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

Abstract

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 masspct) MnO-(53.3-82.8 masspct) SiO2-(8.3-23.1 masspct) 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 masspct MgO) and Al2O3 inclusions, irrespective of the SiO2 contents (1.9 to 9.0 masspct) 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.