Effect of stacking fault energy on formation of deformation twin in high Mn austenitic steel

The effect of stacking fault energy (SFE) on the formation of deformation twin in Fe-18Mn-xAl-0.6C steel with x being 0-3% subjected to a true tensile strain of 0.4 has been investigated. The tensile deformation textures are approximated by major < 111 >// RD and minor < 100 >// RD fibres along the tensile axis parallel to the rolling direction (RD). Twinning is dependent on the grain orientation and takes place well on the < 111 >// RD fibres, and this tendency increases with increasing SFE. The orientation dependence of twinning is well described by Schmid's law. We also measured the twin thickness and lamellae spacing by electron backscattered diffraction. The twin thickness and lamellae spacing increase with increasing SFE. The difference of twin thickness according to SFE was analysed by means of nucleation and growth kinetics of twins during plastic deformation. Using the Hall-Petch relationship, we found the contribution of twinning to the tensile strength.