Steel 31CrMo12 vs Nitralloy 135
Steel · grade comparison
Steel 31CrMo12 and Nitralloy 135 are both steel grades. 31CrMo12 is the stronger of the two: yield strength 900 MPa (131 ksi) against 815 MPa (118 ksi) for Nitralloy 135, about 10% more; tensile strength follows at 1,100 MPa (160 ksi) vs 965 MPa (140 ksi). In exchange, Nitralloy 135 is the more ductile: elongation 17% versus 13% for 31CrMo12, and 31CrMo12 is harder (340 HB vs 302 HB). Nitralloy 135 conducts electricity better (7.8 % IACS vs 6.6 % IACS). On the shop floor, 31CrMo12 welds better (25 vs 15 out of 100).
31CrMo12Choose it when strength drives the design, or when it will be welded.
Nitralloy 135Choose it when the part is bent, formed or impact-loaded.
31CrMo12 vs Nitralloy 135: 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.
Bulk Modulus
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 C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · Poisson's Ratio 0.29 · Reduction in Area 50% · Fracture Toughness (K_IC) 70 MPa·√m63.7 ksi·√in
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Same in both: Liquidus Temperature 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 34 W/m·K19.6 BTU/hr·ft·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 15 / 100
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
Castability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Same in both: Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 30%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Shock Resistance Index
Same in both: Thermal Diffusivity 9.4 mm²/s
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 | 31CrMo12 | Nitralloy 135 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
31CrMo12 vs Nitralloy 135 — frequently asked
Is 31CrMo12 stronger than Nitralloy 135?
Yes. 31CrMo12 has a typical yield strength of 900 MPa (131 ksi) against 815 MPa (118 ksi) for Nitralloy 135 — about 10% more. Tensile strength is 1,100 MPa (160 ksi) vs 965 MPa (140 ksi).
Which is cheaper, 31CrMo12 or Nitralloy 135?
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, 31CrMo12 or Nitralloy 135?
31CrMo12, by a small margin. Both rate fair for machinability — 40/100 against 35/100 for Nitralloy 135; for welding the order is 31CrMo12 first (poor, 25/100) then Nitralloy 135 (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 31CrMo12 and Nitralloy 135 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.