-Quenching: By rapidly cooling, the hardness of the metal is increased. Oil quenching or water quenching are common quenching methods.
-Tempering: By controlling the heating and cooling process, the hardness caused by quenching is reduced while enhancing the metal's toughness. This step usually follows quenching.
-Normalizing: The material is heated to high temperatures and then cooled in the air to improve the uniformity of the structure.
-Annealing: By heating to high temperatures and slowly cooling, stress is relieved, ductility is increased, and the crystal structure is improved.