To provide a high Si-containing high strength galvanized steel sheet having good a coating property and an excellent corrosion resistance without requiring new equipments, and its manufacturing method.
A Zn-Al-Fe alloy plating or a Zn-Al-Mg-Fe alloy plating is formed on the surface of a steel sheet containing 0.4-2.0 wt.% Si which is the oxidized state (SiO2) in the inner sheet. The inner SiO2 is produced at the time, the steel sheet is oxidized under atmosphere having 0.9-1.2 fuel/air ratio in the oxidizing zone, and successively is reduced in the reducing zone, under an atmosphere controlled where the Si content (mass %) (CSi), a water partial pressure (PH2O) and a hydrogen partial pressure (PH2) satisfy the following inequality. -0.8≥log(PH2O/PH2)≤0.5CSi-3.
TAKAHASHI AKIRA
HATANAKA HIDETOSHI
KONDO YASUMITSU
