Alloy structural steel 40CrMnMo is a kind of low alloy steel with good plasticity, toughness and cold deformationability, which is widely used in various parts of automobiles, tractors and other transportation vehicles and engineering machinery.
The 40CrMnMo alloy structural steel belongs to low alloy steel.The content of carbon and other alloy elements in 40CrMnMo alloy structural steel is relatively low, the microstructure is usually martensite or bainite, with some pearlite and ferrite.The amount of pearlite and ferrite is not constant, generally in high temperature quenching and tempering heat treatment state.
1.Chemical composition
According to the standard GB/T 3077-1999, the chemical composition specification range of 40CrMnMo alloy structural steel is as follows:
Carbon: 0.37%-0.44%;
Silicon: 0.17%-0.37%;
Manganese: 0.50%-0.80%;
Chromium: 0.80%-1.10%;
Molybdenum: 0.15%-0.25%;
Manganese: 0.35%-0.50%;
Niobium: 0.003%-0.004%;
Phosphorus: 0.035% max;
Sulfur: 0.035% max;
Copper: 0.25% max;
2.Geological structure
The result of the tempering heat treatment of 40CrMnMo alloy structural steel is mainly martensite and semi-martensite, with a small amount of bainite or tempered martensite.The grain size of martensite is usually finer.
The tempering heat treatment of the 40CrMnMo alloy structural steel increases the plasticity and toughness of the steel, and reduces the hardenability of the steel, so that the quenching and tempering process can be simplified and the microstructure is easier to control.
3.Physical properties
The 40CrMnMo alloy structural steel has a slightly higher strength than the 40Cr alloy structural steel.The yield strength in the case of cold deformation is ≥940MPa, the tensile strength is ≥1150MPa and the elongation percentage is ≥9%.
In general, 40CrMnMo alloy structural steel is more brittle than 40Cr alloy structural steel, so it is more suitable for machining parts.
4.Mechanical properties
The mechanical properties of the 40CrMnMo alloy structural steel mainly depend on the chemical composition, heat treatment process and process parameters.
Under the quenching heat treatment process, the yield strength of 40CrMnMo alloy structural steel reaches ≥980MPa and its hardness reaches HRC29-34.After tempering heat treatment, the yield strength of 40CrMnMo alloy structural steel is ≥940MPa and its hardness is HRC19-24.
5.Application
The application of the 40CrMnMo alloy structural steel covers a wide range and includes parts for cars, tractors and other transportation vehicles, engineering machinery and aircraft structures, etc.
40CrMnMo alloy structural steel is mainly used in the transmission parts of automotive engine, transmission case, transmission shaft, camshaft, universal joint, bearing and various fasteners.
In addition, 40CrMnMo alloy structural steel can also be used in manufacturing other parts of automobiles, tractors and other transportation vehicles, such as gears, crankshafts and connecting rods.
In conclusion, 40CrMnMo alloy structural steel has good performance and is widely used in manufacturing various parts of automobiles, tractors and other transportation vehicles, and has been recognized in the industry.
