Effects of Silicon Content on Oxidation at 1000°C of Aisi 1045, Aisi 5160 and Aisi 9254 Steels.

The main objective was to analyze the influence of silicon content on high-temperature oxidation of low-alloy steels. Samples of AISI 1045, AISI 5160, and AISI 9254 steels, with different silicon contents, were oxidized at an isothermal temperature of 1000°C for times of 20 minutes, 40 minutes, and 60 minutes. The oxide layers formed mainly contain hematite, magnetite wustite, and fayalite. The average thickness of the oxide layer can decrease with an increase in silicon content below 1% but can increase for contents greater than 1% due to the difference in density between fayalite and iron oxides. Silicon tends to accumulate on the surface of steel and form a SiO2 film in the early stages of oxidation, which can control the oxidation process. The eutectic compound FeO+Fe2SiO4 forms at the oxide-steel interface, and its thickness increases with oxidation time and the silicon content present. The SiO2 film tends to decrease with oxidation time and silicon content.