High-temperature Strength and Microstructure of Strongly Cold Worked Austenitic Stainless Steel

Abstract

The high temperature strength and the microstructural change of strongly cold worked austenitic stainless steel SUS305 were investigated. 60% cold rolled specimens suggested strong decrease of fatigue strength, creep rupture strength and Vickers hardness (hereafter; hardness) after aging, corresponding to the increase of recrystallized grains. On the other hand, 30% cold rolled specimens suggested less decrease of strength and hardness, and revealed no recrystallization. In this study, the microstructure and hardness of strongly deep drawn SUS305 at high temperature were also investigated. On this specimen, similar to 60% cold rolled SUS305, decrease of hardness corresponded to the increase of recrystallized grains. But, since M 23 C 6 precipitations were fine and closely spaced in the material, the recrystallization was delayed. On the other hand, the both materials suggested same relativeness between the softening tendency and recrystallization. Therefore, fatigue strength and creep rupture strength of deep drawn SUS305 should decrease with the recrystallization at high temperature.