Relationship between pre-oxidized film structures and corrosion resistance of ferritic stainless steels in high temperature pure water

The effect of pre-oxidation conditions on metal release of Ti-added SUSXM8 and 410Ti ferritic stainless steels in deaerated pure water at 488 K was investigated. The pre-oxidation treatments in the atmosphere of low oxygen potential, such as high purity argon gas and high vacuum condition at 1123 K for short time, were effective in decreasing the metal dissolution. The pre-oxide films were composed of outer Ti2O3 and inner MnCr2O4 layers. Therefore, a small quantity of titanium addition to high purity ferritic stainless steels was effective in decreasing the metal dissolution through the formation of thin titanium oxide film, together with the suppression of the sensitization, by heat-treatment in the atmosphere of low oxygen potential. The key factors controlling the metal dissolution are thickness and denseness together with chemical composition of the oxide films. (author)