Multiscale strain-rate effects on the shear and thermal behavior of Al2024 and Al7050 alloys

Aluminum-alloy components in aerospace applications must withstand extreme service environments. To assess their performance under such demanding conditions, this study conducts shear tests spanning six orders of magnitude in strain rate on Al2024 and Al7050. Experiments measure full-field strain distributions and temperature evolution, capturing the formation and development of adiabatic shear bands. Simulations further reveal strain-rate-dependent hardening and shear localization mechanisms. Under dynamic shear, Al7050 shows an approximate 22% increase in yield strength compared to quasi-static conditions. In contrast, Al2024 increases by only ∼12% under the same loading. This indicates that Al7050 has stronger strain-rate sensitivity and maintains higher strength. Interestingly, under dynamic loading, Al2024 exhibits much greater shear ductility. Al2024 reaches ∼11% shear strain at failure, whereas Al7050 fails at only ∼7%. In addition, at 2000s −1 , the temperature rise in the shear zone is only 75-95 °C, indicating minimal thermal softening. This suggests that adiabatic shear band formation is driven mainly by intense localized plastic flow and subsequent fracture, rather than heat-induced softening. Microstructural analysis shows narrow shear bands in both alloys. Severe grain refinement occurs across the bands, with grain size decreasing from 50 to 100 μm to ∼20 μm. These observations highlight the critical role of localized plastic flow in the dynamic shear failure of aluminum alloys. Overall, this study clarifies the dynamic shear failure mechanisms of aluminum alloys and informs strategies to enhance their impact resistance.