厚板の高温酸化スケール性状に及ぼす加熱雰囲気中のO₂,H₂O濃度の影響

抄録

The effects of heating atmosphere on oxidation behaviour at high temperature of steels with various Si content(0.060.4%Si), but constant in other elements, have been investigated. The results obtained are summarized as follows.
Fayalite, Fe₂SiO₄, formed at the interface of scale/matrix affected the oxidation behaviour. Therefore, solid Fe₂SiO₄ formed at oxidation temperatures up to 1170°C, which was the eutectic point of Fe₂SiO₄ and FeO phase, raised heat resistance, but liquid phase of Fe₂SiO₄ at oxidation temperatures exceeding 1170°C accelerated the oxidation. The change of oxidation behaviour occurred at the Si content between 0.1% and 0.2%. Increasing Si content in steel, Fe₂SiO₄ formed at the interface of scale/matrix increased gradually. When the whole interface was covered with Fe₂SiO₄, the oxidation behaviour should be affected by the change of diffusion rate on Fe⁺⁺ ion from iron matrix to scale. H₂O and O₂ content in heating atmosphere promoted the oxidation of iron, but the effect of H₂O was much more than O₂. The mean diameter of pores in scale was in proportion to oxidation weight gain, and therefore Si content and oxidation condition affected on mean diameter of pores in scale through the oxidation weight gain.