56 巻 (2006) 6 号 p. 313-316
A treatment consisting of resistance heat treatment and artificial aging was developed to improve the product strength and press formability of Al–Mg–Si alloy sheets having paint bake hardenability used for automobile body panels. In this treatment, the sheets are re-solution heat-treated by resistance heating and water quenching just before the press forming. The formed sheets are artificially aged just after the press forming to increase the product strength. In the experiment, Al–0.60%Si–0.74%Mg (A6061) alloy sheets were chosen. The solution heat treatment of the sheets was sufficiently accomplished by the rapid resistance heat treatment, and the press formability of the sheets was improved. The hardness of formed products is increased by the artificial aging and paint bake hardening. It was found that the present heat treatment is effective in improving the product strength and press formability of the Al–Mg–Si alloy sheets having the paint bake hardenability.