| 摘要 |
PROBLEM TO BE SOLVED: To provide an alloyed hot-dip galvannealed steel sheet which has excellent surface appearance and plating adhesion even if containing Si and Mn in a steel sheet base material.SOLUTION: An alloyed hot-dip galvannealed steel sheet has a plated layer on a surface of a steel sheet. The plated layer contains, by mass, 5.0-20.0% of Fe and 0.01-1.0% of Al, with the remainder comprising Zn and inevitable impurities. A steel sheet base material of the steel sheet contains, by mass, 0.001-0.3% of C, 0.1-3.0% of Si, 0.5-3.0% of Mn, 0.001-0.1% of Al, P, S and N, with the remainder comprising Fe and inevitable impurities. The steel sheet base material further contains one or more of Ti and Nb, and is characterized in that the crystal grain diameter of the steel sheet base material in contact with the plated layer is ≤10 μm, and the minimum value of a ratio, I/I, of an Si intensity (I), measured by GDS, of the steel sheet base material to an average Si intensity (I) at an inner part of the steel sheet base material is ≥0.8. |
