COLD FORGED PRODUCT OF Al-Mg-Si-BASED ALUMINUM ALLOY WITH EXCELLENT APPEARANCE QUALITY

PROBLEM TO BE SOLVED: To obtain a cold forged product of Al-Mg-Si-based aluminum alloy having a good-looking surface by suppressing excessive growth of crystal grains causing biased light reflection. SOLUTION: The aluminum alloy contains 0.3-1.3% Si, 0.4-1.3% Mg, 0.1-0.5% Cu, 0.1-0.5% Fe, and 0.04-0.4% Cr, and optionally contains one or more of 0.05-0.8% Mn, 0.05-0.4% Zr, 0.03-0.4% V, 0.01-0.4% Sn, 0.001-0.03% Ti, and 0.003-0.03% B. The cold forged product is produced by holding an extruded material of the aluminum alloy at 520-580°C for 1-10 hours, quenching the resulting material at a cooling rate of 200°C/min or more, and then cold-forging the hardened material. After the cold forging, the cold forged product is subjected to aging treatment by holding it at 160-220°C for 1-12 hours, thereby suppressing the maximum grain size of the crystal grains exposed to the surface thereof to 1.5 mm or less. COPYRIGHT: (C)2009,JPO&INPIT