Mechanical Properties and Formability of Heat-Treated 7000-Series High-Strength Aluminum Alloy: Experiments and Finite Element Modeling

The feasibility of room-temperature (cold) forming of peak-aged 7075 high-strength aluminum alloy (7075-T6) sheets after solution heat treatment followed by water quenching was investigated. The anisotropic plastic properties of the heat-treated aluminum sheet (7075-WT) were experimentally characterized by performing uniaxial tensile tests (along different loading directions) and a balanced biaxial tension test. Limit dome height (LDH) and cylindrical cup drawing experiments were conducted to evaluate the formability at room temperature. With the obtained anisotropic mechanical properties, different yield functions, including Yld2000-2d, Hill 1948, and von-Mises, were determined and implemented in the finite element simulations to numerically predict the formability at room temperature. The formability of the 7075-WT sheet at room temperature could be significantly enhanced owing to the prior heat treatment, and the finite element simulations performed using the anisotropic yield functions and Voce hardening law were in good agreement with the measured LDH. The LDH of the 7075-WT sheet in the plane strain and biaxial stress modes and the earing in the circular cup drawing tests could be better predicted non-quadratic Yld2000-2d function than those by isotropic and Hill 1948 quadratic yield functions.