Synergistic strengthening effect achieved good ductility in ultrahigh strength Fe–22Mn–8Al-0.8C austenitic lightweight steels

We present an ultra-high tensile strength of 1.86 GPa with an elongation of 11 % achieved in a Fe–22Mn–8Al-0.8C austenitic lightweight steels in this study. A partial recrystallized microstructure and κ carbides were obtained in the investigated steels by utilizing a simple thermomechanical processing. Interestingly, the existence of κ carbides not only increased the tensile strength of the investigated specimens but a dramatical increasement of ductility (from 4 % increase to 11 % in this work) was also achieved. The formation of intragranular κ carbides in the matrix can reduce the incompatibility within the material, which can further enhance tensile strength while providing good elongations. •An ultra-high tensile strength of 1.86 GPa with an elongation of 11 % achieved in a Fe–22Mn–8Al-0.8C lightweight steels.•κ carbides not only increased the tensile strength but a dramatical increasement of ductility was also achieved.•Key points of this work are utilizing the κ carbides to reduce the incompatibility between different zones within materials.•This strategy provides ideas for designing new high-strength austenitic light steels.