Hydrogen embrittlement （HE） is a major concern impeding the durability of structural materials. Numerous parameters affect this phenomenon, such as hydrogen trapping or the presence of a surface layer [1]. Among the characteristics altering the diffusion of hydrogen in polycrystalline materials, the microstructure has a preponderant role. Despite the large documentation about the subject, the contribution of hydrogen on this process remains unclear, especially the influence of the grain boundaries, considered either as fast diffusivity paths or segregation areas [2].

　　In this work, we present an analysis of the effects of the microstructure on hydrogen diffusion and hydrogen trapping, by considering grain boundaries either as diffusion short-circuits or preferential trapping sites. To understand these phenomena, electrochemical permeation tests [3] were simulated using the finite element method （FEM）， for regular hexagonal or random Voronoi 2D-microstructures. The modelled membranes contain several phases （grains, random/sigma grain boundaries, triple junctions） with different diffusion properties.

　　The macroscopic behaviour of the material is affected by the heterogeneous distribution of the phases and their properties. Two main points are considered in this work; scale effects between the representative volume element （RVE） and the size of the membrane, and the role of the connectivity and percolation of grain boundary networks on hydrogen diffusion.

　　[1] E. Legrand, J. Bouhattate, X. Feaugas, H. Garmestani, “Computational analysis of geometrical factors affecting experimental data extracted from hydrogen permeation tests: II - Consequences of trapping and an oxide layer”, Int. J. Hydrogen. Energ. 38 （2012）， pp. 13574-13582.

　　[2] A. Oudriss, J. Creus, J. Bouhattate, C. Savall, B. Peraudeau, X. Feaugas, “The diffusion and trapping of hydrogen along the grain boundaries in polycrystalline nickel” Scr. Mater. 66 （2012）， pp. 37-40.

　　[3] M. A. V. Devanathan, Z. Stachurski., “The adsorption and diffusion of electrolytic hydrogen in palladium”, Proc. R. Soc. Lond. A.270, （1962）， pp. 90-102.

中国腐蚀与防护网官方QQ群：140808414
《中国腐蚀与防护网电子月刊》征订启事
摘要阅读联系：郭静 电话：010-82387968-802
QQ: 815397784 邮箱：guojing733@163.com