Isothermal oxidation of interstitial-free steel in air at different temperatures

Abstract

The oxidation behaviour of interstitial-free (IF) steel at high temperatures was evaluated at 868, 977, 1087, and 1200°C in air for 120 s. Scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analysis were performed to investigate the cross-sectional morphologies, microstructures, and phase constituents of IF steel after isothermal oxidation. Kinetic results showed that the weight gains of IF steel increased with increasing temperature and exhibited an exponential relationship with temperature. Linear and parabolic laws were found to exist in the weight gain process. The activation energy was 89.12 and 274.12 kJ mol⁻¹ during the linear and parabolic stages, respectively. Non-adherent scales were formed on the substrates of IF steel. FeO was determined to be the major component based on the iron–oxygen atom ratios of the scales after oxidation at different temperatures.