| 摘要 |
PURPOSE:To prevent delayed fracture without decreasing strength and without increasing intergranular corrosion crack sensitivity by cold-working the austenite- base stainless steel of high cold work hardenability then subjecting the same to the heat treatment under the specific conditions. CONSTITUTION:The austenite-base stainless steel is cold worked to increase its material strength by work hardening. This cold worked material is heated to temperatures of 500-600 deg.C in an atmosphere other than nitrogen gas or under vacuum. This heat-treatment time is made shorter than the time (t) calculated by formula I. In this way, the residual stress produced by cold working, particularly, the excessive residual stress produced in the stress-concentrated portions is decreased. This heat treatment enables the perfect prevention of delayed fracture without decreasing the strength having been increased by the cold working and without any increase in the intergranular corrosion crack sensitivity owing to deposition of carbide at the grain boundaries. |
