COLD ROLLED STEEL SHEET HAVING SUPERIOR PRESS FORMABILITY FOR CONTINUOUS ANNEALING INCLUDING ROLL COOLING

摘要

PURPOSE:To improve the press formability and productivity of the resulting titled steel sheet by adding specified amounts of Cr and B to a steel contg. prescribed amounts of C, Si, Mn, P, solAl and N and by regulating the atomic ratio of B/N. CONSTITUTION:This cold rolled steel sheet consists of, by weight, 0.002-0.06% C, =0.05% Si, 0.05-0.30% Mn, 0.01-0.30% Cr, =0.01% P, =0.04% solAl, 0.001-0.006% N, B in 0.5-2.0 atomic ratio of B/N and the balance Fe with inevitable impurities. The cold rolled Al killed steel sheet has a low yield point, high elongation, a high r-value and superior press formability.