Is superior in strength, Characteristic, fatigue property and corrosion resistance in sea water the precipitation hardening die rustless steel

摘要

PROBLEM TO BE SOLVED: To provide precipitation-hardening stainless steel whose structure consists of the martensitic phase and the inverse transformation austenitic phase and which is excellent in strength, toughness and sea-water resistance by executing the solid solution heat treatment and precipitation-hardening heat treatment at the prescribed temperature after Ni-Cr stainless steel of the prescribe composition is hot worked. ;SOLUTION: A stainless steel ingot which contains, by weight, ≤0.030% C, ≤0.50% Si, ≤0.60% Mn, ≤0.005% S, 0.50-2.50% Cu, 6.50-8.00% Ni, 15-17% Cr, 0.50-2.00% Mo, and ≤0.030% N, and is of the composition to satisfy the inequality of C+N≤0.040%, is heated to 1150-1200°C, and cogged. After the solid solution heat treatment for 30 minutes at 1040°C, the precipitation- hardening heat treatment is achieved at 500-580°C. The precipitation-hardening stainless steel whose structure consists of the martensitic phase and ≤35% inverse transformation austenitic phase, and which is sea-water resistant, excellent in the fatigue property, and also high in toughness and strength.;COPYRIGHT: (C)1998,JPO