Influence of Temperature and Oxygen Content of Oxidation Atmosphere on Initial Oxidation of Si Containing Steels

Oxidation behavior of Si containing steels in relatively low temperature was investigated. Oxidation rate of 1.5%Si-steel was determined by Si oxide formed at steel/scale interface. Two kinds of Si oxide formed in investigated oxidation condition; SiO2 and Fe2SiO4. In the case that SiO2 formed, the oxidation rate of the steel was suppressed and growth rate of Si inner oxide was also suppressed. SiO2 transformed into Fe2SiO4 at higher temperature and the oxidation rate became larger. The transformation temperature of Si oxide was influenced by oxygen content of the atmosphere. SiO2 is more stable than Fe2SiO4 at higher temperature in higher oxygen content. This transformation behavior is well explained by thermodynamic calculation.