Effect of Ion Selectivity of Corrosion Products on Corrosion Behavior ofP110S Low Alloy Steel in Pure H₂S Environment

A high temperature and high pressure autoclave was used to simulate pure H₂S-Cl^- corrosion environment, and the corrosion weight loss tests of P110S low alloy steel were carried out at different temperatures. The corrosion rate of the steel was evaluated by weight loss method, and the effects of temperature on the corrosion behavior of the steel were investigated by means of scanning electron microscopy (SEM), X-ray diffractometer (XRD), laser confocal microscope and membrane potential test. The results showed that the corrosion rate increased with the increase of temperature. When the temperature was lower than 120℃, the increase of corrosion rate was small, but when the temperature was higher than 120℃, the corrosion rate increased sharply. At low temperature, the corrosion rate of sample was low and uniform, and the corrosion product was mackinawite, showing cation selectivity. At high temperature, the corrosion rate of sample was higher and existed pitting. The corrosion product was pyrrhotite, which was anion selective.