| 摘要 |
PURPOSE:To improve the resistance to powdering of a plated steel sheet and corrosion resistance after painting by increasing the content of iron toward the upper layer of each layer of the double-layered iron-zinc alloy electroplating film formed on a steel sheet and specifying the total content of iron and total plating amt. thereof. CONSTITUTION:An iron-zinc alloy electroplating film having 1-15wt% iron content and 1-50g/m<2> total plating amt. is formed to >=1 layer on the surface of a steel sheet. Plural outside layers having >=15% iron content per layer, and having the iron content higher toward the upper layer and 1-40g/m<2> total plating amt. are formed on such base layer. The difference in the iron content between the adjacent outside layers and the difference in the iron content between the uppermost and lowrmost layer of the base layer are made 1-15wt%, and the total plating amt. of the base layer and the outside layer is made 10-75g/m<2>. The double layered iron-zinc alloy electroplated steel sheet has excellent resistance to powdering and corrosion resistance after painting and is therefore suitable for the outside surface of the outside plate of automobiles, etc. |
