Tempering is carried out by preheating previously quenched or normalized steel to a temperature below the critical range, holding, and then cooling to obtain the desired mechanical properties. Tempering is used to reduce the brittleness of quenched steel. Many products that require hardness and resistance to breakage are quenched and tempered. The temperature chosen for the tempering process directly impacts the hardness of the work piece . The higher the temperature in the tempering process, the lower the hardness.