| 摘要 |
A method of producing a high-strength cold-rolled steel sheet suitable for working uses which utilizes a steel material having the following composition: not more than 0.02 wt% of C, not more than 1.0 wt% of Si, not more than 2.0 wt% of Mn, and not less than 0.01 wt% but not more than 0.10 wt% of Ti, the Ti, C and N contents being determined to meet the condition of Ti > (48/12) C wt% + (48/14) N wt%, the steel also consisting essentially of not less than 0.0010 wt% but not more than 0.0100 wt% of Nb, not less than 0.0002 wt% but not more than 0.0020 wt% of B, not less than 0.03 wt% but not more than 0.20 wt% of P, not more than 0.03 wt% of S, not less than 0.010 wt% but not more than 0.100 wt% of A l , not more than 0.008 wt% of N, not more than 0.0045 wt% of O, and the balance substantially Fe and incidental inclusions. The steel material is cast and hot-rolled and then subjected to a cold rolling conducted at a sheet temperature not higher than 300 DEG C under such a condition that the sum of the rolling reductions of passes which meet the following condition between said sheet temperature (T DEG C) and the strain rate epsilon /<.> (S<-><1>) is 50 % or greater: T x epsilon /<.> >/= 50,000 DEG C S<-><1> The steel sheet is then continuously annealed or galvannealed. <IMAGE> |
