Electroslag remelting experiments have been carried out on En 24 steel using two slag compositions in indigeneously constructed 350 KVA DC and 50 KVA AC ESR units. Detailed quantitative characterisation of the inclusions of different types has been carried out using Quantimet Image Analyser. The inclusion content in terms of volume fraction and density (No/mm2) and their size distribution in the refined ingot and the unrefined steel have been assessed. The chemical composition of selected inclusions has been established by electron probe microanalyser (EPMA). These studies are supplemented by scanning electron microscopy on typical fractured specimens. The present study shows that the DC reverse polarity mode of melting using a slag with higher silica content (10 wt%) offers the best conditions with particular reference to removal of inclusions and modification of inclusion morphology as compared to the ingots produced by DC straight polarity and AC modes of melting.

Abstract

1994