Abstract: Zn-Ni-alloy electroplating of steel sheets is carried out using a plating bath containing 10-40 g/l zinc, 15-160 g/l nickel, 0.1-5 g/l cobalt and 0.2-10 g/l titanium and 0.1-5 g/l aluminum or 0.1-5 g/l magnesium existing in the form of salts, the pH of which is 1.5-2.5. The obtained plated product exhibits improved excellent corrosion resistance and corrosion peeling resistance. The product can be subjected to heating to 60.degree.-200.degree. C., preferably in hot water, steam, or atomized water mist. This treatment further increases corrosion resistance.

Abstract: Improved Zn-Ni-alloy-electroplated steel sheet can be prepared by electroplating steel sheet with an acid electroplating bath containing Zn ions, Ni ions and a small amount of titanium ions, preferably after pre-electroplating with an electroplating bath containing Zn ions and a larger amount of Ni ions and heating the plating sheet in the presence of water.

Abstract: The adhesion of a corrosion resisting Zn-Ni-alloy plated layer on a steel sheet is improved by pre-plating the steel substrate with a Zn-Ni layer containing Ni in an amount higher than said Zn-Ni-alloy plated layer.