Kinetics of Decarburization and Manganese Loss from Fe–15Mn–1C Alloy by Bubbling of Argon–Oxygen Gas Mixtures

In this work, the kinetics of decarburization and demanganization of Fe–15Mn–1C alloy by bubbling mixtures of Ar–O2 into the melt at 1823 K was studied. Experiments were conducted at total gas flow rates of 200 and 300 Nml/min and gas mixtures of Ar containing 6.7 to 20 pct O2. Increasing the gas flow rate and oxygen in the gas mixture resulted in higher overall rates of decarburization and demanganization. However, the experiments with the lowest oxygen concentration were the most efficient in terms of oxygen utilization for decarburization. The ratio of manganese loss to decarburization was found to be controlled by the relative mass transport of manganese and carbon in the metal. Based on the estimated mass transfer coefficient for either carbon or manganese, the reaction time for each bubble was estimated to be 0.001 seconds which is about 1 pct of the residence time of the bubble in the liquid. Although the initial competition for oxygen between manganese and carbon was controlled by relative mass transport rates, this work found no evidence that manganese and carbon repartitioned towards the equilibrium over the remaining lifetime of the bubble.