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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.