Effect of Temperature and Strain Rate on Deformation Mode and Crack Behavior of 7B52 Laminated Aluminum Alloy Under Impact Loading

The dynamic mechanical behaviors of 7B52 laminated aluminum alloy under different impact deformation conditions were investigated using split Hopkinson pressure bar, optical microscopy, electron backscatter diffraction and transmission electron microscopy. The results show that the 7B52 laminated aluminum alloy displays positive strain rate sensitivity and negative temperature sensitivity. Cracks are formed firstly at the interface between the 7A62 hard layer and the 7A01 middle layer under a low strain rate of 2200 s−1. When the strain rate increases to 3500 s−1, the deformation shear band is firstly formed in the 7A52 soft layer. The deformation shear band transformed to the transition shear band with the increase of strain rate, and then crack initiated. Adiabatic shear bands and cracks are formed in both of the hard and soft layers when samples impacted at a high strain rate (5500 s−1). Most of the cracks and adiabatic shear bands are unable to penetrate the middle layer due to the good toughness of the 7A01 alloy. The deformation of each layer of 7B52 laminated aluminum alloy becomes more uniform when the temperature increases, which was attributed to the reduction of difference in strength among the three layers and the coordinating effect of grain boundary on deformation.