HIGH STRENGTH COLD ROLLED STEEL SHEET FOR DEEP DRAWING, EXCELLENT IN STABILITY OF MATERIAL QUALITY AS WELL AS SURFACE CHARACTERISTICS AFTER PRESS FORMING, AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide a high strength cold rolled steel sheet for deep drawing, excellent in stability of material quality as well as surface characteristics after press forming in spite of containing P of certain quantity, and its production. ;SOLUTION: This steel sheet has a composition consisting of, by mass, ≤0.0040% C, ≤1.0% Si, 0.5-2.0% Mn, 0.03-0.12% P, ≤0.02% S, 0.01-0.10% Al, ≤0.0040% N, 0.02-0.07% Ti, 0.01-0.07% Nb, 0.0003-0.0020% B, elements which satisfy inequalities 0.8≤{100P/(10Si+2.5Mn)}≤3.0 and 10≤{Ti-(48/14)N+(48/92) Nb}/C, respectively, and the balance Fe with inevitable impurities.;COPYRIGHT: (C)1999,JPO