Heat Treatment of Steel is usually intended to accomplish any one of the following objectives :

• Remove stresses induced by cold working or to remove stresses set up by non uniform cooling of hot metal objects.
• Refine the grain structure of hot worked steels which may have developed coarse grain size.
• Secure the proper grain structure.
• Decrease the hardness and increase the ductility.
• Increase the hardness so as to increase resistance to wear or to enable the steel to withstand more service conditions.
• Increase the toughness; That is, to produce a steel having both high tensile strength and good ductility, enabling it to withstand high impact.
• Improve the machine-ability.
• Improve the cutting properties of tool steels.
• Change or modify the magnetic properties of steel.