Heat treatment on metals (1)

Heat treatment on metals (1)

Heat treatment is a method used to alter the physical, and sometimes chemicalproperties of a material. The most common application is metallurgical. Heattreatments are also used in the manufacture of many other materials, such asglass. Heat treatment involves the use of heating or chilling, normally toextreme temperatures, to achieve a desired result such as hardening orsoftening of a material. Heat treatment techniques include annealing, casehardening, precipitation strengthening, tempering and quenching. It isnoteworthy that while the term heat treatment applies only to processes wherethe heating and cooling are done for the specific purpose of alteringproperties intentionally, heating and cooling often occur incidentally duringother manufacturing processes such as hot forming or welding furnace.
Process：
Metallic materials consist of a microstructure of small crystals called"grains" or crystallites. The nature of the grains (i.e. grain sizeand composition) is one of the most effective factors that can determine theoverall mechanical behavior of the metal. Heat treatment provides an efficientway to manipulate the properties of the metal by controlling rate of diffusion,and the rate of cooling within the microstructure.
Complex heat treating schedules are often devised by metallurgists to optimize an alloy's mechanical properties. In the aerospace industry, a super alloy may undergo fiveor more different heat treating operations to develop the desired properties.This can lead to quality problems depending on the accuracy of the furnace'stemperature controls and timer.