Microstructure and Mechanical Properties of Al-Added High Mn Austenitic Steel

Many studies about high Mn austenitic steels have been done due to their excellent mechanical properties such as tensile strength, uniform ductility, and wear resistance. In this paper, we tried to summarize the effects of Al addition on carbide precipitation, stacking fault energy (SFE), dynamic strain aging (DSA), tensile properties, and hydrogen delayed fracture in high Mn austenitic steels such as Hadfield and TWIP steels. The addition of Al suppressed the cementite precipitation due to the decreases in both activity and diffusivity of C in austenite. However, the κ′-carbide precipitation with a chemical formula (Fe, Mn)₃AlC _x may occur in the high Mn and Al austenitic steel. The addition of Al linearly increased the stacking fault energy of austenite. The Al addition increased the strain hardening rate in the Hadfield steels owing to the increase in the DSA effect caused by the increased solute C content, while it decreased the strain hardening rate in the high Mn TWIP steel because of the decreases in mechanical twinning caused by high SFE and in DSA effect caused by slow diffusivity of C atoms. The addition of Al improved the resistant property to the hydrogen delayed fracture in the high Mn TWIP steels.