The high intensity galvanized steel sheet and the production mannered null mass which are superior in processability, paint printing hardenability and normal temperature

摘要

PROBLEM TO BE SOLVED: To provide a galvanized steel sheet which has a tensile strength of 390-600 MPa, has a low yield strength and a low yield ratio, is excellent in strength-ductility balance and has BH property and resistance to natural aging, and an inexpensive production method thereof.;SOLUTION: The high-strength galvanized steel sheet excellent in workability, paint baking hardenability and resistance to natural aging comprises, by mass, 0.02-0.08% C, ≤0.5% Si, 1.0-2.5% Mn, ≤0.05% P, ≤0.02% S, 0.0005-0.014% Al, 0.2% but ≤1.5% Cr, 0.001-0.008% N and the balance being Fe and unavoidable impurities, provided that Cr/Al is ≥30 and the area ratios of martensite and ferrite in a metallic structure are 3-20% and ≥80%, respectively. The galvanized steel sheet optionally further contains at least one element chosen from B, Mo, W, Nb, Ti, V, Cu, Ni, Ca, Mg, Zr, La and Ce.;COPYRIGHT: (C)2008,JPO&INPIT