| 摘要 |
<p>Disclosed are a high-strength steel sheet which has high strength more than the tensile strength of 780 MPa or greater and obtains excellent hole scalability via transformation induced plasticity (TRIP); and a manufacturing method thereof. The manufacturing method of the high-strength steel sheet includes a step (a) of hot-rolling a slab plate comprising 0.1-0.25 wt% of C, 1.5-3.0 wt% of Si, 1.0-2.0 wt% of Mn, 0.01-0.1 wt% of P, 0.001-0.01 wt% of S, 1.5-3.0 wt% of Al, 0.001-0.005 wt% of N, and the rest of Fe and inevitable impurities at a finishing delivery temperature of 860-900°C; and a step (b) of cooling the hot-rolled plate at a temperature of 450-550°C and winding. The cooling step includes a primary cooling step and a secondary cooling step, and the primarily cooling speed is faster than the secondary cooling speed. [Reference numerals] (AA) START; (BB) END; (S110) Hot rolling (FDT : 900~860°C); (S120) Cooling / winding (CT : 450~550°C)</p> |
