Why should the gears be quenched?

The purpose of quenching is to transform all or most of his organization into martensite to obtain high hardness. Gear quenching can increase the hardness of the workpiece and more wear resistance, can greatly improve the strength, toughness and fatigue strength of the metal, and the martensite hardness can reach higher. The rapid cooling during quenching will cause internal stress within the workpiece, and when it is large to a certain extent, the workpiece will be deformed or even cracked. For this reason, a suitable cooling method must be selected.