| 摘要 |
PURPOSE:To manufacture the titled steel with a low cost, by hot rolling a steel slab contg. specified ratios of C, Sn, Mn, P, S, Al by a specified draft in the course of cooling under a specified condition, next cold rolling and annealing the sheet. CONSTITUTION:Molten contg. by weight 0.0010-0.150% C, <=0.30% S, <=1.5% Mn, <=0.080% P, 0.005-0.025% S, 0.005-0.070% Al, further if necessary capable of adding <=0.10% Ti, <=0.10% Nb, <=0.0050% B singly or totally by 0.0010-0.100% and the balance iron with inevitable impurity is continuously cast to slab. It is hot rolled by 1.0-20 draft (slab thickness/thickness at completion of hot rolling) in the course of cooling by <=2 deg.C/sec average rate in 1,400-1,000 deg.C range, and the hot rolling is finished at >= about Ar3 point. The plate is wound up at <= about 700 deg.C, then descaled, cold rolled by 60- about 90% draft and annealed at temp. range of >= recrystallization temp. - <= about A3 point.
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