Presence of ε-martensite as an intermediate phase during the strain-induced transformation of SUS304 stainless steel

Abstract

We have investigated the formation process of α′-martensite from the γ-phase induced by external strain using in situ synchrotron diffraction experiments, combined with Lorentz transmission electron microscopy (TEM) and high-resolution TEM observations. It is clearly demonstrated that ε-martensite with hexagonal symmetry appears as an intermediate structure during the plastic deformation of SUS304 stainless steel. In addition to stacking faults and dislocations, interfaces between the twin structures presumably play a key role in the formation of ε-martensite.

Keywords:

• Austenitic stainless steel
• induced α′-martensite
• deformation structures
• stacking fault
• dislocation
• stacking-fault energy

Acknowledgements

The authors would like to thank Professor M. Nagumo at Waseda University for fruitful discussions. We appreciate Drs. K. Sugimoto and N. Yasuda for their kind help with the synchrotron X-ray diffraction experiments. The synchrotron X-ray diffraction experiments were performed at the beamline BL02B1 of SPring8 with the approval of the Japan Synchrotron Radiation Research Institute (Proposal No. 2012B1611).