Ausforming, the plastic deformation of metastable austenite in temperature ranges above the M_s temperature but within the range of allowed (non flash) temperatures of oil quenching media, produces two distinct beneficial changes in the microstructure of as-sintered P/M high carbon steels. The first is porosity reduction, with as-sintered contents of 10% to 12% by volume being reduced to less than one percent. There is a clear and quantitatively definable relationship between equivalent plastic strain and porosity reduction. The second microstructural change is the generation of physical metallurgical microstates that are the direct consequence of ausform straining. These include unique martensite morphologies, sizes, and orientations that significantly alter strength, durability, and toughness parameters. In addition, the eventual martensite formed subsequent to ausforming contains inherited dislocation arrays and precipitated microcarbides that also contribute to enhanced user responses. The present paper addresses these process-induced microstates and their influence on mechanical behavior parameters.
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