| 摘要 |
PROBLEM TO BE SOLVED: To provide a Zn-Al alloy hot-dip plated steel sheet superior in corrosion resistance, workability, further appearance after having been plated and spot weldability, and to provide a production method therefor. SOLUTION: A plating bath has a composition adjusted so as to give the plated layer a composition, by average mass%, 25 to 70% Al, 0.5 to 5% Mg, 0.1 to 5% Si, 0.005×(Si%) to 0.05×(Si%)% Sr, or further 0.02 to 2% Cr, 0.02 to 2% Ni, and the balance Zn with unavoidable impurities. A method for forming the hot-dip plated Zn-Al alloy layer on the surface of a steel sheet comprises the steps of: dipping the steel sheet in the above plating bath; raising it up from the plating bath; and cooling it at a cooling rate of 10 to 100°C/s until the steel sheet reaches 350°C. The method may further comprises: temper-rolling the steel sheet at a rolling reduction of 0.5 to 5%; and overaging it at 150 to 350°C. Thereby produced Zn-Al alloy hot-dip plated steel acquires superior corrosion resistance, workability, further appearance after having been plated, and spot weldability. COPYRIGHT: (C)2008,JPO&INPIT
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