Ductile fracture evaluation behaviors in warm forming of advanced high-strength aluminum alloy 7075-T761

: High-strength aluminum alloys, particularly the 7xxx series, are increasingly being adopted in the automotive and aerospace sectors owing to their exceptional strength-to-weight ratio and lightweight characteristics. In the present study, the ductile fracture behavior of the high-strength aluminum alloy AA7075-T761 was investigated across a temperature range from room temperature to 200 0 C. To accurately evaluate the mechanical properties and analyze the loading paths to fracture of AA7075-T761, a comprehensive experimental program was executed utilizing a 3D Digital Image Correlation (DIC) system. Specifically, a series of standard flat tensile specimens were utilized to characterize the stress-strain curves, while other specimen geometries, including in-plane shear, central-hole, and plane strain tension specimens, were tested to characterize the strain path to fracture on the material surface. Based on the experimental fracture strain data, the fracture locus, fracture surfaces, and ductile fracture-forming limit diagram (FFLD) of AA7075-T761 at different elevated temperatures were successfully constructed. The SEM results show the effect of temperature on the transition of microscopic void mechanisms inside specimens. Additionally, the loading paths in the space of stress triaxiality and equivalent plastic strain location is most strongly determined and influenced by the geometry of the specimen and the type of load, while forming temperature affects these positions indirectly.