Melt parameters and resulting characteristics in laboratory-scale electroslag remelting

Abstract

Vacuum induction melting (VIM) and electroslag remelting (ESR) are techniques used to produce ingots of alloys with complex chemistries while lowering the amount of defects, inclusions or extent of elemental segregation. Those practices are widely employed in aerospace applications and more recently in fossil-fueled power plant components due to the increasingly demanding operating conditions. Consequently, research is ongoing to improve and control the melting of commercially available alloys for optimal performance in service. In this investigation, a laboratory-scale (200 mm-200 kg) ESR furnace was used to remelt various alloys with a focus on the ingot quality. Several approaches were considered to study and improve the melting characteristics. Targeted additions of minor elements in master alloys were found to improve the melt range which affected the melt pool volume and subsequently increased the remelting efficiency. Furthermore, the melt parameters during ESR of some select alloys were modified to improve the melting characteristics. Finally, the influence of the size of the ESR electrode was observed and provided a better understanding of the mixing mechanisms in the slag region and their effect on the voltage swing and melt rate. The results are presented using a combination of experimental and computational (thermodynamic and CFD-based) data.