Influence of temperature on the corrosion behavior and mechanism of Q235 steel in Dagang soil

The corrosion behavior of Q235 steel in Dagang soil with a 20% water content at different temperatures was studied by the means of polarization curve, linear polarization and electrochemical impedance spectroscopy (EIS). The results indicate that at the range of 20 to 70°C, with increasing temperature the corrosion current density I_corr increases, and the linear polarization resistance R_p and the charge transfer resistance R_t depress. At the range of 100 to 200 mV of anodic polarization, the electrode reaction of Q235 steel is blocked, and the slops of E to lgI curves exponentially decrease with increasing temperature. The value of B which is calculated by the corrosion current density I_corr and the linear polarization resistance R_p is bigger than the one which accounts for active uniformity corrosion, and keeps constant at about 44.2 mV. Due to the control of diffusion process, the linear polarization resistances R_p is much bigger than the charge transfer resistance R_t obtained from equivalent circuit simulation of EIS technology.