Numerical study on the removal and distribution of non-metallic inclusions in electroslag remelting process

Abstract

A transient model coupling the magnetohydrodynamic flow and heat transfer is developed to predict the removal and distribution of non-metallic inclusions in electroslag remelting process. The interaction between the melt and non-metallic inclusions was described by two-way coupled Euler-Lagrange method. Both original inclusions from electrode and newly precipitated ones with solidification were considered. The effect of current on the inclusion behaviour was also studied. The model was validated by experiments. The overall removal ratio of original inclusions 2–20 µm in diameter increases from 80.47% to 94.75%. The inclusions with 30 µm even is completely removed. A proper increase of current is conductive to the removal efficiency. In the mushy zone the drag force and buoyancy force play a major role in the entrapment and distribution of newly precipitated inclusions. The inclusion amount increases along radius, but slightly decreases when ranging from 0.9 to 1.0 radius in the solidified ingot. The buoyancy force is great enough for almost all of the 20 µm inclusions to escape from the mushy zone. The absorption ratio of inclusions into slag decreases from 50.5% to 28.7% when the current increases from 3100 A to 3700 A due to the increase of solidification rate.