Mathematical modeling of local hydrogen concentration around defects

The mechanisms of hydrogen-induced failure and the processes of hydrogen transport in metals are considered. A mathematical model of hydrogen diffusion is proposed, which accounts for the interaction between local elastoplastic deformations and hydrogen diffusion. Using the finite element method, the distribution of hydrogen in the vicinity of crack-like defects on the inner surface of steel pipelines under internal pressure is analyzed. Analytical dependences are derived to assess the local hydrogen concentration near defects of various geometric shapes. It is established that with increasing internal pressure, the concentration of both diffusible and trapped hydrogen significantly increases, contributing to hydrogen embrittlement of the material. The obtained results can be used to predict service life of pipelines in hydrogen power applications.