Nickel Alloy Mu-metal
UNS N14080 · ASTM A753 Type 4 · EN 2.4545 · GB 1J79 · also Mumetal / Permalloy 80
Mumetal (N14080, 2.4545, A753 Type 4, Permalloy 80, 1J79) is an 80 % Ni-Fe-Mo-Cu alloy with extremely high initial and maximum permeability, the classic material for magnetic shielding of sensitive instruments.
Reference datasheet — Mu-metal is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN-H2 condition
Mu-metal tempers and conditions
Mu-metal is supplied in 5 conditions, soft to hard. ANN-H2 is the default FabDigit quotes; the values on this page are for it.
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 |
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?
Mumetal (N14080, 2.4545, A753 Type 4, Permalloy 80, 1J79) is an 80 % Ni-Fe-Mo-Cu alloy with extremely high initial and maximum permeability, the classic material for magnetic shielding of sensitive instruments. Annealed sheet, foil and strip form drawn cans and shields at 250 MPa yield, 550 MPa tensile, 40 % elongation and ~115 HB, with 31 W/m·K thermal conductivity and 3 % IACS electrical conductivity. Saturation induction is lower than 48 % Ni alloys, service is limited to about 400 °C, corrosion resistance is moderate (score 55) and every bend or shear edge destroys local permeability until the part is hydrogen-annealed. Alloy 48 is the alternative when higher saturation is needed. Mu-metal 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). Mu-metal has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 87% of nickel alloy grades. Elongation at break is 40% and the elastic modulus is 215 GPa (31.2 Msi).
What is Mu-metal used for?
- magnetic shielding cans
- sensor and CRT shielding
- current transformer cores
- audio transformer laminations
Advantages
- Conducts heat well — 31 W/m·K (17.9 BTU/hr·ft·°F), better than 94% of nickel alloy grades
- Forms and bends easily — 80/100, better than 91% 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
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 — 250 MPa (36.3 ksi), worse than 87% of nickel alloy grades
Mu-metal properties
Typical room-temperature values for Mu-metal-ANN-H2; bars are the position among nickel alloy grades.
Physical3
Mu-metal 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 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 87% of nickel alloy grades. Elongation at break is 40% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
Mu-metal 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 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 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's machinability is poor (25/100, better than 76% of nickel alloy grades); weldability good (55/100); formability very good (80/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. Mu-metal is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Mu-metal
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.
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 |
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.
Surface treatments FabDigit runs on nickel alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Nickel Alloy Mu-metal in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N14080
- ASTM
- A753 Type 4
- EN / DIN / Werkstoff-Nr.
- 2.4545
- GB (China)
- 1J79
- Trade names
- Mumetal / Permalloy 80
- Other
- 1J85NiFe77CuCr
How much does Mu-metal cost?
Mu-metal is a high-cost nickel alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Mu-metal — frequently asked
What is Mu-metal used for?
Mu-metal 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?
Mu-metal has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 87% of nickel alloy grades. Strength varies by condition: see the 5 listed tempers.
Is Mu-metal easy to machine?
Not especially — machinability is rated poor (25/100, better than 76% 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 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?
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 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?
Mu-metal 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.
How much does Mu-metal cost?
Mu-metal is a high-cost nickel alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.