Processing and Properties of PM 440C Stainless Steel
Alloy 440C is a high carbon, hardenable, martensitic grade of stainless steel, which offers high wear resistance, combined with a moderate resistance to corrosion. A successful PM (powder metallurgy) version of the alloy should exhibit a high sintered density, at least greater than 7.60 g/cm3, i.e., above 98% of full theoretical density. Liquid phase sintering offers an attractive means of achieving this high density via single-press-single-sinter process. In addition, the sintered and heat treated material should have a predominantly martensitic matrix, with minimal amount of grain boundary carbides for achieving good impact strength. The current paper covers the process parameters used, and the mechanical properties achieved, for a liquid phase sintered 440C alloy in both as-sintered and heat-treated conditions. The sintered density and hardness of this PM version of the alloy are comparable to those of the wrought and MIM (metal injection molding) processed 440C materials.