Vacuum Arc Remelting (VAR)
Vacuum arc remelting (VAR) is a refractory technology that uses a vacuum environment to melt and refine metals. The process utilizes a double electric arc created within a high vacuum environment and applied across two identical materials being melted together, resulting in a refined and homogeneous product. Vacuum arc remelting is commonly used when producing high-purity and high-performance alloys, such as those used in aerospace, nuclear, and military applications.
The VAR process involves creating a vacuum environment inside a large, sealed vessel. The vessel, filled with a noble gas such as argon, has two electrodes positioned on opposing sides of the vessel. The electrodes are connected to either side of the power source. When connected to the power source, an electric arc is created between the two electrodes. This arc, when created, is hot enough to melt the two materials on each end, creating a fused pool of molten metal.
The molten metal is maintained in a vacuum environment, as oxygen would immediately react and ruin the integrity of the product. As the molten metal cools and solidifies, it is refined and homogenized within the vessel. As a result, a uniformly strong, high-purity alloy is produced.
The VAR process is typically used to refine, alloy, and homogenize a material from its raw or “as-cast” state where it may contain contaminants and impurities. The process can also help restore the characteristics of a material that has become damaged due to device failure, corrosion, or heat damage.
The VAR process has been in use since the 1960s and continues to be used as an effective refractory technology today. The benefits associated with the process include improved mechanical and physical properties, improved resistance to oxidation, uniform distribution of trace elements, removal of inclusions and dendrites, and improved life expectancy of parts. The process also results in improved surface integrity and surface finish properties.
In addition to providing these benefits, the VAR process is also relatively economical and environmentally friendly compared to other methods of refractory and similar operations. The vacuum environment within the closed vessel helps ensure that the atmosphere is not affected nor pollutants or gasses produced, and in terms of cost, the process can be used to reutilize scrap materials.
The VAR process is well suited for those seeking a uniform and high-strength product, such as the aerospace, military, and nuclear industries. From the VAR process, a high-strength and high-purity alloy can be created, providing improved strength, life expectancy, and reliability for those parts that require a little extra protection and performance.
