Mechanical properties, springback, and formability of W-temper and peak aged 7075 aluminum alloy sheets: Experiments and modeling

High strength aluminum alloys have drawn much attention as the requirement for lightweight vehicle design increases in the automotive industry. However, inferior formability due to higher strength poses a technical hurdle against successful application of high strength aluminum sheets in automotive components. In this study, the mechanical properties of 7075 aluminum alloy sheet after W-temper heat treatment, which consists of solution heat treatment and subsequent quenching, are investigated. Detailed experimental and numerical studies are conducted on the anisotropy, non-proportional deformation behavior, and corresponding constitutive modeling in comparison with the corresponding characteristics of peak aged T6 heat-treated as-received alloy sheets. Based on the experimentally characterized mechanical properties and associated constitutive laws, the formability and springback of the W-tempered sheet are analyzed using the Marciniak-Kuczyinski forming limit diagram and U-draw bending springback simulations, respectively, by employing the Yld2000-2d anisotropic yield function and distortional hardening-based homogeneous anisotropic hardening model. Additionally, the improved constitutive modeling of the W-tempered 7075 aluminum sheets due to the effect of serrated flow characteristics on the hardening and frictional behaviors is discussed.