Characterization of phases in Argon Oxygen Decarburization slag

Sammanfattning: Slag is an important part of steelmaking with the AOD (Argon Oxygen Decarburization) process. In this work the focus was on developing a methodology for characterizing phases in slagsamples obtained after decarburization, reduction and desulphurization. Six samples from two heats, or batches, (heat A and B) were prepared by baking in Bakelite and polishing. These were analysed in SEM (Scanning Electron Microscope), with BSE (Backscattered Electrons) and EDS (Energy Dispersive XraySpectroscopy). Images from BSE were then processed inImageJ with a denoise method for advanced fraction analysis. Average composition for each noticed phase analysed with EDS is presented in element tables. A systematic portraying of the cross section was performed on samples from heat B. This gave a more in-depth composition and fraction analysis. Due to the nature of slag, scratches were often induced during polishing.The negative effect of these scratches could be reduced with the denoise method in the fraction analysis. There are three main phases in each stage of the AOD process with similar composition and structure between the two heats. Results showed the importance of measuring different zones of the slag due to its heterogeneity. More specifically, at least four random images from the cross section were required for accurate fraction analysis of samples after decarburization. Overall, the methodology for characterization was sufficient for samples after decarburization and desulphurization.