Multi-scale three-dimensional analysis on local arrestability of intergranular crack in high-strength martensitic steel

The present study investigated the local arrestability of intergranular crack in high-strength martensitic steel through multi-scale three-dimensional (3D) analysis using X-ray computed tomography and focused ion beam machining (FIB)-scanning electron microscopy (SEM) serial sectioning combined with backscattering diffraction (3D EBSD). Macroscopic demonstrated discontinuous propagation cracks, indicating arrest propagation. An opening displacement each component revealed that resolved normal stress was not only factor determining path. relationship between microstructure crack-arrestability microscopically analyzed FIB-SEM sectioning. 3D EBSD clearly suggested propagations were arrested at low-angle grain boundary plane segments triple junctions surrounded by relatively large martensite variants. Moreover, larger variants around boundaries contributed to plastic accommodation concentration promoted crack-tip blunting. We propose increasing fraction as well existing can enhance retard fracture steels.