Annealing is a heat treatment process used mostly to increase the ductility and reduce the hardness of a material. This change in hardness and ductility is a result of the reduction of dislocations in the crystal structure of the material being annealed.
Annealing is often performed after a material has undergone a hardening or cold working process to prevent it from brittle failure or to make it more formable for subsequent operations.
As mentioned above, annealing is used to reduce hardness and increase ductility. Changing these mechanical properties through annealing is significant for many reasons:
Annealing improves the formability of a material. Hard, brittle materials can be difficult to bend or press without creating a material fracture. Annealing helps eliminate this risk.
Annealing can also improve machinability. A material that is extremely brittle can cause excessive tool wear. Reducing the hardness of a material via annealing can reduce the wear on the tool being used.
Annealing removes residual stresses. Residual stresses can create cracks and other mechanical complications, and it is often best to eliminate them whenever possible.
