Corrosion Electrochemical Parameters Test of Rusted Carbon Steel in Seawater

As it is known that the existence of a rust scale on a steel surface may complicate the electrochemical corrosion process of the steel, thereby it is difficult to accurately measure the corro- sion rate of carbon steel by traditional electrochemical methods. In this paper, weight-loss method and different electrochemical tests such as polarization curves (PC), electrochemical impedance spectra (EIS) and linear polarization resistance (LPR) were used to study the corrosion behavior of the Q235 carbon steel immersed in seawater for 1 a. The results show that the corrosion rates mea- sured by both the electrochemical and weight-loss measurement show the same degressive trends during a short immersion period (for about 8 weeks), while those measured by electrochemical measurement turn to increase after 8 weeks' immersion in seawater. The longer the immersion time is, the bigger the deviation occurs for the corrosion rates measured by the two kind methods. It is