The chemical composition and mechanical properties of 20CrMnMo, along with its main applications
20CrMnMo is a type of alloy structural steel defined by the Chinese national standards. Its unified numerical code is A34202. This high-strength alloy is widely used in the manufacturing of critical mechanical components that require excellent strength, toughness, and wear resistance.
**Chemical Composition (in weight %):**
- 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 (based on a sample size of 15mm):**
- **Heat Treatment:**
- Quenching temperature: 850°C, oil as coolant
- Tempering temperature: 200°C, water or air as coolant
- **Tensile Strength (σb/MPa):** ≥1180 MPa
- **Yield Strength (σs/MPa):** ≥885 MPa
- **Elongation after fracture (δ5/%):** ≥10%
- **Reduction of area (ψ/%):** ≥45%
- **Impact absorption work (Aku2/J):** ≥55 J
- **Brinell Hardness (HBS100/3000):** ≤217 (annealed or high-temperature tempered)
The material is delivered either through heat treatment (normalizing, annealing, or high-temperature tempering) or in the non-heat-treated state, depending on the requirements specified in the contract.
**Key Characteristics:**
20CrMnMo is a high-grade carburizing steel known for its superior strength compared to 15CrMnMo, although it exhibits slightly lower plasticity and toughness. It has better hardenability and mechanical properties than 20CrMnTi. When quenched and tempered at low temperatures, it offers excellent comprehensive mechanical properties and low-temperature impact toughness. After carburizing and quenching, it provides high bending strength and wear resistance. However, cracks may occur during grinding, so care must be taken during this process.
**Weldability and Machinability:**
It has poor weldability, but it can be welded using resistance welding methods. Preheating before welding and post-weld tempering are recommended. It also shows good machinability and hot workability.
**Applications:**
This steel is commonly used to produce high-strength carburized parts requiring high hardness, strength, and toughness—superior to those of 15CrMnMo. Typical applications include crankshafts, camshafts, connecting rods, gear shafts, gears, pins, and other similar components. It can also serve as an alternative to 12Cr2Ni4 in certain cases.
For more information on materials and their properties, visit [ChinaWJ.com](http://news.chinawj.com.cn).
Editor: Hardware Business Network Information Center
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