Corrosion Behavior of J55 Carbon Steel in NaCl Solution at Different Flow Velocities

The corrosion behavior of J55 carbon steel in 3.5wt% NaCl solution with different flow velocities was investigated by means of electrochemical measurements and immersion tests. The mechanism and the effect of solution flow velocity on corrosion of J55 carbon steel were analyzed. The results show that NaCl solution flow made open circuit potential and self-corrosion potential shift toward positive, self-corrosion current density increase and polarization resistance of double layer decrease. Flow of solution had little effect on the mechanism of the anodic reaction in the corrosion process, but increased the value of Tafel slope for the cathodic reaction. The average corrosion rate of J55 steel in the solution with flow velocity of 1 mm·s-1 was higher than in the stagnant solution and the flow enhanced the occurrence of localized corrosion. Solution flow promoted cathode ion transfer and demoted the resistance of corrosion product.