| 摘要 |
PROBLEM TO BE SOLVED: To obtain an Al-Mg-Si base aluminum alloy extruded material for automotive frame free from the generation of cracks at the time of bending working, furthermore small in the amount of spring back and excellent in bending workability. SOLUTION: This material has a composition containing, by mass, Mg of 0.30 to 0.70%, Si of 0.10 to 0.50% which is more surplus than the balance composition of Mg2 Si, Cu of 0.1 to 0.4%, Ti of 0.005 to 0.2%, Cr of <0.04%, also one or more kinds among Mn, Cr and Ze of 0.10 to 0.40% in total, and the balance Al with inevitable impurities, is subjected to aging treatment after press quenching by air cooling, has a fibrous microstructure and has proof stress of 200 MPa or more.
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