Magnetic Pure Iron (Armco)
Low-carbon iron for DC
Typical values for the temper in the title
Magnetic pure iron (such as Armco) is high-purity iron with very low carbon. It is a cheap soft magnetic material with high saturation (about 2.1 T, typical) and low coercive force.
It is especially suited to DC: cores for electromagnets, relays and solenoids, pole pieces and shielding in strong fields. In AC its low electrical resistivity causes high eddy current losses, so electrical steel is used there.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Density ρ | 7.87 g/cm³ | |
| Magnetic saturation Bs | ≈2.1 T (typical) | |
| Machinability | 50% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Fe iron | about 99.8 (nominal) | |
| C carbon | very low | low coercive force |
Standards: ASTM A848 (low-carbon magnetic iron) and ASTM A1126 (magnetic pure iron).
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 |
|---|---|---|
| Annealed | maximum magnetic properties | cores |
| Worked | stronger, less magnetic | mechanical parts |
Applications
- Electromagnet cores
- Relays and solenoids
- Pole pieces
- Shielding in strong fields
- Accelerator parts
Fabrication
Machining
Soft and "gummy". Sharp tools.
Annealing
Anneal after machining to restore magnetic properties.
Corrosion
It rusts. Coat it.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Electrical Steel (Silicon Steel) | — / | — | electrical steel: for AC · material page |
| Hiperco 50 | — / | — | Hiperco 50: higher saturation, expensive · material page |
| 1010 | 365 / 180 MPa | Excellent | 1010 steel: cheaper, less magnetic · material page |
Common mistakes
Using it in AC
High eddy current losses.
Leaving it unannealed after machining
Magnetic properties suffer.
Leaving it unprotected
It rusts.
Equivalents, standards and supply
| Standards | ASTM A848 / ASTM A1126 |
|---|---|
| Forms | bar · sheet · plate |
| Producers | AK Steel (Armco) · Cleveland-Cliffs |
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