| 摘要 |
PURPOSE: A high strength hot rolled steel sheet and a manufacturing method thereof are provided to reduce the amount of Nb deposited during finishing mill by optimizing the winding temperature after hot rolling. CONSTITUTION: A high strength hot rolled steel sheet comprises C 0.05~0.07 weight%, Si 0.10~0.25 weight%, Mn 1.0~1.8 weight%, S 0.01 weight% or less, P 0.01 weight% or less, Nb 0.01~0.03 weight%, V 0.06~0.13 weight%, Cu 0.01~0.09 weight%, Sn 0.01~0.09 weight%, and Fe and inevitable impurities of the rest amount. A manufacturing method of the high strength hot rolled steel sheet comprises steps of: reheating steel slab to the set extraction temperature, carrying out hot-rolling finishing mill at a finishing mill temperature over the Ar3 transformation point and then cooling it, and winding the cooled steel slab at the set winding temperature.
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