Quenching and tempering are two different methods in metal heat treatment. Their main differences are heating temperature, cooling rate, hardness, toughness and application scenarios.

Heating temperature.

Quenching is to heat the metal material above the critical temperature, keep it for a period of time, make it fully or partially austenitized, and then cool it rapidly to improve its hardness and wear resistance; quenching and tempering is to heat the metal material to the appropriate temperature. temperature (usually higher than the quenching temperature), and after a period of heat preservation, high temperature tempering is performed to obtain good comprehensive mechanical properties, such as hardness, toughness and plasticity.

Cooling rate.

Quenching usually involves very rapid cooling to achieve high hardness, while tempering involves slower cooling to retain the toughness and strength of the material.

Hardness and toughness.

Quenching mainly improves the hardness and wear resistance of metal materials, but the toughness is relatively weakened; quenching and tempering can improve the toughness and ductility of metal materials while ensuring a certain hardness.

Application scenarios.

Quenching is suitable for parts that require high hardness and surface strength, such as frames and transmission shafts; quenching and tempering is usually used for materials that require high strength and good toughness, such as automobile crankshafts and machine tools.