Steel FeNi42 vs Super Invar
Steel · grade comparison
Steel FeNi42 and Super Invar are both steel grades. FeNi42 is the stronger of the two: tensile strength 540 MPa (78.3 ksi) against 500 MPa (72.5 ksi) for Super Invar, about 8% more. Super Invar is harder — 150 HB against 140 HB for FeNi42 — which matters for wear surfaces and threads. FeNi42 runs hotter in service (350°C vs 150°C continuous) and FeNi42 conducts electricity better (2.5 % IACS vs 2.2 % IACS). On the shop floor, FeNi42 forms better (excellent vs very good).
FeNi42Choose it when strength drives the design, or when the part sees heat.
Super InvarChoose it when surface hardness matters.
FeNi42 vs Super Invar: 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Compressive Strength
Fracture Toughness (K_IC)
Same in both: Elastic (Young's) Modulus 145 GPa21 Msi · Shear Modulus 57 GPa8.3 Msi · Yield Strength (0.2% offset) 300 MPa43.5 ksi · Hardness, Rockwell B 80 HRB
Physical
Density and transition temperatures.
Density
Same in both: Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,450°C2,642 °F
Thermal
How each material carries heat and how hot it can run.
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Thermal Conductivity 10.5 W/m·K6.1 BTU/hr·ft·°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 Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Same in both: Machinability 30 / 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)
Specific Stiffness (E / density)
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Modulus of Resilience 310 kJ/m³
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 | FeNi42 | Super Invar |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
FeNi42 vs Super Invar — frequently asked
Is FeNi42 stronger than Super Invar?
Yes. FeNi42 has a typical tensile strength of 540 MPa (78.3 ksi) against 500 MPa (72.5 ksi) for Super Invar — about 8% more.
Which is cheaper, FeNi42 or Super Invar?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
When should I choose FeNi42 over Super Invar?
Pick FeNi42 when strength drives the design, or when the part sees heat. Pick Super Invar when surface hardness matters.
Ready to make it?
Upload a CAD file and FabDigit prices the part in FeNi42 and Super Invar 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.