Experimental study on erosion-corrosion of carbon steel in flowing NaCl solution of different pH

The pure corrosion, pure erosion and erosion-corrosion behaviours of X65 carbon steel in corrosive fluid and slurry of different pH were studied at low flow velocity. Results show that the corrosion pattern changed from general corrosion to pitting damage along with the occurrence of erosion in pH = 3 solution and it is postulated that this feature might be associated with changes in the cathodic reaction. The sand impacts would cause the transient of main cathodic reaction from hydrogen evolution to oxygen reduction. Density and connected small pits generated in pH = 7 solution containing sand particles. While, the increase of the solution pH from 7 to 11 resulted in more scattered and serious pitting damage, which is caused by more focused initial anodes. The occurrence of pitting damage has complicated the analysis of the electrochemical results. The sand impacts in pH = 13 solution could cause the local breakdown of passive film, leading to a significant decrease of pitting resistance.