Abstract

X-ray line profile analyses results incorporating the dislocation induced strain anisotropy is reported to understand the influence of Al content on deformation microstructure of three high-Mn steels with different Al contents (0, 1, 3 wt%) deformed under uniaxial tension until fracture. Deformation induced ε-martensite was detected only in the deformation microstructure of the steel not containing any Al. However, deformation twinning and dislocation substructures were frequently observed for steels containing 1 wt% and 3 wt% Al, respectively. The population of screw dislocations in the microstructure increased with increasing Al content. Further, the estimated dislocation densities are in the order of ∼10¹⁵ m⁻² and that they gradually decrease with increasing Al content in the steel — the minimum value was estimated in 3Al steel, attributed to the interrelation between the stacking fault energy of the steel and dynamic recovery. Accordingly, the stacking fault energies of the steels estimated from a modified X-ray diffraction line profile analyses approach were: 18.1, 25.7 and 41.6 mJm⁻² for steels containing: 0, 1, 3 wt% Al, respectively — corresponding to a linear increment of ∼7.85 mJm⁻² per 1 wt% Al concentration. Transmission electron microscopy also corroborated the X-ray line profile analyses results.