Diffusion and Trapping of Hydrogen in a Bead-on-Plate Weld

Abstract

An analytical model for diffusion of hydrogen in presence of reversible and irreversible traps in the metal is given. A numerical model for solution of the resulting system of nonlinear partial differential equations is developed. The temperature dependence of the material parameters is estimated. The transient distributions of temperature, stress and hydrogen are numerically found for a bead-on-plate weld. The effects of trapping, stress, thermotransport and plastic strain on the hydrogen distribution are discussed. Calculated amounts of residual and diffusible hydrogen are compared with existing experimental data. It is concluded that an increased knowledge of the mechanisms behind formation of residual hydrogen is needed for practical welding situations with large amounts of residual hydrogen.