20CrMnMo Chemical Composition and Mechanical Properties, Main Applications
20CrMnMo is a type of alloy structural steel specified by the Chinese national standard. Its unified numerical code is A34202. This steel grade is widely used in mechanical engineering due to its excellent strength, toughness, and hardenability.
**Chemical Composition (in weight percentage):**
- Carbon (C): 0.17–0.23%
- Silicon (Si): 0.17–0.37%
- Manganese (Mn): 0.90–1.20%
- Sulfur (S): ≤0.035%
- Phosphorus (P): ≤0.035%
- Chromium (Cr): 1.10–1.40%
- Nickel (Ni): ≤0.030%
- Copper (Cu): ≤0.030%
- Molybdenum (Mo): 0.20–0.30%
**Mechanical Properties (sample blank size: 15mm):**
- Heat Treatment:
- Quenching temperature: 850°C, cooled with oil
- Tempering temperature: 200°C, cooled with water or air
- Tensile Strength (σb): ≥1180 MPa
- Yield Strength (σs): ≥885 MPa
- Elongation (δ5): ≥10%
- Reduction of Area (ψ): ≥45%
- Impact Toughness (Aku2): ≥55 J
- Brinell Hardness (HBS100/3000) in annealed or high-temperature tempered condition: ≤217
The material is typically delivered in heat-treated conditions such as normalizing, annealing, or high-temperature tempering, or it can be supplied without heat treatment, depending on the contract requirements.
20CrMnMo is a high-strength, high-grade carburizing steel. It offers better strength than 15CrMnMo, slightly lower plasticity and toughness, but higher hardenability and mechanical properties compared to 20CrMnTi. After quenching and low-temperature tempering, it exhibits good overall mechanical properties and low-temperature impact resistance. When carburized and quenched, it has high bending strength and wear resistance, although it is prone to cracking during grinding.
It has poor weldability, making it suitable for resistance welding only. Preheating before welding and tempering after welding are recommended. However, it has good machinability and hot workability.
**Applications:**
This steel is commonly used for manufacturing high-strength carburized parts that require high hardness, strength, and toughness—exceeding those of 15CrMnMo. Examples include crankshafts, camshafts, connecting rods, gear shafts, gears, and pins. It can also serve as an alternative to 12Cr2Ni4 in certain applications.
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Editor: Hardware Business Network Information Center.
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