| 摘要 |
PROBLEM TO BE SOLVED: To obtain a plated steel sheet excellent in slip resistance and suitable for use requiring unslipperiness of surface, by spraying water on a Zn-Al alloy plating layer containing specific amounts of Al while the plating layer is in a molten state and regulating surface roughness to a specific Ra value. SOLUTION: The surface roughness Ra of a plating layer on a steel sheet plated with an Zn-Al alloy containing 3.1-5.5% Al is regulated to >=1.5μm. By this procedure, the plated steel sheet, capable of securing >= about 1.0 surface roughness Ra after roll forcing and excellent in slip resistance, is obtained. Further, it is preferable to sharpen the projecting part of the ruggedness of the plating layer to regulate its coefficient of static friction (μ) to >=0.23. This Zn-Al alloy plated steel sheet can be obtained by immersing a steel sheet in a Zn-Al alloy plating bath having 3.1 to 5.5% Al content, regulating coating weight by a gas squeezing method, etc., and then spraying water or an aqueous solution of phosphate, etc., on the plating layer, while the plating layer is in a molten state, on an airless spray system, etc., to roughen the surface.
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