Annealing

A general term applied to several softening operations in metal.

Iron

A general term applied to several softening operations affecting the grain size and cementite structures within a particular steel. Full annealing is carried out with forging on modern steels in order to obtain grain refinement in combination with high ductility. Hypo-eutectoid steels are heated to about 50̊C above the upper critical point and hyper-eutectoid steels 50̊C above the lower critical point. The steel is held for a while at this temperature, depending on its thickness, followed by very slow cooling, usually in the furnace. This produces a softer steel than normalising. Microscopy of a sample of the metal will reveal which operation has taken place.

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