After we harden the workpiece, we take it to tempering, this process is done after the hardening process, the pre-hardened steel will be stressed (strain) internally and harden will increase. But steel will lack the properties of toughness (Ductility), making it unsuitable for use. because if there is a bump Steel pieces may crack. Therefore, it is necessary to improve the bad properties by annealing. By the method of firing in the furnace at a low temperature of about 200 ° C - 400 ° C, leave it for about 1 - 3 hours, then take the workpiece out and let it cool down in normal temperature. Steel will have better toughness properties, so in order to solve and reduce such problems.g. This process is done after hardening process. Because of the steel after hardening will be most structures are Martensite or Bainite and have some residual Austennite. In addition, there will be stress occurs internally Which is caused by the rapid cooling process, so in order to fix and reduce the said problem should be reheated after hardening.