Heat treatment of steels and other suitable metals involves the heating of the items to specific temperatures where desired metallurgical changes to microstructure takes place . These temperatures can range from as low as 250°C  on temper hardened steels to as high as 1150°C on certain tool steels. The main purpose of heat treatment is to obtain the desired hardness, Tensile strength, Ductility, internal stress levels and Microstructure in the steel.