Abstract
The martensitic transformation induced by plastic deformation at sub-zero temperatures in 18-8 type austenitic stainless steels has been studied a great deal.
In the present work the martensitic transformation not induced by deformation but by holding isothermally above the Ms temperature was investigated by means of transmission electron and light microscopy (especially by using the magnetite powder method). In an earlier stage of isothermal holding, both ε and α′ martensites were often observed, but the former decreased and the latter increased with increasing holding time.
By comparing with isothermal martensitic transformation in an Fe-Ni-Mn alloy containing no ε martensite in transformation products, ε was found to contribute to the nucleation of isothermal martensite in an Fe-Cr-Ni alloy. These observation suggest that most of α′ formed isothermally should be related to the ε.
