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What is heat treatment process ?

know the Heat Treatment...!

Heat treatment is defined as the operations involving the heating and cooling of a metal or an alloy within a solid-state to obtain desire properties (physical or chemical) without change composition. The heat treatment process is carried out to change the grain size, modified the crystal structure of the material, and relieve the stress set up in the material after hot or cold working. Heat treatment also uses in many manufacturing processes, eg. glass working. The heat treatment process is performed in the furnace or oven with a controlling the environment of step-by-step heating and cooling within a specific period of time, apart from this the gases are used to control the furnace environment in some processes. 

Fig.1 - Heat treatment process of gears

Heat treatment consists of heating of metal near of above re-crystallization temperature of the material, hold for a particular time, and then finally cooling the metal in some medium which may be air, water, brine, oil, etc. Heat treatment associate with increasing material strength and also changes manufacturing aspects like improves machining, formability, and also restores ductility while operation gets over the material. 

Fig.2 - Cooling effect on the grain structure of steel

The objective of heat treatment processes are :

  • Refine grain size.
  • Helps to archive the desire mechanical, physical, or chemical properties of the material.
  • Reduce/ Eliminate internal residual stress.
  • Increase the machinability of material.
  • Change surface composition by diffusion.
  • Resoftening the hardened steel.

Classification of heat treatment processes :

the heat treatment process can be classified into the following types


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