Corrosion behavior of zinc and copper coated structural steels in soil environments

Abstract Corrosion behavior of structural carbon steels grade SS400 coated with copper and zinc exposed to soil sample extracted from the central part of Thailand is studied using weight loss analyses and electrochemical methods, including open circuit potential monitoring for 3600 seconds, electrochemical impedance spectroscopic analyses and potentiodynamic polarization measurements. Bare carbon steels are also examined as a reference. Open circuit potential and polarization resistance of all samples are measured on (1, 2, 3, 4, 7, 10, 15, 30, 45, 60, 77 and 91) days of exposure. Corrosion potential is monitored only on the first and last days. After 91 days, corrosion rate in millimeter per year is calculated from weight loss and corrosion product is characterized. Effects of coating material, thickness and process on corrosion resistance of carbon steel subjected to soil environment are reported and discussed.