Electrochemical Studies of the Corrosion Behavior of Carbon and Weathering Steels in Alternating Wet/Dry Environments with Sulfur Dioxide Gas

Electrochemical impedance techniques were used to investigate the corrosion behavior of carbon steel (CS) and weathering steel (WS) in sulfur dioxide (SO₂)-containing environments. Impedance measurements were conducted in a modified three-electrode electrochemical cell covered by a thin electrolyte layer during the wet/dry period. Results showed WS was more resistant to SO₂-induced atmospheric corrosion than CS. Three forms of impedance spectra were observed, depending upon exposure period. Accordingly, three impedance models were proposed to explain the characteristic impedance data and corrosion behaviors in different stages of exposure. The proposed models and equivalent circuits produced good agreement with experimental impedance data.