Heat treatments are a group of metal working processes used to alter the physical, and sometimes chemical, properties of materials. The most common application is metallurgical. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result such as hardening or softening of materials. Heat treatment techniques include annealing, hardening, strengthening, tempering, normalizing and quenching. The termheat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally.