Zn-Ni alloy-plated steel sheet with improved impact adhesion and a manufacturing process therefor.

摘要

A Zn-Ni alloy electroplated steel sheet exhibiting improved corrosion resistance as well as improved adhesion upon impact and resistance to powdering and a manufacturing process therefor are disclosed. The electroplated steel sheet comprises a steel sheet; a thin Zn-Ni alloy electroplated underlayer on at least one side of the steel sheet in which microcracks having a width of 0.01- 0.5 mu m and covering 10 - 60% of the surface area of the electrolplated layer are randomly oriented; and a Zn-Ni alloy electroplated toplayer. The underlayer is prepared by dipping the initially electroplated sheet into an acidic solution containing 20 g/ l or more of Ni<2><+> and 20 g/ l or more of Zn<2> <+> with a ratio of Ni<2><+> / Zn<2><+> of 1.0 SIMILAR 4.0 at a bath temperature of 40 SIMILAR 70 DEG C for a period of time (T, seconds) of (5 SIMILAR 20) x W (W: weight of electroplated layer in g/m<2>) without applying an electric current to form an Ni-rich pretreated underlayer.