Simulation of dislocation recovery in lath martensite steels using the phase-field method

Simulation of dislocation recovery using the phase-field method is used to clarify the collapse process of the lath martensite phase in high-Cr ferritic steels, in which densely packed and tangled dislocations exist. Edge dislocations move more rapidly than screw dislocations at elevated temperatures, and when stress is applied, the tendency becomes more pronounced. Dislocations form sub-boundaries, a so-called polygonization structure, in order to decrease the total energy. The size of the sub-boundary is estimated to be smaller than the lath width. As a result, it is found that collapse of the lath martensite microstructure starts with the division of laths caused by dislocation rearrangement.