HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET HAVING SUPERB STRETCH-FLANGEABILITY, IN-PLANE STABILITY OF STRETCH-FLANGEABILITY, AND BENDABILITY, AND METHOD FOR PRODUCING SAME.

摘要

Provided are: a high-strength hot-dip galvanized steel sheet having superb stretch-flangeability, in-plane stability of stretch-flangeability, and bendability; and a method for producing the same. The high-strength hot-dip galvanized steel sheet comprises 0.12-0.25% of C, 0.01-1.00% of Si, 1.5-4.0% of Mn, at most 0.100% of P, at most 0.02% of S, 0.01-0.10% of Al, 0.001-0.010% of N, 0.005-0.100% of Ti, 0.0005-0.0050% of B, and the balance of Fe and inevitable impurities, where Ti 4N is satisfied. The high-strength hot-dip galvanized steel sheet includes, by area ratio, 80-100% of martensite, at most 5% (including 0%) of polygonal ferrite, and less than 3% (including 0%) of residual austenite, wherein the average hardness, in terms of Vickers hardness (Hv), of the martensite is 400-500 Hv inclusive, the average crystal grain size of the martensite is at most 20 µm, and the standard deviation of the martensite crystal grain size is at most 7.0 µm.