What Is The Purpose Of Steel Quenching And Tempering?

DALIAN, China - Nov. 28, 2022 - PRLog -- The heat treatment method of high temperature tempering after quenching is called quenching and tempering treatment. High temperature tempering refers to tempering at 500-650 ℃. Quenching and tempering can greatly adjust the properties and materials of steel, and its strength, plasticity and toughness are good, with good comprehensive mechanical properties.

Tempered sorbite is obtained after quenching and tempering. Tempered sorbite is martensite formed during tempering. It can be distinguished after being magnified by more than 500~600 times under the optical metallographic microscope. It is a composite structure with carbide (including cementite) particles distributed in the ferrite matrix. It is also a tempering structure of martensite, a mixture of ferrite and granular carbide. At this time, the ferrite has almost no carbon supersaturation, and the carbide is also a stable carbide. It is a kind of balanced tissue at room temperature.

The quenched and tempered steel includes carbon quenched and tempered steel and alloy quenched and tempered steel. Whether it is carbon steel or alloy steel, its carbon content is strictly controlled. If the carbon content is too high, the strength of the quenched and tempered workpiece is high, but the toughness is not enough. If the carbon content is too low, the toughness is improved and the strength is not enough. In order to obtain good comprehensive performance of quenched and tempered parts, the carbon content is generally controlled at 0.30~0.50%.

During quenching, tempering and quenching, the entire section of the workpiece is required to be hardened to obtain a microstructure dominated by fine needle quenched martensite. The microstructure of uniformly tempered sorbite was obtained by high temperature tempering. The hardness after quenching must reach the quenching hardness of the material, and the hardness after tempering shall be checked according to the drawing requirements.

Hardening And Tempering Of 45 Steel

45 steel is a medium carbon structural steel with good cold and hot workability, good mechanical properties, low price and wide sources, so it is widely used. Its biggest weakness is that the workpieces with low hardenability, large section size and high requirements should not be used.

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