Study of the effect of temperature on corrosion behavior of galvanized steel in seawater environment by using potentiodynamic polarization and EIS methods

In this study, the effect of temperature on the corrosion behaviour of galvanized steel in the seawater environment was studied. To this end, a cylindrical galvanized steel specimen with a 20 mm diameter and 50 mm height was prepared. Then, the electrochemical reactions were investigated in a 3.5 wt% NaCl solution at 10, 20, 30, 40, 50, 60, 70 and 80 degrees C by using potentiodynamic polarization and electrochemical impedance spectroscopy methods. The potentiodynamic polarization plots showed that by increasing the ambient temperature, both anodic and cathodic branches of Tafel diagram were shifted to higher corrosion current densities. The obtained Nyquist plots of electrochemical impedance spectroscopy possessed two time constants and showed that the corrosion resistance of the galvanized layer is bigger than that of the steel substrate. Moreover, it was revealed that the equivalent circuit of the electric double layer for the galvanized steel in a 3.5 wt% NaCl solution includes two polarization resistant elements, a solvent resistance element, and two fixed phase elements with resistive behaviour.