HIGH STRENGTH STEEL SHEET EXCELLENT IN FORMABILITY AFTER WELDING AND HARDLY CAUSING SOFTENING IN WELD HEAT- AFFECTED ZONE

摘要

PROBLEM TO BE SOLVED: To provide a high strength cold rolled steel sheet and a high strength surface treated steel sheet, capable of improvement in press formability after welding and further capable of suppression of deterioration in strength in a weld heat-affected zone. ;SOLUTION: This steel sheet has a composition consisting of, by weight, 0.01-0.15% C, 0.005-1.0% Si, 0.1-2.2% Mn, 0.001-0.06% P, 0.001-0.01% S, 0.0005-0.01% N, 0.001-0.1% Al, 0.001-0.02% Ti, 0.005-0.05% Nb, 0.05-0.5% Mo, and the balance essentially Fe and satisfying inequality 0.22≥C(%)+(Si/30)(%)+(Mn/20)(%)+(MO/15)(%).;COPYRIGHT: (C)2000,JPO