Coupled mesoscopic constitutive modelling and finite element simulation for plastic flow and microstructure of two-phase alloys

A mesoscopic dislocation-based model was coupled with macro-scale finite element analysis for concurrent study of local plastic flow and microstructure of two-phase alloys during thermomechanical deformation. The model was implemented in the ABAQUS code to simulate the thermomechanical processing of a Ti-6Al-4V alloy in the (α + β) phase field, with consideration of the effects of local dislocation density variation, deformation heating and phase volume fraction. The simulation show that the intergranular interaction results in non-uniform distribution of dislocations within each grain, particularly in the initial stages of deformation. Phase boundaries pose stronger influence on deformation than grain boundaries. The onset of shear localization was strongly influenced by the strain rate sensitivity parameter, deformation heating, phase volume fraction, and the die/sample friction coefficient. Both deformation heating and phase transformation in the shear-localized region contributes to the flow-stress variation during processing. The phase volume fraction largely affects the microstructure, distribution of the equivalent stress, but not the equivalent strain.