A Future for Vacuum Arc Remelting and Electroslag Remelting—A Critical Perspective

Abstract

In the secondary metals refining processes, vacuum arc remelting (VAR) and electroslag remelting (ESR), the consumable electrode is commonly produced by vacuum induction melting (VIM) which employs the regrettably primitive casting technique of simply pouring into the open top of the mold. Despite the vacuum, the resulting oxidizing conditions and the immensely powerful turbulence accompanying the top-pouring of the electrode is now known to create a substantial density of serious cracks. The cracks in the cast electrode are bifilms (double oxide films), which in turn are proposed to be responsible for the major faults of the VAR ingot, including undetectable, horizontal macroscopic cracks, white spots (clean and dirty varieties) and in-fallen crown. The remedial action to solve all these issues at a stroke is the provision of a counter-gravity cast electrode, cast in air or vacuum, or provision of any similar electrode substantially free from bifilm defects. The ESR process is also described, explaining the reasons for its significantly reduced sensitivity to the top-poured VIM electrode, but indicating that with an improved electrode, this already nearly reliable process has the potential for perfect reliability. The target of this critical overview is an assessment of the potential of these secondary refining processes to produce, for the first time, effectively defect-free metals, metals we can trust.

Recent Advancements in Material Waste Recycling: Conventional, Direct Conversion, and Additive Manufacturing Techniques

“…Chips can be recycled using methods like electric arc furnace (EAF) [141][142][143][144][145][146], electroslag remelting (ESR) [147][148][149][150][151][152], vacuum arc remelting [153][154][155][156], vacuum induction melting [136,[157][158][159], electron beam melting [160][161][162][163][164], and plasma arc melting [165][166][167][168]. The various conventional processes for remelting chips generated from diverse materials can be further elaborated for understanding.…”

“…The biofilms (double oxide films), which are the cracks in the cast electrode, are responsible for major faults like fallen crown, white spots, and undetectable and horizontal macroscopic cracks in the VAR ingot. The solutions recommended to resolve these issues are a counter gravity cast electrode or an electrode cast in a vacuum or air such that it will be free from bifilm defects [154].…”

“…Biofilms defects [154], VAR process requires structural integrity and electrical conductivity of the starting material [166].…”

Numerical Simulation of Electromagnetic Field in Slab Electroslag Remelting Process with Double Electrode Series

“…Because a layer of slag shell is formed between the mold wall and the ingot, the lubrication between the ingot and the mold wall can be increased, and the surface quality of the ingot can be improved. The formation of the slag shell also reduces the heat loss in the radial direction of the ingot, which is beneficial to the formation of the directional solidification structure and improves its internal quality [1][2][3][4]. In addition, the electroslag remelting process is simple in operation, is low in equipment investment and operating costs and can produce ingots of different shapes.…”