Microstructure evolution of adiabatic shear band in AZ31 alloy under dynamic compression

Abstract

The formation of adiabatic shear band (ASB) and its damage behaviour in AZ31 alloy under high strain rate compression (2000 s−1) were investigated in this study by using a split Hopkinson pressure bar. Microstructure of the ASB was characterised by electron back-scattering diffraction and transmission electron microscopy, and the adiabatic shear damage behaviour was analysed through finite element simulation by LS-DYNA. The results show that the ASB and the surrounding microstructure form a gradient microstructure distribution, and the formation of ultra-fine grains in the ASB is due to rotational dynamic recrystallisation. The combination of work hardening and grain refinement in ASB leads to a high microhardness. Micro-voids grow in the ASB and eventually form macro-cracks, leading to material failure.