Deformation behavior of duplex austenite and ε-martensite high-Mn steel

Deformation and work hardening behavior of Fe-17Mn-0.02C steel containing epsilon-martensite within the austenite matrix have been investigated by means of in situ microstructural observations and x-ray diffraction analysis. During deformation, the steel shows the deformation-induced transformation of austenite -> epsilon-martensite -> alpha'-martensite as well as the direct transformation of austenite -> alpha'-martensite. Based on the calculation of changes in the fraction of each constituent phase, we found that the phase transformation of austenite -> epsilon-martensite is more effective in work hardening than that of epsilon-martensite -> alpha'-martensite. Moreover, reverse transformation of epsilon-martensite -> austenite has also been observed during deformation. It originates from the formation of stacking faults within the deformed epsilon-martensite, resulting in the formation of 6H-long periodic ordered structure.