Title: Adsorption of hydrogen on iron and the hydrogen embrittlement of steel
Abstract: The mechanical properties of certain steels become severely degraded in the presence of a hydrogen environment. It is generally accepted that adsorption of hydrogen on to the surface of the steel is the first step in this phenomenon known as hydrogen embrittlement. A review of the literature with respect to hydrogen adsorption on iron and hydrogen embrittlement reveals that good correlations between the two do exist. A model for the chemisorption of hydrogen on iron is developed and the calculated energies of the adsorbed states agree well with observed experimental values. The model is used to explain some of the experimental observations associated with the hydrogen embrittlement of steels. For example, the observed temperature dependence of crack growth rates can be readily interpreted within the framework of the model. The indications are that adsorption may be the key step in the embrittlement process. 4 figures, 2 tables.