| 摘要 |
PURPOSE: A manufacturing method of hot rolled steel sheet for processing having less material quality deviation in coil length direction and high ductility compared with conventional hot rolled steel sheet by adding trace of boron to low carbon component system as controlling temperature of coiling and top and tail parts of coil appropriately. CONSTITUTION: The method comprises the processes of hot rolling a steel slab under the condition that finishing rolling temperature is Ar3 transformation point or more, wherein the steel slab comprises 0.01 to 0.03 wt.% of C, 0.1 wt.% or less of Si, 0.10 to 0.30 wt.% of Mn, 10 to 30 ppm of B, 0.015 wt.% or less of P, 0.010 wt.% or less of S, 0.01 to 0.04 wt.% of Al, 40 ppm or less of nitrogen and a balance of Fe and other inevitable impurities, and a ratio of B/N is in the range of 0.5 to 1.0; and coiling the hot rolled steel sheet in such a way that temperature of top and tail parts of coil is higher than a target coiling temperature by less than 40 deg.C.
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