Although untempered martensitic steel is very hard, it is very brittle due to its low toughness and ductility. This is an undesirable situation for most sectors. In this case, tempering process is applied to martensitic steel. This application, which is applied to almost all of the materials after quenching, is done in a way to give the steel a sufficient amount of toughness. This application, which is applied at a level lower than the lower critical temperature of the steel, is made between 180 degrees and 690 degrees depending on the desired properties.