Selective appearance of ϵ-martensitic transformation and dynamic strain aging in Fe–Mn–C austenitic steels

Abstract

The influence of stress-induced ε-martensitic transformation on the serrated flow behavior associated with dynamic strain aging was investigated. The ε-martensitic transformation was controlled by changing the deformation temperature and adding Si to Fe–17Mn–xSi–0.3 C alloys. The addition of Si promoted the ε-martensitic transformation, and suppressed the slip deformation due to solution hardening. The initiation of serrations around room temperature was delayed by the promotion of ε-martensitic transformation which initiated plastic deformation. The critical stress for the occurrence of serrations and the critical stress for the occurrence of slip deformation were found to have a linear relationship.

Keywords:

• martensitic transformation
• Fe-based alloy
• planar defect
• stress–strain measurement
• tensile testing
• dynamic strain aging
• austenitic steel
• solution hardening

Acknowledgements

M.K. acknowledges Research Fellowship of NIMS Junior Researcher (2009–2010) and the Japan Society for the Promotion of Science for Young Scientists (2011). The Materials Manufacturing and Engineering Station and Materials Analysis Station at the National Institute for Materials Science supported this work through the production of the samples and carrying out the analysis of the chemical compositions.