Abstract
17-7-PH stainless steel has been studied for its superior mechanical properties since several years before. In this study, 17Cr, 7Ni stainless steel containing 0.73%Al was experimented upon unveiling the effects of cold reduction degree, intermediate heat treatment and aging temp. and time on its mechanical properties. The following results were obtained: (1) As the Ms point of this steel is in the range of sub-zero, martensite was not formed through ordinary heat treatment only. (2) Austenite of this steel is remarkablly hardened by cold-working and also by the martensite formation during cold-working. Its hardening degree was stronger than that of 18·8 stainless steel. (3) Samples of this steel cold-rolled by 50∼70% reduction were used for aging experiment at 400∼500° for up to 500 hours. The highest mechanical properties were obtained by aging at 450°×8 hrs to 500°×1 hr (Figs. 5∼8). (4) Heat-treated specimens without cold-working were subjected to aging, but higher hardness could not be obtained from them.
