| 摘要 |
PROBLEM TO BE SOLVED: To provide an aluminum alloy extruded material having a high surface gloss after anodic oxidation treatment, and in which the surface gloss is made uniform by specifying the number of the particles of Mg2 Si precipitates with specified particle size precipitated in a matrix. SOLUTION: The components in an aluminum are composed of, by weight, 0.45 to 0.9% Mg, 0.2 to 0.6% Si, <=0.1% Cu, <=0.35% Fe as impurities, and the balance Al with impurities. The number of particles of Mg2 Si series precipitates with >=0.5μm particle size precipitated in the matrix of the extruded material thereof is regulated to <=15 pieces/100μm<2> . This allay billet is heated at 500 to 590 deg.C for 2 to 24 hr, is thereafter cooled to <=250 deg.C at a cooling rate of >=200oC/h, is reheated, is subsequently extruded so as to regulate the material temp. to 560 to 590 deg.C at the outlet of an extruding die, is air-cooled to a room temp. and is then subjected to aging treatment at 150 to 200 deg.C for 1 to 10 h. Each content of impurities other than Fe, i.e., Mn, Zn and Cr in the allay is limited to <=0.1%. In this way, the Al alloy effective as the members for building, electrical machinery and appliances and vehicles can be obtd.
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