Introduction
40Cr alloy structure steel is one of the commonly used medium carbon quenching and tempering structural steel, which is also called Structural Steel or Special Steel. It is a medium carbon steel with high strength and strength: medium plastic and good welding performance. Its quenching and tempering hardness is higher than that of ordinary carbon structural steel, and its long-term working temperature is below 500 °C. 40Cr alloy steel is mainly used to manufacture machine parts with certain strength, toughness and wear resistance. Its widely used in the manufacture of high load and medium speed transmission machine parts such as gears, shafts, spindles, studs, nuts, splined shafts, bolts and keys.
Characteristics and properties of 40Cr alloy structure steel
Due to its medium carbon content, 40Cr alloy structure steel has good comprehensive mechanical properties, hardenability and machinability, but its cutting performance is low, and its welding performance is generally good. Its acid-base resistance, atmospheric corrosion resistance and certain corrosive media are related to the content of chromium and nickel in the material. The quenched and tempered microstructure consists of martensite, lath martensite and fine carbide particles, which gives the steel high hardness and high strength, as well as wear and tear resistance. The tensile strength of the steel can reach 1045 MPa, and its toughness is slightly poorer than that of the 30Crsi steel of the same strength. 40Cr alloy structure steel can be electroplated on the surface to improve its corrosion resistance.
Heat treatment process of 40Cr alloy structure steel
The quenching and tempering treatment is the main heat treatment method for 40Cr alloy structure steel. Hardening and tempering process parameters: heating temperature 760-780 ℃, heat preservation time is not less than 30 minutes; quenching media is oil and water, quenching temperature 860 ℃; tempering temperature can be selected according to the mechanical properties of the parts. In general, it is 180-200 ℃, and the tempering time is not less than 30 minutes. After quenching and tempering, the hardness of the steel reaches HRC21-25.
In addition, 40Cr alloy structure steel can also be nitrided, carbonitrided, carburized and other surface strengthening treatment to improve its wear resistance. Nitriding treatment temperature of 40Cr alloy steel is usually 480-520 ℃, nitrogen supply is 0.40-0.50%, tempering temperature is 150-170 ℃. After nitrogen treatment, the hardness of the steel can reach HRC50.
40Cr alloy structure steel is used for what parts
40Cr alloy structure steel is widely used for manufacturing parts with high strength, good toughness and wear resistance, such as gears, shafts, transmissions, load transmitters, power take-off shafts, shear blades and other machine components.
Conclusion
40Cr alloy structure steel is a medium carbon quenching and tempering steel, which has good comprehensive mechanical properties, hardenability and machining performance. It is mainly used for manufacturing parts with high strength, toughness and wear resistance, such as gears, shafts, transmissions, load take-off shafts, shear blades, etc. It is an important structural material. The quenching and tempering process is the main heat treatment method for 40Cr alloy structure steel, and nitriding treatment can also be performed at appropriate temperature.
