The determination of experimental parameters necessary for the modelling of hydrogen embrittlement or stress corrosion cracking using the electrochemical permeation technique

Détermination à l’aide de la technique de perméation électrochimique de quelques paramètres nécessaires à la modélisation des phénomènes de fragilisation par l’hydrogène ou de corrosion sous contrainte

Abstract

The knowledge of the diffusion coefficient of hydrogen in metals and the related problems of surface effects, trapping and short path for hydrogen diffusion is necessary for the understanding of hydrogen embrittlement and stress corrosion cracking phenomena. This paper presents the capabilities of the electrochemical permeation technique to get quantitative information on the effect of surface effects (passive, oxide or corrosion films), deformation or grain boundaries on the hydrogen diffusion and permeability to hydrogen of iron, ferritic steels and nickel. These factors may govern the diffusion process as well as the electrochemical conditions, leading to a wide range of data for hydrogen diffusivity. They must be taken into account in the analysis of embrittling phenomena where hydrogen is supposed to be involved.