Induction equipment for annealing heat treats a material to increase its ductility and to make it more workable. It involves heating a metal or glass to above its critical temperature, maintaining a suitable temperature then cooling it. Annealing can induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.
In the cases of copper, steel, silver, and brass, the process is performed by heating the material (generally until glowing) then slowly letting it cool to room temperature in still air. Copper, silver, and brass can be cooled slowly in air, or quickly by quenching in water, unlike ferrous metals, such as steel, which must be cooled slowly to anneal. In this fashion, the metal is softened and prepared for further work—such as shaping, stamping, or forming. A water-cooled, fully machined high electrolytic, oxygen-free copper inductor is used for pipe induction annealing.