Vacuum Arc Remelting

Vacuum arc remelting, commonly abbreviated VAR, is a secondary melting process that refines a metal ingot a second time by striking a direct-current electric arc between the ingot, used as a consumable electrode, and a cooled copper mold inside a vacuum chamber, so the electrode melts and re-solidifies drop by drop into a new, denser ingot with far fewer trapped gases and inclusions than the original casting. The technique was developed and industrialized in the United States in the 1950s, driven especially by the aerospace industry's need for titanium and nickel-based superalloys free of the internal defects that could cause a jet engine component to fail catastrophically. VAR remains a standard final processing step for the most demanding aerospace, medical implant and specialty alloy applications, valued for the exceptional structural uniformity and cleanliness of the metal it produces even though it adds significant cost compared to a single conventional melt.