Influence of CO2 partial pressure and flow rate on the corrosion behavior of N80 steel in 3.5% NaCl

Abstract

In this paper, weight loss and in situ electrochemical measurements were carried out to investigate the influence of CO2 partial pressure and flow rate of corrosive media on the corrosion of N80 steel in 3.5% NaCl at 120 ℃. The corrosion product films obtained at different conditions were also analyzed by SEM and EDS. The results showed that with the increase of CO2 partial pressure, the corrosion rate decreases significantly. EIS results showed that the total resistance and charge transfer resistance of the film under all soaking times increased gradually with the increase of CO2 partial pressure, which indicates that the product film formed at high CO2 partial pressure was denser and had better protection to the matrix. Flow rate has limited influence on corrosion rate of N80 steel at tested conditions. EIS revealed that at different flow rates, the protection of corrosion product films increased with the soaking time. High flow rate is not favoarable to the formation of corrosion product film, or it is easy to break corrosion product film. And wall shear stress (WSS) is generally considered to be the main cause of failure, thus resulting in high corrosion rate of N80 steel.