HIGH NICKEL ALLOY SUPERIOR IN RESISTANCES FOR GENERAL CORROSION, GRAIN BOUNDARY CORROSION AND GRAIN BOUNDARY STRESS CORROSION CRACKING RESISTANCE

摘要

PURPOSE:To improve resistances for general corrosion, grain boundary stress corrosion and said corrosion cracking, by decreasing C content, and adding Ti, Nb so that a prescribed condition is satisfied in high Ni alloy steel. CONSTITUTION:The alloy is composed of =1wt% C, =1.0% Si, =1.5% Mn, =0.015% S, 30.0-35.0% Ni, 19.0-25.0% Cr, =1.0% Cu, 0.1-1.0% Al, 0.05-1.0% Ti, 0.05-1.0% Nb and the balance Fe with inevitable impurities. In the alloy compsn., conditions of (3Ti+Nb)/S=150 and (Ti+Nb)/C=15 are satisfied. By the compsn., general corrosion resistance under high temp. water circumstance is improved, resistances for generations of grain boundary corrosion and said corrosion cracking is raised even under condition in which welding and low temp. aging are superimposed.