| 摘要 |
<p>Non-ageing cold rolled steel sheets having a very excellent formability are produced by hot rolling a steel consisting of not more than 0.008% of C, not more than 0.20% of Si, 0.04-0.30% of Mn, not more than 0.03% of P, 0.01-0.10% of Al, a content of Al being more than N%ax4, not more than 0.02% of S, not more than 0.01 %of N, 0.01-0.07%of Nb, a content of Nb being C%x3-{C%x8+0.02}%, and the remainder being substantially Fe, at a total reduction of not less than 90%, a rolling speed of not less than 40 m/min in the finishing rolling and a finishing temperature of not lower than 830°C, coiling the hot rolled strip at a temperature of 600-800°C, cold rolling the coiled strip following to conventional manner to obtain a cold rolled strip having final gauge and then continuous annealing the cold rolled strip within a temperature range of 700-900°C for 10 seconds-5 minutes. It is possible to hot dip galvanize the thus treated strip continuously.</p> |
