Steel 31CrMoV9 vs 34MnB5
Steel · grade comparison
Steel 31CrMoV9 and 34MnB5 are both steel grades. 31CrMoV9 is the stronger of the two: yield strength 880 MPa (128 ksi) against 420 MPa (60.9 ksi) for 34MnB5, about 110% more; tensile strength follows at 1,100 MPa (160 ksi) vs 620 MPa (89.9 ksi). In exchange, 34MnB5 is the more ductile: elongation 14% versus 12% for 31CrMoV9, and 31CrMoV9 is harder (330 HB vs 185 HB). 31CrMoV9 runs hotter in service (450°C vs 400°C continuous) and 34MnB5 conducts heat better (44 W/m·K vs 36 W/m·K). On the shop floor, 34MnB5 machines more easily (good vs fair) and 34MnB5 welds better (good vs poor).
31CrMoV9Choose it when strength drives the design, or when the part sees heat.
34MnB5Choose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
31CrMoV9 vs 34MnB5: 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.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Hardness, Rockwell B
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 45% · Charpy V-Notch Impact (RT) 40 J29.5 ft·lbf
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)
Same in both: Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Galvanic Potential (seawater, vs SCE)
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Polishability
Same in both: Brazeability / Solderability 45 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 25%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 26.8 MN·m/kg
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 | 31CrMoV9 | 34MnB5 |
|---|---|---|
| CNC machining | Yes | — |
| Default condition | Q&T | CR |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | 0.8 mm | — |
| Best machined surface | Ra 1.6 µm | — |
| AlCrN | Yes | — |
| AlTiN | Yes | — |
| CVD Al2O3 | Yes | — |
| CVD TiCN | Yes | — |
| CVD TiN | Yes | — |
| CrN | Yes | — |
| DLC | Yes | — |
| HVOF Coating | Yes | — |
| MoS2 | Yes | — |
| Multilayer CVD | Yes | — |
| TiAlN | Yes | — |
| TiB2 | Yes | — |
| TiCN | Yes | — |
| TiN | Yes | — |
| WC/C | Yes | — |
| ZrN | Yes | — |
Both are offered for Sheet metal. They share 22 finishes: Black Oxide, Cerakote, Chrome Plating, Copper Plating, E-Coating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Hot-Dip Galvanizing, Manganese Phosphate, Nickel Plating and 10 more.
31CrMoV9 vs 34MnB5 — frequently asked
Is 31CrMoV9 stronger than 34MnB5?
Yes. 31CrMoV9 has a typical yield strength of 880 MPa (128 ksi) against 420 MPa (60.9 ksi) for 34MnB5 — about 110% more. Tensile strength is 1,100 MPa (160 ksi) vs 620 MPa (89.9 ksi).
Which is cheaper, 31CrMoV9 or 34MnB5?
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.
Which is easier to machine, 31CrMoV9 or 34MnB5?
34MnB5. Its machinability rates good (55/100) against fair (40/100) for 31CrMoV9; for welding the order is 34MnB5 first (good, 55/100) then 31CrMoV9 (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 31CrMoV9 and 34MnB5 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.