Nickel Alloy Mu-metal ANN-MILL
Heat-treated state
UNS N14080 · ASTM A753 Type 4 · EN 2.4545 · GB 1J79 · also Mumetal / Permalloy 80
Standard as-shipped sheet/strip condition: ductile for deep drawing, spinning and shearing; magnetic properties only partly developed until final hydrogen anneal.
Values for the ANN-MILL condition
Other Mu-metal tempers and conditions
Mu-metal is listed in 5 conditions; see the grade overview at Mu-metal.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANN-H2Default Annealed | Final condition for magnetic shields and cores: maximum permeability, lowest coercivity — do not cold-work or machine after this anneal. | 250 | 550 | 40 | 115 HB | 3 % IACS |
ANN-MILLThis page soft, formable (supplied for fabrication, anneal after forming) | Standard as-shipped sheet/strip condition: ductile for deep drawing, spinning and shearing; magnetic properties only partly developed until final hydrogen anneal. | 280 | 580 | 35 | 130 HB | 3 % IACS |
Half hard | Intermediate cold-worked strip for stampings and springs that need extra stiffness before the final magnetic anneal. | 560 | 750 | 10 | 10 HRC | 3 % IACS |
Cold drawn | Cold-drawn rod and wire for machined cores, pole pieces and shield fittings; machine first, then hydrogen anneal the finished part. | 680 | 830 | 8 | 20 HRC | 3 % IACS |
Cold worked | Full-hard rolled strip/foil for laminations and shims that must stay flat and dimensionally stable; permeability is low until the parts are hydrogen-annealed. | 760 | 900 | 3 | 22 HRC | — |
What is Mu-metal ANN-MILL?
Mu-metal ANN-MILL is Mu-metal heat treated to ANN-MILL — standard as-shipped sheet/strip condition: ductile for deep drawing, spinning and shearing; magnetic properties only partly developed until final hydrogen anneal. Mu-metal ANN-MILL has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 82% of nickel alloy grades. Elongation at break is 35% and the elastic modulus is 215 GPa (31.2 Msi). Mu-metal ANN-MILL has a density of 8.74 g/cm³ (0.316 lb/in³), heavier than 79% of nickel alloy grades. It melts at 1,400°C (2,552 °F). ANN-H2 is the default condition FabDigit quotes; ANN-MILL is available on request or by drawing note.
Advantages
- Conducts heat well — 31 W/m·K (17.9 BTU/hr·ft·°F), better than 94% of nickel alloy grades
- Easy to machine — 30/100, better than 90% of nickel alloy grades
- Low embodied carbon — 10.5 kg CO₂/kg, better than 88% of nickel alloy grades
- High electrical conductivity — 3 % IACS, better than 87% of nickel alloy grades
- Forms and bends easily — 78/100, better than 87% of nickel alloy grades
Limitations
- Limited service temperature — 400°C (752 °F), worse than 94% of nickel alloy grades
- Needs corrosion protection — 55/100, worse than 92% of nickel alloy grades
- Low strength — 280 MPa (40.6 ksi), worse than 82% of nickel alloy grades
Mu-metal ANN-MILL properties
Typical room-temperature values for Mu-metal ANN-MILL; 21 are specific to this condition. Other listed values are Mu-metal reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Mu-metal ANN-MILL has a density of 8.74 g/cm³ (0.316 lb/in³), heavier than 79% of nickel alloy grades. It melts at 1,400°C (2,552 °F).
Mechanical14
Mu-metal ANN-MILL has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 82% of nickel alloy grades. Elongation at break is 35% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
Mu-metal ANN-MILL is rated for continuous service to 400°C (752 °F). It conducts heat at 31 W/m·K (17.9 BTU/hr·ft·°F), better than 94% of nickel alloy grades. Thermal expansion is 12.7 µm/m·K (7.06 µin/in·°F).
Electrical3
Mu-metal ANN-MILL conducts electricity at 3 % IACS, better than 87% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 92% of nickel alloy grades.
Sustainability4
Producing a kilogram of Mu-metal ANN-MILL takes about 140 MJ of energy and emits 10.5 kg of CO₂ — less than 81% of nickel alloy grades. Typical recycled content is 25%.
Manufacturability8
Mu-metal ANN-MILL's machinability is poor (30/100, better than 90% of nickel alloy grades); weldability good (55/100); formability very good (78/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Mu-metal ANN-MILL
Is Mu-metal easy to machine?
Gummy and work-hardening: use sharp positive-rake carbide or HSS-Co, low speed (20–30 m/min), heavy feed, flood coolant, and re-anneal in dry hydrogen after machining to restore permeability.
Can Mu-metal be welded?
TIG, laser and electron-beam weld readily with matching or Ni-Fe filler; keep heat input low, avoid sulphur contamination, and hydrogen-anneal the assembly afterwards.
Can Mu-metal be formed, bent or molded?
Annealed sheet deep-draws, spins and rolls easily; plan for a final 1100–1175 °C dry-hydrogen anneal on the finished shape since every bend or shear edge destroys local permeability.
What surface finishes work on Mu-metal?
Not anodizable — protect with electroless nickel, tin plate, chromate-free passivation or paint; avoid abrasive blasting or hard handling on annealed shields as shock re-introduces stress.
Mu-metal 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 |
|---|---|---|
| NiNi (+Co) content sets the permeability peak | 79 – 82 | 80 |
| Moraises resistivity, improves µi | 3.8 – 5.5 | 4.2 |
| Cuup to ~5 % in the classic Ni-Fe-Cu-Cr 'Mumetal' composition | 0 – 0.5 | 0.1 |
| Mn | 0.3 – 1 | 0.5 |
| Si | 0.15 – 0.5 | 0.3 |
| Ckept very low for magnetic softness | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | 0.01 |
| P | ≤ 0.02 | 0.01 |
| Febalance ≈14–16 % | balance | — |
Mu-metal ANN-MILL — frequently asked
What is Mu-metal ANN-MILL used for?
Mu-metal ANN-MILL is typically used for magnetic shielding cans, sensor and CRT shielding, current transformer cores and audio transformer laminations. In short: highest-permeability shielding alloy; classic magnetic shield material; anneal after final forming.
What is the yield strength of Mu-metal ANN-MILL?
Mu-metal ANN-MILL has a typical yield strength of 280 MPa (40.6 ksi) and a tensile strength of 580 MPa (84.1 ksi) — weaker than 82% of nickel alloy grades. Strength varies by condition: see the 5 listed tempers.
Is Mu-metal ANN-MILL easy to machine?
Not especially — machinability is rated poor (30/100, better than 90% of nickel alloy grades). Gummy and work-hardening: use sharp positive-rake carbide or HSS-Co, low speed (20–30 m/min), heavy feed, flood coolant, and re-anneal in dry hydrogen after machining to restore permeability.
Can Mu-metal ANN-MILL be welded?
Yes — weldability is rated good (55/100). TIG, laser and electron-beam weld readily with matching or Ni-Fe filler; keep heat input low, avoid sulphur contamination, and hydrogen-anneal the assembly afterwards.
What surface finishes work on Mu-metal ANN-MILL?
Not anodizable — protect with electroless nickel, tin plate, chromate-free passivation or paint; avoid abrasive blasting or hard handling on annealed shields as shock re-introduces stress.
Can Mu-metal ANN-MILL be formed, bent or molded?
Annealed sheet deep-draws, spins and rolls easily; plan for a final 1100–1175 °C dry-hydrogen anneal on the finished shape since every bend or shear edge destroys local permeability.
What is the maximum service temperature of Mu-metal ANN-MILL?
Mu-metal ANN-MILL is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Mu-metal ANN-H2 and Mu-metal-CW?
ANN-H2 is the default condition — final condition for magnetic shields and cores: maximum permeability, lowest coercivity — do not cold-work or machine after this anneal. CW: full-hard rolled strip/foil for laminations and shims that must stay flat and dimensionally stable; permeability is low until the parts are hydrogen-annealed. Yield strength is 250 MPa in ANN-H2 versus 760 MPa in CW.
Sources
- ASTM A753 — Wrought Nickel-Iron Soft Magnetic Alloys (Type 4) — ASTM International (2019)
- GB/T 14986 (1J79) (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (soft magnetic alloys) — ASM International (1990)
- High-permeability Ni-Fe magnetic shielding alloy datasheets (Mumetal / Co-Netic / PERMENORM class) — shielding alloy producers (2023)
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.