Effect of Deformation Induced Transformation of ε-Martensite on Ductility Enhancement in a Fe-12 Mn Steel at Cryogenic Temperatures

Metastable ε-martensite (ε-Ms) formed during a prior heat treatment of Fe-12Mn steel has been reported totransform into α-Ms during subsequent inelastic deformation. This deformation induced phase transforma-tion (DIPT) from ε-Ms to α-Ms has been investigated in the present study within the framework of kineticsrelation proposed based upon an internal variable theory of inelastic deformation. The ε-Ms phase was found tobecome more stable at lower temperatures to provide more prolonged DIPT from ε-Ms to α-Ms during aninelastic deformation at cryogenic temperatures, contrary to the case of austenite phase in various transformationinduced plasticity steels being more stable at higher temperatures. This reversed stability-temperature rela-tionship in Fe-12Mn steel appeared to provide a significant ductility enhancement at lower temperatures as wellas significant strengthening effect. KCI Citation Count: 14