48% Nickel-Iron (Permalloy 50)
A nickel-iron alloy with balanced saturation and permeability
Typical values for the temper in the title
A nickel-iron alloy with about 48% nickel sits in the middle: its saturation (about 1.5–1.6 T, typical) is about double that of Mu-metal, and its permeability much higher than electrical steel.
It is used for transformer and inductor cores, relays, stepper motors and sensors, and for the outer layer in multilayer magnetic shielding.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Density ρ | 8.25 g/cm³ | |
| Magnetic saturation Bs | ≈1.5–1.6 T (typical) | |
| Machinability | 60% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Ni nickel | about 48 (nominal) | |
| Fe iron | balance |
Nominal composition. Standard: ASTM A753.
Conditions and product forms
In soft magnetic materials the magnetic properties are set by the final anneal. Any machining, bending or impact after the anneal lowers permeability and increases losses.
| Condition | Properties | When to choose it |
|---|---|---|
| Worked | low permeability | forming |
| Hydrogen annealed | maximum magnetic properties | the finished part |
Applications
- Transformer and inductor cores
- Relays
- Stepper motors
- Sensors
- Outer shielding layer
Fabrication
Annealing
In hydrogen after forming.
Handling
Impact and machining after the anneal hurt properties.
Selection
When the field is too strong for Mu-metal and too weak for iron.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Mu-metal | — / | — | Mu-metal: higher permeability, lower saturation · material page |
| Electrical Steel (Silicon Steel) | — / | — | electrical steel: cheaper, lower permeability · material page |
| Hiperco 50 | — / | — | Hiperco 50: maximum saturation · material page |
Common mistakes
Machining after the anneal
Properties suffer.
Choosing it for a very weak field
Mu-metal is better.
Confusing it with Invar or Kovar
There nickel serves expansion, not magnetics.
Equivalents, standards and supply
| Standards | ASTM A753 |
|---|---|
| Forms | strip · sheet · bar |
| Producers | Carpenter (High Permeability 49) · VAC |
Learn more
Values are typical and for comparison only. For design, rely on the standard, the producer specification and the mill certificate. Sources: ASTM standards (B86, B386, B392/B393, B551, B708, B760 and others), producer data, and the METAL HUB materials database.
Updated: October 31, 2026