Steel 4-79 Mo-Permalloy vs Fe-Co 50 (unalloyed)
Steel · grade comparison
Steel 4-79 Mo-Permalloy and Fe-Co 50 (unalloyed) are both steel grades. Fe-Co 50 (unalloyed) is the stronger of the two: yield strength 800 MPa (116 ksi) against 260 MPa (37.7 ksi) for 4-79 Mo-Permalloy, about 3.1 times as much; tensile strength follows at 900 MPa (131 ksi) vs 550 MPa (79.8 ksi). In exchange, 4-79 Mo-Permalloy is the more ductile: elongation 40% versus 1.5% for Fe-Co 50 (unalloyed), and Fe-Co 50 (unalloyed) is harder (300 HB vs 120 HB). Fe-Co 50 (unalloyed) is lighter (8.2 g/cm³ vs 8.74 g/cm³ for 4-79 Mo-Permalloy) and Fe-Co 50 (unalloyed) conducts heat better (43 W/m·K vs 19 W/m·K). On the shop floor, 4-79 Mo-Permalloy machines more easily (30 vs 20 out of 100) and 4-79 Mo-Permalloy welds better (good vs poor).
4-79 Mo-PermalloyChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
Fe-Co 50 (unalloyed)Choose it when strength drives the design, or when weight is the constraint.
4-79 Mo-Permalloy vs Fe-Co 50 (unalloyed): 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.
4-79 Mo-PermalloyFe-Co 50 (unalloyed)
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Shear Modulus
Bulk Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Compressive Strength
Shear Strength
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Poisson's Ratio 0.3
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)
Min Service Temperature
Latent Heat of Fusion
Same in both: Max Service Temperature (continuous) 400°C752 °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 | Fe-Co 50 (unalloyed) |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
4-79 Mo-Permalloy vs Fe-Co 50 (unalloyed) — frequently asked
Is Fe-Co 50 (unalloyed) stronger than 4-79 Mo-Permalloy?
Yes. Fe-Co 50 (unalloyed) has a typical yield strength of 800 MPa (116 ksi) against 260 MPa (37.7 ksi) for 4-79 Mo-Permalloy — about 3.1 times as much. Tensile strength is 900 MPa (131 ksi) vs 550 MPa (79.8 ksi).
Which is cheaper, 4-79 Mo-Permalloy or Fe-Co 50 (unalloyed)?
Both sit in the same relative cost tier ($$$$, 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 Fe-Co 50 (unalloyed)?
4-79 Mo-Permalloy, by a small margin. Both rate poor for machinability — 30/100 against 20/100 for Fe-Co 50 (unalloyed); for welding the order is 4-79 Mo-Permalloy first (good, 60/100) then Fe-Co 50 (unalloyed) (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4-79 Mo-Permalloy and Fe-Co 50 (unalloyed) 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.