Steel 20MnCr5 vs 31CrMoV9
Steel · grade comparison
Steel 20MnCr5 and 31CrMoV9 are both steel grades. 31CrMoV9 is the stronger of the two: yield strength 880 MPa (128 ksi) against 460 MPa (66.7 ksi) for 20MnCr5, about 91% more; tensile strength follows at 1,100 MPa (160 ksi) vs 750 MPa (109 ksi). In exchange, 20MnCr5 is the more ductile: elongation 18% versus 12% for 31CrMoV9, and 31CrMoV9 is harder (330 HB vs 210 HB). 31CrMoV9 runs hotter in service (450°C vs 250°C continuous) and 20MnCr5 conducts heat better (44 W/m·K vs 36 W/m·K). On the shop floor, 20MnCr5 machines more easily (good vs fair) and 20MnCr5 welds better (fair vs poor).
20MnCr5Choose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
31CrMoV9Choose it when strength drives the design, or when the part sees heat.
20MnCr5 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.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Fracture Toughness (K_IC)
Hardness, Rockwell C
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%
Physical
Density and transition temperatures.
Melting Point (Solidus)
Liquidus Temperature
Same in both: Density 7.85 g/cm³0.28 lb/in³
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Same in both: Min Service Temperature -40°C-40 °F
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)
Brazeability / Solderability
Polishability
Same in both: Castability 25 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 60 L/kg7.2 gal/lb
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 | 20MnCr5 | 31CrMoV9 |
|---|---|---|
| Default condition | HR | 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.
20MnCr5 vs 31CrMoV9 — frequently asked
Is 31CrMoV9 stronger than 20MnCr5?
Yes. 31CrMoV9 has a typical yield strength of 880 MPa (128 ksi) against 460 MPa (66.7 ksi) for 20MnCr5 — about 91% more. Tensile strength is 1,100 MPa (160 ksi) vs 750 MPa (109 ksi).
Which is cheaper, 20MnCr5 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.
Which is easier to machine, 20MnCr5 or 31CrMoV9?
20MnCr5. Its machinability rates good (55/100) against fair (40/100) for 31CrMoV9; for welding the order is 20MnCr5 first (fair, 45/100) then 31CrMoV9 (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 20MnCr5 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.