This paper illustrates the results of laboratory tests on the influence of AC interference on carbon steel corrosion under different conditions, i.e. free corrosion, anodic or cathodic polarization. Anodic polarization simulates corrosion conditions of buried structures in the presence of galvanic coupling, typically with bare copper grounding systems. Cathodic polarization simulates the buried structures under various cathodic protection levels. The environments considered were: sulfate and chloride aqueous solutions, aerated or de-aerated conditions, simulating soils with different electrical resistivity, and seawater. AC was overlapped to the specimens (200-2,500 mm 2) at different current densities, ranging from 10 to 6,000 A/m 2. Anodic and cathodic DC current were in the range of 0.1-10 A/m 2. The influence of AC on anodic and cathodic overpotentials was studied. In the case of anodic polarization, the influence of AC on anodic current density was also measured.
Keywords: AC interference, carbon steel, anodic polarization, cathodic polarization.