Microscopic insights of the extraordinary work-hardening due to phase transformation

相変態による驚異的な加工硬化の微視的的理解

Ma, Y.*; Naeem, M.*; Zhu, L.*; He, H.*; Sun, X.*; Yang, Z.*; He, F.*; Harjo, S.   ; 川崎 卓郎   ; Wang, X.-L.*

Ma, Y.*; Naeem, M.*; Zhu, L.*; He, H.*; Sun, X.*; Yang, Z.*; He, F.*; Harjo, S.; Kawasaki, Takuro; Wang, X.-L.*

We report an in situ neutron diffraction study of 316 L that reveals an extraordinary work-hardening rate (WHR) of 7 GPa at 15 K. Detailed analyses show that the major contribution to the excellent strength and ductility comes from the transformation-induced plasticity (TRIP) effect, introduced by the austenite-to-martensite (-to-') phase transition. A dramatic increase in the WHR is observed along with the transformation; the WHR declined when the austenite phase is exhausted. During plastic deformation, the volume-fraction weighted phase stress and stress contribution from the '-martensite increase significantly. The neutron diffraction data further suggest that the -to-' phase transformation was mediated by the -martensite, as evidenced by the concurrent decline of the phase with the phase.