Numerical Investigation of the Interaction between the Martensitic Transformation Front and the Plastic Strain in Austenite

Phase-field simulations of the martensitic transformation (MT) with plastic deformation are carried out. The elasto-plastic phase-field approach of semicoherent MT is used. The evolution equation for the dislocation density field is extended by taking into account the thermal and athermal annihilation of the dislocations in the austenitic matrix that leads to an inhomogeneous distribution of the total dislocation density. During the phase transformation one part of the dislocations in the austenite being responsible for the plastic strain is inherited by the martensitic phase and this inheritance depends on the kinetics and the crystallography of the MT. Another part of dislocations moves with the transformation front and decreases the total plastic strain. Based on the simulation results the specific type of phenomenological dependency between the inherited plastic strain and the martensite phase fraction is proposed.