THREE-DIMENSIONAL ANALYSIS ON HYDROGEN-RELATED INTERGRANULAR CRACK PROPAGATION IN MARTENSITIC STEEL
Akinobu ShibataGrand Ballroom C
This study investigated three-dimensional propagation behavior of hydrogen-related intergranular crack in martensitic steel by X-ray computed tomography and FIB-SEM serial sectioning. Macroscopic analysis using X-ray computed tomography revealed that the crack morphology exhibited more continuous in the hydrogen-charged specimen. Through FIB-SEM serial sectioning, we found that the crack-tip blunting and ductile rupture of un-cracked ligaments were associated with a certain grain boundary segment in the uncharged specimen. In the case of hydrogen-related intergranular crack propagation, even very fine low-angle grain boundary segments (sub micro-meter size) could act as obstacles to crack propagation. Based on the results, we can propose that misorientation of each grain boundary segment has a large influence on local crack arrestability of intergranular crack propagation.