High-strength Ministry of alloy type duplex stainless steel with excellent corrosion resistance of the weld heat affected zone

摘要

PROBLEM TO BE SOLVED: To provide a duplex stainless steel of an alloy-saving type having high strength and corrosion resistance in a weld heat-affected zone (HAZ).;SOLUTION: The steel has a composition containing, by mass, ≤0.06% C, 0.1 to 1.0% Si, 4.0 to 7.0% Mn, ≤0.05% P, ≤0.005% S, 20.0 to 23.0% Cr, 1.0 to 4.0% Ni, ≤1.0% Mo, 0.5 to 3.0% Cu, 0.05 to 0.35% V, 0.003 to 0.050% Al, ≤0.007% O and 0.15 to 0.30% N, and the balance Fe, wherein the area ratio of a γ phase is 40 to 70%, γpre expressed by formula (2); γpre=-15Cr-28Si-12Mo+19Ni+4Mn+19Cu+770N+1160C+1475, and Npre expressed by formula (3); Npre=12Cr+50Si+36Mo-20Ni-15Mn+28Cu+470N-290C+620 satisfy inequality (1); Npre≤0.8×γpre-180, and the γpre is 1,370 to 1,450.;COPYRIGHT: (C)2011,JPO&INPIT