Effect of chromium–sulphur interactions on decarburisation of levitated Fe–C alloy droplets by CO2–Ar gas mixtures

This study provides an evaluation of the influence of chromium and sulphur on the decarburisation kinetics of Fe–Cr–C alloy droplets when exposed to argon gas mixtures containing carbon dioxide as the oxidant. For droplets containing the same amount of surface active sulphur, it was found that the decarburisation rate of iron–chromium droplets was substantially faster than that of chromium free alloys. This enhanced rate can be explained in terms of the attractive interaction between chromium and sulphur, which results in a decrease in the number of surface sites occupied by sulphur. An appropriate rate equation has been developed to characterise this behaviour. The findings from this work have beneficial implications with respect to the preferential oxidation of carbon rather than chromium when stainless steel is refined with argon–carbon dioxide gas mixtures.