| 摘要 |
PURPOSE: A method for manufacturing hot-rolled steel sheets with excellent formability and the hot-rolled steel sheets manufactured by the same are provided to improve formability, strain aging resistance, and paintability by optimizing a manufacturing process and short blasting conditions while adding boron. CONSTITUTION: A method for manufacturing hot-rolled steel sheets is as follows. A short blasting process is implemented by spraying short balls with a size of 0.1-0.4 mm to the surface of the hot-rolled steel sheets at 40-65 m/sec. The component of steel satisfies 0.025<=[B(wt.%)×Al(wt.%) / N(wt.%)]<=0.055. The steel is composed of 0.01-0.12 wt.% of C, 0.1-0.5 wt.% of Mn, 0.025 wt.% or less of P(not including 0 wt.%), 0.02 wt.% or less of S(not including 0 wt.%), 0.05-0.15 wt.% of Al, 0.0005-0.0020 wt.% of B, 0.002-0.004 wt.% of N, and the rest of Fe and other inevitable impurities. [Reference numerals] (AA) Evaluation value(Fluting index and machinability); (BB) Fluting index; (CC) Machinability; (DD) Illumination index ratio(Rmax/Ra) |
