Mechanical Characterization and Microstructural Analysis of Extruded 2017A Aluminum Alloy: Effects of Heat Treatments on Fatigue Damage Behavior

This study examines the impact of heat treatment on the mechanical properties, microstructure, and fatigue performance of extruded AA2017 aluminum alloy. Tubular specimens undergo various heat treatments and quenching methods. The mechanical properties were assessed through hardness, tensile, and fatigue tests, whereas the microstructure was analyzed using microscopy techniques. Results show that T6 state (120°C and 160°C) enhances hardness, tensile strength, and fatigue life due to fine, coherent Al₂Cu precipitates. T7 states (240°C) produce over-aged microstructures with larger, incoherent precipitates, reducing strength and ductility. Icy saltwater quenching yields finer precipitates and better fatigue resistance than liquid nitrogen quenching. T6 conditions favor elastic adaptation, whereas T7 conditions show plastic shakedown. Fracture surface analysis reveals ductile failure in T6 states and mixed ductile-brittle behavior in T7 states. These findings provide insights for optimizing heat treatment parameters to enhance 2017A alloy performance in high-strength, fatigue-resistant applications.