Modeling the skin effect associated with hydrogen accumulation by means of the micropolar continuum

Abstract

This paper is concerned with a mechanical explanation of a highly inhomogeneous distribution of hydrogen within metal specimens, based on the micropolar continuum approach. The primary focus is on the modeling of the nonuniform stress–strain state of a cylindrical metal specimen that rapidly fades away from the border and changes the inner structure of the material near the lateral surface. The boundary condition used in the considered boundary value problem reflects the influence of the structural defects located on the boundary. Thus, this model considers inner stresses and strains due to the structural inhomogeneity. Large values of the strain energy within the area comparable to the size of the structural inhomogeneity lead to a significant increase in the diffusion coefficient in the vicinity of the border. As a result, fast accumulation of hydrogen within a thin boundary layer produces a highly nonuniform distribution of hydrogen across the specimen. The comparison between the concentrations of hydrogen measured experimentally and estimated analytically was made.