High-speed perforation of high-entropy alloy CrMnFeCoNi plates: Experiments and modeling

The perforation behavior of 2 -mm thick CrMnFeCoNi high -entropy alloy plates is investigated via ballistic impact experiments using spherical stainless steel 304 projectiles with high-speed photography at impact velocities ranging from 500 m s-1 to 2213 m s-1. Postmortem target samples are characterized with macro photography, three-dimensional laser scanning, optical metallography, scanning electron microscopy, electron backscatter diffraction and microhardness tests. The absorbed energy and aperture area show a nearly linear increase with increasing the initial kinetic and absorbed energy, respectively. Dislocations, twins and kink bands are the main microstructural deformation modes. As the distance away from the bullet hole sidewall, both the deformation degree and hardness decrease. Besides, shear -dominated and tensile/shear-dominated fracture are found in the middle part and near the rear side of the bullet hole sidewall, respectively. Parameters of the Johnson-Cook(JC) constitutive model are obtained via the split Hopkinson pressure bar system. A finite element method (FEM) model comprised of the JC constitutive and JC progressive damage model is established and reproduces experimental observations.