Impact

Impact Technical Publications

192. Stainless Steel AISA Grades for PM Applications Applications requiring stainless steels are growing at a rate of about 5% annually. Opportunities for using powder metallurgy (PM) exist, but additional grades not covered by MPIF Standard 35 are required. The American Iron and Steel Institute (AISI) has standards for a broad range of stainless steels that can be used in many applications, but the compositions of these grades must be modified to be conducive to manufacture by conventional PM techniques. Several of these grades have been produced as standard press and sinter powders. The physical properties, mechanical properties and microstructures of these various grades are reviewed to serve as a guideline for PM parts manufacturers and potential applications of these grades are addressed.

188. Surface Densification Coupled with Higher Density ProcessesTargeting High-Performance Gearing This paper will describe a powder and processing method that facilitates single press-single sintered densities approaching 7.5 g/cm³. At this sintered density, mechanical properties of the powder metal (P/M) component are significantly improved over current P/M technologies and begin to approach the performance of wrought steels. High performance gears have the added requirement of rolling contact fatigue durability that is dependent upon localized density and thermal processing. Combining high density processing of engineered P/M materials with selective surface densification enables powder metal components to achieve rolling contact fatigue durability and mechanical property performance that satisfy the performance requirements of many high strength automotive transmission gears. Data will be presented that document P/M part performance in comparison to conventional wrought steel grades.

185. Precipitation Hardening PM Stainless Steels Applications requiring high strength stainless steels are growing rapidally. Precipitation-hardening stainless steels have seen limited use in powder metallurgy despite their high strength. Strengthening of these alloys is achieved by adding elements such as copper and niobium, which form intermetallic precipitates during aging. The precipitation-hardening grades exhibit corrosion resistance levels comparable with those of the chromium-nickel (300 series) grades. The physical properties and microstructures of two precipitation hardening PM stainless powders are presented: 17-4 PH, a high-chromium, martensitic precipitation hardening stainless steel, has been optimized for use in PM applications; and a new low chromium (12 w/o) alloy that utilizes copper in the precipitation reaction. This alloy (410LCu), is considered to be a cost-effective alternative in applications that require high strength and moderate corrosion resistance.

182. Lower Molybdenum Steels for High Performance Powder Metallurgy Applications Molybdenum has long been known to be a useful alloying element in powder metallurgy steels because of its enhancement of hardenability at relatively modest alloying levels. Since their introduction to the industry two decades ago, hybrid alloys based on prealloyed Mo steels such as FLN2-4405 have often been used in the heat-treated state to provide high performance properties. However, as raw material prices have become increasingly unstable in the last few years, the economic benefit to such alloys has reduced, forcing parts manufacturers to seek alternative materials systems. The current work provides a comparative analysis of a recently developed 0.3 wt.% Mo steel with more conventional 0.85 wt.% Mo and Mo-free steels. Property data and metallography are presented for crankshaft sprockets processed in the as-sintered, oil quenched & tempered, and induction hardened conditions.

177. High Density Processing of Cr-Si-Ni-Mo Containing Steel Ancorsteel 4300, an iron alloy containing Cr-Si-Ni-Mo, was recently introduced and is capable of achieving high mechanical strength with exceptional dimensional stability. With the ability to be sintered at conventional temperatures, this alloy offers a unique blend of performance capabilities that can provide an economic advantage over alloy systems requiring high temperature sintering or secondary quench hardening. The current work discusses the performance of the new chromium steel at densities above 7.2 g/cm³at various cooling rates using an advanced lubricant/binder system. Comparisons to a hybrid Ni-Mo steel and a diffusion alloyed Ni-Cu-Mo steel are presented.

175. Surface Densified P/M Steel - Comparison With Wrought Steel Grades The next major opportunity of P/M steels is in automotive transmission gears. The stress levels in these types of gears arise from rolling contact of gear teeth with certain amount of sliding. RCF studies have been undertaken to study the fatigue properties of powder metal gears using ZF test rig. AISI 8620 grade steel was also tested. Results of these investigations suggest that P/M gears are competitive with wrought steel grades.

171. Development of a High-Strength-Dual-Phase P/M Stainless Steel Applications requiring high strength stainless steels are growing at a fast pace. Typical alloys used for these applications are either highly alloyed materials such as 17-4PH or materials that require a secondary heat treatment such as SS-410HT. A new dual-phase stainless steel has been developed as a lower cost option. The microstructure of the dual-phase stainless steel consists of a mixture of ferrite and martensite, the proportions of which are dictated by the chemical composition of the alloy. This unique microstructure results in high strength and hardness, while maintaining ductility. The mechanical properties of this new alloy are compared with those of competing materials such as 17-4PH, SS-409LE and SS-410HT. Potential applications for this new material are reviewed.

169. Rolling Contact Fatigue Performance Contrasting Surface Densified, Powder Forged, and Wrought Material Previous experimental work demonstrated that rolling contact fatigue durability of high-density powder metallurgy samples was influenced by depth of surface densification (achieved via roll densification), sintering temperature, and heat treat practice. One observation of the previous work was reduced rolling contact fatigue life at high Hertz stress levels relative to wrought machined steel samples. There were also some questions regards the influence of nickel rich regions and how they affected rolling contact fatigue performance. In an effort to understand the influence of elemental nickel additions, FLN2-4405 samples were sintered at 2050 °F (1120 °C) and 2300 °F (1260 °C) and subsequently powder forged to full density. This experimental work was designed to clarify the effects of elemental nickel additions on rolling contact fatigue durability. Additionally, wrought AISI 8620 carburizing steel was machined into rolling contact fatigue samples, carburized and tested. Additionally, the AISI 8620 was evaluated for tensile, impact and fatigue characteristics in the quench and tempered condition.

167. High Performance Applications of Chromium Steels Sintered at Conventional Temperatures To meet the rigorous demands of automotive gearing, sprocket and other power transmission applications, double-press / double-sinter (DP/DS) techniques are often used to achieve the desired level of static and fatigue performance. Ancorsteel 4300, a new Cr-bearing material, has shown improved strength levels compared to traditional P/M steels. By employing such an alloy, core property requirements can be met at densities around 7.0 g/cm³. Replacing the pre-sinter and secondary press operations with selective densification, which will ensure sufficient contact fatigue resistance, can provide an economic benefit. The current work demonstrates the viability of processing a sprocket for a power transmission application with this high performance alloy system sintered at 1120 °C (2050 °F) in a production furnace. Subsequent selective densification and surface carburization provides a wear resistant and durable case layer. The results are compared with those achieved using FLN2-4405 processed through the traditional route of DP/DS, heat-treat.

166. A New CR-Bearing Alloy for High Performance Applications Ancorsteel 4300 was recently introduced to the marketplace and is the first in a series that will simulate wrought steel compositions. This new alloy represents a technological breakthrough with low sintered oxygen contents in a system that employs both chromium and silicon. Its main advantages include the ability to be effectively sintered at 1120 °C (2050 °F), good compressibility, high hardenability, and exceptional dimensional stability across a variety of processing conditions. These characteristics make this material an attractive cost-effective alternative to alloys that require secondary quench hardening treatments and enable the penetration of P/M into higher performance applications. The current work reviews the effects of density, cooling rate, and carbon content on the static and dynamic properties of this new product, along with comparisons to Q&T properties for wrought AISI grades 4340 and 8620.

165. High Density Processing of a New CR-Bearing Steel The application of P/M steels in highly stressed applications requires both high density processing and high performance alloys. Ancorsteel 4300, a new high performance alloy that contains Cr, Si, Mo, and Ni, utilizes the hardenability and mechanical property enhancement of chromium while maintaining low sintered oxygen contents. The elevated mechanical properties compliment the high compressibility of the powder allowing for use in high density applications. When combined with high density processing techniques such as the advanced lubricant/binder system AncorMax D, high densities and excellent properties can be achieved. This paper presents the effects of processing on density and mechanical properties with this new material, with a comparison to FLN2-4405 and FD-0405.

164. Full Density Properties of Low Alloy Steels Full density produces the best mechanical properties in a P/M or P/F component. Full density properties are available for traditional P/F materials, which are based on unalloyed base iron or low alloys with Ni and Mo additions. Additional base alloys have been developed which may be suitable for full density processing. This paper outlines the full density properties of these steels. Mechanical properties and microstructure will be presented.

163. Effect of Heat Treatment and Case Carburizing High-Density P/M Steels Recent advancements in high-density lubricants enable P/M steels to be processed to densities approaching 7.40 g/cm³in a single compaction step using heated compaction tools via the AncorMax D® process. This broadens the number of suitable applications for P/M steels, including high performance gears. However, in addition to high-density, the microstructural and mechanical property requirements vary depending on the application. This objective of this paper is to quantify and understand the mechanical property differences obtained by subjecting high-density P/M steels to various heat-treatments. Mechanical properties, fatigue properties, and microstructural analysis will be presented in the as sintered, quenched and tempered, and carburized states.

151. Properties of High Density Diffusion Bonded Alloys For P/M components, overall mechanical properties can be improved by increasing the density coupled with alloy additions. This can be seen by the excellent properties achieved for high performance applications with material compositions based on 1.75% Ni and 4% Ni diffusion bonded steel powders processed to high densities. Through the use of an advanced binder system, higher densities with subsequent increases in mechanical properties can be achieved in a single compaction step. Further densification can be achieved through the use of the double press, double sinter process coupled with the warm compaction process. The static and dynamic mechanical properties of warm compacted and double pressed, double sintered FD-0205 and FD-0405 with densities up to 7.5 g/cm³are presented.

143. Development of a High Performance Nickel-Free P/M Steel Chromium and manganese are used frequently in the wrought steel industry to improve mechanical properties and hardenability. However, these elements have been difficult to incorporate into P/M steels due to their high affinity for oxygen. A new nickel-free P/M steel containing Cr, Mn, Si and Mo is being developed for high performance applications. Sintering studies performed over a range of temperatures have shown that reasonable oxygen contents along with superior mechanical properties can be achieved with this new steel. The effect of sintering temperature and density on mechanical properties will be discussed.

142. Chromium Containing Materials for High Performance Components Recently developed silicon-bearing alloys were engineered to replace malleable and ductile cast irons, and have shown excellent property combinations at high sintering temperatures. A modification to these alloys merges the power of silicon and chromium in one system, and allows for extraordinary performance. The presence of chromium improves both static and dynamic properties with the added benefit of being close to die-size after sintering. The current work details extensive laboratory data that show the effects of compaction pressure on this modified alloy processed at high sintering temperatures. Also presented is a field experience on a heat-treated production component that combined the high performance alloy system with warm compaction technology. Static and dynamic properties are presented for samples sintered in both laboratory and production scale furnaces.

140. A Metallographic Investigation Into the Effect of Sintering on a FC-0205 Premix The properties of ferrous P/M materials are developed during the sintering process where metallurgical bonds are formed at particle-to-particle contacts and alloying of mixed and bonded additives occurs. Increasing either the sintering temperature or time can produce improvements in the microstructure and, consequently, the ensuing properties. In this paper, an FC-0205 premix, sintered for various times at 1120 °C (2050 °F), will be used to study the microstructural changes resulting from increases in sintering time. Features of interest include, changes to the surface-to-volume ratios at the particle boundary and pore surface areas, diffusion of the copper in the solid state and as a liquid component, and the homogenization of the microstructrue with increasing sintering times. Stereological techniques, using light optical microscopy, will be employed to examine the diffusion of the added alloying materials and to quantify the improvement in the degree-of-sinter. Additionally, electron microscopy (SEM) will be used to examine Charpy impact fracture surfaces from specimens sintered at the various times.

133. Advanced Performance Alloys Processed by High Temperature Sintering Technique As the demand for improved performance of P/M components increases, requirements for selection of proper alloy composition as well as its processing routine continue to climb. Major areas of process improvement include utilization of high performance alloy systems, high temperature sintering to create more homogeneous diffusion throughout the alloy matrix, and higher final densities of the processed components. This paper demonstrates the benefits gained by combining all of these factors. Specifically, the properties of recently developed MD compositions compacted to high initial green densities by using an advanced binder system and subsequently subjected to high temperature sintering in a pusher furnace at full-scale production conditions are investigated.

132. High Density Processing of Ancorloy MDC Materials Previous experimental work has shown that silicon containing steels exhibit high tensile properties and impact strength at relatively low densities ranging from 7.0 to 7.1 g/cm3. Higher densities via AncorMax D^® processing has shown that sintered densities in excess of 7.3 g/cm3 are possible at compaction pressures ranging from 550 to 760 MPa. (40 to 55 tsi) This paper will examine the metallurgical and mechanical enhancements achieved through the AncorMax D process and high temperature sintering of the Ancorloy^® MDC and Ancorloy^® MDCL materials at densities ranging from 7.0 to in excess of 7.3 g/cm³.

128. Chromium Additions to the Ancorloy MD Series Ancorsteel 41AB, introduced several years back, demonstrated the benefits of chromium and manganese additions to molybdenum steels. The more recently developed Ancorloy MD series provides enhanced ductility and strengths in P/M steels. This paper examines the mechanical properties achieved through the combination of high performance materials with chromium additions and high temperature sintering. Two chromium-modified materials were developed by replacing a portion of admixed nickel with a high carbon ferroalloy to improve dimensional properties and hardenability. Reviews of properties such as tensile, impact, transverse rupture, rotating bending fatigue, hardenability, and compressibility are presented.

124. Properties and Applications of High Density Sinter-Hardening Materials Sinter-hardening materials are characterized by their high hardenability which enables the formation of >80% martensite during accelerated cooling. However, these moderately alloyed materials often exhibit lower compressibility and the resulting lower density limits their use in potential high strength applications.

What is needed is a method to improve the green and sintered density of current sinter-hardening materials that will enable these materials to be utilized in new high strength applications. This paper describes how the green and sintered density of standard sinter-hardening alloys can be improved using new alloy systems coupled with advanced binder technology. The resulting improvements in mechanical properties will be presented as well as the potential use of high density

118. Processing of Ferro-Phos-Containing Mixes in Low Hydrogen Atmospheres Ferrophosphorus-containing premixes with iron are used extensively in magnetic applications. Recent trends toward reducing cost necessitate reduction of hydrogen content in the sintering atmosphere. This reduction of hydrogen leads to occasional brittle fracture in parts made from ferrophosphorus mixes. The objective of this investigation is to develop a robust powder that could be used in low hydrogen-containing sintering atmosphere. A design of experiments was developed to include residual elements and oxygen level in the ferrophosphorus powder. The results suggest controlling the oxygen in the ferrophosphorus is critical in achieving high impact energies while sintering in low hydrogen atmospheres. Addition of a minute amount of graphite can improve the impact strength of the otherwise low impact material.

117. Properties of High Density Sinter Hardening P/M Steels Processed Using an Advanced Binder System Sinter-hardening P/M alloys offer an excellent opportunity for a part manufacturer to produce hardened components in an economical fashion by eliminating secondary heat-treatments. Unfortunately, sinter-hardening P/M base iron grades are prealloyed with substantial levels of Ni, Mn, and Mo which increase hardenability but reduce compressibility. Furthermore, Cu and graphite are added to further increase strength and hardness. These alloying additions all reduce compressibility limiting the maximum attainable green and sintered densities. This paper explores how processing sinter-hardening alloys with a new proprietary binder system can improve compressibility and lead to higher densities and mechanical properties. The data show green density increases of 0.05-0.15 g/cm3 and be achieved and can result in tensile strength and hardness improvements.

111. Economics and Benefits of High Temperature Sintering of High Performance Alloys Today’s global economy has produced an extremely competitive marketplace. Design engineers constantly compare the economics and benefits of powder metallurgy (P/M) with those of stamping, casting and wrought machining. While parts manufacturers have traditionally exploited the near net shape cost savings of conventional P/M compositions, many have turned to higher performance alloys and elevated temperature sintering in an effort to optimize the metallurgical and mechanical properties of their products. Powder producers and furnace manufacturers have continued to support these endeavors through new product and process development.

This study will examine the metallurgical and mechanical enhancements achieved through the combination of high performance alloy systems and high temperature sintering. In addition, it will show how these benefits can be exploited to produce superior parts economically. High performance silicon-containing P/M steels sintered at 1150 to 1343 °C (2100 to 2450 °F) will be used to explore these property enhancements. These silicon-containing P/M steels yield excellent properties when sintered above 1260 °C (2300 °F) and are capable of attaining high apparent hardnesses .

110. Enhanced Processing of Silicon-Containing High Performance Materials In 2001, an extensive program was initiated to evaluate new silicon-containing materials designed to compete with various grades of ductile and malleable cast irons. These bindertreated, press-ready premixes were compared to a standard FLN4-4405 in a production environment on a complicated, high volume application. This year’s work investigates both double pressed / double sintered and heat-treated performance of the new silicon-containing materials. Mechanical properties and dimensional stability information are presented and compared to several standard material candidates containing no silicon.

105. Advances in P/M Gear Materials Powder Metallurgy is an efficient manufacturing process for the production of gearing and similar net shape components. Because of limitations arising from the inherent porosity and limited alloy systems available, the traditional uses for P/M gearing was in relatively low stress applications. The recent introduction of new compaction techniques and new alloy materials has produced P/M components with significantly higher yield and tensile strengths approaching the strength levels of wrought gearing materials. This paper will review the new P/M processes and materials and their suitability for gear type applications. Mechanical property comparisons will be made to the common automotive gearing materials including ductile and malleable cast irons and wrought low alloy steels.

103. The Development of Engineered Binder-Treated Alternatives to Duffusion-Alloyed Powders Engineered binder-treated premixes have been developed as alternatives to diffusion alloyed powders. The binder-treated materials meet the chemical composition limits for the diffusion alloyed materials listed in MPIF Standard 35, Materials Standard for P/M Structural Parts.

At an equivalent combined carbon content the binder-treated materials exhibit higher strength than the diffusion alloyed materials. When the combined carbon content of the binder-treated materials is reduced, to provide an equivalent strength level, the binder-treated materials match the tensile ductility and impact energy of the diffusion alloyed products.

The as-sintered and the quench-hardened and tempered performance of the new materials is reviewed and compared with diffusion alloyed materials of similar chemistry. These recently developed materials represent the first in a new family of high performance ferrous P/M materials.

99. Effect of Microstructural InHomogeneities on The Mechanical Properties of Hybrid P/M Steels The effect of microstructural inhomogeneities on the tensile and impact response of a prealloyed (FL-4405) and two hybrid (FLC2-4405 and FLN2-4405) P/M steels was investigated. Tensile and impact response, microstructures, pore characteristics and fracture modes were determined in the sintered, quenched + tempered and sinterhardened conditions. Sintering temperatures of 1120°C (2050°F) and at 1260°C (2300°F) were utilized anddensities in the range 7.0 - 7.4 g/cm3 were achieved by single and double pressing and sintering. Over this sintered density range, tensile strength increases by >30%. In the quenched + tempered condition tensile strength exceeds 1000 MPa. Tensile properties are rationalized in terms of the attendant microstructures and modes of fracture.

94. Silicon Containing High Performance Alloys - Machinability and Mechanical Properties With the introduction of several silicon-containing materials, the potential for replacing ductile and malleable cast irons with P/M alloys has never been greater. These materials exhibit extremely competitive property combinations when conventionally compacted and sintered at 1260 °C (2300 °F). However, additional opportunities exist if advanced densification processes such as double press / double sinter or warm compaction are employed. This paper investigates several important manufacturing processes including advanced densification techniques, vacuum sintering, and machinability.

93. High Performance Materials - Ancorloy MD Series New silicon-containing materials were recently introduced to compete with various grades of ductile and malleable cast irons. These binder-treated, press-ready premixes offer extremely good physical and mechanical property combinations. This work focuses on the evaluation of these materials in a production environment. Properties such as impact energy, tensile strength, elongation, dimensional change and apparent hardness are presented.

90. Advanced Processing of Sinter-Hardening Materials The sinter-hardening process has been shown to provide excellent mechanical properties and part-to-part size control. Previous work has indicated that exceptional mechanical properties and high apparent hardness values can be achieved by sinter hardening in a high temperature furnace with standard cooling. This work focuses on combinations of advanced techniques intended to optimize mechanical properties for stringent applications. While warm compaction is utilized to increase density, various material alloy combinations are blended together in an effort to study green density variables. Where applicable, specific market opportunities are identified.

89. Newly Developed P/M Materials to Replace Malleable and Ductile Cast Irons Malleable and ductile cast irons are used extensively in automotive applications such as clutches, gears, carriers, shafts, bearings, cam, racers, hubs, etc. Recently developed P/M materials can be processed cost efficiently to replace malleable and ductile iron castings. An UTS in excess of 1240 MPa and a YS in excess of 825 MPa can be achieved with one of these new materials. These tensile properties can be coupled with elongations over 2% and impact energies over 25 Joules. This presentation will cover processing routes for these new materials and will identify parts that may benefit from this new technological advancement.

85. New High Performance P/M Alloy Substitutes for Malleable and Ductile Cast Irons Ferrous P/M alloys generally do not exhibit a good combination of strength, ductility, and impact toughness. A series of new P/M alloy systems has been developed to match the performance characteristics of malleable and ductile cast irons. The new materials maintain excellent tensile ductility at high strength levels while possessing good impact resistance. The performance characteristics and benefits of the new P/M materials will be presented.

83. New High Performance Ferrous P/M Materials for Demanding Automotive Applications Diffusion-alloyed powders have been used for many years in automotive applications such as synchronizer hubs where there is a need for a combination of tensile strength, ductility, and impact energy. Recently, engineered binder-treated premixes have been developed as alternatives to diffusion-alloyed powders including those based on a prealloyed powder (1.5 w/o molybdenum). The engineered binder-treated materials will be compared with their diffusion-alloyed counterparts.

82. New Higher Performance Materials Through the use of enhanced atomization, annealing, and binder treatment technologies, several new silicon-containing alloy grades have been introduced for high performance automotive applications. This presentation will include data on compacts produced from these new grades using conventional compaction, warm compaction, and double press / double sinter processing. With these new material systems, single compaction can achieve ultimate and yield strengths in excess of 1200 MPa and 800 MPa with elongation over 2%. Such tensile properties can be developed in conjunction with apparent hardness values over 65 HRA and impact energies exceeding 25 Joules.

81. Opportunities for Conversion of Powertrain Components from Malleable/Ductile Cast Irons to Powder Metallurgy Malleable and ductile cast irons are used extensively in gearing and high strength applications within automotive power train applications. Advantages of malleable and ductile cast irons are low material cost with mechanical properties that meet or exceed the requirements of the intended application(s). One disadvantage of the malleable cast iron is the extensive heat treating required to obtain the proper microstructure and mechanical properties. Both malleable and ductile iron components require extensive machining to produce the finished component. The combination of heat treating and extensive machining often results in a component that is costly to manufacture. Recent advances in the Powder Metallurgy (P/M) process including high strength material systems and high density processing have achieved mechanical properties that meet or exceed the level achieved with the current malleable and ductile cast iron materials. This paper will present an evaluation and comparison of the mechanical properties of malleable cast iron with selected P/M material systems and processing parameters. This property discussion will demonstrate the suitability of the P/M process in replacing these cast and machined components. Examples of specific parts will be cited and discussed.

79. New High Performance P/M Alloy Substitutes for Malleable and Ductile Cast Irons To advance applications of powder metallurgy (P/M) into areas where current products do not have the desired performance characteristics, a series of new alloys has been developed. These new materials exhibit mechanical properties comparable to those of malleable and ductile cast irons. Some possible applications include ring gears, pinion gears, and carriers. The tensile and impact properties of the new materials are presented for compaction pressures of 415, 550, and 690 MPa and comparisons are made with current high performance P/M materials as well as with various cast irons.

78. Binder-treated Analogs of Diffusion Alloyed Compositions Based On Ancorsteel 150 HP The powder, green and sintered properties of binder-treated analogs of two diffusion alloyed steels based on Ancorsteel 150 HP are presented. These new additions to the binder-treated family of compositions are made according to a proprietary practice that does not include diffusion alloying. It is shown by direct comparison that these new premixes offer significantly improved compressibility and otherwise generally similar powder, green and sintered properties to compositionally similar premixes of the diffusion alloyed steels. The sintered property comparisons presented include the TRS, tensile, and impact properties of the subject compositions in the as-sintered and sintered and tempered conditions.

74. Improved Efficiency by Use of Sinter-Hardened P/M Automotive Components Sinter-hardening, accelerated cooling, of P/M components directly from the sintering furnace is an increasingly popular production process. Sinterhardened P/M steels possess similar macrohardness and strength to heat treated P/M steels processed by quenching and tempering. Where design permits, sinter-hardening enables P/M fabricators to improve process efficiencies by omitting a separate heat treatment operation. This paper examines the interaction of material selection and process conditions required to develop a sinterhardened P/M component for an automotive application.

68. Performance Characteristics of a New Water-Atomized Prealloyed Powder (0.5 weight % Molybdenum A new prealloy material containing 0.50 w/o Mo was introduced recently. This medium hardenability material can be admixed with a variety of alloying ingredients to produce superior tensile properties. Results of admixing this prealloyed powder with nickel, copper, manganese, and graphite will be presented. In addition, quench and temper properties will also be discussed.

67. A Comparison of ANCORDENSE Processed Materials with Malleable Cast Iron A study was conducted that compared the mechanical properties of a series of ANCORDENSE prepared materials with malleable cast iron. This paper will present the mechanical properties (TRS, tensile, impact, and fatigue) of various ANCORDENSE prepared premixes in the as sintered condition compared with a malleable cast iron. The objective of this investigation was to demonstrate that an engineered P/M material coupled with ANCORDENSE processing can replace a malleable cast iron component giving equivalent mechanical property performance and potentially equivalent gear performance.

66. A Superior Sinter-Hardenable Material Sinter-hardening technology has been assisting the P/M parts fabricator by improving processing efficiencies and reducing costs. Furthermore, the barriers to attaining good sinterhardenability and part performance have been reduced through improvements in materials and equipment developments. Recent material advances have focused on new alloys with increased hardenability and compressibility.

A new sinter-hardenable alloy has been introduced which provides improvements in hardenability and compressibility over the well-established FLC-4608 composition. These improvements will allow fabricators to reach higher densities and mechanical performance under typical compaction and sintering conditions. Mechanical performance and material capabilities are investigated as a function of density and admixed composition. Additional processing to achieve higher green densities and mechanical performance will also be reviewed.

65. Ancorloy Premixes: Binder Treated Analogs of the Diffusion Alloyed Steels The properties at two carbon levels of binder treated analogs of the diffusion alloyed steels are presented. These Ancorloy premixes are made according to a proprietary practice that does not include diffusion alloying. It is shown by direct comparison with compositionally similar premixes of the diffusion alloyed steels that the Ancorloys generally exhibit similar powder, green and dimensional change properties and significantly enhanced mechanical properties. Tensile, impact and fatigue property data in the sintered, sintered and tempered and quenched and tempered conditions are presented.

43. Single Compaction to Achieve High Density in Ferrous P/M Materials in Automotive Applications The continued growth of ferrous powder metallurgy in automotive applications is dependent on the development of higher density and improved dynamic properties. New powder metallurgy applications also must be cost effective through the continued use of the process's, net shape forming capabilities and a reduced number of manufacturing steps. The processes utilized to manufacture some of these new parts also must provide the ability to produce thin walled parts with complex geometries.

The use of the warm compaction process (ANCORDENSE™) will be shown to develop high density levels with a single compaction process. The process also provides increased green strength and reduced ejection forces. The dependence of mechanical properties on density will be demonstrated.

An example of a potential application of the warm compaction technology is an output shaft. The capability of manufacturing this part with the warm compaction process is outlined and compared with the same part made by the double press/double sinter (DPDS) process. Part density and performance from both processes are compared.

41. Properties of Several ANCORDENSE Processed High Performance Materials The effect of powder and compaction temperature on the ANCORDENSE™ warm compaction system is evaluated. Detailed property analysis is presented on several warm compacted high performance materials systems. Properties evaluated include density, tensile, and impact performance. A detailed assessment of the microstructure resulting from various alloy compositions and processing techniques is performed. The materials involved in the tests were conventional and high temperature sintered and tested in the as sintered and heat treated condition.

33. An Investigation Into the Effects of Processing Methods on the Mechanical Characteristics of High Performance Ferrous P/M Materials The mechanical properties of high performance ferrous P/M materials are influenced by the material composition and processing method. This paper investigates the effects of the ANCORDENSE™ process, a new, high density, single compaction method, on the mechanical properties of Distaloy® 4800A based materials. The results of this study are discussed with a comparison to the mechanical properties for the same materials developed through single-pressed and double-pressed, doublesintered processing methods. In addition, a case study is performed on a component produced via the ANCORDENSE method.

32. Properties of Diffusion Bonded Alloys Processed to High Densities Diffusion bonded alloys have been shown to exhibit excellent properties. Recent advancements in compaction technology have allowed these materials to reach green density levels of over 7.3 g/cm³ in a single compaction process. Various capabilities of this new compaction system will be demonstrated utilizing diffusion bonded alloys. Properties of several diffusion bonded materials will be investigated at these high density levels. A variety of processing techniques will be utilized including high temperature sintering and heat treatment to demonstrate the flexibility of these materials.

31. Advanced Properties of High Density Ferrous Powder Metallurgy Materials The introduction of the ANCORDENSE™ system has provided significantly higher density levels than previously possible in a single press/single sinter operation. This paper will explore the role that higher density has on mechanical properties. Various properties will be evaluated, including transverse rupture strength, tensile strength, and impact. Additionally, the effect of other processes, such as high temperature sintering and heat treatment, will be addressed.

26. High Performance Ferrous P/M Materials For Automotive Applications The majority of automotive components (transmission, chassis, suspension, and engine) for which parts with densities up to about 7.0 g/cm3 are suitable have already been converted to P/M and there are few opportunities for growth in this density range. In order to meet the requirements of more demanding applications there has been a trend toward higher densities through the use of infiltration, double pressing/double sintering, or powder forging (l - 4) to produce parts such as synchronizer hubs, crankshaft sprockets, chain sprockets, gerotors, steering column tilt levers, planetary gear carriers, parking gears shift levers, and connecting rods. While powder forging has been shown capable of producing parts, which are superior to wrought, or cast products process economics have limited market penetration by this technology (5). The double press and sinter route also adds process costs and is probably too expensive for other than premium applications. There is a real need for a systems approach that will permit double pressed and sintered or infiltrated performance characteristics to be achieved by means of single compaction processing. The mechanical properties of P/M materials are directly related to their microstructure and the size, distribution, and morphology of the porosity they contain. Alloying additions are made to develop specific material performance characteristics. However, the manner in which the alloys are constituted has a significant effect on the porosity and microstructure of the final product (6).

24. Properties of High Density Ferrous P/M Materials, A Study of Various Processes Several methods of achieving higher density in ferrous P/M parts are possible. Double press/double sinter allows densities in excess of 7.3 g/cm3 but is limited by cost and geometry considerations. A new method of single processing high performance materials is evaluated and compared to other methods of processing. The comparison is performed utilizing Ancorsteel 85HP and Distaloy 4800A base materials. Various green and sintered properties are evaluated including; green strength, transverse rupture strength, tensile properties and impact values.

The data clearly demonstrates that the patented (1) ANCORDENSE™* process offers performance comparable to double press/double sinter processing. Green density values of approximately 98.5% of the pore free density limit are achieved with a single compaction step.

18. Properties of Heat Treated P/M Alloy Steels Further development of ferrous P/M technology into highly stressed applications will require the development of P/M steels with mechanical properties approaching those of cast or wrought products. The P/M process offers many routes to improve mechanical properties through alloy design, increased density and high temperature sintering. The paper will present the results of a study into the effects of density and composition upon the microstructure and properties of quenched and tempered P/M alloy steels.

17. Sinter-Hardening Low-Alloy Steels The availability of prealloyed steel powders employing molybdenum as the major alloying element offers new levels of compressibility and mechanical properties. When the prealloyed powders are combined with conventional P/M additives such as copper, nickel and graphite, it is possible to develop high strength martensitic microstructures directly from the sintering cycle. The impact and tensile properties of copper, nickel, graphite premixes based upon the prealloyed molybdenum steels are compared under controlled cooled conditions. The ability to balance tensile strength, toughness and hardness by control of alloy chemistry is illustrated.

16. High Performance Ferrous P/M Materials Utilizing High Temperature Sintering Several new and more challenging P/M applications require materials that exhibit higher strength along with improved dynamic property characteristics. To meet these requirements, development efforts focused on material grades capable of achieving high performance properties when sintered at elevated temperature. Several elements, specifically nickel and copper, were admixed to the water atomized, prealloyed low-alloy steel powders Ancorsteel® 85 HP and 150 HP using the patented ANCORBOND® process. Tensile and impact performance of the resulting materials have been reviewed along with quantitative metallography of selected as-sintered samples. The results indicate the type and amount of each admixed element plays an important role in achieving specific characteristics. In addition, the overall performance values are greater for the single press and sinter technique used in this investigation than could previously be achieved using a double press - double sinter process.

13. Performance Characteristics of a New Sinter-Hardening Low-Alloy Steel A martensitic microstructure can be developed in some powder metallurgy materials without the need for a secondary heat treatment operation provided the material is cooled sufficiently rapidly from the sintering temperature. These P/M materials are termed "sinter-hardening" steels. The partially alloyed powder, Distaloy 4800A, and nickel-molybdenum prealloyed steels such as Ancorsteel ® 4600V with copper additions are capable of being sinter-hardened. Ancorsteel 85 HP, a new highly compressible low-alloy powder employing molybdenum as the primary alloying element, is also capable of being sintered-hardened when copper and graphite additions are made to it. Ancorsteel 85 HP has a higher compressibility than nickel-molybdenum prealloyed powders. The effect of cooling rate has been studied on the microstructure and mechanical properties of Ancorsteel 85 HP + 2% copper + 0.9% graphite. Tensile and impact properties have been evaluated for a range of material densities and compared with those obtained with samples based on Ancorsteel 4600V.

12. Improved Dimensional Control and Elimination of Heat Treatment for Automotive Parts The automotive industry has expressed concern about the general quality of heat treatment (austenization and quenching) and the desire to reduce or eliminate dependence upon this process whenever possible. Therefore, in a continuing effort for improvement during the past year, a process has been developed that eliminates the conventional heat treating operation for some applications. Some of these finished parts require both a high impact strength and a hardened wear resistant surface. The Charpy impact, tensile and TRS properties of a binder treated premix based on a partially alloyed powder have been evaluated utilizing a variety of processing conditions. These include various carbon contents, sintering temperatures and sintering times. Quantitative metallography was used to evaluate the pore size, pore shape and microstructural constituents present as a result of the various materials and processes. These factors were then correlated with the measured properties.

11. Tensile, Impact and Fatigue Performance of New Water ATomized Low-Alloy Powder - Ancorsteel 85 HP A new water atomized, prealloyed powder has been developed containing 0.85% molybdenum as the alloying addition. The as-sintered and heat treated tensile, impact and fatigue performance have been determined for a range of graphite additions using both single and double pressing techniques. Results indicate that the new powder, Ancorsteel 85 HP, has a unique ability to be compacted and repressed to densities not attainable with existing prealloyed nickel-molybdenum powders. The higher densities achieved produce performance equivalent to or better than Ancorstee12000 or Ancorstee14600V using conventional single compaction techniques. However, the additional density increment achieved during repressing results in mechanical properties in excess of what is possible with the existing low-alloy steels. It is expected that the new prealloyed powder will be used in high-density applications requiring good hardenability. It will also provide a base for our high performance ferrous material development program.

10. Steering Column Tilit Lever - P/M Material Development Automotive steering columns use a variety of levers to lock the flit mechanism in position. A new P/M material has been developed to withstand the impact and hardness performance requirements of this application. The new material is currently subjected to a brief surface carburizing and tempering treatment to impart wear resistance. The P/M part only requires honing of the pivot hole to meet the specified tolerance.

Long term plans are to achieve the desired performance requirements using a modified version of the new P/M material, with a higher graphite addition, which can be used after tempering the" as-sintered" product. The Charpy impact properties of three P/M materials, each based on a partially alloyed powder (Distaloy 4800A) but with different percentages of added graphite, have been tested for a variety of processing conditions. Neutral hardening, carburizing, and sinter-hardening treatments have been compared. The influence of tempering temperature and the incorporation of a cryogenic treatment in the process cycle have been reviewed. Quantitative metallography has been used to compare the pore size, pore shape, and percentage of microstructural constituents present in the different P/M materials. The measured impact properties are discussed in relation to these factors.

7. High Performance Ferrous P/M Materials: The Effect of Alloying Method on Dynamic Properties A comparison has been made between fully prealloyed, partially prealloyed, and elementally admixed alloys in the "as sintered" condition in order to assess the influence of microstructural and chemical homogeneity on the tensile, impact, and fatigue properties. Elementally admixed and completely prealloyed powders were prepared with chemistry similar to that of the diffusion bonded Distaloy 4600A (nominally 1.8 wt. % Ni, 1.6 wt. % Cu, and 0.55 wt. % Ho). An addition of 0.6% graphite was made to each of these materials. In one series of experiments, test pieces were prepared from each of the materi`1als pressed to a green density of 6.9 g/cm3. Sintering was carried out at 2050°F for 30 minutes at temperature in a dissociated ammonia atmosphere. A second series of experiments was carried out in which a fixed compaction pressure of 45 tsi was applied to each of the materials. Sintering was carried out in a similar manner to the first series. An additional prealloyed material, Sumiron 4100S, was included in this second series of experiments. However, this material was sintered at 2300°F to reduce the tendency for oxidation of this chromium and manganese steel alloy. For the samples pressed to a fixed green density of 6.9 g/cm3, the tensile strength of the partially prealloyed material was significantly higher than the other materials. The impact energy of the partially prealloyed material was also higher. A similar trend was found for the samples pressed at a fixed compaction pressure of 45 tsi. The partially prealloyed product, sintered at 2050OF, was even superior to the Sumiron 4100S; sintered at 2300°F. The differences in the tensile and impact properties were significant at the one percent level. The rotating bending fatigue performance of the partially prealloyed material was superior to that of the Sumiron 4100S.

1. Impact and Fatigue Characterization of Selected Ferrous P/M Materials Dynamic property data on pressed and sintered ferrous powder metallurgy materials have come under increasing demand as the P/M industry has grown into areas of application involving more highly stressed components. Data collected from relatively simple dynamic property tests will provide new avenues for P/M alloy development. Un-notched Gharpy impact energy and rotating bending fatigue tests have been used to characterize commonly used P/M steels. The endurance ratios of porous steels have been found to be relatively insensitive to processing, with higher strength materials giving proportionally higher endurance limits. Since impact energy was not strongly affected by varying the carbon content up to the eutectoid composition, increasing the carbon content of low alloy steels is a viable way of increasing endurance limit. Impact energy transition temperature has been found to be a factor in carbon-free phosphorus steels, but not in conventional low alloy steels. As has been indicated in the literature, sintered density is crucial to both impact energy and fatigue endurance limit. Metallographic examination of the fatigue cracks has provided some insight into the nature of the R.B.F. test.

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