Electrochemical characteristics of the dynamic progression of erosion-corrosion under different flow conditions and their effects on corrosion rate calculation

The erosion-corrosion performance of X65 carbon steel at different flow conditions was electrochemically studied. Results show that the anodic polarization branch would have a significant distortion in the flowing electrolytes, leading to an overestimation of the Stern-Geary coefficient using the traditional Tafel extrapolation. It is found that the critical impact energy for the initiation of erosion-corrosion is around 0.016 μJ. Surface morphology was obviously changed from “flow mark” appearance to continuous craters with the initiation of erosion-corrosion. The results indicate that the synergy of erosion and corrosion is the main factor contributing to the erosion-corrosion damage under active corrosion. The dynamic progression of erosion-corrosion is associated with the propagation of impingement pits at anodic sites and the wear of the corrosion product film at cathodic sites.