| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for producing a cold-rolled steel sheet excellent in deep-drawability in high efficiency. Ž<P>SOLUTION: To a steel ingot or a steel slab composed by mass% of <0.010% C, ≤1.5% Si, ≤2.0% Mn, ≤0.10% P, ≤0.010% S, 0.0005-0.10% Al, ≤0.0060% N, 0.001-0.10% Ti, 0.001-0.10% Nb and 1.4≥(C/12+N/14+S/32)/(Ti/48+Nb/93) and the balance Fe with impurities, a hot-rolling, in which this rolling is completed at ≥(Ar<SB>3</SB>point-30°C), is applied and this hot-rolled steel is cooled to 750°C at ≥400°C/sec average cooling speed within 0.5sec after completing this hot-rolling, and after coiling at ≥400°C to <640°C, a pickling is applied and the cold-rolling is applied at 60-95% rolling-reduction ratio and an annealing is performed at 750-880°C. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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