1993 Volume 79 Issue 6 Pages 692-698
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.
