| 摘要 |
PURPOSE: To produce an extruded material excellent in high strength, particularly in high fatigue strength and the formability of an anodically oxidized film by specifying its compsn. CONSTITUTION: The compsn. of an Al alloy is constituted of the one contg., by weight, 8.5 to 12.0% Zn, 1.5 to 3.0% Mg, 2.1 to 3.0% Cu and 0.05 to 0.3% Zr, and the balance Al with inevitable impurities. Preferably, one or >= two kinds among 0.1 to 0.8% Mn, 0.12 to 0.30% Cr and 0.01 to 0.15% V are incorporated to the same compsn. More preferably, one or two kinds of <=0.1% Ti and <=0.08% B are added thereto as well. Moreover, the contents of Si and Fe as impurities are limited to <=0.15% and <=0.20%. As for the extruded material of this Al alloy, it is subjected to solution treatment at 450 deg.C, is subjected to water quenching and is thereafter subjected to two stage aging treatment of 120 deg.C×5hr and 150 deg.C×8hr, by which 700MPa tensile strength and <=250MPa of 10<6> times fatigue strength can be obtd.
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