Dynamic response and microstructure evolution of oxygen-free high-conductivity copper liner in explosively formed projectile

Abstract

The dynamic response and microstructure evolution of oxygen-free high-conductivity copper in a shaped charge liner are investigated through microstructural examination of a soft-recovery EFP. Adiabatic shear bands and voids which is the failure original of copper EFP can be observed in the rear part of the projectile. Numerical simulation results illustrate that the highest plastic strain reaches about 2.9 which can fully accommodate the grains deformation of copper EFP during the formation process at strain rates of the order of 104s-1. Theoretical calculation results indicate that the highest temperature increase of EFP caused by shock wave and plastic deformation can reach 747K, which is 0.55Tm (where Tm is the melting temperature of copper). The main body of the EFP undergoes completely dynamic recrystallisation, and the average size of the refined grains significantly decreases to approximately 10μm. A slight increase in grain size occurs mainly away from the center and extends towards the head and rear sections of the EFP. During the DRX process, the dislocation movement is believed to be the controlling mechanism significantly refining the microstructure.