Influence of pre-twinning on adiabatic shear sensitivity of AZ31 magnesium alloy
In order to study the effect of different twin volume fractions on the adiabatic shear sensitivity of materials,AZ31 magnesium alloys with different twin volume fractions were obtained by pre-compression.The hat-shaped samples were subjected to high speed impact at the temperature of 200℃and the strain rate of 944 s-1 by using split Hopkinson pressure bar(SHPB).The microstructure evolution before and after high strain rate deformation was characterized by electron backscatter diffractometer(EBSD)and optical microscope(OM).The absorbed energy of samples during adiabatic shear process was calculated,and the micro-hardness within and without the adiabatic shear band(ASB)was tested.The results show that the adiabatic shear band can be found in samples with different twin volume fractions.With the increase of twin volume fraction,the width and absorb energy of the adiabatic shear band decrease,while the adiabatic shear sensitivity increases.