| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength galvannealed steel sheet excellent in plating adhesion. <P>SOLUTION: The galvannealed steel sheet has a plating layer comprising, by mass, 7-15% Fe, 0.01-1% Al and the balance being Zn and unavoidable impurities on a surface of a steel sheet comprising 0.05-0.50% C, 0.01-3.0% Mn, at least one chosen from ≤3.0% Si, ≤2.0% Al and ≤2.0% Cr, provided that Mn+Si+Al+Cr is ≥0.4%, and the balance being Fe and unavoidable impurities. Here, in a region of the steel sheet within 10 μm from a boundary between the steel sheet and the plating layer, (x) a microstructure exists which (x1) has a grain size of 2 μm or less and (x2) includes at least one chosen from oxides of Mn, Si, Al and Cr and/or at least one composite oxide comprising at least two chosen from Mn, Si, Al and Cr, and (y) a Zn-Fe alloy phase exists around a portion of the oxide and/or the composite oxide. <P>COPYRIGHT: (C)2013,JPO&INPIT |
