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Modelling hydrogen dragging by mobile dislocations


In metallic materials, hydrogen atoms diffuse trough lattice sites and can be trapped on defects, as vacancy or dislocations. These traps can move, leading to an induced mobility of the trapped hydrogen, modifying the hydrogen distribution in the sample. Hydrogen dragging by moving dislocation has been observed in various materials, leading to an increase of the apparent hydrogen diffusion coefficient. While numerous experimental investigations have been conducted in the 80’s on hydrogen transport by mobile dislocation, little attention has been paid to its modelling. Recently, a revised hydrogen transport and trapping model accounting for this phenomenon has been proposed, using an extra flux term. In the present work, an alternative revision is considered, based on trap mobility. Reaction-diffusion equations are used to describe the temporal evolution of the trapped hydrogen concentration and of the trap density. A transient trapping kinetics permits to link the diffusive and the trapped hydrogen. These equations are implemented in Abaqus finite element software by using User Subroutines. This allows to describe interactions between trap creation (by plasticity), trapping process, hydrogen diffusion and hydrogen dragging by mobile traps. By using a Small-Scale Yielding (SSY) configuration, and based on literature results, this approach is proven to be an extension of the classical transport and trapping equation as initially proposed by Sofronis and latter modified by Krom. A parametric study is then conducted to illustrate the acceleration of hydrogen transport due to hydrogen dragging by mobile dislocation and, especially, the effect of trapping kinetics, hydrogen diffusion, and mechanical loading rate on the hydrogen distribution.
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Dates and versions

hal-03886801 , version 1 (06-12-2022)


  • HAL Id : hal-03886801 , version 1


Y. Charles, Jonathan Mougenot, Monique Gaspérini. Modelling hydrogen dragging by mobile dislocations. International Conference on Metals and Hydrogen, Oct 2022, ghent, Belgium. ⟨hal-03886801⟩
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