Weibull Model for Hydrogen-induced Fracture of High Strength Steel

Abstract

This study proposes a new evaluation model of hydrogen-induced unstable fracture of high strength steel and/or its welds. In this model, a new driving force for hydrogen-induced fracture, Hydrogen-Weibull stress, is proposed on the basis of the original Beremin model, where cohesive energy reduction due to diffusible hydrogen is implemented into the local unstable fracture model. The Hydrogen-Weibull stress, which is enlarged not only by the local stress but also by diffusible hydrogen content, can be independent of geometrical parameters of components as well as diffusible hydrogen content. The validity of this Hydrogen-Weibull stress is demonstrated by constant load test conducted with different load level and with various initial hydrogen contents.KEY WORDS: hydrogen embrittlement; hydrogen-induced unstable fracture; delayed fracture; high strength steel; hydrogen content; weibull stress.

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

“…This equation represents the effect of hydrogen diffusing to a crack tip and assisting in further propagation. Additionally, Ohata et al [151] have used a semiempirical expression for that was obtained by the weakest link theory. They tested the model for different loading and H concentrations, showing that local stress concentrations are not only influenced by the diffusible hydrogen but also by the geometry of the components.…”