Influence of hydrogen on the strength of metallic structures

Abstract

The study examines the physicochemical and mechanical mechanisms of degradation of metallic structures under the action of hydrogen that adsorbs and diffuses into the region of the stress-strain field. The equations describing the influence of surface processes on the critical pressure at which unstable crack propagation occurs are presented. A macro-level criterion for hydrogen-induced fracture is constructed, combining hydrogen concentration, stress state parameters, and strain energy. It is shown that this criterion is consistent with the local conditions of hydrogen accumulation at the crack tip. A local criterion for achieving a critical concentration governed by stress intensities and plastic shear deformation is also considered. The relationship between surface adsorption processes, hydrogen diffusion transport, and the micromechanisms of microcrack initiation and growth is established. The developed model provides a unified, multiscale description of hydrogen effects on the fracture toughness of metals, ranging from surface energy changes to local and macro-fracture criteria. The proposed relations form a basis for further numerical studies and can be used to assess the residual life and predict the durability of structural components operating in hydrogen environments.