| 摘要 |
PURPOSE:To inexpensively produce a cold rolled steel sheet for deep drawing having the small intra-surface anisotropy of an r value and slow aging characteristic by subjecting a specifically composed steel successively to soaking, hot rolling, quick cooling, coiling, cold rolling, and continuous annealing under specific conditions. CONSTITUTION:The slab contg., per weight %, 0.005-0.0050% C, 0.001-0.50% Mn, <0.01% S, 0.0005-0.0070% N, <=0.02% acid solAl, and at least one kind of Ti and Zr in the range of 3.4XN+4(C-0.0015)<=Ti+48/91Zr<3.4XN+4.C except the same contained in the form of oxide and sulfide and consisting of the balance iron and inevitable impurities is soaked at >=1,100 deg.C. The slab is then hot rolled at 700-880 deg.C finish temp. and is rolled down at >=30% of the sheet thickness after the rough hot rolling in the temp. region of the finishing temp. +100 deg.C. The rolled sheet is quickly cooled down to 300-550 deg.C at >=5 deg.C/sec upon completion of the hot rolling and is coiled as it is at 300-550 deg.C. The sheet is further cold rolled at 70-95% draft and is continuously annealed at 680-850 deg.C.
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