AC interference on hydrogen absorption in low carbon steel under cathodic protection

Abstract

The effect of AC and cathodic protection (CP) potentials on hydrogen evolution and absorption in carbon steel 1010 is investigated by hydrogen permeation tests, using a Devanathan-Stachurski electrochemical cell. Hydrogen evolution reaction occurs via the coupled discharge-recombination mechanism under CP and AC. Hydrogen permeation is controlled by bulk diffusion and less than 1% of the total hydrogen permeates through the steel membrane. A significant increase in the hydrogen uptake occurs as the AC voltage increases with more negative CP potentials. More negative CP potentials increase the hydrogen flux and absorption under AC imposition. The highest effective hydrogen diffusivity (∼5 × 10−8 cm2/s) and subsurface hydrogen concentration (∼3.5 × 10−5 mol/cm3) are found at −1.5 VSCE with AC imposition. These results demonstrate a synergy between the CP potential and AC voltage on the hydrogen evolution and absorption behavior in steel and provide insights into the implications of AC interference with CP on hydrogen embrittlement.