| 摘要 |
PROBLEM TO BE SOLVED: To provide high-strength cold-rolled steel sheet which has a high workability, is excellent in strain age-hardening property and shows little aging degradation at room temperature, and high-strength plated steel sheet. SOLUTION: Steel slab comprising, by mass,≤0.015% C,≤0.5% Si, 1.0-3.5% Mn,≤0.10% P,≤0.003% S,≤0.02% Al and 0.0050-0.025% N is heated to≥1,000°C, thereafter subjected to hot rolling employing a finishing mill exit temperature of≥800°C, coiled at≤650°C, thereafter subjected to cold rolling, subsequently subjected to continuous annealing at a temperature which is≤950°C and yields≥50% austenitic phase, cooled to≤500°C at a cooling rate of≥20°C/s and, if required, further subjected to plating treatment. COPYRIGHT: (C)2004,JPO&NCIPI
|
