Discrete distribution dislocation study on fracture behavior of nanocrystalline materials in the hydrogen environment

Abstract

A lot of experimental and theoretical work has been done on the traditional macroscopic mechanism of hydrogen embrittlement (HE). There are a lot of theoretical studies on the micro-mechanism of HE recently published. In this article, based on the discrete dislocation method, taking into account the interaction between hydrogen atoms fixed in the defects of crystal materials and dislocation, a theoretical calculation method for the fracture of hydrogen-induced nanocrystalline (NC) materials is proposed. Considering the influence of hydrogen in the dislocation emission (DE) model, the theory of hydrogen inhibiting dislocation emission is put forward under the stable equilibrium state, which restrains the passivation of cracks and intensifies brittle fracture. At the same time, the pinning effect of hydrogen on dislocation is studied by theoretical method. In this paper, the relationship between the grain size and dislocation number in hydrogen free environment and hydrogen environment is described. The results show that the critical stress intensity factor (SIF) of crystal materials in hydrogen environment decreases by about 18.6%, indicating that hydrogen promotes the fracture of crystal materials. This paper provides a theoretical study for understanding the fracture behavior of hydrogen-induced materials.