Modeling of Atmospheric Corrosion Behavior of Weathering Steel in Sulfur Dioxide-Polluted Atmospheres Available to Purchase

Atmospheric corrosion resistance of carbon steel (CS) and high-phosphorus weathering steel (WS, Acr-Ten A) was compared after exposure for up to 6 years in Taiwan. In an industrial atmosphere, corrosion kinetics of WS after 3 years of exposure deviated from behavior predicted by the well-known bilogarithmic law. This deviation was simulated using a laboratory accelerated test under cyclic wet/dry conditions with addition of 1 ppm sulfur dioxide (SO₂). In-situ electrochemical impedance measurements also were carried out in a modified three-electrode cell covered by a thin electrolyte layer to investigate corrosion behavior of WS in SO₂-polluted environments. Three impedance models were proposed to explain the characteristic corrosion behavior of WS in various stages of exposure.