| 摘要 |
PROBLEM TO BE SOLVED: To produce a hot dip Al-Zn base alloy coated steel sheet excellent in the surface appearance and bending workability, and its producing method. SOLUTION: A hot dipping Al-Zn base alloy bath has a composition containing Zn, Al and Si and the bath temperature is made to≤600°C, and dipping steel sheet temperature is made to≤600°C, and after forming the hot dip Al-Zn base alloy coated film on the surface of the steel sheet, this coated steel sheet is cooled to 540°C at≥20°C/s. In this way, the hot dip Al-Zn base alloy coated film having the composition containing 30-70 mass% Al, 0.1-1.0 mass% Si, 0.5-2% of Si to Sr, and the thickness of the interface alloy layer at≤20% of the coated film thickness is formed. COPYRIGHT: (C)2004,JPO
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