| 摘要 |
PROBLEM TO BE SOLVED: To provide an galvannealed steel sheet having a beautiful surface appearance without plating deficiency and further having excellent plating adhesiveness even when a high strength steel sheet containing high Mn and Cr contents is used as a base steel sheet, and to provide a method for manufacturing the galvanized steel sheet. SOLUTION: The galvannealed steel sheet comprises a base steel sheet containing Mn by 0.5 to 3.0% and a Fe-Zn alloy plating film formed on the surface of the base sheet. The plating layer contains a spinel type oxide containing Al. Preferably, a spinel type oxide having a Cr/(Mn+Cr) as an atomic ratio of 0.1 to 0.67 and containing Al is present as the spinel type oxide. The spinel type oxide has high reactivity with Al, resulting in excellent wettability with the molten zinc containing Al during plating immersion, and preventing plating deficiency. The adhesiveness between the alloy plating and the spinel type oxide is increased through Al in the spinel type oxide, and plating adhesiveness as a whole is improved. COPYRIGHT: (C)2010,JPO&INPIT
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