Abstract
The purpose of the present investigation was to determine the effect of SO2 gas dissolved in water containing Cl- ion on the pitting corrosion of austenitic stainless steel. Inhibiting effect of NO3- ion and NO2- ion was also studied. 18-8 stainless steel is passivated by water containing dissolved SO2 owing to the oxidizing power of HSO3- ion, but it is more susceptible to pitting corrosion in water containing both Cl- ion and dissolved SO2 than in water containing Cl- ion and sulphuric acid owing to the less protective effect of HSO3- ion than SO42- ion for pitting corrosion. Nitrite added to above solution passivates 18-8 stainless steel, but inhibits less effectively pitting corrosion than nitrate. Nitrate, on the other hand, inhibits effectively pitting corrosion, but not passivates 18-8 stainles steel.
