Hot dip galvanized steel plate excellent in balance of strength and ductility and in adhesiveness between steel and plating layer

摘要

The present invention discloses 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 includes: 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 not less than 50 % of martensite phase, 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. The present invention also discloses a method of producing the aforementioned hot dip Zn galvanizing steel sheet.