Effect of post heat treatment on microstructure and mechanical properties of hot-rolled AA2017 aluminum alloy

This study investigates the effects of heat treatment, involving solubilization and aging, on the microstructure of AA2017-T451 aluminum alloy. Samples of 4 mm thick rolled plate of AA2017 underwent solution treatment at 500 °C for two different durations, namely 2 h and 6 h, followed by either water quenching (WQ) or air quenching (AQ). Subsequently, they were artificially aged (AA) at 175 °C for 8 h. The samples were investigated in terms of microstructures using techniques such as optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) and in terms of mechanical properties. Hardness measurements (HV) and tensile tests were conducted on samples oriented along different directions (rolling RD and transverse TD directions). Best results in terms of mechanical properties were obtained with samples solution treated at 500 °C for 6 h, followed by water quenching and an 8-h artificial aging, exhibiting the highest yield and tensile strength. Fracture analysis revealed predominantly ductile behavior in AA2017, characterized by micro-void nucleation, growth, and coalescence. Additionally, the heat treatment response concerning phase constitutions as a function of input composition, temperature, and time was compared with the data obtained by the JMatPro software. The results highlighted the significant influence of quenching rate post-solution heat treatment, aging time, and temperature on the precipitation-hardening process of AA2017, particularly emphasizing the formation of Al₂Cu (θ-phase) and Mg₂Si during the aging process.