Cold Formabilities of Martensite-Type Medium Mn Steel

Cold stretch-formability and stretch-flangeability of 0.2%C-1.5%Si-5.0%Mn (in mass%) martensite-type medium Mn steel were investigated for automotive applications. High obtained in the subjected to an isothermal transformation process at temperatures between Ms Mf − 100 °C. Both formabilities decreased compared with those 0.2%C-1.5%Si-1.5Mn -3Mn steels (equivalent TRIP-aided martensitic steels), despite a larger or same uniform total elongations, especially stretch-flangeability. The decreases mainly caused by presence large amount martensite/austenite phase, although metastable retained austenite made positive contribution formabilities. content contributed increasing stretch-formability.