HIGH TENSILE STRENGTH STEEL, EXCELLENT IN LARGE HEAT INPUT WELDABILITY, WELD CRACKING SENSITIVITY, AND ATMOSPHERIC CORROSION RESISTANCE, AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce a 600N/mm² class heat treated type high tensile strength steel, excellent in large heat input weldability, weld cracking sensitivity, and atmospheric corrosion resistance, and to srovide its production method. ;SOLUTION: This high tensile strength steel, excellent in large heat input werldability, weld cracking sensitivity, and atmospheric corrosion resistance, has a composition which consists of, by weight 0.06-0.1% C, 0.01-0.4% Si, 0.5-1.4% Mn, 0.2-0.5% Cu, 0.05-0.3% Ni, 0.3-0.8% Cr, 0.005-0.05% Nb, 0.005-0.1% Al, 0.0005-0.005% N, 0.005% Ti, 0.0003% B, and the balance iron with inevitable impurities and in which the value of Pcm, defined by Pcm=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B, and the value of Ceq, defined by Ceq=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14, are regulated to ≤0.21 and ≤0.40, respectively. Further, the steel has ≥570N/mm² tensile strength.;COPYRIGHT: (C)1998,JPO