POSCO Holdings Inc.
Cold-rolled steel plate for hot forming, having excellent corrosion-resistance and spot-weldability, hot-formed member, and method for manufacturing same

Abstract:

Provided is a cold-rolled steel plate for hot forming, which is excellent in corrosion-resistance and spot-weldability, contains, by weight %, C: 0.1-0.4%, Si: 0.5-2.0%, Mn: 0.01-4.0%, Al: 0.001-0.4%, P: 0.001-0.05%, S: 0.0001-0.02%, Cr: 0.5% to less than 3.0%, N: 0.001-0.02%, and a balance of Fe and inevitable impurities, satisfying formula (1) below, and includes an Si amorphous oxidation layer continuously or discontinuously formed at a thickness of 1 nm-100 nm on the surface thereof. Formula (1): 1.4.ltoreq.0.4*Cr+Si.ltoreq.3.2 (wherein element symbols denote measurements of respective element contents by weight %).