| 摘要 |
<p>PURPOSE: A formable hot-rolled steel sheet with excellent surface properties and a manufacturing method thereof are provided to obtain anti-aging properties by optimizing component control and a manufacturing process and to improve workability and painting efficiency. CONSTITUTION: A method for manufacturing formable hot-rolled steel sheet with excellent surface properties is as follows. The hot-rolled steel sheet comprising 0.001-0.003 wt% of carbon, 0.05-0.3 wt% of manganese, 0.001-0.020 wt% of phosphorus, 0.02 wt% or less of sulfur, 0.03-0.12 wt% of aluminum, 0.001-0.004 wt% of nitrogen, 0.05-0.25 wt% of tin, and the rest of iron and unavoidable impurities is surface-treated in a direction of the thickness of the hot-rolled steel sheet so that the area of a transformed ferrite structure becomes 3-10% in respect to the whole surface of the hot-rolled steel sheet. A short ball of which the size is 0.10-0.40mm is short-blasted on the surface of the hot-rolled steel sheet at a speed of 40-65 m/sec. [Reference numerals] (AA) Evaluation value (fluting index & processability); (BB) Fluting index; (CC) Processability; (DD) Illumination index ratio (Rmax/Ra)</p> |
