Open Access Conference Proceedings

A physical model describing the diffusion of interstitial atoms was developed and has been repeatedly used to study the redistribution of hydrogen, as well as predicting the risk of hydrogen damage during various real manufacturing processes.A particular advantage of this model is that, contrary to some simplified commercial and academic models, it contemplates diffusion in its most comprehensive description, i.e., with the driving force for atom diffusion being the gradient in chemical activation (and not simply occurring down a composition gradient). As the model also incorporates thermal history, microstructure, matrix solubility, multiple trapping distributions, interaction with the atmosphere and others, that is especially suitable to study of real manufacturing processes.In this case, two applications of interest both to academia and industry are presented. Fist, the model is applied to simulate a Thermal Desorption Analysis (TDA) test. By using the model, it is possible to relate desorption fluxes with the redistribution between different trapping sites within the metal.Then hydrogen permeation is considered. In the case studied hydrogen is transported through a metal wall separating one volume with high hydrogen pressure and temperature from another volume with low hydrogen pressure and temperature. By using such comprehensive physical model, it is possible to study the effects of hydrogen pressure and temperature gradient, wall thickness, metal microstructure and trap distribution on the flux across the wall and on the accumulation of hydrogen within the metal. Furthermore, it makes possible to estimate the embrittlement risk and when necessary the time to fracture.

Keywords: Hydrogen, steel, permeation, Thermal Desorption Analysis, physical model

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