Procee for the production of a HIGH-STRENGTH HOT-DIP ZINC-COATED STEEL SHEET HAVING EXCELLENT SURFACE APPEARANCE

摘要

There is provided a high strength galvanized steel sheet with excellent appearance that does not have ununiformity of coating or a coating defect or allow a linear defect to occur after press forming, and a method for manufacturing the same. The high strength galvanized steel sheet includes a steel sheet having a ferrite single-phase structure and having a composition containing 0.0005% to 0.0040% by mass of C; 0.1% to 1.0% by mass of Si; 1.0% to 2.5% by mass of Mn; 0.01% to 0.20% by mass of P; 0.015% by mass of less of S; 0.01% to 0.10% by mass of Al; 0.0005% to 0.0070% by mass of N; 0.010% to 0.080% by mass of Ti; 0.0005% to 0.0020% by mass of B; 0.05% to 0.50% by mass of Cu; 0.03% to 0.50% by mass of Ni; and the balance of Fe and incidental impurities. The composition satisfies Relationships (1) and (2). The high strength galvanized steel sheet has a tensile strength (TS) of 440 MPa or more: Ti ‰¥ 47.9 / 14 × N + 47.9 / 12 × C 1 ; and Ni ‰¥ 0.4 × Cu 2 .