| 摘要 |
PROBLEM TO BE SOLVED: To suppress the progress of natural aging to aging treatment and to provide an Al-Mg-Si-type aluminum alloy extruded material with highly stabilized strength by aging treatment. SOLUTION: An Al-Mg-Si-type aluminum alloy is extruded, and the resultant extruded material is held at >=20 deg.C in the course from the point of time when extrusion is completed to the point of time when aging treatment is started. As the Al-Mg-Si-type aluminum alloy, an aluminum alloy which has a composition containing 0.2-0.9% Si, 0.4-1.2% Mg, 0.1-0.3% Fe, 0.005-0.2% Ti and 0.001-0.01% B and further containing, if necessary, one or more kinds among 0.01-0.35% Cu, 0.05-0.2% Cr, 0.05-0.2% Zr and 0.05-0.3% Mn is used.
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