Effects of Chloride Concentration, Flow Velocity and Temperature on Pitting Corrosion of 304L Stainless Steel Tubes

摘要

Effects of chloride concentration, flow velocity and temperature on pitting corrosion of stainless steel grade 304L tubes were investigated in this study. A loop test was constructed in order to vary flow velocity (2.1, 4.2 and 6.3 m/s), chloride concentration (615, 5900 and 11800 ppm) and temperature (32, 37 and 42 °C) of the electrolyte. Investigation of corrosion behavior was conducted using electrochemical impedance spectroscopy (EIS) and visual observation. Pits of the tube samples after testing were characterized by means of optical focusing technique. Computational Fluid Dynamics simulation was performed to study influence of pit morphology on pit propagation. The results show that the controlled parameters do not show any specific trend of effect on polarization resistance (R_p) of the tested materials. Based on the computational simulation, pit depth above 20 μm may facilitate pit propagation due to a stagnant condition of the electrolyte inside the pit.