Corrosion performance of mild steel and galvanized iron in clay soil environment

Clay is a naturally occurring material, and it has been utilized for many industrial processes. In this study, two types of clay namely white clay (WC) and black clay (BC) was used for this investigation. The corrosion performance of the clay samples was carried out using mild steel and galvanized pipes under a buried condition in the field and laboratory exposure studies were carried in the clay extracts. Generally mild steel (MS) and galvanized iron (G.I) are being used as an encasing material for earthing applications. In some places, the soil was enriched with acidic clay, and it causes corrosion of the MS and G.I and it needs periodic replacement of pipes. In this context, a detailed study has been carried out to evaluate the relative corrosion performance of the MS and G.I exposed to the clay environment. Electrochemical corrosion behavior of MS and G.I in clay medium were carried out by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The corrosion product formation was characterized by X-Ray Diffraction and Carbon Hydrogen Nitrogen Spectrum analysis. The surface morphology of MS and G.I after the exposure was characterized by Scanning Electron Microscopy (SEM) studies. The results proved that G.I in clay soil was severely affected by corrosion. The reason may be attributed to the insufficient thickness of the zinc coating and the presence of microbes which enhanced the G.I corrosion. Keywords: Clay, Mild steel, Galvanized steel, Corrosion, Electrochemical studies