Shaolou Wei¹, Jinwoo Kim¹, Cemal Cem Tasan¹; ¹Massachusetts Institute of Technology

Classical transformation-induced plasticity (TRIP) effect is considered as one of the most effective strain hardening mechanisms in metallic alloys. While appreciable effort has been accomplished to maximize the strain hardening contribution of this mechanically-induced transformation in Fe-based alloys, the resultant transformation product, ferrous martensite, possesses extensive defect density and limited strain hardenability, which inevitably leads to local embrittlement. In this presentation, we will demonstrate that the parent-FCC phase in an Fe-Mn-rich alloy can exhibit the strain-induced HCP-martensitic transformation, and the resulting HCP phase can further transform, activating a mechanically-induced FCC-HCP-FCC dual-TRIP effect. With the aid of in-situ synchrotron X-ray diffraction, integrated SEM/EBSD, and microstructural-based strain mapping techniques we reveal the corresponding deformation micro-mechanisms including transformation kinetics, kinematics, and global-local strain evolution. We will show that this sort of dual-TRIP mechanism exhibits a desirable potential to overcome the inherent property improvement limit of classical-TRIP effect.