| 摘要 |
PURPOSE:To produce a delayed-aging high strength cold-rolled steel plate having excellent deep drawability and press workability easily by hot rolling steel contg. limited ompsns. of C, Mn, P and AlN to deposit and subjecting the same to continuous annealing under specific conditions after cold rolling. CONSTITUTION:In the stage of hot rolling the steel consisting of 0.015-0.045% C, 0.08-0.70% Mn, <=0.13% P, 0.020-0.080% Al and the balance Fe and unavoidable impurities and coiling the same at >=630 deg.C then subjecting the same to continuous annealing after cold rolling, the steel plate is soaked for 10sec- 2min at 750-900 deg.C. In the primary cooling thereafter, the plate is cooled slowly at <=20 deg.C/sec cooling rate from the soaking temp. down to the temp. for starting of quick cooling between 720-650 deg.C and is cooled at >=40 deg.C/sec cooling rate from the above-mentioned temp. for starting of quick cooling down to 520 deg.C. The cooling in succession to said cooling is stopped at >=300 deg.C and the plate is subjected to an overaging treatment for >=30sec at 300-500 deg.C, whereby the delayed-aging high strength cold-rolled steel plate having high deep drawability and excellent press workability is obtained. |
