Prediction of Hot Formability of AA7075 Aluminum Alloy Sheet

A uniaxial high-temperature tensile test of an AA7075 aluminum alloy sheet was conducted using an established induction heating test system. Five different types of specimens were designed to obtain the stress-strain curves at different forming temperatures and strain rates so as to construct and modify the Johnson-Cook constitutive model. The uniaxial tensile test of different stress states was numerically simulated using ABAQUS finite element software, and the stress triaxiality and equivalent fracture strain parameters were extracted. The Johnson-Cook ductile fracture model was constructed, and an error evaluation scheme was designed to determine the best failure parameter combination. Based on the obtained Johnson-Cook ductile fracture model, finite element models of different strain paths were constructed, and theoretical forming limit curves at different temperatures and strain rates were obtained. The results of the Nakazima test and finite element simulation are mostly consistent, which confirms the reliability of the constructed fracture model and theoretical forming limit curves.