Heat treatment can be defined as a combination of processes or operations in which the heating and cooling of a metal or alloy is done in order to obtain desirable characteristics without changing the compositions. Some of the motives or purpose of heat treatment are as follows:

☛ > In order to improve the hardness of metals.

☛ > For the softening of the metal.

☛ > In order to improve the machinability of the metal.

☛ > To change the grain size.

☛ > To provide better resistance to heat, corrosion, wear etc.

Heat treatment is generally performed in the following ways:

☛ > Normalizing

☛ > Annealing

☛ > Spheroidising

☛ > Hardening

☛ > Tempering

☛ > Surface or case hardening