2021 Volume 70 Issue 9 Pages 284-294
Authors studied surface hardening of shot-peened or cold rolled Type 316 stainless steels during aging at 340℃ in air. We first introduce our shot peening method using PSZ （yttrium partially stabilized zirconia） shots which has been utilized as the countermeasure against the chloride stress corrosion cracking （SCC） of chemical process and nuclear energy equipment, and reveal the structure and physical properties of the peened Type 316 stainless steel. Next, we study change of both structure and properties of the peened or cold rolled Type 316 stainless steel during aging at 340℃ in air. We discuss mechanism why the cold worked and then aged Type 316 stainless steel in air tends to suffer intergranular cracks by few percent surface strains. Feasibility of the grain boundary hardening and cracking by internal diffusion of oxygen via thin layer of strain-induced martensite is proposed.
