| 摘要 |
PURPOSE:To develop the titled steel sheet having high ductility and super deep drawability, by decreasing quantities of C and Ti in steel contg. Ti, Nb, Cr, and hot, cold rolling the steel slab incorporated with a specified quantity of Nb in relation to an effective Ti quantity, and annealing said sheet. CONSTITUTION:The steel slab contg. by weight 0.001-0.01% C, <0.1% Si, <0.5% Mn, 0.01-0.10% Sol, Al, 0.06-0.20% Cr, <0.03% P <0.015% S, 0.007% N, <0.01% O, 4 times of C%-0.15% Ti as effective Ti quantity expressed by a formula (1) and Nb quantity satisfying 0.05% [effective Ti quantity] + Nb<=0.20% is cast. The slab is hot rolled to plate of 5mm thickness, then said plate is pickled, cold rolled to sheet material of 1.2mm thickness by >=40% draft and said sheet is batch annealed at 800 deg.C.
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