HIGH-STRENGTH COLD-ROLLED STEEL SHEET WITH EXCELLENT WORKABILITY, CORROSION RESISTANCE AND TARNISH RESISTANCE AND A MANUFACTURING METHOD THEREOF WHICH FORMS Cu-BASED SULFIDE COATING

摘要

PURPOSE: A high-strength cold-rolled steel sheet and a manufacturing method thereof are provided to improve workability, corrosion resistance and tarnish resistance by reducing solid elements.;CONSTITUTION: A high-strength cold-rolled steel sheet comprises 0.0005-0.0020wt.% of C, 0.05-0.35wt.% of Sn, 0.3-0.6wt.% of Mn, 0.03-0.08wt.% of P, 0.01-0.10wt.% of Al, 0.05-0.30wt.% of W, 0.001-0.004wt.% of N, 0.10-0.40wt.% of Cu, 0.015wt.% or less of S, and the remaining amount of Fe and inevitable impurities, where the atomic ratio of Cu to S is 5-25. Cu-based sulfide is formed on the surface of the cold-rolled steel sheet.;COPYRIGHT KIPO 2013