| 摘要 |
PURPOSE:To produce a rolled sheet of Al alloy exellent in the moldability for the high-strength molding and processing by heat-treating and rolling an Al alloy ingot in the proper conditions wherein Si, Cu, Mg, Mn and Fe are incorporated in relation wtih the specified composition amount and the composition. CONSTITUTION:The homogenonizing treatment at 550-620 deg.C for 24 hours is performed for an Al alloy ingot wherein by weight 0.25-0.60% Si, 0.3-1.0% Cu, 0.6-2.0% Mg, 0.6-1.3% Mn and 0.25-0.80% Fe are incorporated and the remainder consists of A4l and the inevitable impurities and a value P speci fied by the following formula P=Mn+5Ti+Fe+0.2Mg+0.3Cu+0.7Si is <1.9. Then the rolled sheet is heated up to the temp. region of 500-600 deg.C in>=0.5 deg.C/ second heat-up velocity and immediately or after holding it for <=120 seconds, it is quickly cooled. Furthermore the cold rolling of >=20% degree of rolling is performed for the rolled sheet, and the rolled sheet of A4l alloy which is excellent in the moldability and has not the decrease of the strength in the baking and coating processes after the molding and excellent in the strength of a molded article is obtained.
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