Stray Current Corrosion of Q235 Steel in Hainan Soil

Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were applied to observe and analyze the corrosion morphology and corrosion products of Q235 steel under the interference of DC/AC stray current in Hainan soil. The electrochemical parameters in corrosion process were also measured. The results show that stray current corrosion had obvious electrolytic corrosion characteristics. The areas of metal components where current flowed into were protected as cathode, on the contrary, the areas of metal components where current flowed out were corroded as anode. DC/AC stray current corrosion showed concentrated corrosion characteristics. The corrosion products were flocculent. The phenomena of delaminating and detachment were obvious in both product layers, so the product layers could not protect substrate. The corrosion products of DC/AC stray current corrosion were similar, which were mainly composed of Fe₃O₄ and Fe₂O₃, with a small amount of FeS. The existence of stray current aggravated the corrosion of Q235 steel. Under the same external current condition, the damage degree of AC stray current corrosion was 15.9% of that of DC stray current corrosion.