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The PM Industry Roadmap prepared in 2001 identified six top-priority research needs for the industry, including one entitled “develop material and processing technologies to achieve 100% density while maintaining dimensional tolerances and cost-effectiveness”. The Center for Powder Metallurgy Technology (CPMT) recognized this need as its top priority and put together a task force to establish a multi-year program plan to meet this need. Additional targeted funds were solicited to help offset the added costs of this major project, including the hiring of a special project leader. A two phased program was developed with the first target a 7.5+ g/cc density for structural steels through single press-single sinter processing and then a “stretch” target for Phase 2 of 7.7+ g/cc density. The four tasks identified for the Phase 1 program are described including the advanced technologies being investigated, the materials, equipment and processes used and the outcomes to be measured.

The Global Powder Metallurgy Property Database was released to the general public in October 2004, with a definite focus on the automotive end user community. The Database is the culmination of four years of planning, formulating and joint development between the North American, European and Japanese powder metallurgy communities. This unique data offering includes ferrous, non-ferrous and bearing alloys and covers mechanical, physical and fatigue data. Nearly 200 different alloys are included. Materials and properties can be searched using MPIF and ISO material codes, following standard or advanced search methods with up to six variables simultaneously. Graphical presentation of the data is available throughout the system. Examples of search outputs are presented along with helpful hints for getting the most out of this new and exciting powder metallurgy database.

The effect of high density on critical performance properties for stainless steel powder metal (P/M) has been studied. Sinter-Hot Isostatic Pressing (HIP) cycles were optimized to yield stainless steel P/M samples with density levels of 94% to 98% of theoretical density. These samples were then tested for corrosion resistance, stress-rupture strength, tensile strength and toughness. Conventional-density stainless steel P/M samples and wrought samples, when possible, were tested simultaneously to provide a direct comparison. The high density stainless steel P/M samples consistently perform better than those at conventional density levels and exhibit properties that are very close to those of wrought material.

High temperature sintering of ferrous powder metal parts, i.e., sintering above the conventional temperature range of 2050-2100F, can provide improved physical and mechanical properties, a widening scope of unique material systems, and new opportunities for growth of the P/M industry. Three specific aspects of this technology are reviewed: (1) the reasons for considering high temperature sintering, (2) the materials/properties which have been developed through this technique, and (3) selected applications found in the automotive industry. By selecting high temperature sintering the material undergoes further densification, improved particle bonding, and more spherical porosity but at the expense of grain growth and dimensional control.

The sintered and heat treated properties of 4100 prealloyed powder (0.9Cr, 0.8 Mn, 0.25Mo) were examined over a range of densities (6.8, 7.1, and 7.2 gm/cm3 and carbon contents (0.25, 0.5, and 0.9%). The effect of alloying elements on as-sintered UTS was also studied. For comparison, elementally blended 4600 was used as a “standard” wherever practical. In the “as-sintered” condition, 4100 offers exceptionally superior mechanical properties especially at higher carbons, which exceed even the heat treated properties of conventionally processed 4600 alloy, In the heat treated condition, there are no significant differences between the two alloys, but the superior hardenability of 4100 makes it more attractive. Potential automotive applications are identified where 4100 can be a candidate to replace heat treated P/M forged or wrought components.