Plastic deformation and microstructural evolution during cryogenic charpy impact of high-Mn austenitic steel

Jiang, L.*; Wang, H. H.*; Su, Y. H.  ; 徐 平光   ; 篠原 武尚   ; Xia, B.*; Wang, Y. W.*

Jiang, L.*; Wang, H. H.*; Su, Y. H.; Xu, P. G.; Shinohara, Takenao; Xia, B.*; Wang, Y. W.*

In this study, pulsed neutron Bragg-edge transmission imaging was employed to characterize plastic deformation of high-manganese austenitic steel during cryogenic impact fracture. Electron backscatter diffraction was used to examine the microstructural evolution. The results reveal that the Bragg-edge width was identified as the critical value for large plastic deformation. Both crack initiation and stable crack growth regions exhibited higher levels of plastic deformation, twin density, and dislocation density compared to unstable crack growth regions. As the test temperature decreased from 273 K to 77 K, the transition point from stable to unstable crack growth occurred earlier. This is responsible for the reduction in impact absorbed energy. These findings provide new insights into the cryogenic toughening mechanism of high-manganese steel.