Plastic flow for non-monotonic loading conditions of an aluminum alloy sheet sample

Non-linear deformation paths obtained using uniaxial tension followed by simple shear tests were performed for a 1050-O aluminum alloy sheet sample in different specimen orientations with respect to the material symmetry axes. In order to eliminate the time influence, the time interval between the first and second loading steps was kept constant for all the tests. Monotonic uniaxial tension tests interrupted during loading were used to assess the recovery that takes place during this time. In order to eliminate the influence of the initial plastic anisotropy and to compare the results as if the material hardening was isotropic, the flow stress was represented as a function of the plastic work. The behavior of the material after reloading was analyzed in terms of dislocation microstructure and crystallographic texture evolutions. For more quantitative assessment, the full constraints [Int. J. Plasticity 13 (1997) 75] and visco-plastic self-consistent [Acta Metall. Mater. 41 (1993) 2611] polycrystal models were used to simulate the material behavior in the non-linear deformation paths. Based on experimental and simulation results, the relative contributions of the crystallographic texture and dislocation microstructure evolution to the anisotropic hardening behavior of the material were discussed.