| 摘要 |
PURPOSE:To produce a cold-rolled steel sheet provided with excellent press formability, secondary processability after pressing and resistance to corrosion due to coating by painting by hot rolling and cold rolling a slab, which is produced by continuous casting from a dead soft steel having a specific compsn., under specific conditions then subjecting the same to recrystallization annealing by a continuous annealing method. CONSTITUTION:A continuously cast billet of a dead soft steel contg. <0.004% C, 0.10-0.50% Mn, <=0.01% P, 0.005-0.05% Al, <0.0030% N, 0.01-0.05% Ti, where Ti/(C+N)=1-7, or further contg. 1 or 2 kinds of B<=15ppm and Nb= (1-4.5)XC% is cooled once down to <=750 deg.C. The billet is reheated to <=1,100 deg.C, and the hot rolling is completed at >=750 deg.C, then the hot-rolled sheet is cold- rolled at 75-95% draft, whereby the steel sheet of an intended thickness is obtd. Such sheet is subjected to recrystallization annealing for <=5min at 650- 800 deg.C by a continuous annealing method. The cold-rolled steel sheet having excellent deep drawing property and bulging property is obtd. |
