Electrochemical corrosion behaviour of austenitic stainless steel (type 304) in dilute hydrochloric acid solution

摘要

The effect of sodium chloride concentrations on the electrochemical corrosion behaviour of austenitic stainless steel (type 304) in dilute HCl solution at ambient temperature was studied with the aid of potentiodynamic polarization technique. Results show that increase in concentration of sodium chloride causes a proportionate increase in corrosion rate in 2M HCl solution. At 5M HCl, progressive increase in sodium chloride concentration initially resulted in sharp increase in corrosion rate before decreasing proportionately. Observation reveals that at a threshold concentration increase in sodium chloride concentration does not result in increase in corrosion rate and it was found that the addition of chloride ion destroyed the protective passive film on the surface and increased the corrosion current density. The kinetics of dissolution in the acid chloride solution resulting in pitting and general corrosion was also studied.