Pressing (HIP 2005), Paris, edited by G. Raisson, Société Francaise de Metallurgie et de Matériaux, Paris, France, 2005, pp. 181–188. 2. T. Fujikawa, Y. Manabe, M. Yoneda and S. Kofune, “HIP/T6 Integrated Treatment System for Al Castings”, ibid. reference no. 1, pp. 189–195. 3. T. Fujikawa, M. Moritoki, T. Kanda, K. Homma and H. Okada, “Hot Isostatic Pressing: Its Application in High Performance Ceramics”, Proc. Int. Symp. on Ceramic Components for Engines—1983, edited by S. Somiya, KTK Scientific Publishers, Tokyo, Japan, 1984, pp. 425–433. 4. T. Fujikawa and Y. Manabe, "Trends of HIP Research and Commercial Applications in Japan", Proc. Int. Conf. on Hot Isostatic Pressing (HIP 2002), edited by M. Yermanok, JSC All-Russian Institute of Light Alloys, Moscow, Russia, 2002, pp. 143–147. ijpm
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APPLICATIONS FOR LARGE-SCALE PREALLOYED HOT ISOSTATICALLY PRESSED POWDER METALLURGY MATERIALS Brian McTiernan*
FERROUS CLAD PM PRODUCTS Clad Mill Rolls A major improvement in avoiding costly downtime in steel mills is the use of high-wear-resistant HIP clad steel mill rolls. For many years, clad rolls reflected weld padding using conventional ferrous alloys such as D2. This approach was subject to the costs associated with the labor-intensive weld clad process, to dissolution of the clad material at the interface of the clad roll, and to the inherent difficulty in machining and grinding a conventional as-cast layer of carbide material on the roll before it is placed in service. The PM clad concept was introduced by the UltraClad Corporation and documented as a potential life-cycle cost-reduction approach by McGeever1 as early as 1993. This concept utilized a patented process2 to combine fine carbides in a substrate of PM M-2, T15, H-11, or M-4 tool steels and achieving effective pore-free density via HIPing. Currently, UltraClad remains the sole source of this unique clad PM solution. Subsequently, a variety of custom PM tool steel grades have been applied to clad mill rolls, with alloy choice depending on the need for higher wear resistance, wear and temperature resistance, or high wear resistance and high relative toughness. The clad process comprises HIP cladding a PM high-speed or wearresistant steel on a low-alloy shaft. Initially, a hollow mild steel container is welded to a relatively ductile carbon steel or low-alloy steel working shaft. The hollow container forms an empty space around the area that, once clad, constitutes the working zone of the clad roll during rolling, Figures 1 and 2. HIP clad mill rolls before and after machining are illustrated in Figure 3. After closure welding and attachment to the low-alloy steel shaft, the
Three important attributes of powder metallurgy (PM) materials justify their utilization in highly stressed and elevated-temperature applications: minimal segregation, fine grain size, and pore-free density. Widespread application of large-scale, prealloyed hot isostatically pressed (HIPed) PM components exists utilizing nickel-base, ferrous, titanium, and other nonferrous systems, taking advantage of the three cited attributes. In most areas, the applications also benefit from an improved level of ultrasonic inspection (UI) permitted by fine-grain, homogenous microstructures. A further benefit is the capability of producing entirely new alloy combinations utilizing nonequilibrium microstructures that result in higher property levels than do the microstructures that encumber many ingot metallurgy products. Applications illustrated here include PM clad steel mill rolls, plastic extrusion barrels and screws, rotating aircraft and land-based gas-turbine components, and titanium–boron alloys for airframes. As the employment of HIPing-PM solutions becomes more extensive in the design community, the demand for these products, as well as the worldwide HIPing capacity, will dramatically increase beyond current high growth rates. Presented at HIP ‘08, the 9th International Conference on Hot Isostatic Pressing, organized by IHC, the International HIP Committee, May 2008, Huntington Beach, California
*Vice President, General Manager, Crucible Materials Corporation, Crucible Research, 6003 Campbell’s Run Road, Pittsburgh, Pennsylvania 15205; E-mail:
[email protected]
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HIPed products. The vacuum loading of HIP-PM components was patented by Crucible Materials Corporation in 1998.3 During HIPing the PM tool steel powder is consolidated to its pore-free density and forms a wear-resistant clad layer that lasts significantly longer than conventional or weld clad rolls. The additional time in service, as well as the unscheduled mill downtime, more than justify the higher price of the clad product. A similar process for cladding is offered by Carpenter Technologies Inc.
Figure 1. Welding of HIPing container for clad mill roll
Figure 2. Clad mill roll vacuum loaded with prealloyed powder and sealed prior to HIPing
Extrusion Barrels and Screws PM alloys can also be used to clad plastic extrusion barrels and screws to enhance life and throughput speeds. The plastics contain fiberglass threads or other abrasive particles that require wear resistant grades that can only be furnished by means of HIPing-PM. Plastic extrusion screws clad with wear-resistant materials are illustrated in Figure 4. More recently, the addition of corrosive media, including copper sulfate, chlorides, and various acids, has increased the need for both wear-resistant and corrosion-resistant grades in this industry. Microstructure of PM Clad Products As described previously, clad steel mill rolls were typically refurbished utilizing ingot metallurgy weld clad D2 prior to the growth of HIPing-PM. A representative microstructure of this clad, exhibiting coarse carbides, is shown in the optical micrograph (OM) of Figure 5. Microstructures of two PM grades most commonly used in these applications, (CPM M4® and CPM 9V®) are illustrated in Figures 6 and 7. High-speed steel T15
Figure 3. HIP clad mill roll: as-HIPed (left) and after machining (right)
assembly is loaded under vacuum with PM tool steel powder and crimped to hermetically seal the container prior to HIPing. Vacuum loading of clad product provides a major quality advantage and production capacity advantage for clad and other
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Figure 4. Plastic extrusion screw segments clad with wear-resistant materials
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Figure 5. Ingot metallurgy D2 exhibiting coarse carbides. OM
Figure 6. CPM M4® HIPed-PM steel, Vilella’s reagent. OM
and CPM S90V, a wear- and corrosion-resistant tool steel, can also be used for HIP clad rolls to achieve desired characteristics and properties of the working surface. CPM 9V® is a wear-resistant tool steel which contains about 15 w/o of vanadium-rich primary carbides. It is typically used at a relatively low hardness range (52 Rc to 56 Rc). This combination provides a high level of toughness. Thus, where initial rolling passes may involve high impact rates with processed billets, CPM 9V® may be the preferred choice in rolling. This alloy is also resistant to heat checking in roll applications where water cooling is reduced or unavailable. M4 contains approximately 12 v/o carbide and is typically used in the tempered condition at a hardness level 62 Rc to 64 Rc. The HIPed-PM microstructure is characterized by fine carbides uniformly distributed within the matrix and only available through PM processing, Figure 6. Wear can be further improved by using CPM T15®, which contains a higher carbide content (~14 v/o), most of which are vanadium-rich (type MC). This alloy is also capable of attaining a slightly higher hardness than M4. In rolling applications where corrosion is a concern, CPM S90V® can be used to take advantage of its corrosion resistance. It contains 14 w/o Cr and 9 w/o V, which provide an excellent combination of wear resistance and corrosion resistance. This alloy contains 20 v/o of total carbides, about half of which are hard vanadium rich (type MC). The attainable hardness of this alloy is 61 Rc to 63 Rc, but for HIP clad applications it is typically used at a lower hardness (54 Rc to 56 Rc) in order to take advantage of its higher toughness in this condition. Regardless of the solutions available, utilizing HIP clad PM rolls can increase the useful life by a Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
Figure 7. CPM 9V® HIPed-PM steel, Vilella’s reagent. OM
factor of five or six. This minimizes downtime and maintenance costs while providing an improved roll-working surface. PM NICKEL-BASE SUPERALLOYS Next to the high tonnage use of ferrous PM high-speed steels and tool steels, nickel-base superalloys for rotating components in aircraft engines constitute the widest use of pore-free HIPing-PM alloys. These are predominantly nickel-base alloys strengthened by solid solution elements including cobalt, molybdenum, and tungsten, and by the precipitation of γ’ (gamma prime) Ni3Al. Initial PM superalloy compositions were modifications of existing ingot metallurgy alloys such as IN-100, Astroloy, and Rene 95.4 Extrusion Vs. HIPing and Extrusion The majority of PM superalloy components in current production utilize high-temperature extrusion for consolidation prior to isothermal forging. Here again the primary attributes of homogeneity and a fine PM grain size permit isothermal forging at lower stresses while providing greater ductility than in ingot metallurgy grades. More recently, R&D has focused on consolidation by HIPing prior to extrusion; examples are shown in Figures 8, 9, and 10. The rationale is that extended heating times prior to consolidation by extrusion provide an opportunity for the adsorption of oxygen on powder-particle surfaces to form oxides which grow in the unconsolidated powder prior to extrusion. Utilizing HIPing prior to extrusion reduces the time of heating significantly in the unconsolidated state, minimizing the potential for degradation. Historically, this phenomenon has been observed for oxides and sulfides in ferrous tool steels atomized with inert nitrogen gas,
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Figure 8. Two stainless steel containers prior to cleaning and loading. Cylinders hold 3,600 kg of PM superalloy powder prior to HIPing and extrusion to a 260 mm dia. billet
Figure 9. As-extruded 260 mm nickel-base superalloy billets
Figure 10. Nickel-base superalloy billets (230 mm dia.) after UI
but not melted in vacuum furnaces.5 The use of HIPing prior to extrusion does add cost and an additional operating step. However, the billet consolidated by HIPing provides greater input weight per unit volume and effectively reduces the cost of extrusion conversion per unit weight of product. At this point, the unit price of HIP conversion per kg of product remains far below that of large-scale consolidation by extrusion (pressing force greater than 20 mt) for billets weighing >2 mt or with input billet diameters >400 mm. Considering the large capital investment required to design and build large-scale extrusion facilities, current aircraft-component designers should consider the widest application of as-HIPed alloys and components in order to minimize turbine-component acquisition costs. PM Superalloys Consolidated by HIPing Over 200,000 as-HIPed PM components have been produced and are flying in aircraft gas turbines around the world. The earliest large-scale use of as-HIPed PM superalloys was during the late 1970s in the GE T-700 engine which utilized over 40,000 HIP-PM Rene 95 components. At the same time, as-HIPed Rene 95 became the alloy of choice for blade retainers in the GE F-110 and GE-SNECMA CFM-56 engines utilized primarily on the Boeing 737. As-HIPed Rene 95 blade retainers are still being produced as both original equipment and as spares in the F-100 and CFM56 engines. A representative HIPed Rene 95 blade
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retainer sleeve and finish-machined components are shown in Figure 11. The HIPing process for producing these components is essentially unchanged over the past 30 years. It consists of eight major steps illustrated in Figure 12: 1) Atomize powder with inert argon gas 2) Determine heat chemistry, size distribution, tap density, and flow rate 3) Screen and blend powder to form large lots (not to meet chemistry) 4) Determine blend chemistry, size distribution, tap density, and flow rate 5) Load containers under vacuum, inert gas, or in a clean-room atmosphere 6) Outgas and seal containers
Figure 11. HIPed Rene 95 blade retainer sleeve and finish-machined components
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Atomize
Screen
Blend
Vacuum Load
Evacuate
HIP
Figure 12. Major steps in HIPing—schematic
Astroloy and Alloy 720, APU turbine discs now operate at higher temperatures and rotational speeds than conventional ingot metallurgy discs produced from 718 or Waspalloy®. Notably Honeywell (formerly AlliedSignal) has utilized a fine-grain low-carbon Astroloy hub while HIP bonding a coarse grain, creep-resistant cast blade ring to the outer diameter to create a hybrid dualalloy wheel. This hybrid component has been in commercial service for over 10 years.
Figure 13. As-HIPed superalloy components. Smaller components are HIPed turbine discs and spacers made from as-HIPed low-carbon astroloy and 720. Turbine disc and shaft integrated as one component eliminates weld joining
7) Consolidate via HIPing (typically 100 MPa at 1,125°C) 8) Process after HIP: heat treat, machine, UI, and dimensional inspection An even greater number of as-HIPed parts are utilized as turbine discs in aircraft auxiliary power units (APU), Figure 13. Typical commercial airliners have historically carried two such units to furnish power to control surfaces and navigation systems as well as providing power for other airframe functions and passenger amenities including heating, ventilation, and air conditioning. When they could not be eliminated entirely by battery power and fuel starters, typical military aircraft frames carried no more than one APU in order to save weight and reduce fuel consumption. Within the past 20 years, commercial airframes have followed suit and have benefited from lower APU weight, better utilization of space and cargo volume, and reduced fuel consumption. By using higher-strength alloys including HIPed low-carbon Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
Large Land-Based Turbine Applications While it is intuitive that the higher strength and temperature resistance of PM alloys, combined with weight savings, justify use in aircraft turbines, the case for PM alloys in land-based turbines has not been as obvious. For land-based turbines, the total weight of the turbine has not been a factor in specific fuel consumption. Historically, these turbines, capable of generating more than 10 MJ/s (10MW), have utilized iron–nickel-base alloys such as wrought 7066 or 718. Starting ingot weights can range anywhere from 5 to 8 mt (10,000 to 15,000 kg) In large ingot cross sections, which take several days to cool from tap temperature, segregation occurs. Thus, subsequent extensive upsetting and forging are necessary to work the large ingot into a turbinedisc preform with a refined through-volume microstructure. This process requires large-scale forging equipment with attendant forces of up to 20 mt. The process also involves repeated reheating to maintain working temperatures, and can result in material losses of up to 35%. The turbine discs and spacers in these engines can be as much as 3 m in dia. after finish machining. As ingot sizes have increased, the potential for the segregation of defects and thermal cracking has
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Figure 14. 6,000 kg as-HIPed forging preforms
also increased. These problems are not insoluble, but their occurrence can add significantly to the cost of processing and rejection-hazard risk. By utilizing a HIPed-PM billet, the amount of hot working needed to obtain a final disc shape is reduced, Figure 14. A decrease in yield loss also results from less hot working, lowering input raw material costs. PM processing also yields a smaller population of large refractory inclusions carried over from the melt, and a finer grain size which, other things being equal, improve both strength and ductility. The fatigue life of 706 has been shown to improve by a factor of three to five times by utilizing a combination of PM processing and heat treatment.7 The fine grain size also permits a higher level of confidence in detecting any inclusions or potential discontinuities upon UI inspection, prior to finish machining and insertion into the rotating apparatus. These advantages lower rejection-hazard costs in these high-value-added components and provide an increased margin of operating reliability. All of these factors can be utilized to permit tolerance to higher stresses which in turn allows for higher rotational speeds and gas temperatures. This provides an immediate increase in Carnot efficiency and decreasing specific fuel consumption. With the relative increase in the price of natural gas, the cost of fuel consumption is gaining as much importance as capital acquisition costs in large turbines. These concepts have been proposed before but have not been sufficient to supplant conventional ingot metallurgy discs in large turbines. With the added cost of higher raw material prices, however, PM is again being considered for these applications. When metallurgists and
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mechanical design engineers finally take advantage of PM processing and design alloys that can only be made via PM to provide higher strength and fatigue resistance, land-based turbine design will once again parallel aircraft turbine design. This will result in a similar set of benefits in the land-based gas turbine power generation industry. Perhaps marine turbines will provide the next broad-based opportunity following land-based turbines. Regardless, the large PM billets needed as starting stock for land-based turbine discs are too large to be consolidated by existing extrusion equipment. Therefore, the HIP industry will have to provide consolidation services in the near future and perhaps be required to produce vessels even larger than any currently in existence to provide the required starting stock diameters for forging. PREALLOYED HIPED-PM TITANIUM–BORON ALLOYS Prealloyed titanium powder has been produced by various methods for nearly 25 years. Attendant advantages and different methods of manufacture are well documented.8 Prealloy processing, particularly induction skull melting followed by inertgas atomization, affords the widest range of possible compositions. This is due to the fact that a homogeneous melt is held at, or above, the liquidus temperature and stirred by the induction field until all constituent elements are completely dissolved. Only then does the melt inert-gasatomized powder result in particles with virtually no segregation. In the titanium–boron binary system, the precipitation of high boron phases within the powder particles cannot be suppressed. This results in a microstructure characterized by a uniform distri-
Figure 15. As-HIPed Ti-6Al-4V-1B consolidated at 1,000°C. OM
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Figure 16. As-HIPed Ti-6Al-4V-1B plate compacts prior to rolling
Figure 17. As-HIPed Ti-6Al-4V-1B plate compacts after rolling (450 mm wide × 900 mm long × 5 mm thick)
TABLE I: PROPERTIES OF HIPED AND ROLLED TI-6AL-4V-1B PLATE 9 Condition
UTS: MPa (psi × 103)
0.2% YS: MPa (psi × 103)
Elongation: %
Area Reduction: %
E:GPa (psi × 106)
As-HIPed
1,085 (157)
964 (140)
6.9
8.7
128 (18.6)
HIPed + Hot Rolled 6.35 mm Plate (Longitudinal)
1,225 (178)
1,093 (158)
10.4
19.0
132 (19.2)
HIPed + Hot Rolled 6.35 mm Plate (Transverse)
1,162 (168)
1,058 (154)
9.6
12.5
127 (18.5)
bution of fine TiB precipitates which enhances strength in the final HIPed product without significantly degrading ductility, Figure 15. Examples of plate compacts fabricated from Ti-6Al-4V-1B powder are illustrated in Figure 16.9 By adding up to 1 w/o boron to Ti-6Al-4V, a fine grain microstructure is achieved in the as-HIPed condition. This results in increases in modulus and strength (up to 25%) while maintaining sufficient workability to be forged or rolled using conventional hotworking equipment, Figure 17 and Table I. The combination of prealloyed gas-atomized powder consolidated by HIPing and hot working provides a lightweight, high-strength material for future airframe construction. This combination of properties will be particularly useful in areas where the properties of the standard Ti-6Al-4V alloy material are not adequate for the required loads. SUMMARY This review demonstrates how with highly alloyed tool steels, nickel-base superalloys, and advanced titanium–boron compositions, prealloyed HIPing-PM technology offers commercialVolume 44, Issue 5, 2008 International Journal of Powder Metallurgy
scale solutions to modern materials challenges. For the systems discussed, the three primary virtues of HIP prealloyed PM are minimal segregation, fine grain size, and pore-free density; in combination, these provide a new range of material properties and increased performance. ACKNOWLEDGEMENTS The author wishes to acknowledge the assistance of, contributions by, and technical discussions with Andrzej Wojcieszynski and C. Frederick Yolton, Crucible Research, Crucible Materials Corporation, Pittsburgh, Pennsylvania. REFERENCES 1. J.O. McGeever, "Improving Thermal Fatigue and Wear Resistance of Tooling through HIP Cladding of Components”, Industrial Heating, 1993, vol. LX, no. 5. pp. 52–55. 2. J. Runkle “Method for Making Tool Steel With High Thermal Fatigue Resistance”, U.S. Patent No. 5,290,507, March 1, 1994. 3. T.C. Rhodes, H.E. Brinzer and F.J. Rizzo, “Method for Vacuum Loading”, U.S. Patent No. 5,849,244, December 15, 1998. 4. J.H. Moll and B.J. McT iernan, “Powder Metallurgy
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5.
6.
7.
8. 9.
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Superalloys”, ASM Handbook, Vol. 7: Powder Metallurgy, Technologies and Applications, ASM Inter national, Materials Park, Ohio, 1998, pp. 887–902. W.B. Eisen, W. Haswell, K.J. Wojslaw and J.K. Wright, “Method for Compacting High Alloy Tool Steel Particles”, U.S. Patent No. 6,099,796, August 8, 2000. G.W. Kulhman, A.K. Chakrabarti, R.A. Beaumont, E.D. Seaton and J.F. Radavich, “Microstructure Mechanical Properties Relationships in Inconel 706 Superalloy”, Proc. International Symposium on Superalloys 718, 625, 706 and Various Derivatives, edited by E. Loria, The Metallurgical Society, Warrendale, PA, 1994, pp. 441–450. U. Habel, F. Rizzo, J. Conway, R. Pishko, V. Sample and G. Kuhlman, “First and Second Tier Properties of HIP and Forged P/M 706”, Proc. International Symposium on Superalloys 718, 625, 706 and Various Derivatives, edited by E. Loria, The Metallurgical Society, Warrendale, PA, 1997, pp. 247–256. J.H. Moll and C.F. Yolton, “Production of Titanium Powder”, ibid. reference no. 4, pp. 160–166. C.F. Yolton, “Atomization of Titanium Alloys Containing Boron”, TMS 2007 Annual Meeting, Orlando, FL, February 25–March 1, 2007, Oral Presentation. ijpm
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HOT ISOSTATIC PRESSING
CLADDING OF BRIQUETTING TOOLS BY HOT ISOSTATIC PRESSING FOR WEAR RESISTANCE Christoph Broeckmann*, Axel Höfter** and Andreas Packeisen***
INTRODUCTION Tools in mineral processing applications often suffer from heavy abrasive wear. Sometimes these tools are also subjected to high mechanical loads. Generally, superior wear resistance coupled with high mechanical strength and toughness of the tool material are incompatible. A typical example is a roller press used for over 100 years in the continuous production of briquettes. A roll nip is formed between two synchronized rotating rolls and the feedstock is fed into the roll nip either by gravity or by assistance from a screw feeder. Pockets, machined into the surface of the roll by electrochemical machining (ECM), are filled with the feed material to form the briquettes, Figure 1. Modern roller presses use adjustable hydraulic systems in order to control the press force.1 Figure 2 illustrates a typical roller press. Originally these machines were used for the processing of coal fines in which wear was a minor issue. Today, these presses are used to pro-
Figure 1. Principle of a briquetting process with a roller press
Figure 2. Modern roller press
In order to increase the wear resistance of tooling for the briquetting of minerals the surface should contain hard particles such as carbides, borides, or nitrides. The type, size, and volume fraction of the hard phases can be optimized based on the intended application. Cladding by hot isostatic pressing (HIPing) is a well-established method for producing thick coatings on ferrous-base substrates, and coatings up to 35 mm in thickness are now standard. Successful applications of clad tools in briquetting suggest utilization of this technology for the fabrication of other wear-resistant components.
Presented at HIP ‘08, the 9th International Conference on Hot Isostatic Pressing, organized by IHC, the International HIP Committee, May 2008, Huntington Beach, California
*Professor & Head, Institute for Materials Applications, Mechanical Engineering Division: Ceramic Components, Nizzallee 32, 502072 Aachen, Germany; E-mail:
[email protected], **Managing Director, ***R&D Engineer, Köppern Entwicklungs-GmbH, P.O. Box 80 07 07, 45507 Hattingen, Germany; E-mail:
[email protected]
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duce briquettes from a spectrum of minerals, for example, steel dust, MgO, iron ore fines, or sponge iron. With increasing hardness of the feed material, tool wear has become important in the overall operating cost of a briquetting plant. The press force acting on the rolls has increased from 20 kN/cm in early coal briquetting applications to 130 kN/cm in modern hot briquetting machines for processing direct-reduced iron (DRI). Early tool designs featured segments or thinwalled tires which were bolted or clamped onto a cast or forged shaft. An increase in the press force requires a stronger joint between the tool and the shaft. In modern cold briquetting machines the tire-shaft design illustrated in Figure 3(a) is used. The tires (2) are assembled on the shaft (1) using a thermal shrink joint which is designed to carry the required torque without slippage. The tires have to withstand high mechanical loads and during shrink-fitting the Lamé-pressure (p) between the tire and the shaft develops, Figure 3(b). This pressure results in static tangential tensile stresses in the tire which are maximized at the inner surface of the tire. Superposition of the periodic load due to the press force results in fatigue loading. This loading is characterized by a relatively high static component and a relatively small stress amplitude at the inner diameter, but a relatively low static component with a relatively high stress amplitude at the outer diameter. Hard mineral particles in the feedstock contribute to wear of the pressing tools. These hard particles can either be the feed material, as is the case with MgO and ore-briquetting, or ceramic impurities within the feed material, for example, in the case of the briquetting of steel mill dust or hot DRI. Figure 4 shows typical wear patterns on a conventional tool-steel-roll surface. This pressing tool was used for the briquetting of MgO in the fabrication of refractories. Due to the uneven distribution of the pressing force over the width of
Figure 3. (a) Tool design, and (b) mechanical loading of tool
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the roller, the edges wear more slowly, compared with the central area. Wear of the individual pockets is most pronounced at the “land areas” which separate the pockets. These locations are first sharpened, followed by a reduction in height. The bottom of the pockets wear out at a much slower rate. Finally, when the briquettes cease to leave the press as separate (individual) entities, the tool has to be replaced. In order to effectively reduce wear, the wear mechanisms acting in a roller press must be understood and analyzed. Overall wear can be divided into two regions, Figure 5. The two regions are separated by the nip angle γ, at the line where friction between the roller surface and the feed material is high enough to grip the feed material. In region I, ahead of the nip angle, relative tangential movement between the roller surface and the feed-material particles prevails. In region II, below the nip angle, no further relative movement is observed. As a consequence the tool surface in region I wears primarily due to abrasion caused by scratching of the surface by minerals. In contrast, single accumulated indentations lead to surface fatigue in region II, reflecting indentation.2 TOOL MATERIALS Briquetting rings require a combination of high fatigue strength and toughness in order to withstand the mechanical loads caused by shrink fit and cyclic press forces. Usually the lifetime of the tool is limited by the wear resistance of the surface and not by fatigue within the bulk material. A maximum in both toughness and wear resistance cannot be achieved in a monolithic material. Therefore, high-performance briquetting tools are produced as composite components. The base material is a hardenable carbon–chromium– molybdenum steel exhibiting strength and toughness after heat treatment. This steel ring is coated
Figure 4. (a) Worn briquetting tool: macro profile showing uneven pressure distribution, and (b) sharpening of land areas between pockets
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with a thick wear-resistant layer of low toughness. The microstructure of this layer is optimized to achieve high wear resistance to the feed material in each particular application. Wear attack by abrasive particles can be minimized by the presence of hard phases such as carbides, borides, or nitrides in the tool material, Figure 6. The optimal condition for these hard phases is that they must be harder than the feed material (mineral particles). Table I cites hardness data for a number of minerals (feed material) and carbides used for wear protection. Typical metals for the individual carbide types are given in parenthesis. The hardness of the carbides in Table I is dictated primarily by composition. Other factors influencing the hardness of a carbide are grain size and microstructure. Thus, the hardness data in Table I cover a wide range. Also the hardness of minerals exhibits a wide scatter band. In consequence, the successful application of carbide-rich materials mandates a careful investigation of the particular mineral and correct choice of the chemical composition of the tool material, as well as careful control of the production process. The volume fraction (v/o) of hard phases contributes to the microindentation hardness of the tool material. The relation between macrohardness (HT) and the hardness of the mineral (HM) gives a first estimate of wear resistance. A qualitative plot of wear resistance versus the hardness ratio (HT/HM) shows a curve with low-level/high-level regions, Figure 7. Below a certain hardness ratio, wear resistance is not influenced by the hardness of the tool. With increasing tool hardness, wear resistance increases rapidly up to a higher level. Further increases in tool hardness do not influence the wear resistance. The transition from the low-level region to the high-level region in wear resistance frequently occurs at values of HT/HM <1 and depends strongly on the type of tool material. In particular, the v/o and microindentation hardness of the hard phases are important. As noted previously, the prevailing wear mechanisms in roller presses are abrasion and indenta-
tion. The difference between these two mechanisms is illustrated in Figure 6. Abrasion is characterized by a relative movement between the particles and the tool surface. This relative movement leads to material removal by scratching, caused by the minerals. In order to reduce this material loss, the hard phases should be large compared with the size of the grooves produced by the abrasive particles. If the hard phases are too small, the wear resistance of the tool material is determined primarily by the hardness of the
Figure 5. Two regions of wear in a roller press
Figure 6. Wear mechanisms in a roller press
TABLE I. MICROINDENTATION HARDNESS (HV 0.05) OF CARBIDES* AND MINERALS3 Carbides
M3C (Fe) 750–1,200
M23C6 (Cr) 950–1,450
M7C3 (Cr) 1,200–1,600
MC/M2C (W) 2,500–3,000
MC (Nb, V, Ti) 2,200–3,200
Minerals
Flint 500–1,200
Quartz 1,100–1,300
Garnet 1,400–1,600
Al2O3 2,000–2,150
SiC 2,600–3,200
*M refers to metal element in carbide Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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metallic matrix. In the case of indentation, mineral particles are pressed into the tool surface without relative movement parallel to the surface and this process is repeated multiple times. Due to microfatigue, small cracks contribute to chipping and hence to overall wear. Material loss can be minimized by reducing the distance between the individual hard-phase particles. In order to fulfill both requirements, the overall v/o of hard phases should be relatively high. The distribution of hard phases in the matrix is important in relation to the mechanical properties of the material.4,5 A high v/o of hard phases often leads to a net-like microstructure. Examples are eutectic and hypereutectic alloys used in hard facing, or white cast irons. Cracks propagate along the carbides which, in turn, result in low overall fracture toughness. Figure 8 shows the influence of the v/o of the hard phases on the fracture toughness of a powder metallurgy (PM)
metal matrix composite (MMC). Depending on the size ratio of the hard phases and the matrix material, the resulting hard-phase distribution is either a net or a homogeneous dispersion. This results in significant differences in fracture toughness. Nevertheless, when processed correctly, PM results in a uniform dispersion of hard phases, even at a high v/o. Thus, the mechanical properties of a PM alloy are superior compared with those of cast/wrought materials with the same v/o of hard phases. The microstructure of a representative carbide-rich PM alloy is illustrated in Figure 9; this is a scanning electron micrograph (SEM) backscattered image (BSI). A number of standard wear tests are available with which to characterize the wear resistance of materials. In our study, the “pin on disk” test was used, Figure 10. From the results obtained in this wear test, a suitable PM alloy can be chosen for a particular feed material. Figure 11 shows the
Figure 7. Wear resistance as a function of the ratio between tool hardness (HT) and mineral hardness (HM)
Figure 8. Fracture toughness of carbide-rich materials4
Figure 9. Microstructure of carbide-rich PM alloy. SEM/BSI
Figure 10. Pin-on-disk wear test
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influence of v/o of MC carbides on the wear rate. Clearly, the wear rates with Al2O3 and SiC do not depend significantly on the v/o of carbides. For both combinations, the wear resistance remains at a low level (Figure 7). Due to the different hardness levels of these abrasives, the wear rate of SiC is significantly higher, compared with Al 2 O 3 . When the abrasive is softer than the carbides, the wear rate is strongly influenced by the carbide v/o. At a certain v/o of carbides, a high level of wear resistance is achieved and a further increase in carbide v/o does not significantly decrease the wear rate. CLADDING OF COMPONENTS Carbide-rich materials are needed only in those parts of the tool surface in contact with abrasive mineral particles. In order to obtain acceptable mechanical properties of the overall component, the base of the tool should be free of carbides. Therefore, composite structures consisting of a tough base and a wear-resistant surface layer have been developed. The lifetime of such tools depends primarily on the thickness of the wearresistant coating. Using HIPing for cladding, carbide-rich sur face layers of up to 35 mm in thickness can be produced. A forged or cast metallic substrate is wrapped in a capsule made from thin sheet steel. This process is shown schematically in Figure 12 for a ring with an outer wear-resistant layer. The capsule is usually TIG-welded. The gap between the capsule and the substrate is filled with a highalloy tool-steel powder or a mixture of quasiceramic hard phases and a metal powder. After
filling the capsule with powder, it is evacuated, helium leak tested, and sealed. Under HIPing conditions, the powder is consolidated. In contrast to sintering in vacuum or ambient, pressures up to 100 MPa lead to plastic deformation and enhanced sintering activity which in turn result in pore-free densification of the powder. With the correct evacuation procedure, and if no inert gas (e.g., argon) remains in the capsule, all porosity is removed. Metallic bonding integrity is found between the powder layer and the substrate, Figure 13(c). Figure 13(a) shows element line scans across the interface, obtained by energy dispersive spectroscopy (EDS)/scanning electron microscopy (SEM). It can be seen that small atoms (e.g., carbon) diffuse over relatively large distances and even large atoms (e.g., chromium) show concentration gradients over distances ~50 µm. Therefore, integrity in bonding between the powder layer and substrate is expected. Due to the gradient in chemical composition, the mechanical properties should show a gradient at the interface. This has been confirmed by determining the hardness profile across the interface. Figure 13(b). Heat treatment of clad composite components warrants special attention. Due to differences between the layer and substrate with respect to thermal expansion coefficients, elastic constants, and phase transformations, internal stresses develop during quenching. These stresses can lead to fracture of the component. Based on finite element (FE) calculations, the temperature during heat treatment can be controlled to avoid any risk of crack initiation. CASE STUDIES Components up to 1,500 mm dia. and 10 kg in weight have been produced. The diameter is limited by the size of available HIPing units. The
Figure 11. Dimensionless wear rate of carbide-rich PM alloys as function of carbide content
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Figure 12. Cladding of a ring by HIPing
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Figure 13. Interface between substrate and layer: (a) element line scan (EDS/SEM), (b) hardness profile, (c) microstructure (SEM)
largest clad rings are used in high-pressure grinding rolls (HPGRs) in comminution circuits for cement clinker or metal ore.6,7 A number of briquetting presses also have been equipped with HIPing facilities for clad tools. Briquetting Tools for Magnesia Roller presses are used in the production of refractory materials. One example is the briquetting of a mixture of MgO dust, chrome ore fines, and clay. The Mohs hardnesses are 6.0 for MgO (800 HV) and 5.5 for chrome ore (660 HV). The particular roller press under consideration is equipped with four rings (1,004 mm dia. × 250 mm width). The press has been operating for many years with rings made of conventional carbide-free tool steel. In this application the wear pattern after a short period of service is characterized in Figure 4. A first set of clad rings was produced and delivered, Figure 14. Due to the high carbide v/o of the clad layer, a significant increase in the lifetime of the tools steel is expected.
Figure 14. Clad tools for a roller press to briquette MgO
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Briquetting of Iron Ore Fines A second application of roller presses is the production of iron ore briquettes. The feed material is a mixture of ~40 w/o iron ore fines, 40 w/o steel mill dust, and 20 w/o coal fines. The ore is magnetite Fe2O3 (taconite type) with an average hardness of 7 Mohs (1,150 HV). The average size of the individual feed material particles is 0.8 mm. The briquetting plant was commissioned in 2002 with two presses. The original machines were equipped with segmented tools made of white cast iron (ASTM A532 Class I type DNIHARD4). This material contains approximately 26 v/o M 7 C 3 type carbides. As the lifetime of these segments was relatively short, one press was redesigned in order to carry clad rings (870 mm dia. × 790 mm width). Figure 15(a) shows a complete roller equipped with PM rings. Details of the PM layer are seen in Figure 15(b). The wear performance of the tools can be monitored by tracking the total throughput of the machine which was produced with one set of tools, Figure
Figure 15. Clad roll for briquetting iron ore fines: (a) complete roller, and (b) detail of one ring
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Figure 17. Briquetting-press tools for hot converter dust: (a) conventional tool after three weeks, (b) clad tool after 33 weeks of continuous operation
Figure 16. Improvement in tool life by material optimization
16. The first choices of a PM material (PM1, PM2) gave a small increase in lifetime. Detailed analysis of the operative wear mechanisms and continuous improvement of the layer material and its heat treatment finally resulted in a significant increase in lifetime. Compared with NIHARD4, a factor of 4.5 increase in lifetime was achieved (PM3). The thickness of the wear-resistant layer was 25 mm in the first sets of rings. Worn rings are being refurbished by turning and ECM of the pockets. Thus, a set of clad rings can be reused with the same expectation of lifetime. Meanwhile, layers up to 35 mm in thickness can be produced. The increase in layer thickness from 25 to 35 mm allows for a second refurbishment. The cost for the refurbishment of rings is small compared with the production cost of new rings. Therefore, the higher thickness of the layer improves the economic benefit of clad rolls in this application. Briquetting of Hot Steel Mill Dust A third application of roller presses with abrasive feed material is the hot briquetting of converter dust in a steel mill. The feedstock contains about 45 w/o of metallic iron which acts as a binder at a pressing temperature of 550°C. Thus, the strength of the briquettes is sufficient to replace scrap in steel melting. The wear-related loading of the rolls is characterized by the combination of a high feedstock temperature and ~4.0 w/o hard oxides in the feedstock. The resulting surface temperature in the tool has been determined to be in the range of 230°C to 260°C. The hard oxides are SiO2, Al2O3, and TiO2. The Mohs hardness of SiO2, is 7 (1,100 HV), and that of Al2O3 is 9 (2,100 HV). Originally the briquetting press was equipped Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
with tools fabricated from a flame-hardened hotworked tool steel. Figure 17(a) shows the tool surface after three weeks of continuous operation. Due to heavy wear of the land areas between the pockets, individual briquettes are no longer separated correctly and the average total throughput that could be achieved with conventional tools was limited to 12,000 mt. This corresponds to a lifetime ~four to six weeks. Using HIP cladding technology it is possible to replace the hot-worked steel with a cold-worked tool-steel layer with ~23 v/o of hard phases. After 33 weeks in continuous operation essentially no wear was visible, Figure 17(b). Finally, the clad rings were taken out of operation after 70 weeks in service. To the end of their lifetime, the quality of the briquettes could be maintained at a high level. The total throughput was 65,000 mt, or 5.4 times higher than with conventional tools. SUMMARY Tools for roller presses in briquetting applications are subject to high loads and frequently have to withstand abrasive mineral particles. Cladding by HIPing is a viable method to produce a composite component consisting of a tough core and a wear-resistant outer layer. Layers up to 35 mm in thickness can be produced using this technology and have been proven to perform in service. The layer material must be chosen based on a careful analysis of the particular feed material. The influence of the microstructure of the carbide-rich layer on overall wear resistance is analyzed. First experiences with clad tools in briquetting applications are available and show that tool lifetimes which are about four to six times higher compared with those of conventional tools can be achieved. This technology can be extended to other components and applications in the mineral processing industry.
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CLADDING OF BRIQUETTING TOOLS BY HOT ISOSTATIC PRESSING FOR WEAR RESISTANCE
TRUST must be earned For 90 years, ACuPowder has been delivering the finest quality powders and the most conscientious service. Our customers know that serving their needs and solving their problems is our highest priority.
REFERENCES 1. H. Rieschel, “Die technische Entwicklung von Brikettpressen in den letzten 25 Jahren”, Aufbereitungstechnik, 1984, vol. 25, no. 1, pp. 1–16. 2. M. Schumacher and W. Theisen, “HEXADUR® – Ein neuer Verschleißschutz für Hochdruck-Walzenmühlen”, ZKGInternational, 1997, vol. 50, no. 10, pp. 529–539. 3. W. Theisen, “Gefügebestandteile und –Arten”, Hartlegierungen und Hartverbundwerkstoffe, edited by H. Berns, Springer Verlag, Berlin, Heidelberg, New York, 1998, pp. 27–52. 4. C. Broeckmann, “Mechanische Eigenschaften”, ibid reference no. 3, pp. 125–153. 5. C. Broeckmann, “Microstructure and Mechanical Properties of Tool Steels”, Proc. 5Th Inter national Conference on Tooling, Leoben, Austria, edited by F. Jeglitsch, R. Ebner, H. Leitner, Institut für Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Austria, 1999, pp. 49–58, 6. C. Broeckmann and A. Packeisen, “Under Pressure HEXADUR®, a New Wear Resistant Concept for High Pressure Grinding Rolls”, World Cement, 2004, vol. 35, no. 5, pp. 55–58. 7. C. Broeckmann and A. Gardula, “Developments in HighPressure Grinding Technology for Base and Precious Metal Minerals Processing”, 37th Canadian Mineral Processors Conference, Ottawa, Canada, Canadian Institute of Mining, Metallurgy and Petroleum, Canada, 2005,pp. 285–300. ijpm
Bring us your toughest assignments. We want to earn your trust, too. The finest powders are from ACuPowder: Copper, Tin, Bronze, Brass, Copper Infiltrant, Bronze Premixes, Antimony, Bismuth, Chromium, Manganese, MnS+, Nickel, Silicon, Graphite and P/M Lubricants.
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HOT ISOSTATIC PRESSING
HOT ISOSTATIC PRESSING SIMULATION FOR TITANIUM ALLOYS Takuji Teraoku*
NUMERICAL SIMULATION AND ANALYSIS MSC.Marc, a non-linear FE program1 was used for numerical simulation and analysis. A unified viscoplastic approach was selected from this program for simulating the HIPing of metal powder. This simulation is a thermomechanically coupled analysis since both mechanical properties and thermal properties are prescribed. Furthermore, the material behavior is both temperature and density dependent. The powder is represented by means of a modified Shima model.2 The yield function is:
(
2 1 — 3 σdσd + p F= — —2 γ 2 β
)
1/2
– σy
(1)
where σy is the uniaxial yield stress, σd is the deviatoric stress tensor, where σd σd specifies σdij σdit and p is the hydrostatic pressure. γ and β are material parameters. σy can be a function of temperature and relative density and γ and β are functions of relative density only. For β and γ: q q4
(2)
b b b2ρ 3) 4
(3)
β = (q1 + q2ρ 3) γ = (b1 +
where ρ is the relative density and q1, q2, q3, q4, b1, b2, b3, b4, are parameters derviced from compression tests for the determination of γ and β. As the powder mass densifies, ρ approaches 1 and the classical von Mises model is operative.
In aerospace, gas turbines, and other critical areas, titanium-base alloys are used due to their low weight and high strength. These alloys have a high melting point and are difficult to machine. In consequence, hot isostatic pressing (HIPing) of titanium alloy powder is a preferred method for processing. The cost of HIPed parts can be reduced by minimizing material waste and by reducing machining. To utilize near-net-shape powder metallurgy (PM) processing, it is important to determine the initial capsule dimensions. Methods for predicting the final dimensions of the HIPed product by simulation using numerical-solution techniques exist. Current computer technology enables finite element (FE) simulation for the HIPing of metal powders. In this study, we describe methods for calculating material properties, cite the input data required for simulation, and compare our simulation values with results obtained from actual Ti-6Al-4V products.
DETERMINATION OF MECHANICAL PROPERTIES A uniaxial compression test was performed to determine the parameters γ and β in the Shima model. Details of the test method have been described by Yabu et al.3 Fabrication of Test Specimens HIPing conditions were determined to obtain test specimens of different relative densities. HIPed test specimens were machined into cylinders prior to the measurement of relative density. The relative densities of the HIPed specimens were 82.8%, 90.3%, and 100%, respectively, of the pore-free values. Figure 1 shows scanning electron
Presented at HIP ‘08, the 9th International Conference on Hot Isostatic Pressing, organized by IHC, the International HIP Committee, May 2008, Huntington Beach, California
*Manager, Technical Center, Kinzoku Giken Co. Ltd., Tokyo, Japan; E-mail:
[email protected]
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HOT ISOSTATIC PRESSING SIMULATION FOR TITANIUM ALLOYS
ρ = 82.8%
ρ = 90.3%
ρ = 100%
Figure 1. Microstructure at end surface of test specimens. SEM/BSI
micrographs (SEM) in the backscattered electron image mode (BSI) of the microstructure at the ends of the test specimens for the three relative density levels. Uniaxial Compression Test Uniaxial compression tests were performed at ambient temperature, 700°C, and 900°C and at strain rates of 1.4E-3/s, 1.4E-4/s, and 1.4E-5/s. The tests were performed in vacuum on a hightemperature tension/compression test machine with a maximum temperature capability of 1,100°C and maximum load capacity of 100kN, Figure 2. Calculation of β and γ The uniaxial compression test gives the values of σ11 = ρ, σ22 = σ33, σij = 0 (i≠j). By measuring the incremental strain during a specified period of compression, β can be obtained from the relation: dε11P – dε22P β = (2/3) ——————— dePij
{
}
–0.5
(4)
The parameter γ can be found by plotting the yield point ratio σo*/σo as a function of relative density ρ, where ρo* is the yield strength at each density level and σo is the yield strength at the pore-free density. Other Data It is necessary to take into account the mechanical properties and heat transfer properties of the powder that are dependent on temperature and relative density. To this end, the values of Young’s modulus, Poisson’s ratio, yield point, heat-transfer ratio, and specific heat were used as a function of temperature and relative density. For the capsule, its mechanical properties and heat-transfer properties were used which were functions of temperature. MANUFACTURE OF HIPED PM TI-6AL-4V COMPOSITE Ti-6Al-4V Powder The powder used in this study was manufactured by the plasma rotating electrode process (PREP). Turbine Disk After fabricating the capsule from jointed coldreduced carbon sheet steel (SPCC, JIS G 3141), it was filled with powder and HIPed. Figure 3 shows the capsule before HIPing. A cross section of the turbine disk after HIPing is shown in Figure 4. In this figure, the capsule has been removed from the HIPed piece on the right by chemical processing.
Figure 2. High-temperature tension/compression test machine
58
Turbo Pump Impeller The core of the pump impeller shown in Figure 5 was produced by selective laser sintering (SLS) of stainless steel powder. The Ti-6Al-4V powder and Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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HOT ISOSTATIC PRESSING SIMULATION FOR TITANIUM ALLOYS
Figure 4. Cross section of turbine disk after HIPing
Figure 3. Capsule before HIPing
Figure 6. Section of turbo pump impeller after removal of capsule
(a)
Figure 7. Complete turbo pump impeller
the several cores were contained in a capsule made of jointed sheet steel (Figure 5) and HIPed. Figure 6 shows a section of the turbo pump impeller after the capsule has been chemically removed, and a complete impeller is shown in Figure 7. (b) Figure 5. Core of turbo pump impeller (a) after SLS, and (b) encapsulated for HIPing
Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
HIP SIMULATION The turbine disk and the turbo pump impeller are the examples used to describe the HIPing simulation. Turbine Disk Figure 8 shows the dimensions of the turbine
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HOT ISOSTATIC PRESSING SIMULATION FOR TITANIUM ALLOYS
Figure 9. Dimensional comparison for turbine disk in radial direction before and after HIPing
Figure 8. Comparison of turbine disk dimensions before and after HIPing. Dimensions in mm
disk before and after HIPing. The dimensions were determined by means of a three-dimensional (3D) measuring machine. After HIPing, the turbine disk radius was reduced by 18 mm (from 159 mm to 141 mm) on the upper face and by 16 mm (from 159 mm to 143 mm) on the lower face. Using the material properties obtained from the uniaxial compression test, a HIPing simulation was performed using the MSC.Marc program. Figure 9 shows the results of the analysis for longitudinal deformation. In the figure, “Inc. 413” denotes the number of calculation increments, “lcase4” refers to “load case 4” at the end of the HIPing load history, and Y is the amount of compression in the radial direction of the turbine disk. HIP simulation resulted in a maximum deformation of 18 mm which is in general agreement with the actual measurements. Considering the likely presence of irregularities in capsule construction and in non-uniform powder density, this result confirms the viability of the HIPing simulation model. Turbo Pump Impeller The analytical model is shown in Figure 10. The capsule, core, and powder are represented using the 3D solid element. Figure 11 shows representative analytical results for the displacement distribution. This evaluation was made by comparing
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Figure 10. Analytical model for turbo pump impeller
Figure 11. Sample of analytical results for displacement distribution
the analytical results with the actual product dimensions. In this figure, displacement refers to the total compression in each direction (x, y, z). Volume 44, Issue 5, 2008 International Journal of Powder Metallurgy
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HOT ISOSTATIC PRESSING SIMULATION FOR TITANIUM ALLOYS
SUMMARY The objective of this study was to develop a model to simulate HIPing utilizing properties derived from uniaxial tests on materials of differing relative densities. The methods used to calculate the material properties are explained and the input data required for the simulation cited. Results of the HIPing simulation model for a titanium alloy are in reasonable agreement with those measured on an actual part. FUTURE CONSIDERATIONS We intend to conduct further tests on HIPed parts of more complex shape and compare the results with those obtained from a 3D simulation model. The goal is to increase efficiency in manufacturing and in the use of materials. It is necessary to utilize the capability of net-shape PM processing to keep the cost of manufacturing down and to make the process commercially viable. To this end, we intend to enhance accuracy in the analysis and to improve our production techniques. REFERENCES 1. Theory and User Infor mation "Powder Material", MSC.Marc 2005 r3 User's Guide, Volume A, pp. 478–480, MSC Software Corporation, Santa Ana, CA, www.mscsoftware.com. 2. S. Shima and M. Oyane, “Plasticity Theory for Porous Metals”, Int. J. Mech. Sci., 1976, vol. 18, pp. 285–291. 3. T. Yabu, T. Nakagawa and A. Nohara, “Numerical Simulation of HIP Process”, R&D Kobe Steel Engineering Report, 1998, vol. 40, no. 4. ijpm
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MEETINGS AND CONFERENCES MEETINGS AND CONFERENCES
2008 2008 CHINA (SHANGHAI) INTERNATIONAL POWDER METALLURGY EXHIBITION & CONGRESS October 25–26 Shanghai, China www.china-pmexpo.com/en SINTERING 2008 November 16–20 La Jolla, CA www.ceramics.org/sintering 2008 PMP III THIRD INTERNATIONAL CONFERENCE—PROCESSING MATERIALS FOR PROPERTIES December 7–10 Bangkok, Thailand www.tms.org/meetings/ specialty/pmp08
2009 PM-09 5TH INTERNATIONAL CONFERENCE & EXHIBITION February 16–18 Goa, India www.pmai.in/
PIM2009 INTERNATIONAL CONFERENCE ON POWDER INJECTION MOLDING & WORKSHOP ON MEDICAL APPLICATIONS OF MICRO POWDER INJECTION MOLDING March 2–5 Lake Buena Vista (Orlando), FL MPIF* MATERIAIS 2009 5TH INTERNATIONAL MATERIALS SYMPOSIUM April 5–8 Lisbon, Portugal http://www.demat.ist.utl.pt/ materiais2009/ 17TH PLANSEE SEMINAR ON HIGHPERFORMANCE PM MATERIALS May 25–29 Reutte, Austria www.plansee.com TOOL 09—TOOL STEELS June 2–4 Aachen, Germany www.tool09.rwth-aachen.de POWDERMET2009: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 28–July 1 Las Vegas, NV MPIF*
THERMEC 2009: SIXTH INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS AND PROCESSES August 25–29 Berlin, Germany SDMA 2009/ICSF VII—4TH INTERNATIONAL CONFERENCE ON SPRAY DEPOSITION AND MELT ATOMIZATION/7TH INTERNATIONAL CONFERENCE ON SPRAY FORMING September 7–9 Bremen, Germany www.sdma-conference.de/
2010 POWDERMET2010: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 27–30 Hollywood (Ft. Lauderdale), FL MPIF* PM2010 WORLD CONGRESS October 10–14 Florence, Italy
*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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ABBOTT FURNACE COMPANY __________________(814) 781-7334 ___________www.abbottfurnace.com__________________________8 ACE IRON & METAL CO. INC.___________________(269) 342-0185 _________________________________________________________6 ACUPOWDER INTERNATIONAL, LLC _____________(908) 851-4597 ___________www.acupowder.com ___________________________56 AMERICAN ISOSTATIC _____________________________________________________________________________________________25 ARBURG GmbH + Co KG ______________________(860) 667-6522 ___________www.arburg.com _______________________________4 AVS ____________________________________________________________________________________________________________14 BODYCOTE _________________________________(978) 475-2951 ___________www.bodycote.com ____________________________28 BÖHLER UDDEHOLM _________________________(603) 883-3101 ___________www.bucorp.com ______________________________10 CENTORR __________________________________(603) 595-9220 ___________www.centorr.com ______________________________61 CM FURNACES, INC. _________________________(973) 338-1625 ___________www.cmfurnaces.com __________________________12 ELNIK SYSTEMS _____________________________(973) 239-6066 ___________www.elnik.com ________________________________48 HOEGANAES CORPORATION ___________________(856) 786-2574 ___________www.hoeganaes.com ___________INSIDE FRONT COVER INCO SPECIAL PRODUCTS _____________________(201) 848-1022 ___________www.incosp.com _______________________________3 KITTYHAWK PRODUCTS_______________________(714) 895-5024 ___________www.kittyhawkinc.com__________________________31 KOBELCO/KOBE STEEL, LTD. ___________________81-3-5739-6967___________www.kobelco.co.jp _____________________________32 KOPPERN __________________________________+49 (0) 2324 207 – 301 ____www.koeppern-research.com ____________________26 NORILSK NICKEL ____________________________(+ 7 495) 785 58 08 _______www.norilsknickel.com _________________________13 NORTH AMERICAN HÖGANÄS INC. ______________(814) 479-2636 ___________www.nah.com __________________INSIDE BACK COVER SCM METAL PRODUCTS, INC. __________________(919) 544-7996 ___________www.scmmetals.com ____________________________7 UNION PROCESS ____________________________(330) 929-3034 ___________www.unionprocess.com _________________________30 QMP ______________________________________(734) 953-0082 ___________www.qmp-powders.com ________________BACK COVER
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