HEAT RESISTANT AUSTENITIC STEEL EXCELLENT IN CHARACTERISTICS FOR SENSITIZATION, HIGH-TEMPERATURE STRENGTH AND CORROSION RESISTANCE, AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To economically provide heat resistant austenitic steel for boilers, which has excellent characteristics for sensitization in heat treatment of the welded heat affected zone, when used as a welded joint with a different material of heat resistant ferritic steel, and satisfactory high-temperature strength and corrosion resistance in a harsh environment of the boilers.;SOLUTION: The heat resistant austenitic steel excellent in characteristics for sensitization, high-temperature strength and corrosion resistance, comprises a chemical composition of, by mass%, 0.005 to less than 0.03% C, 0.05-0.4% Si, 0.5-2% Mn, 0.01-0.04% P, 0.0005-0.005% S, 18-20% Cr, 7-11% Ni, 0.2-0.5% Nb, 0.2-0.5% V, 2-4% Cu, 0.10-0.30% N, 0.0005-0.0080% B, and the balance Fe with unavoidable impurities; 0.6% or more of the total contents of Nb and V; 0.15% or more of dissolved quantity of Nb in the steel; and satisfying the both expressions of N/14≥Nb/93+V/51 and Cr-16C-0.5Nb-V≥17.5. The manufacturing method is also disclosed.;COPYRIGHT: (C)2003,JPO