Heat Treating: Quenching

Quenching is the process of heating a metal above its critical temperature, or the temperature at which ferrite is completely transformed to austenite *View diagram*, then cooling it quickly with water, brine, polymer, oil, or forced air depending on the desired cooling rate. The type of metal must be taken into consideration when choosing the cooling method since certain metals can crack if cooled too quickly. Quenching causes ferrous alloys to harden, however, non-ferrous metals will soften when quenched. Quenching is usually followed by tempering to improve the stability of the metal.

Photo credit: Christophe Dang Ngoc Chan- CC BY-SA 3.0