LAUSR

Abstract The characteristics of calcareous deposits under strong cathodic current and their effect on hydrogen uptake of X80 steel in simulated soil environments were studied by scanning electron microscopy (SEM), hydrogen permeation technique, and hydrogen content tests. When the impressed cathodic current density was in the range of 10–75 mA/cm2, granular or squamous CaCO3 deposits were generated on the surface, forming discontinuous surface layer with pores and gaps of various sizes. When the current density was increased to 100 mA/cm2 and 125 mA/cm2, a dense Mg (OH)2 film was formed on the surface. With the increase of current density, the sub-surface hydrogen concentration and average hydrogen content first increased and then decreased, reaching the turning point at 75 mA/cm2. Combined with the structure and component characteristics of calcareous deposits, the mechanism of their effect on hydrogen uptake was analyzed.