Corrosion Kinetics Studies of AISI 1020 Carbon Steel from Dissolved Oxygen Consumption Measurements in Aqueous Sodium Chloride Solutions

A study was made of the kinetic behavior of AISI 1020 (UNS G10200) carbon steel corrosion as carbon steel shavings were immersed in distilled water and aqueous 0.02-M and 0.1-M sodium chloride (NaCl) solutions. The rate of corrosion was determined from time profile measurements of dissolved oxygen concentrations in a solution stream circulating in a closed loop through a tubular reactor containing the corroding specimen, and accessories to help intermittent oxygenation of the solution. The results showed that the corrosion process in distilled water followed first-order kinetics with respect to dissolved oxygen concentration. This kinetic expression was maintained after several hours of immersion before being affected by the oxide layer formed on the steel surface. In the presence of NaCl solutions the corrosion kinetic behavior was altered significantly not only by immersion time, but also by the dissolved oxygen concentration in the electrolyte. The experimental evidence is in agreement with known mechanisms of oxide transformation in contact with a metal surface.