Constitutive behavior and microstructural evolution of 2060 Al–Li alloy under high strain rate: Experiment and simulation

Abstract

Being impacted at higher strain rates, the dislocation density in the metal material increases, which leads to the phenomenon of grain refinement. The refined grains demonstrate the hardening effect of the material processed by high-velocity impacts well. However, the mechanical response and the microstructure evolution of the new material, 2060 Al–Li alloy, under high-velocity impact remain to be unclear. In this study, the mechanical behavior of 2060 Al–Li alloy at high strain rates was investigated by split Hopkinson pressure bar (SHPB), and the influence of higher strain rates on the microstructure evolution of 2060 Al–Li alloy was further revealed by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) experiments. Meanwhile, a coupling constitutive model was proposed to correlate the macro and micro properties of the material and was applied to characterize the mechanical behavior and microstructure evolution of 2060 Al–Li alloy. The experimental results showed that when the strain rate increased from 3189 s−1 to 9053s−1, a significant strain rate hardening phenomenon was exhibited in 2060 Al–Li alloy, which could be ascribed to the significant increase in the dislocation density. Meanwhile, as the strain rate increases, the proportion of low-angle grain boundaries (LAGB) in the material increases, along with the augmented sub-grains. After the impact, the Goss texture {110}<001> became conspicuous, while the Cube texture {100}<001> in the material became gradually eclipsed. When the strain rate is up to 9053s−1, the Goss texture took on orientational dominance. Finally, based on the coupling constitutive model, the dislocation density and grain size of the specimen after impact were predicted, and the calculated results were in good agreement with the experiments.