Effects of Initial Temperature, Melting Temperature, Density, Heat Capacity and Work to Heat Conversion Factor on Thickness of Phase Transformed Adiabatic Shear Band

摘要

Gradient-dependent plasticity where a characteristic length is involved to consider the microstructural effect (interactions and interplaying among microstructures due to the heterogeneous texture) is introduced into Johnson-Cook model considering the effects of strain-hardening, thermal softening and strain rate sensitivity. Effects of initial temperature, melting temperature, density, heat capacity and work to heat conversion factor on the occurrence of phase transformation and the thickness of phase transformed adiabatic shear band (ASB) in deformed ASB are numerically investigated. In deformed ASB, the temperature is highly nonuniform due to the microstructural effect. When the peak temperature in deformed ASB reaches the melting temperature of ductile metal, transformed ASB appears at the center of deformed ASB. With an increase of exerted plastic shear strain, the width of transformed ASB increases. Lower initial temperature, density and heat capacity as well as higher melting temperature and work to heat conversion factor lead to earlier occurrence of phase transformation (lower average plastic shear strain). For the same flow shear stress, the thickness of transformed ASB is wider at lower initial temperature and work to heat conversion factor as well as higher melting temperature, density and heat capacity. Gradient-dependent plasticity considering the microstructural effect can well predict the effects of physical parameters and initial temperature on the thickness of transformed ASB and ASB's development with decreasing flow shear stress, as cannot be predicted by classical elastoplastic theory applicable to completely homogenous material.