Crystal plasticity evaluation of the effect of grain morphology on compressive deformation behavior of AA2099 Al–Li alloy

The strip-like grain shape is one of three important factors (the strip-like grain shape, strong crystallographic texture and plate-like T1 precipitate) influencing the mechanical properties of the third-generation Al–Li alloys. However, studies on its effect have seldom been investigated to date. In the present study, an extended crystal plasticity finite element (CPFE) framework considering the strain gradient effect via incorporating the geometrically necessary dislocation (GND) density is constructed to investigate the compressive deformation behavior of studied AA2099 Al–Li alloy with strip-like grain shape. Good consistency with respect to the true stress-strain curve and texture characteristics between experimental and predicted results confirms the validity of constructed CPFE framework, as well as these fitted material parameters. Simulation results show the occurrence of aggregation for GND density not only near grain boundaries but also at grain interiors, which benefits in blocking the motion of the statistically stored dislocation (SSD) and the occurrence of obvious stress concentration in the constructed polycrystalline model. This demonstrates that the strip-like grain shape could exsert a nonnegligible influence on the mechanical response of studied AA2099 Al–Li alloy. Moreover, the difference between the predicted orientation distribution functions (ODFs) and the difference about the evolution of accumulative shear strain in 12 slip modes collectedly confirm that the strip-like grain shape does exert some influence on slip activities of studied AA2099 Al–Li alloy.