Influence of SO₄^2- on Corrosion Behavior of X80 Steel in Simulated Acid Red Soil Solution

The influence of SO₄^2- on corrosion behavior of X80 pipeline steel in simulated acid red soil solution was investigated by analysis of potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) and three-dimensional video microscopy. The results show that the corrosion rate of X80 steel firstly decreased and then substantially increased with the increase of SO₄^2- concentration; when the mass fraction of SO₄^2- was 5%, the weight loss and the corrosion current density of X80 pipeline steel were minimum. EIS results show that the concentration of SO₄^2- could affect the corrosion behavior of X80 steel. When the mass fraction of SO₄^2- was 1%~5%, SO₄^2- blocked the adsorption of Cl^- on the electrode surface, and slowed down the corrosion; the concentration of SO₄^2- could damaged the film forming on the electrode surface, and then accelerated the corrosion rate.