Investigation of Mechano-Electrochemical Effects on Hydrogen Distribution at Corrosion Defects

This study employed tensile test, hydrogen permeation measurements, and potentiodynamic polarization testing to investigate the mechanical properties, hydrogen diffusion coefficients, and electrochemical behavior of X80 steel. A multifield coupled finite element (FE) model was developed that incorporated the mechano-electrochemical (M-E) effect to analyze the stress–strain distribution, anodic equilibrium potential, cathodic exchange current density, and hydrogen distribution characteristics at pipeline corrosion defects under varying tensile strains. The results indicated that tensile strain significantly modulated the anodic equilibrium potential and cathodic exchange current density, leading to localized hydrogen accumulation at corrosion defects. The stress concentration and plastic deformation at the defect site intensified as the tensile strain increased, further promoting hydrogen enrichment. The study concluded that the M-E effect exacerbated hydrogen enrichment at the defect sites, increasing the risk of hydrogen-induced cracking. The simulation results showed that the hydrogen distribution state aligned with the stress–hydrogen diffusion coupling model when considering the M-E effect. However, the M-E effect slightly increased the hydrogen concentration at the defect. These findings provide critical insights for enhancing the safety and durability of hydrogen transmission pipelines.