酸化皮膜処理したフェライト系ステンレス鋼の皮膜構造と高温純水中の耐食性

抄録

The effect of oxidation conditions on metal release of Type 439 and Mod. 409 ferritic stainless steels in deaerated pure water at 488K was investigated. The behavior of metal release was also discussed in relation to the surface films which were formed by various oxidation conditions. The results obtained are as follows: (1) The oxidation treatments in the atmosphere of low oxygen potential such as high purity argon gas and high vacuum condition at 1123K for short time were effective to decrease the metal dissolution, and the oxide films primarily consisted of double oxide layer consisted of Ti₂O₃ in outer and MnCr₂O₄ in inner layer. (2) Titanium concentration into surface oxide film was increased in proportion to the logarithm of heating time at 1123K. (3) It could be obtained that a small quantity of titanium addition to high purity ferritic stainless steels was effective to decrease the metal dissolution through the formation of thin titanium oxide film, together with the suppression of the sensitization, by heat-treated in the atmosphere of low oxygen potential.