Strain-induced martensite to austenite reverse transformation in an ultrafine-grained Fe–Ni–Mn martensitic steel

Abstract

Research was conducted to evaluate the effect of heavy cold rolling on microstructural evolution in an Fe–10Ni–7Mn (wt.%) martensitic steel. The chemical driving force for the strain-induced martensite to austenite reverse transformation was calculated using thermodynamic principles and a model was developed for estimating the effect of applied stress on the driving force of the martensite to austenite reverse transformation through heavy cold rolling. These calculations show that, in order to make a reverse transformation feasible, the applied stress on the material should supply the total driving force, both chemical and non-chemical, for the transformation. It is demonstrated that after 60% cold rolling the required driving force for the reverse transformation may be provided. Experimental results, including cold rolling and transmission electron microscopy images, are utilized to verify the thermodynamic calculations.

Keywords:

• sheet metal forming
• ultrafine-grained metals
• martensitic transformations
• transmission electron microscopy
• thermodynamics

Acknowledgements

The authors express their thanks to the Iran National Science Foundation (INSF) for the financial support of this research. Additional support was provided by the European Research Council under ERC Grant Agreement No. 267464-SPDMETALS (TGL).