| 摘要 |
PROBLEM TO BE SOLVED: To prevent the blackening of an aluminum alloy to which free-cutting elements, such as Bi, Pb, and Sn, are added by the addition of Be, and to obtain an extruded material having excellent surface. SOLUTION: A composition, containing 0.5-1.0% Si, 0.8-1.2% Mg, 0.1-0.30% Fe, 0.001-0.2% Be, and 0.15-0.4% Cu and further containing 0.4-1.2%, independently, of one element among Bi, Pb, and Sn or 0.4-2.2%, in total, of two or more elements among them, is provided. If necessary, 0.05-0.3%, in total, of one or <=2 kinds among 0.05-0.2% Cr, 0.05-0.2% Mn, and 0.05-0.1% Zr can be added. The content of Zn contained as an impurity is limited to <=0.25%. Because an oxide film of Be is formed on the surface of the extruded material, the occurrence of a blackening caused, e.g. by the oxidation of Mg can be prevented.
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