Annealing is a heat-treatment carried out on a metal or alloy, usually with the aim to alter the microstructural or chemical structure of the metal to the advantage of the metal-worker. In a simple metal (pure metal or solid solution) annealing will be used to soften the work-hardened material to allow further deformation (e.g. hammering). The lowest temperature at which a metal will soften varies with the degree of cold-working, greater amounts of work tending to reduce it.
With more complex alloys (those with more than one phase present), annealing may be used to alter the microstructure in terms of the phases present, their distribution, or simply to even out the elemental distribution. Thus, an annealing process may be further classified, for example the anneal may be described as a stress-relief anneal, solid solution anneal, or simply normalizing (anneal implied); the additional term indicating the purpose of the heat treatment.
Related terms: Cold Work, Microstructure, Recovery