Effect of SO₄^2- on pitting corrosion behavior of X80 pipeline steel in NaHCO₃ solution containing Cl^-

Effect of SO₄^2- on the pitting corrosion behavior of X80 pipeline steel has been investigated in 0.5 mol/L NaHCO₃ solution containing 0.01 mol/L NaCl by potentiodynamic polarization experiment, and the mechanism was discussed based on capacitance measurements technique. The potentiodynamic polarization curves showed that the values of pitting potential (E_pit) reduced and number of pitting corrosion increased after adding SO₄^2-. The reason was the increase of defects due to the adsorption of SO₄^2- on X80 steel surface, and the pitting initiation sites and occurrence probability were enhanced.