Patent ID: 6558815
Filing Date: 2003-05-06
Classification: C21D,C22C,C23C,Y10S,Y10T

Abstract:
A hot dip Zn galvanized steel sheet having excellent balance between tensile strength and ductility and excellent coating adhesion, an average composition of a base steel thereof comprising:0.05-0.25 mass % of C; not more than 2.0 mass % of Si; 1.0-2.5 mass % of Mn; and 0.005-0.10 mass % of Al, wherein the C content at the base steel surface layer portion right under a coating layer is not more than 0.02 mass %, the base steel structure contains martensite phase, by not less than 50% as a fraction, the martensite phase including both tempered martensite phase and fine size martensite phase, and the remaining portion of the base steel structure being formed by ferrite phase and residual austenite phase.