Crystal crack dislocation model and micro-crack nucleation criterion in the hydrogen environment

Abstract

Based on the theory of fracture mechanics, a hydrogen brittleness model of microcrystalline Al materials is proposed by using the distributed dislocation method. The distinguishing feature of this study is that the model can be used to clarify the dependence of hydrogen atoms at different positions and different numbers of hydrogen atoms on dislocation emission in the initial stage of corrosion fracture. At the same time, the mechanism of crack nucleation at the grain boundary in the hydrogen environment is studied. The results indicate that hydrogen can facilitate the emission, proliferation and motion of dislocations at the crack tip, and increase the accumulation energy of dislocations at the grain boundary, making it easier to generate micro-cracks. In the corrosive environment with hydrogen, a large number of hydrogen atom segregation at the grain boundary reduces the surface energy, and cracks are more likely to occur, and the length of microcracks is longer than that in the absence of hydrogen. These studies are helpful to deepen the understanding of the hydrogen embrittlement of materials.