Influences of carbon concentration on microstructure and tensile properties of Fe–18Mn–9Cr–2Al-xC steels

Abstract As an effort to develop corrosion resistant and highly formable austenitic steels, Fe–18Mn–9Cr–2Al-(0–0.5)C steels in wt. % were designed and their microstructures and tensile properties were investigated with particular attention being paid to the effects of carbon concentration. The carbon-free steel consisted of the austenite, δ-ferrite and e-martensite phases in as heat-treated condition while those of carbon-added steels had an austenite single phase with the (Fe,Cr)23C6 carbides at grain boundaries. When tensile strained at room temperature, all the steels exhibited extensive deformation twinning, resulting in large work-hardening and excellent ductility. Deformation twinning was suppressed at 300 °C, and dynamic recrystallization took place partially at grain boundaries when strained at 600 °C. The addition of Cr and hence formation of carbides in carbon-added steels have little influence on plasticity of the conventional twinning-induced plasticity steels, suggesting the possibility of developing Cr-bearing TWIP steels with both corrosion resistance and excellent formability.