Modelling the combined effects of hydrogen traps and surface films on hydrogen permeation in ferritic steels
Anti-Corrosion Methods and Materials
ISSN: 0003-5599
Article publication date: 31 January 2020
Issue publication date: 11 March 2020
Abstract
Purpose
The purpose of this study is to develop a model extending Oriani’s formula by introducing a normalised concentration to simulate hydrogen diffusion in a multi-material system such as coated steels, under the presence of traps.
Design/methodology/approach
Implemented through the finite element method based on the analogy between mass diffusion and heat transfer, the governing equation was applied to investigate the combined effects of hydrogen traps and surface oxide films on hydrogen permeation in ferritic steels.
Findings
This study shows that the effective diffusivity varies over several orders of magnitude depending on the traps and films. This explains the divergence of measured hydrogen diffusivities in steels. It is revealed that hydrogen permeation in steels with Pd or Ni film is a trapping-dominant transport process, while hydrogen permeation in steel with oxide film is a process controlled by both trapping effect and retarding effect of oxide film. The oxide film enhances total hydrogen concentration within the steel substrate and is therefore detrimental. The Pd or Ni film has a little influence on total hydrogen concentration distribution depending on trapping energy.
Originality/value
Hydrogen flux curves and transient hydrogen concentration distributions can be directly obtained through the developed model. The proposed approach can also be extended to investigate other interstitial (i.e. carbon, oxygen and nitrogen) diffusion with traps revisited in complex systems.
Keywords
Acknowledgements
This project was supported by the National Nature Science Foundation of China (Grant No. 51571028) and National High-Tech Research and Development Program of China (Grant No. 2015AA034201).
Citation
Zhi, H., Yu, H., Gao, L., Zhang, Z. and Su, Y. (2020), "Modelling the combined effects of hydrogen traps and surface films on hydrogen permeation in ferritic steels", Anti-Corrosion Methods and Materials, Vol. 67 No. 2, pp. 240-247. https://doi.org/10.1108/ACMM-10-2019-2202
Publisher
:Emerald Publishing Limited
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