Steel 30CrNiMo8 vs 31CrMoV9
Steel · grade comparison
Steel 30CrNiMo8 and 31CrMoV9 are both steel grades. 30CrNiMo8 is the stronger of the two: yield strength 1,000 MPa (145 ksi) against 880 MPa (128 ksi) for 31CrMoV9, about 14% more; tensile strength follows at 1,200 MPa (174 ksi) vs 1,100 MPa (160 ksi). 30CrNiMo8 is harder — 355 HB against 330 HB for 31CrMoV9 — which matters for wear surfaces and threads. 31CrMoV9 runs hotter in service (450°C vs 350°C continuous).
30CrNiMo8Choose it when strength drives the design, or when surface hardness matters.
31CrMoV9Choose it when the part sees heat.
30CrNiMo8 vs 31CrMoV9: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Shear Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Elongation at Break 12%
Physical
Density and transition temperatures.
Liquidus Temperature
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Latent Heat of Fusion 250 J/g107 BTU/lb
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Same in both: Brazeability / Solderability 45 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Specific Stiffness (E / density) 26.8 MN·m/kg · Thermal Shock Resistance Index 16
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 30CrNiMo8 | 31CrMoV9 |
|---|---|---|
| Default condition | Q&T | Q&T |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining and Sheet metal. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
30CrNiMo8 vs 31CrMoV9 — frequently asked
Is 30CrNiMo8 stronger than 31CrMoV9?
Yes. 30CrNiMo8 has a typical yield strength of 1,000 MPa (145 ksi) against 880 MPa (128 ksi) for 31CrMoV9 — about 14% more. Tensile strength is 1,200 MPa (174 ksi) vs 1,100 MPa (160 ksi).
Which is cheaper, 30CrNiMo8 or 31CrMoV9?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
When should I choose 30CrNiMo8 over 31CrMoV9?
Pick 30CrNiMo8 when strength drives the design, or when surface hardness matters. Pick 31CrMoV9 when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 30CrNiMo8 and 31CrMoV9 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.