Electro Slag Remelting Process
Just like with VAR vacuum furnace, in the ESR process an air melted ingot is suspended over a vessel into which the ingot is melted by electrical current, to reform drip by drip as a new ingot. Instead of a vacuum atmosphere, a layer of slag floats on top of the molten steel, protecting it from oxygen and other atmospheric gases during melting. Non-metallic inclusions are removed by physical flotation through the slag which functions as a filter and sponge, straining out sulphur and other non-metallic inclusions as the alloy drips down through it. Additionally, the slag allows any residual gasses to rise up out of the remelted material, further refining it. Harmful alloy segregation is also reduced from the original air-melted ingot. ESR produces an excellent ingot surface and improved resulting yield when compared to VAR.