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Heat treatment is a method used to alter

the physical, and sometimes chemical properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering and quenching. It is noteworthy that while the term heat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding

As Steelworkers, we are interested in the heat treat-ment of metals, because we have to know what effectsthe heat produced by welding or cutting has on metal.We also need to know the methods used to restore metalto its original condition. The process of heat treating isthe method by which metals are heated and cooled in aseries of specific operations that never allow the metalto reach the molten state. The purpose of heat treating isto make a metal more useful by changing or restoringits mechanical properties. Through heat treating, we canmake a metal harder, stronger, and more resistant toimpact. Also, heat treating can make a metal softer andmore ductile. The one disadvantage is that no heat-treat-ing procedure can produce all of these characteristics inone operation. Some properties are improved at theexpense of others; for example, hardening a metal maymake it brittle.