| 摘要 |
PURPOSE:To produce a high strength cold-rolled steel plate which has high baking hardness, and is superior in again resistance and press workability by subjecting a steel contg. specific ratios of C, Mn, P, Al to hot rolling and cold rolling then to continuous annealing under specific conditions. CONSTITUTION:The steel contg. 0.045-0.150% C, 0.08-0.70% Mn, <=0.13% P, 0.020-0.080% Al, and <=0.17% C+P and the balance consisting of Fe and unavoidable impurities is hot-rolled. It is coiled at >=630 deg.C, and is cold-rolled. Thence, in performing continuous annealing, the steel plate is soaked for 10sec- 2min at 700-900 deg.C, and is cooled at >=40 deg.C/sec cooling rates between 650- 520 deg.C. Subsequently, the cooling is stopped at 300 deg.C, and aging treatment of >=30sec is carried out at 300-500 deg.C temps. |
