The Effect of Ladle Treatment on Inclusion Composition in Tool Steel Production

An in‐depth SEM‐investigation of the inclusion composition change in the ladle refining process during tool steel production was done. Plant trials were carried out at Uddeholm Tooling AB in Hagfors, Sweden. A series of samples was taken during ladle refining, from deslagging through vacuum treatment. The goal was evaluating the effects of the top slag and other process parameters on the inclusion composition during ladle refining. The main conclusion was that normal variations in the process have a large influence on inclusion composition. Furthermore, it was concluded that the MgO content in the top slag had a large influence on the inclusion composition throughout the whole ladle refining process. Also, the SiO₂ content in the ladle slag originating from the EAF‐slag, had a noticeable effect on the inclusions. The inclusions belonging to the system Al₂O₃‐CaO‐MgO‐SiO₂ showed a continuous composition change throughout the ladle refining process, from high Al₂O₃, via MgO‐spinel to finally complex types rich in CaO and Al₂O₃.