Theoretical Clarification of Facet like Fracture in Hydrogen Embrittlement

Abstract

Based on a two-dimensional physical model of a mode I crack with a slip band, the analysis of mechanical interaction between hydrogen and dynamic dislocations with non-steady emission from a stressed source around a crack tip is conducted. To analyze the mechanical interaction between a crack and dynamic dislocations on a neighboring slip band, a crack is replaced by static discrete dislocations mechanically equivalent with the crack and a physical model of analyzing the mechanical interaction between static, dynamic dislocations and hydrogen is constructed. The occurrence conditions of the mechanisms of corrosive anodic chemical reaction, inter-granular cracking due to hydrogen concentration and facet like fracture due to the interaction between hydrogen and dynamic dislocations were clarified. These results were found to be in good agreement with previous results based on a convenient one-dimensional model. Furthermore, the competitive interaction between hydrogen and dynamic dislocations which causes the facet like fracture is found to occur under the limited velocity range of hydrogen and dynamic dislocations which is closely related to the corresponding range of yield stress.