In-situ study of tensile deformation behaviour of medium Mn TWIP/TRIP steel using synchrotron radiation

This investigation proposes a pathway for generating optimum microstructure for a medium Mn containingtwinning-induced plasticity/transformation-induced plasticity (TWIP/TRIP) steels. The steel contains a twophasemicrostructure consisting of austenite and ferrite phase arranged in a lamellar fashion. The microstructurewas developed following a specially designed thermo-mechanical processing schedule that involvedquenching and partitioning. The feedback for the design of thermo-mechanical processing was obtained bycarrying out in-situ deformation in high energy synchrotron radiation under tensile loading. Diffraction patternswere analysed for estimating the retained austenite phase fraction and other aspects of microstructural evolution.X-ray line profile analysis was performed to determine crystallite size, dislocation density, and twin density atindividual stages of deformation. In the early stages, deformation occurs by dislocation slip in both phases, whilein the later stages, deformation in the austenite phase occurs via twinning and martensitic transformation, and inthe ferrite phase by dislocation slip. Strain hardening behaviour has been analysed and correlated with microstructuralparameters