Dynamic microstructure evolution and mechanism of Fe-38Mn alloy during hot shear-compression deformation

The dynamic microstructure evolution and mechanism were investigated for Fe-38Mn alloy during hot shear-compression deformation under wide ranges of deformation temperature and strain rate. It was found that increasing the strain rate or the deformation temperature can promote the dynamic recrystallization of Fe-38Mn alloy. In comparison, increased strain rate is more beneficial to obtain fine grains. However, when the deformation temperature reached 1100 degrees C the obvious growth of dynamic recrystallized grains occurred under all strain rates. Benefited from the strain path of the shear-compression deformation and low stacking fault energy of Fe-38Mn alloy, numerous micro-shear bands were introduced into deformed microstructures. The dynamic recrystallization is discontinuous in appearance but continuous in nature, which is actually caused by the micro-shear bands. Furthermore, the mechanism of twinning induced nucleation was confirmed. Particularly, the deformation twinning played a key role on grain refinement and exhibited strong dependence on the strain rate.