PRODUCTION OF HEAT TREATMENT TYPE ALUMINUM ALLOY HAVING EXCELLENT FORMABILITY

PURPOSE:To improve formability of an Al alloy member by subjecting a casting ingot of an Al alloy to a soaking treatment then to hot working and cold working followed by a heat treatment under a specific condition. CONSTITUTION:An ingot of a heat treatment type Al alloy of Al-Cu, Al-Cu-Mg, Al-Mg-Si, Al-Zn-Mg or the like is subjected to a soaking treatment by heating for 24hr, and is subjected to working such as hot rolling, whereafter the ingot is further subjected to working such as cold rolling. The worked steel is subjected to a solution heat-treatment by heating and holding the same at 400-550 deg.C to solutionize the alloy components such as Cu, Mg, Zn and Si and thereafter the alloy is cooled to room temp. at a cooling rate of >=30 deg.C/min. The alloy is then heated to an overaging temp. of 200-400 deg.C at a heating rate of 150 deg.C/hr and is held at said temp. within