In an annealing furnace or oven, the heat treatment process makes hard, brittle metals softer and more ductile, which in turns makes them easier to work and form. This is especially beneficial for manufacturers as there is less risk of fracturing when the material is being bent or pressed.

Depending on the metal and the desired result, heat treatment processes can vary, however, annealing is usually one of the earliest steps as it prepares the metal to be worked by increasing ductility. Once it has been formed into the desired shape, it may then be “hardened” then “tempered” to increase its strength and flexibility. Cold-worked metal can be annealed several times to relieve stresses and reduce the risk of material failure.

Steel manufacturers, metalworkers, and jewellers all use annealing heat treatment to make the metals that they work with easier to manipulate, due to the reduction in dislocations and internal stresses. Annealing typically reduces the yield strength of the metal, therefore the material is usually subjected to a quenching and/or tempering process to restore any lost strength.

Precise annealing temperatures are dependent on the metal. The material will take on different properties depending on the temperature at which it is annealed, therefore the correct annealing temperature is defined by the desired properties. Both ferrous and non-ferrous metals can be annealed at a range of temperatures, provided these are below their respective melting points, and should be allowed to cool slowly in air.