Electrochemical corrosion behavior of X80 pipeline steel in a near-neutral pH solution

In this work, the electrochemical corrosion behavior of X80 pipeline steel was investigated in a near-neutral pH solution using electrochemical impedance spectroscopy (EIC) and photo-electrochemical (PEC) measurements as well as X-ray photo-electron spectroscopy (XPS) technique. The effects of hydrogen-charging and stress were considered. The results show that the steel is in an active dissolution state, and a layer of corrosion product is formed and deposited on the electrode surface, which is subjected to further oxidation to form ferric oxide and hydroxide. Photo-illumination enhances anodic dissolution of the steel when it is under anodic polarization due to destroying of the corrosion product film. When the steel is under cathodic polarization, the cathodic current density decreases upon laser illumination due to the photo-oxidation of hydrogen atoms generated during cathodic reactions, which behaves as an anodic reaction to offset the cathodic current density. Hydrogen-charging and stress decrease the corrosion resistance of the steel and enhance the dissolution rate of the steel.