Dynamic impact constitutive model of 6008 aluminum alloy based on evolution dislocation density

In this study, a systematic experimental evaluation of 6008 Al alloys was conducted using split Hopkinson pressure bar equipment and a transmission electron microscope. The macro- and micro-mechanical responses and mechanisms for plastic deformation of 6008 Al alloy were analyzed at various strain rates and temperatures. At the microscopic level, the results revealed that an increase in the strain rate led to an increase in dislocation density under impact compression conditions. Moreover, dislocation movement and flow stress were prevented by second-phase particle precipitation. In contrast, impact deformation of the material involved the dissolution of the supersaturated solid solution and thermal activation during high temperature impact loading. A constitutive model of impact dynamics was constructed based on the evolutionary mechanism of the microscopic density of dislocation. The main consideration was the internal stress, which took into account the effects of grain size and dislocation sub-cells on the evolution of the density of immobile dislocation. The novelty of this model, which is based on thermally activated dislocation motion, lies with the inclusion of equivalent stress. The proposed constitutive model can reasonably describe the dynamic plastic evolution of 6008 Al alloys over a wide range of strain rates and temperatures.

Automated summary

In this study, a systematic experimental evaluation of 6008 Al alloys was conducted to analyze the macro- and micro-mechanical responses and mechanisms for plastic deformation at various strain rates and temperatures. It was found that an increase in strain rate led to an increase in dislocation density, while second-phase particle precipitation prevented dislocation movement and flow stress. On the other hand, impact deformation involved the dissolution of a supersaturated solid solution and thermal activation. A constitutive model based on the evolutionary mechanism of dislocation density was proposed, which reasonably described the dynamic plastic evolution of 6008 Al alloys.