Adiabatic shear sensitivity of ductile metal based on gradient-dependent JOHNSON-COOK model

Abstract

Based on the expression proposed by WANG for the local plastic shear deformation distribution in the adiabatic shear band (ASB) using gradient-dependent plasticity, the effects of 10 parameters on the adiabatic shear sensitivity were studied. The experimental data for a flow line in the ASB obtained by LIAO and DUFFY were fitted by use of the curve-fitting least squares method and the proposed expression. The critical plastic shear strains corresponding to the onset of the ASB for Ti-6Al-4V were assessed at different assigned ASB widths. It is found that the proposed expression describes well the non-linear deformation characteristics of the flow line in the ASB. Some parameters in the JOHNSON-COOK model are back-calculated using different critical plastic shear strains. The adiabatic shear sensitivity decreases as initial static yield stress, work to heat conversion factor and strain-rate parameter decrease, which is opposite to the effects of density, heat capacity, ambient temperature and strain-hardening exponent. The present model can predict the ASB width evolution process. The predicted ASB width decreases with straining until a stable value is reached. The famous model proposed by DODD and BAI only can predict a final stable value.