| 摘要 |
PURPOSE:To improve the corrosion resistance, workability, weldability, and coating properties of the titled steel plate by sticking an iron-containing material onto a metallic zinc internal layer formed in a fused galvanizing bath containing Al, and containing alloy of zinc in the internal layer by a heat treatment. CONSTITUTION:In a fused galvanizing bath having >=0.13wt% Al concentration, an internal layer 2 consisting of metallic zinc with >=2mum thickness is formed on a steel plate 1. Then, an external layer 3 consisting of an iron element containing material, e.g. powdery metallic iron is stuck onto said internal layer 2. The metallic iron on the external layer 3 and the metallic zinc in the internal layer 2 are made into alloy by a heat treatment to form a zinc-iron alloy layer A. Then, a metallic zinc layer B having relatively reduced thickness is formed. Thus, a surface-treated steel plate having layers A and B of double structure as a surface-treated layer is obtained. |
