| 摘要 |
PURPOSE: A hot rolled steel sheet with excellent surface property and manufacturing method thereof are provided to improve process ability, surface property and painting property. CONSTITUTION: A method for manufacturing a hot rolled steel sheet with excellent surface property comprises following steps. A shot ball of 0.10-0.40 is short-blasted on a surface of the hot rolled steel sheet which consists of 0.001-0.003 weight% of carbon (C), 0.5-1.5 weight% of manganese (Mn), 0.01-0.05 weight% of phosphorus (P), less than 0.020 weight% of sulfur (S), 0.01-0.07 weight% of aluminum (Al), 0.001-0.004 weight% of nitrogen (N), 0.01-0.05 weight% of vanadium (V), 0.01-0.05 weight% of cobalt (Co), Fe and impurities. Steel components satisfy a formula, 0.0015<=[(V×Co)/C]atom rate <=0.0030. The steel with this composition is rolled at 860 - 950°C and cooled at 20 - 80°C/s. The steel is reeled at 580 - 700°C. [Reference numerals] (AA) Evaluation value (fluting index & processability); (BB) Fluting index; (CC) Processability; (DD) Illumination index ratio (Rmax/Ra) |
