| 摘要 |
PROBLEM TO BE SOLVED: To produce a hot dip galvannealed steel sheet having good formability, excellent in powdering resistance, flaking resistance and low temp. chipping resistance and suitable for use for an automotive exterior. SOLUTION: This hot dip galvannealed steel sheet is the one in which the surface of a base metal contg., by weight, <=0.007% C, 0.015 to 0.08% Si, 0.05 to 0.8% Mn, <=0.014% P and 0.01 to 0.08% sol. Al and furthermore contg. Ti or the like is applied with a galvanizing layer contg. 9 to 11% Fe, the surface of the plating layer has a smooth part in which Ra is regulated to <=1.2μm, and the area ratio is regulated to <=60%, and the weight ratio of Al to Zn, i.e., Al/(Al+Zn) in the oxidized film on the surface of the plating layer is regulated to <=0.2. Then, as for the method for producing it, after alloying treatment, the oxidized film on the surface of the plating layer is dissolved to remove by using an alkali soln. and/or an acid soln.
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