| 摘要 |
PROBLEM TO BE SOLVED: To allow a clear crystal grain pattern to appear on the surface of an Al-Mg-Si based alloy extruded shape material while deterioration in its extrusion moldability and cross-sectional shape is prevented. SOLUTION: The method for allowing a crystal grain pattern to appear comprises: subjecting an Al-Mg-Si based alloy extruded shape material containing, by weight, 0.2 to 2.0% Zn and 0.05 to 0.15% Fe to heat treatment at 510 to 560°C and aging treatment; subjecting the above treated material to single alkali etching or hydrochloric acid etching and alkali etching treatment; and thereafter subjecting the etched material to surface treatment of anodic oxidation, electrolytic coloring and electrodeposition coating. In this way, Zn is deposited on the surface of the extruded shape material, thus a clear crystal grain pattern of about 30 to 40 mm on the maximum and about 10 mm on the average is made to appear, further, its extrusion moldability is maintained by the incorporation of Zn, and a phenomenon in which the extruded shape material is softened by the heat treatment and its cross-sectional shape is deteriorated can be prevented. COPYRIGHT: (C)2006,JPO&NCIPI
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