Numerical Modeling for Hydrogen Permeation Through Steel Under Sour-Corrosion and Tensile Stress

New perspectives arise from the application of the finite difference method (FDM), which incorporates the dynamic change in sub-surface hydrogen concentration ( C S ) on the steel surface, for analyzing hydrogen permeation behaviors under the combined action of sour corrosion and tensile loading. With this modified-FDM modeling and quantified C S values, it can be mechanistically understood that the loaded steel undergoes a cycle consisting of a higher hydrogen evolution rate on the surface, weakening the stability of the corrosion scale (FeS X ) with more defects, and increased electrical conductivity. This leads to maintaining higher C S level, based on a higher cathodic reduction reaction.