Steel Permendur-MA (Magnetic final anneal)
Heat-treated state · default condition
Standard delivered/finished condition for laminations, pole pieces and cores — gives full 2.3 T saturation and low coercivity, but the ordered structure is brittle so no forming afterwards.
Values for the MA condition
Other Permendur tempers and conditions
Permendur is listed in 4 conditions; see the grade overview at Permendur.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
MADefaultThis page Magnetic final anneal | Standard delivered/finished condition for laminations, pole pieces and cores — gives full 2.3 T saturation and low coercivity, but the ordered structure is brittle so no forming afterwards. | 340 | 520 | 3 | 92 HRB | — |
Hot-rolled / forged bar and billet, mill annealed | Bar, billet and ring stock for machined pole pieces, rotor hubs and magnetic-bearing parts; machine first, then final magnetic anneal. | 360 | 560 | 5 | 200 HB | 4.3 % IACS |
Rapid-cooled (disordered) ductile condition, ~750–800 °C water/oil… | Choose when the part must be deep-drawn, bent or heavily machined: quenching suppresses B2 ordering and restores ductility; a final magnetic anneal is still required. | 400 | 620 | 15 | 172 HB | 3.8 % IACS |
Cold rolled | The normal purchase condition for stamping stock: hard, dimensionally stable strip that is blanked/etched first and magnetically annealed afterwards. | 720 | 900 | 2 | 30 HRC | 4.1 % IACS |
What is Permendur-MA?
Permendur-MA is Permendur heat treated to MA — standard delivered/finished condition for laminations, pole pieces and cores — gives full 2.3 T saturation and low coercivity, but the ordered structure is brittle so no forming afterwards. Permendur-MA has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 76% of steel grades. Elongation at break is 3% and the elastic modulus is 207 GPa (30 Msi). Permendur-MA has a density of 8.12 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,440°C (2,624 °F).
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- Good corrosion resistance — 22/100, better than 90% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited ductility — 3%, worse than 99% of steel grades
- High embodied carbon — 7.5 kg CO₂/kg, worse than 99% of steel grades
- Difficult to machine — 22/100, worse than 95% of steel grades
- Limited formability — 12/100, worse than 92% of steel grades
- Poor heat conductor — 29.8 W/m·K (17.2 BTU/hr·ft·°F), worse than 84% of steel grades
Permendur-MA properties
Typical room-temperature values for Permendur-MA; 12 are specific to this condition. Other listed values are Permendur reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Permendur-MA has a density of 8.12 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,440°C (2,624 °F).
Mechanical14
Permendur-MA has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 76% of steel grades. Elongation at break is 3% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
Permendur-MA is rated for continuous service to 500°C (932 °F). It conducts heat at 29.8 W/m·K (17.2 BTU/hr·ft·°F), worse than 84% of steel grades. Thermal expansion is 9.6 µm/m·K (5.33 µin/in·°F).
Electrical3
Permendur-MA conducts electricity at 4.3 % IACS, worse than 82% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (22/100), better than 90% of steel grades.
Sustainability4
Producing a kilogram of Permendur-MA takes about 95 MJ of energy and emits 7.5 kg of CO₂ — more than 99% of steel grades. Typical recycled content is 25%.
Manufacturability8
Permendur-MA's machinability is poor (22/100, worse than 95% of steel grades); weldability fair (40/100); formability not recommended (12/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Permendur-MA
Is Permendur easy to machine?
Machine in the as-rolled or quenched-disordered state with sharp carbide tooling, rigid setups, low speed and flood coolant — the ordered annealed material chips and cracks; finish-machine before the final magnetic anneal.
Can Permendur be welded?
GTAW, laser and electron-beam welding are feasible with matching or Fe-Co filler and preheat; welds must be re-annealed in dry hydrogen to restore permeability, and weld zones stay locally hard and crack-prone.
Can Permendur be formed, bent or molded?
Blank, stamp, etch or draw in the hard as-rolled or quenched condition; never bend after the ordering anneal, and stress-relieve/final-anneal parts at 840–885 °C in dry H₂ with a slow (≤150 °C/h) cool.
What surface finishes work on Permendur?
No inherent corrosion resistance — apply electroless nickel, Ni/Sn plating, phosphate or an inorganic C-5-type lamination coating; pole faces polish well but must be protected against humid-air rusting.
Permendur chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cogives the 2.3 T saturation | 48.5 – 50 | 49 |
| Vraises resistivity and workability, suppresses ordering embrittlement | 1.4 – 2.2 | 2 |
| Ckept low for low coercivity | ≤ 0.03 | 0.01 |
| Mn | ≤ 0.3 | 0.05 |
| Si | ≤ 0.3 | 0.05 |
| Niresidual | ≤ 0.5 | 0.1 |
| S | ≤ 0.02 | 0.01 |
| P | ≤ 0.02 | 0.01 |
| Febalance, ~49 % | balance | — |
Permendur-MA — frequently asked
What is Permendur-MA used for?
Permendur-MA is typically used for aerospace generator/motor laminations, magnetic pole pieces, high-flux transformer cores and electromagnet pole tips. In short: highest saturation soft-magnetic alloy; highest service temperature here; brittle after ordering anneal.
What is the yield strength of Permendur-MA?
Permendur-MA has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 76% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is Permendur-MA easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of steel grades). Machine in the as-rolled or quenched-disordered state with sharp carbide tooling, rigid setups, low speed and flood coolant — the ordered annealed material chips and cracks; finish-machine before the final magnetic anneal.
Can Permendur-MA be welded?
With care — weldability is rated fair (40/100). GTAW, laser and electron-beam welding are feasible with matching or Fe-Co filler and preheat; welds must be re-annealed in dry hydrogen to restore permeability, and weld zones stay locally hard and crack-prone.
What surface finishes work on Permendur-MA?
No inherent corrosion resistance — apply electroless nickel, Ni/Sn plating, phosphate or an inorganic C-5-type lamination coating; pole faces polish well but must be protected against humid-air rusting.
Can Permendur-MA be formed, bent or molded?
Blank, stamp, etch or draw in the hard as-rolled or quenched condition; never bend after the ordering anneal, and stress-relieve/final-anneal parts at 840–885 °C in dry H₂ with a slow (≤150 °C/h) cool.
What is the maximum service temperature of Permendur-MA?
Permendur-MA is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Permendur-MA and Permendur-CR?
MA is the default condition — standard delivered/finished condition for laminations, pole pieces and cores — gives full 2.3 T saturation and low coercivity, but the ordered structure is brittle so no forming afterwards. CR: the normal purchase condition for stamping stock: hard, dimensionally stable strip that is blanked/etched first and magnetically annealed afterwards. Yield strength is 340 MPa in MA versus 720 MPa in CR.
Sources
- Hiperco 50 Alloy technical datasheet — Carpenter Technology (2020)
- VACOFLUX 50 soft magnetic cobalt-iron alloy — Vacuumschmelze (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Soft Magnetic Materials) — ASM International (1990)
- ASTM A801 — Standard Specification for Wrought Iron-Cobalt High Magnetic Saturation Alloys — ASTM (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.