| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high-strength steel sheet having X100 grade or higher showing excellent SR resistance property and deformation performance and a method for manufacturing the same. <P>SOLUTION: The steel containing, by mass%, 0.03-0.10% C, 0.01-0.5% Si, 1.5-2.5% Mn, 0.1-0.5% Mo, 0.08% or less Al, one or more elements of Ti, Nb, and V and the balance being Fe and unavoidable impurities, and having a PCM value of not less than 0.19 and not more than 0.25, and a P value of 0.20 or more, is heated to 1,100-1,300°C, hot-rolled at a rolling finishing temperature of 750°C or more, then treated with accelerated cooling at a cooling speed of 20°C/s or more to reach not less than 350°C and not more than 550°C, thereafter, reheated to 550-700°C at a temperature increase rate of 0.5°C/s or more. The PCM value is represented by the formula (1): C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5×B and the P value is represented by the formula (2): [Mo]+[Ti]+[Nb]+[V]. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
