Influence of a Regression Heat Treatment on the Material Properties of a Copper-free 7xxx Series Aluminum Alloy

The alloy used in the investigation is a copper-free Al-Zn-Mg-alloy in the strength optimized T6 temper. The aim of the study is the increase of the typical requirements for formability by a regression heat treatment of the whole sheet. Therefore, the necessary material properties are determined according to temperature and time of the heat treatment to deduce a potential process range. Various test methods of uniaxial and multi-axial stress conditions are used to evaluate a possible influence of the regression heat treatment on the material behavior under different stress states.