Argon-Oxygen Decarburization of High Manganese Steels: Effect of Temperature, Alloy Composition, and Submergence Depth

In this study, kinetics of decarburization and manganese losses from Fe-Mn-C steels containing 10, 15, and 25 pct Mn and 0.18 and 0.42 pct C during Ar-O-2 bubbling in the temperature range of 1823 to 1913 K were studied. The results showed that higher temperature resulted in higher rate of decarburization because of more oxygen partitioned to carbon oxidation than to manganese. Manganese loss was explained by considering multiple mechanisms: oxide formation and vapor formation, and evaporation-condensation. Manganese loss increased at higher temperatures which has been attributed to an increase in vapor pressure. Changing the depth of nozzle submergence did not make any difference in the decarburization and manganese loss, the reactions occurred well within the time the bubble was present in the melt. Prolonged time after reaction did not lead to a repartitioning of the species. Comparison of thermodynamic calculations with experimental observations showed that manganese and carbon in the bulk metal were not in equilibrium with the gas species in the bubble. After the bubble reacted near the tip of nozzle, the system did not proceed to true equilibrium.