| 摘要 |
PROBLEM TO BE SOLVED: To impart good mechanical properties, spot weldability and excellent corrosion resistance to a galvanized steel sheet by a applying an Fe-P-αlayer contg. specified metallic elements to the boundary between a galvanizing layer and a steel sheet. SOLUTION: A cold roller steel sheet is subjected to alkali degreasing, is pickled, is washed, is thereafter applied with an Fe-P-αplating layer contg. at least one kind of element selected from Ni, Cu, Co, Cr, and Mn and is next applied with galvanizing. The content of P in the Fe-P-αlayer formed on the boundary is preferably regulated to 0.01 to 10wt.%. Furthermore, the coating weight of the Fe-P-αlayer is preferably regulated to 0.1 to 10g/m<2> per side of the steel sheet. By the synergetic effect between the Fe-P-αlayer and the galvanizing layer, its corrosion resistance improves, and the coating weight of zinc can be reduced. Moreover, deterioration in the mechanical properties of the steel sheet caused by the excessive addition of P to the steel sheet stock can be prevented.
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