| 摘要 |
PURPOSE: To produce a three-layer plated steel material excellent in corrosion resistance after heating and spot weldability by forming a three-layer plating whose lowermost layer is a plated layer of Ni, etc., and its coverage is specified, intermediate layer is Zn-based plated layer and uppermost layer is Al-based plated layer on the steel material. CONSTITUTION: The three-layer plating whose lowermost layer is composed of at least one metal selected from Ni, Cr and Co and its coating wt. is 0.1-30g/m<2> , intermediate layer is Zn or Zn alloy-plated layer (coating wt. is order of 1-30g/m<2> ) and uppermost layer is Al or Al alloy-plated layer (coating wt. is order of 1-50g/m<2> ) is formed on the steel material. In this way, the three layer plating steel material excellent in corrosion resistance after heating and in spot weldability is obtained.
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