Short-time Oxidation Behavior of Low-carbon, Low-silicon Steel in Air at 850–1,180 °C––I: Oxidation Kinetics

In this study, the oxidation kinetics of low-carbon, low-silicon steel in flowing air at 850–1,180 °C within 30 or 60 s were examined. The parabolic kinetics were established from the very early stage at 850° and 1,000 °C, whereas the oxidation kinetics at 1,100–1,180 °C appeared to obey a linear law initially and a more-parabolic one at a later stage. When the oxidation kinetics followed the linear law, “rough”-scale with an undulating, saw-teeth like microstructure developed, whereas when the parabolic law was followed, smooth scale developed. It appeared that a critical scale thickness existed, at which the scale-growth mechanism changed from linear to parabolic. This thickness was less than 7 μm at 850 °C, about 10 μm at 1,000 °C, about 50 μm at 1,100 °C and in the range of 60–80 μm at 1,180 °C under the conditions examined. Blister formation at 900 °C prevented clear observation of the linear-to-parabolic transition.