| 摘要 |
PURPOSE:To improve the suitability of a galvannealed steel sheet or an Al-Zn alloy plated steel sheet to chemical conversion treatment for forming a phosphate film, a chromate film or the like by plating the surface of the steel sheet with a metal such as Fe, Zn, Ni, Sn, Sb or Co. CONSTITUTION:The surface of a steel sheet having a galvannealed platedlayer consisting of 15-40wt% Fe and the balance Zn or a plated Al-Zn alloy layer is plated with at least one kind of metal such as Fe, Zn, Ni, Co, Sn or Sb by >=0.05g/m<2> by chemical plating or electroplating. By this plating, the formation of a phosphate film or a chromate film on the galvannealed steel sheet or the Al-Zn alloy plated steel sheet is facilitated and the corrosion resistance of the steel sheet after painting, the adhesion to a paint film and the spot weldability are improved as well.
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