Hydrogen is likely to play a key role (worldwide) in a future clean energy economy. Although pipeline transmission appears to be the most economical means to transport gaseous hydrogen, fundamental understanding of the deleterious effects of hydrogen on the fatigue and fracture properties of pipeline steels is lacking. Furthermore, engineering tools for design and lifetime prediction of pipeline steels in gaseous hydrogen are yet to be developed and implemented into national codes. This work proposes a phenomenological fatigue crack propagation (FCP) model for API-5L X100 pipeline steel exposed to high-pressure gaseous hydrogen. The semi-empirical model is predicated upon the hypothesis that one of two mechanisms dominate the fatigue crack growth (FCG) response, depending upon the applied load and the material hydrogen concentration. The proposed model predicts fatigue crack propagation as a function of applied driving force (ΔK) and hydrogen pressure. Results of fatigue crack growth tests in gaseous hydrogen, as well as fracture morphology, are presented in support of the proposed model. The model correlates well with test results, and elucidates how the deformation mechanisms contribute to fatigue crack propagation in pipeline steel in environments similar to those found in-service.
Citation: International Journal of Fatigue
Pub Type: Journals