Deformation Induced Phase Transformation from epsilon martensite to alpha prime martensite in Fe-12Mn steel at low temperatures

摘要

High manganese steels has been reported to show an excellent combination of strength and ductility,which could be attributed to microstructural change during the plastic deformation.This deformation induced phase transformation (DIPT) of austenite phase intomartensite phase was indeed found to raise the ductility of Fe-12Mn steel through continuousrelaxation process of internal strain energy accumulated during the plastic deformation.This transformation rate was investigated in the present study through the stability of epsilon martensite based on an internal variable theory of inelastic deformation.The epsilonmartensite phase was found to become more stable as the test temperature was reduced down to liquid nitrogen temperature,contrary to the case of austenite phase being more stable at higher temperatures.This reversed stability-temperature relationship appearedto provide enhanced ductility at lower temperatures exhibited in the present Fe-12Mn steel.