COLD-ROLLED STEEL SHEET HAVING EXCELLENT SULFURIC ACID-CORROSION RESISTANT AND SURFACE PROPERTIES AND METHOD FOR MANUFACTURING THEREOF

摘要

The present invention relates to a cold-rolled steel sheet having excellent corrosion resistant in comparison with steels containing copper and excellent corrosion resistant of sulfuric acid in which defective surface caused by copper is not generated and surface properties and a manufacturing method thereof. The cold-rolled steel sheet contains 0.01-0.1 wt% of C, 0.01-1.0 wt% of Si, 0.2-1.5 wt% of Mn, 0.01-0.1 wt% of Al, 0.2-1.0 wt% of Cu, 0.1-0.5 wt% of Ni, 0.03-0.1 wt% of Co, 0.16-0.25 wt% of Sb, less than 0.02 wt% of S, less than 0.02 wt% of P, the remainder of Fe, and impurities. The ratio of Cu and Ni is 0.3-0.7. In a sulfuric acid corrosion process, an oxide layer containing CuO/SbO-based oxide is formed.