Influence of temperature on the structure of oxide films formed on mild steel exposed to hot caustic

Heat exchangers used in the alumina production industry are exposed to high pH solutions and high flow rates, which results in an environment where corrosion can occur rapidly. To understand the influence of temperature, an experiment has been conducted where seven A106B mild steel samples have been exposed to a range of temperatures from 100ºC to 280ºC, and the structures of the resulting oxide films studied through SEM, TEM, and XRD techniques. The results indicate a dissolution driven corrosion mechanism, and structural instability at intermediate temperatures (130ºC-160ºC).