The differences between tempering and annealing mainly lie in the treatment temperature, cooling method, and purpose:
1. Different treatment temperatures
The treatment temperature of tempering is usually below the quenching temperature, such as high-temperature tempering is generally between 500℃-650℃, while low-temperature tempering is usually between 250℃-350℃. The general treatment temperature of annealing is lower, usually below 400℃.
2. Different cooling methods
The cooling methods of tempering and annealing are also different. The cooling of tempering is generally natural cooling in the air or water quenching; while the cooling of annealing is generally slow, and furnace cooling, oil quenching, and other methods can be used.
3. Different purposes
The main purpose of tempering is to improve the toughness, plasticity and tensile properties of the metal, so that it has a certain hardness and strength, while avoiding excessive brittleness caused by quenching. The main purpose of annealing is to eliminate residual stress and structural defects in the metal, and improve the machinability, corrosion resistance and mechanical properties of the material.

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