Evolution of Oxide Inclusions in Si-Mn-Killed Steel During Protective Atmosphere Electroslag Remelting

The current study was motivated to reveal the evolution of MnO-SiO₂-Al₂O₃ inclusions during protective atmosphere electroslag remelting (P-ESR), and the effect of slag composition on the inclusion evolution. The oxide inclusions in the consumable steel electrode were ternary (7.1-26.4 mass pct) MnO-(53.3-82.8 mass pct) SiO₂-(8.3-23.1 mass pct) Al₂O₃ without exception, which were fully removed during the P-ESR in two ways: a portion of these inclusions were dissociated in its individual chemical species into liquid steel, whereas the others were removed by absorbing them into molten slag before liquid metal droplets collected in liquid metal pool during P-ESR. The oxide inclusions both in liquid metal pool and in remelted ingots are mostly MgAl₂O₄ (containing about 3 mass pct MgO) and Al₂O₃ inclusions, irrespective of the SiO₂ contents (1.9 to 9.0 mass pct) in the slag. These inclusions readily formed in the liquid metal pool as a result of the reaction between alloying elements and the dissolved oxygen in liquid steel that dissociated from MnO-SiO₂-Al₂O₃ inclusions.