Alloy Design of 5%Mn-Cr-C System Austenitic Steel

The range of chemical composition for obtaining austenitic single structure was defined in medium-manganese carbon steels. Among the defined composition, Fe-5%Mn-4%Cr-(0.8~1.4)%C was selected as the optimum range of composition to form stable austenitic structure. The tensile property and deformation substructure were investigated in the austenitic steels with corresponding composition. As a result, the work hardening behavior of the steels was varied depending on the carbon content, which was closely related with the development of deformation microstructure. In the 0.8%C steel, deformation-induced martensitic transformation as well as deformation twinning caused large work hardening until fracture took place. With increasing carbon content, namely increasing SFE, the deformation mode tended to shift to dislocation slipping, resulting in the lower work hardening rate. This trend seems to be similar to conventional TWIP steel where the work hardening behavior is explained with SFE.