The differences between 30CrMoV9 and 31CrMoV9 can be analyzed from multiple perspectives, including chemical composition, mechanical properties, heat treatment, and applications. Here is a structured comparison:
1. Chemical Composition
Carbon Content:
30CrMoV9: C 0.26–0.34%.
31CrMoV9: C 0.27–0.34%.
(31CrMoV9 has a slightly narrower carbon range, with a higher minimum value.)
Phosphorus (P) Limits:
30CrMoV9: ≤0.035%.
31CrMoV9: ≤0.025%.
(31CrMoV9 has stricter phosphorus control for improved toughness and reduced brittleness.)
Other Elements:
Both share identical ranges for chromium (Cr: 2.30–2.70%), molybdenum (Mo: 0.15–0.25%), and vanadium (V: 0.10–0.20%)
2. Mechanical Properties
Yield Strength (σ₀.₂):
30CrMoV9:
16–40mm: ≥1020 MPa.
41–100mm: ≥900 MPa.
31CrMoV9:
16–40mm: 900 MPa.
Larger diameters show lower yield strength.
Tensile Strength (σb):
30CrMoV9: 1100–1300 MPa (for 41–100mm).
31CrMoV9: 1100–1300 MPa (for 16–40mm).
Impact Toughness:
31CrMoV9 exhibits better high-temperature creep resistance (up to 550°C) , but its mechanical properties degrade significantly after prolonged aging (e.g., 5000 hours)
3. Heat Treatment and Processing
Primary Heat Treatments:
30CrMoV9: Optimized for nitriding after quenching and tempering .
Common processes include normalizing (870–900°C) and annealing (680–720°C) .
31CrMoV9: Requires complex treatments like solid solution (860–900°C) and double refinement (quenching + high-temperature tempering) to enhance toughness and high-temperature stability.
Weldability:
Both steels are challenging to weld due to their alloy composition, but 31CrMoV9's stricter phosphorus control may marginally improve weldability
4. Applications
30CrMoV9:
Used for automotive components (e.g., camshafts, screws) and parts requiring nitriding for surface hardness .
Common in general engineering and machinery.
31CrMoV9:
Designed for high-stress, high-temperature environments (500–520°C), such as turbine rotors, generator rings, and wind turbine components .
Preferred in aerospace, power generation, and heavy machinery due to its superior creep resistance .
5. Standards and Origin
30CrMoV9: Complies with EN 10250-3 and DIN 17200 .
31CrMoV9: Follows EN 10085 and DIN 17211
(31CrMoV9 is often associated with German standards for specialized industrial applications.)
Summary Table
| Aspect | 30CrMoV9 | 31CrMoV9 |
|---|---|---|
| Carbon (C) | 0.26–0.34% | 0.27–0.34% |
| Phosphorus (P) | ≤0.035% | ≤0.025% |
| Key Application | Nitrided automotive parts | High-temperature turbines, rotors |
| Yield Strength | Up to 1020 MPa (16–40mm) | Up to 900 MPa (16–40mm) |
| Heat Treatment | Normalizing + nitriding | Solid solution + double refinement |
| Standard | EN 10250-3 | EN 10085 |
For detailed specifications or procurement, refer to manufacturers' datasheets or standards cited in the sources.
Just like you, 70% customers choose long-term cooperation with BBN steel not only for our good product and service quality, good reputation in the international market, but also for our experienced one-stop raw material supply and further steel processing!
