Annealing steel consists of heating a metal above a critical temperature and then cooling at a rate that will produce a refined microstructure.
Annealing is most often used to soften a metal after cold working, to improve machinability, or to enhance properties like electrical conductivity.
In many materials such as stainless steels and high temperature alloys that cannot be hardened by heat treatment, annealing is used to relieve the stress and reduce the hardness and ductility loss caused by cold working. The metal is heated to a high temperature, (typically above 1400 oF), held for a predetermined time and cooled, which softens the material and releases the stress introduced during cold working.
Typical applications – Cast irons, stainless steels, superalloys, brass alloys, aluminum alloys