34CrNi3Mo is a high-strength structural steel alloy with good comprehensive mechanical performance and processability.
It is governed by the standard: JB/T6396-2006.
42CrMo steel is an ultra-high-strength steel, with high strength and toughness, good hardenability, no obvious quenching brittleness, high fatigue limit and multiple impact resistance after quenching and tempering, and good impact toughness at low temperatures.
It is governed by the GB/T 3077-1999 standard.
Comparison of chemical composition
| 34CrNi3Mo | 42CrMo |
| C:0.30-0.40% | C:0.38-0.45% |
| S:0.17-0.37% | Si:0.17-0.37% |
| Mn:0.50-0.80% | Mn:0.50-0.80% |
| S:≤0.035% | S:≤0.035% |
| P:≤0.035% | P:≤0.035% |
| Cr:0.70-1.10% | Cr:0.90-1.20% |
| N:2.75-3.25% | Ni:≤0.030% |
| Cu:≤0.020% | Cu:≤0.030% |
| M0:0.25-0.40% | Mo:0.15-0.25% |
Comparison of mechanical properties
After quenching and tempering in accordance with standard JB/T6396-2006, the properties of 34CrNi3Mo are as follows:
- Tensile strength ≥900
- Yield strength ≥785
- Elongation ≥14%
- Shrinkage after fracture ≥40%
- Impact work ≥54J.
After quenching and tempering according to GB/T 3077-1999 standard, the properties of 42CrMo are as follows:
- Tensile strength ≥1080
- Yield strength ≥930
- Elongation ≥12%
- Shrinkage after fracture ≥45%
- Impact work ≥63J.
From the above comparison, it can be seen that 34CrNi3Mo and 42CrMo are quite similar in chemical composition, with only the element Ni making a significant difference. Because the value of Ni element is relatively high, the raw material production cost of 34CrNi3Mo is higher than that of 42CrMo.
Both materials have similar good hardenability, plasticity and toughness. In practical applications, if both mechanical properties (tensile strength ≥900, yield strength ≥785, elongation ≥14%, fracture shrinkage ≥40%, impact work ≥54J) are met and the cost is controlled, the materials of 42CrMo grade can also meet the requirements.
