Microstructural based hydrogen diffusion and trapping models applied to Fe-C-X alloys

Hydrogen embrittlement of modern high strength steels consists of different interacting time-dependent mechanisms. One of these mechanisms is hydrogen diffusion and trapping to accumulate hydrogen in critical areas with high mechanical loads. Therefore, understanding hydrogen diffusion and trapping behavior of carbides containing high strength steels is an essential part to effectively increase the hydrogen resistance. For that purpose, a microstructural based model was developed and parametrized to Fe-C-V and Fe-C-Ti alloys. Generalized analytical equations were derived to describe the evolution of different kinds of trap densities with the measured carbide mean radius, annealing temperature or dislocation density. Finally, the models support the idea of hydrogen trapping at carbon vacancies and coherent interface positions. In future, these models are well suited for finite element process simulations of industrial components to predict the local solubility and chemical diffusion as demonstrated in the last section of this work. (C) 2020 Elsevier B.V. All rights reserved.