English name: tempering

Definition: Heat treatment process of heating quenched steel to below AC 1 and cooling after heat preservation. Tempering is the process of heating quenched steel below austenite transformation temperature, holding for 1 ~ 2 hours, and then cooling. Tempering is often accompanied by quenching, which is the last process of heat treatment. After tempering, the microstructure of steel tends to be stable, the brittleness of quenched steel is reduced, the toughness and plasticity are improved, the quenching stress is eliminated or reduced, the shape and size of steel are stable, the deformation and cracking of quenched parts are prevented, and high temperature tempering can also improve the cutting performance.

Tempering is a heat treatment process that hardens the workpiece, heats it to a certain temperature below AC 1, keeps it for a certain time, and then cools it to room temperature.

After quenching, tempering is usually carried out for the following purposes:

(a) Eliminate the residual stress generated when the workpiece is quenched, and prevent deformation and cracking;

(b) Adjust the hardness, strength, plasticity and toughness of the workpiece to meet the performance requirements;

(c) Stabilize the structure and size to ensure the accuracy;

(d) improve and improve the processability. Therefore, tempering is the last important process to obtain the required properties of the workpiece.

According to the tempering temperature range, tempering can be divided into low temperature tempering, medium temperature tempering and high temperature tempering.