| 摘要 |
PURPOSE:To improve the chipping resistance of a steel sheet after painting by successively forming an underlayer of Ni, an intermediate layer of an Ni-Zn alloy having a low Ni concn. and a top layer of an Ni-Zn alloy having a high Ni concn. on the steel sheet by plating by a specified extent of deposition each. CONSTITUTION:An underlayer of Ni is formed on at least one side of a steel sheet by plating by 0.01-4g/m<2> per one side. An intermediate layer of an Ni-Zn alloy having 5-10wt% Ni concn. is formed on the underlayer by electroplating by 5-60g/m<2> per one side. A stop layer of an Ni-Zn alloy having 10-30% Ni concn. is formed on the intermediate layer by electroplating by 0.5-30g/m<2> per one side. The shock absorbing property of the steel sheet is improved by the three layers and the chipping resistance after painting is also improved. The plated steel sheet is suitable for use as the external plate of an automobile.
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