Experimental and Self-Consistent Modeling Study of De-twinning in a Twinning-Induced Plasticity Steel

The effect of compression-tension loading on the microstructure evolution in a fully annealed Fe-24Mn-3Al-2Si-1Ni-0.06C twinning-induced plasticity steel has been investigated. Electron back-scattering diffraction was used to track a region of interest at true strains of 0 (initial), -0.09 (after forward compression loading), and 0.04 (after reverse tension loading). All deformation twins detected after forward compression loading were found to de-twin upon subsequent reverse tension loading, likely due to the reverse glide of partial dislocations bounding the twins. The reverse loading behavior, including the twinning and de-twinning processes, was successfully simulated using a recently modified dislocation-based hardening model embedded in the visco-plastic self-consistent polycrystal framework, taking into account the dislocation accumulation/annihilation, as well as the twin barrier and back-stress effects.