Carbon restoration heat treatments are applied to steel parts in order to correct the surface oxidation that occurs from high temperature metalworking processes performed in air, such as investment casting and hot forging.  This heat treatment is performed in carbon-controlled atmosphere batch furnaces.  Carbon restoration cycles uses the controlled chemistry of the furnace atmosphere to reestablish the correct carbon content on the surface of the steel part.  Carbon restoration is normally applied to parts intended for applications with critical mechanical performance requirements.