PURPOSE:To strengthen grain boundaries and to improve stress corrosion cracking resistance by applying hardening and tempering to a stainless steel with a specific composition, subjecting this steel to cold working, and further carrying out stress relief annealing, if necessary. CONSTITUTION:A stainless steel whose structure is formed into a structure consisting of =70% martensitic phase and ferritic phase by means of hot working, etc., and which contains 12-15% Cr is tempered at a temp. not higher than the Ac1 transformation point, by which a tempered martensitic structure is formed. Subsequently, cold working is exerted at 3-20% reduction of area. Successively, stress relief annealing is performed at 300-700 deg.C. By this method, the grain boundaries of the martensitic Cr stainless steel can be strengthened and superior stress corrosion cracking resistance can be provided.
展开▼
