Steel 4-79 Mo-Permalloy vs Permendur
Steel · grade comparison
Steel 4-79 Mo-Permalloy and Permendur are both steel grades. Permendur is the stronger of the two: yield strength 340 MPa (49.3 ksi) against 260 MPa (37.7 ksi) for 4-79 Mo-Permalloy, about 31% more. In exchange, 4-79 Mo-Permalloy is the more ductile: elongation 40% versus 3% for Permendur, and Permendur is harder (190 HB vs 120 HB). Permendur is lighter (8.12 g/cm³ vs 8.74 g/cm³ for 4-79 Mo-Permalloy) and Permendur runs hotter in service (500°C vs 400°C continuous). On the shop floor, 4-79 Mo-Permalloy welds better (good vs fair).
4-79 Mo-PermalloyChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
PermendurChoose it when strength drives the design, or when weight is the constraint.
4-79 Mo-Permalloy vs Permendur: 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.
Elastic (Young's) Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Shear Strength
Charpy V-Notch Impact (RT)
Same in both: Shear Modulus 80 GPa11.6 Msi · Fatigue Strength (Endurance Limit) 250 MPa36.3 ksi
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
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)
Latent Heat of Fusion
Same in both: Min Service Temperature -196°C-321 °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)
Castability
Brazeability / Solderability
Polishability
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)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
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 | 4-79 Mo-Permalloy | Permendur |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
4-79 Mo-Permalloy vs Permendur — frequently asked
Is Permendur stronger than 4-79 Mo-Permalloy?
Yes. Permendur has a typical yield strength of 340 MPa (49.3 ksi) against 260 MPa (37.7 ksi) for 4-79 Mo-Permalloy — about 31% more. Tensile strength is 520 MPa (75.4 ksi) vs 550 MPa (79.8 ksi).
Which is cheaper, 4-79 Mo-Permalloy or Permendur?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, 4-79 Mo-Permalloy or Permendur?
4-79 Mo-Permalloy, by a small margin. Both rate poor for machinability — 30/100 against 22/100 for Permendur; for welding the order is 4-79 Mo-Permalloy first (good, 60/100) then Permendur (fair, 40/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4-79 Mo-Permalloy and Permendur 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.