| 摘要 |
<p>Disclosed are a hot-rolled steel sheet and a manufacturing method thereof, wherein the hot-rolled steel sheet can have a high tensile strength of at least 980 MPa and a high hole expansion property. The manufacturing method of the hot-rolled steel sheet comprises: a step (a) of hot-rolling a slab sheet at a finishing delivery temperature of 880-920°C; a step (b) of firstly cooling the hot-rolled sheet to a middle temperature (MT) of 660-720°C; and a step (c) of secondly cooling the firstly cooled sheet to a coiling temperature (CT) of 460-520°C, and coiling the sheet, wherein the slab sheet comprises 0.04-0.08 wt% of C, 0.3-0.9 wt% of Si, 1.5 to 2.0 wt% of Mn, at most 0.02 wt% of P, at most 0.003 wt% of S, at most 0.02 wt% of Al, 0.04-0.06 wt% of Nb, 0.05-0.07 wt% of Ti, at most 0.12 wt% of V, 0.4-0.6 wt% of Cr, 0.002-0.0025 wt% of B, and remnants of Fe and inevitable impurities. [Reference numerals] (AA) Start; (BB) End; (S110) Hot-roll (FDT: 880-920°C); (S120) Firstly cool (MT: 660-720°C); (S130) Secondly cool/coil (CT: 460-520°C)</p> |
