Mechanical behavior and microstructure evolution of Al–Mg–Si–Cu alloy under tensile loading at different strain rates

Mechanical behavior and microstructure evolution of Al–Mg–Si–Cu alloy under tensile loading at different strain rates has been investigated by mechanical property and microstructure characterization in the present study. The results show that strain rate has some influences on the flow stress, mechanical property and microstructure of Al–Mg–Si–Cu alloy. As strain rate increases, both yield strength and ultimate tensile strength increase first, and then almost remain constant, and finally increase. Strain energy density also shows the similar trend. In general, increasing strain rate is more beneficial to improve elongation, however, their relationship is not monotonic increase. Elongation difference could be reflected by the dimple distribution. The dimples in dynamic fracture zone are larger and deeper than those in quasi-static fracture zone. Microstructure in the vicinities of the fracture regions of the tensile specimens is similar and comprised of elongated grains. However, the number of low angle grain boundaries and dislocation density is dependent on the strain rate.