A volume expansion kinetic model of decarburization of liquid Fe-1wt%C alloy by Ar-CO2 blowing

The decarburization kinetics according to the Ar-CO2 ratio with a liquid Fe-1wt%C alloy was studied using a high-frequency induction furnace at 1873K. The carbon content in the liquid alloy decreased linearly with time, and as the CO2 ratio increased, the decarburization rate of the liquid alloy increased. The main reaction turned out to be CO2 + C = 2CO based on thermodynamic calculation. Comparing the amount of CO2 gas blown into the liquid alloy and the carbon content in the liquid alloy, it was found that all CO2 gas reacted with dissolved carbon when present as bubbles. A volume expansion model is proposed that takes into account the change in the partial pressure of gases due to the decarburization reaction and the resulting volume expansion of gases. Upon applying this model when S was low (50 ppm) and when S was high (0.1wt%), no differences were found in the three possible rate-controlling steps (gas phase mass transfer, dissociation&adsorption, and mixed control) when S was low, but Mixed control behavior was observed when S was high.