Permalloy and Nickel-Iron Soft Magnetic Alloys
Basic Description
Sagiant Piping Industries supports enquiries for Permalloy and high-permeability nickel-iron soft-magnetic alloys across the ASTM A753 classes — nominal 45% (Type 1, K94490), 48% (Type 2, K94840), 76% (Type 3, N14076) and 80% Ni (Type 4, N14080) — plus commercial variants (HyMu 80, Mu-metal-type, High Permeability 49, Round/Square Permalloy 80 and Supermalloy) as strip, sheet, bar, wire, laminations and formed shields. These classes have different permeability and saturation and are not interchangeable; performance depends on the final magnetic anneal and on controlling stress after it. Magnetic data are given with test conditions and typical-vs-guaranteed basis, and material is supplied by grade, form and condition with acceptance limits confirmed per order and EN 10204 3.1 or 3.2 documentation. Mu-metal and similar are trademarks of their owners; Sagiant is an independent supplier and stockist, and the verified range is magnetic strip, sheet, bar, wire and shields rather than pressure pipe.
Permalloy (Ni-Fe soft magnetic): grades, magnetic properties, standards and RFQ data
Ni-Fe soft-magnetic grade classes (A753 Types 1–4), per-class chemistry, magnetic reference data with test conditions, mechanical and physical properties, standards status by form, and annealing/shielding guidance. Producer reference values are shown separately from specification acceptance limits confirmed on the certificate; magnetic performance depends on the final anneal.
Technical Specification
| Parameter | Specification |
|---|---|
| Materials | Wrought Ni-Fe soft-magnetic alloys — ASTM A753 nominal 45%, 48%, 76% and 80% nickel classes, plus commercial high-permeability variants |
| Key property | High magnetic permeability and low coercivity in the final magnetically annealed condition |
| Product forms | Strip/foil, sheet/plate, bar, wire, laminations, tape-wound cores and formed shields — by actual grade & route |
| Conditions | Fabrication/stress-relieved stock distinguished from material in its final magnetic condition |
| Basis | Producer reference data; specification acceptance limits, form, condition and edition confirmed per order |
“Permalloy” is a family of Ni-Fe soft-magnetic alloys, not one grade; related materials are comparisons, not assumed equivalents. Mu-metal/MUMETALL and similar are trademarks of their owners; Sagiant is an independent supplier and stockist, and the verified range is magnetic strip, sheet, bar, wire and shields rather than pressure pipe.
Chemical Composition (wt %)
| Class | Ni | Mo | Fe | Other (per spec) |
|---|---|---|---|---|
| ~80% Ni (e.g. HyMu 80, type analysis) | ~80.0 | ~4.2 | Balance | Si ~0.35, C ~0.02, Mn & residuals per spec |
| ~76% Ni | ~76 | ~4–5 | Balance | Cu/Mn/Si/C per selected specification |
| ~48% Ni (High Permeability 49) | ~48 | — | Balance | Mn/Si/C per spec |
| ~45% Ni | ~45 | — | Balance | Mn/Si/C per spec |
Each offered grade carries all controlled elements (Ni, Fe, Mo, Cu, Mn, Si, C and any P, S, Cr, Co residuals) from its selected specification, with nominal, minimum, maximum and balance distinguished. Molybdenum-free 45/48% classes are not given a Mo limit. Specification limits, nominal composition and heat analysis are different datasets; the certificate governs.
Grade & designation register
| Class / product | UNS / type | Notes |
|---|---|---|
| A753 nominal 45% Ni | K94490 / Type 1 | Separate from the 48% class — not one 45–50% range |
| A753 nominal 48% Ni | K94840 / Type 2 | High Permeability 49 (standard, rotor, transformer grades) |
| A753 nominal 76% Ni | N14076 / Type 3 | Distinct grade |
| A753 nominal 80% Ni | N14080 / Type 4 | HyMu 80 / Mu-metal-type high-permeability material |
| Tape-core variants | Round Permalloy 80, Square Permalloy 80, Supermalloy | Core-specific magnetic loop/process — not universal sheet guarantees |
| Wider directory | MUMETALL, VACOPERM, ULTRAPERM, CRYOPERM, PERMENORM (VAC) etc. | Coverage candidates; availability & data confirmed on enquiry, not interchangeable |
A753 covers wrought material and excludes casting and powder metallurgy, so its acceptance requirements are not transferred to other routes. Loose “2.4545/2.4596 family” equivalence is removed — each designation is mapped to its exact producer material or omitted pending verification.
Magnetic Properties
| Class | Permeability (typical) | Coercivity Hc | Saturation Bs |
|---|---|---|---|
| ~80% Ni-Fe-Mo | Very high μi (order 10⁴–10⁵ range achievable after anneal) | Low (fraction of A/m) | ~0.7–0.8 T |
| Supermalloy (core) | Highest μ class, core-specific | Very low | ~0.7–0.8 T |
| ~48% Ni | High μ with higher saturation | Low | ~1.5–1.6 T |
| ~45% Ni | High μ, higher saturation | Low | ~1.5 T |
Rankings such as “highest permeability” depend on field, frequency, condition and measurement, so performance is stated with its conditions rather than as an absolute claim. Each supplied entry states specimen geometry, magnetic circuit, rolling direction, demagnetisation, test method, temperature, thickness, annealing cycle and typical-vs-guaranteed basis; DC coercivity/remanence/loop squareness, AC permeability, core loss (at defined peak flux, frequency, waveform) and magnetostriction are added per grade where supported, otherwise identified as unavailable. Relative permeability is dimensionless; A/m and Oe are not mixed without conversion, and saturation polarisation J is not confused with induction B.
Mechanical Properties
| Class (condition) | Tensile (MPa) | Yield 0.2% (MPa) | Elong. % | Hardness |
|---|---|---|---|---|
| ~80% Ni (annealed) | ~550 | ~270 | ~30 | ~120 HV |
| ~45–48% Ni (annealed) | ~530 | ~250 | ~30 | ~130 HV |
| Supermalloy | Per producer product data, or explicitly unavailable — not borrowed from another grade | |||
Each row needs alloy/producer, form, dimensions, supplied temper, final magnetic treatment, test temperature and orientation. Reduction of area, bend/formability and fatigue are added where relevant and published; typical values are not converted into minima, and impact/fatigue data are not invented to fill cells.
Physical Properties
| Property | ~80% Ni | ~45–48% Ni |
|---|---|---|
| Density | ~8.7 g/cm³ | ~8.2 g/cm³ |
| Electrical resistivity | ~55–60 µΩ·cm | ~45 µΩ·cm |
| Curie temperature | Per producer datasheet | Per producer datasheet |
| Thermal / elastic | Thermal conductivity, specific heat, expansion, elastic/shear modulus & Poisson ratio per producer series | |
High-temperature annealing capability is distinguished from usable magnetic service temperature. Approximate density and saturation are sourced orientation values, not dimensional-weight or acceptance limits; unavailable properties are marked rather than borrowed.
Standards by Product Form
| Reference | Status / scope |
|---|---|
| ASTM A753 | Wrought Ni-Fe soft-magnetic material, Types 1–4 (nominal 45/48/76/80% Ni); excludes casting & powder metallurgy; edition & type stated per order |
| MIL-N-14411 | Canceled (2025) — the cancellation notice directs acquisition to its Table I; the actual material is mapped from that table, not a single invented replacement |
| Form-specific tests | Magnetic test condition (specimen, anneal, field/induction) specified per form; raw-material compliance does not certify a finished shield or room |
Blanket “ASTM/ASME/EN” availability is not claimed; no ASME material reference is established here, and a dimensional standard does not certify the material.
Available Forms, Sizes & Dimensions
| Form | Basis |
|---|---|
| Strip / foil | Thickness, width, coil/length, flatness, edge/burr, finish & insulation/coating |
| Sheet / plate | Thickness, width, length & tolerances |
| Bar / wire | Diameter, tolerances, temper & condition |
| Laminations / tape-wound cores | Dimensions, tape thickness, stacking factor, insulation & effective magnetic dimensions |
| Formed / tubular magnetic shields | Diameter, wall, length, seam, end geometry, roundness, anneal & magnetic acceptance — not pressure piping |
No verified Permalloy pipe/tube material standard or schedule range is claimed: generic stainless/nickel pipe standards are not applied by analogy, a schedule is not a pressure rating, and where an order adopts a dimensional schedule it is stated separately from material and design basis. Unsupported forms are marked “subject to technical review”.
Magnetic Shielding & Applications
| Aspect | Consideration |
|---|---|
| Low-field shielding | High-μ 80% Ni material; may need combined-material (saturation-resistant outer layer) design in stronger fields |
| Higher-flux / core service | Higher-saturation 45/48% Ni classes or tape cores by application |
| Finished shield | Attenuation/shielding factor vs frequency & field, geometry, openings, seams, joints, layer spacing & test setup — a toroidal coupon does not certify the installed shield |
| MRI / RF | Static/low-frequency magnetic shielding distinguished from RF shielding; field levels, location, design & installation scope defined — not a blanket “MRI room” suitability claim |
Corrosion/storage guidance covers humidity, contamination, dissimilar-metal contact and coatings that must preserve the magnetic condition; these alloys are not marketed as general corrosion-resistant pressure materials.
Annealing & Fabrication
| Topic | Guidance |
|---|---|
| Final anneal | Producer-specific hydrogen-anneal temperature/time, atmosphere quality, controlled cooling and any field-annealing to obtain the desired loop — a core treatment is not applied indiscriminately to shielding parts |
| Stress sensitivity | Forming, machining and mounting stress can substantially degrade magnetic performance (amount depends on material/processing); post-anneal deformation is controlled |
| Fabrication | Machining, punching, laser cutting, forming and joining with cleanliness, fixtures, filler compatibility, distortion and heat-affected-zone effects |
| Condition | Stress-annealed sheet, fully annealed foil and finished shields are different conditions, not one generic “annealed” label |
After final annealing, bending, clamping, assembly stress and transport damage are controlled, and whether demagnetisation and final verification are required is defined for the part.
Testing & Documentation
| Item | Scope |
|---|---|
| Magnetic test | Test, specimen, sampling, anneal condition & acceptance values defined; raw-material property distinct from installed-shield attenuation |
| Mechanical | Tensile & hardness per contracted method & acceptance criteria |
| PMI | Confirms alloy identity within the instrument/method capability; does not establish complete chemistry |
| Certification | EN 10204 3.1 (manufacturer) vs 3.2 (independent/third-party); document type does not inherently require every test |
Contracted tests, specimen condition, anneal and acceptance values are agreed at ordering with heat/lot traceability; a finished shield or room is qualified separately from raw-material certification.
Product Range
The permalloy range can be supplied with related pipes, tubes, butt weld fittings, forged fittings, flanges, fasteners and custom fabricated items where required by the BOQ.
Applications
For dimensional references, see the Pipe Schedule & Fittings Guide. For related supply, review Pipes & Tubes, Butt Weld Fittings, Forged Fittings and Flanges.
Types of Products
| Type | Description |
|---|---|
| Pipes & Tubes | Seamless, welded and large-diameter supply |
| Fittings | Butt weld, forged and fabricated fittings |
| Flanges | Forged flanges and special machined items |
| Plates / Bars / Round Bars | Subject to grade and project availability |
Available Forms
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Frequently Asked Questions
Are Permalloy 45 and Permalloy 48 (4750) the same grade?
No. ASTM A753 defines four distinct nominal nickel classes — 45%, 48%, 76% and 80% — so the ~45% (Type 1, K94490) and ~48% (Type 2, K94840) materials are separate identities and are not treated as one 45–50% acceptance range. They differ in permeability and saturation, and the applicable type and edition are confirmed per order.
Are Permalloy 80, Mu-metal and Supermalloy interchangeable?
Not automatically. They are related ~80% Ni-Fe-Mo high-permeability materials, but brand, exact chemistry, product route, anneal, magnetic-loop shape and acceptance differ — and Supermalloy and Round/Square Permalloy 80 are core-specific products whose values are not universal sheet guarantees. We compare them with sourced data rather than treating slash-separated names as equivalents.
What permeability does Permalloy reach?
Very high — but a single number is not meaningful without conditions. Permeability depends on field, frequency, thickness, specimen geometry and, above all, the final magnetic anneal, and initial permeability (μi), a finite-field value (μ4) and maximum permeability (μmax) are different quantities. High-nickel material reaches very high μ after annealing, but that is a conditioned typical, not an acceptance guarantee, and high μ alone does not make a material the best shield because it can saturate.
What is the chemistry of high-permeability Permalloy?
For ~80% Ni material a producer type analysis (HyMu 80) is about Ni 80, Mo 4.2, Si 0.35, C 0.02, iron balance — a type analysis, not complete acceptance chemistry. The 45% and 48% classes are molybdenum-free with their own controlled Mn, Si and C. Full limits come from the selected specification, and the mill certificate governs; a dash is not zero.
Which specifications apply, and is MIL-N-14411 still current?
ASTM A753 covers the four wrought Ni-Fe classes (Types 1–4) and excludes casting and powder metallurgy. MIL-N-14411 was canceled in 2025, with its cancellation notice directing acquisition to a replacement table — so the actual material is mapped from that table rather than an invented single successor. Neither a material spec nor a UNS by itself certifies a finished shield; the applicable edition, type and acceptance are confirmed per order.
How is Permalloy annealed, and why does handling matter?
The magnetic properties come from a producer-specific hydrogen anneal (temperature, time, atmosphere quality, controlled cooling, and field annealing where a particular loop is wanted) — not a universal ~1100°C recipe. After that anneal, forming, machining, mounting and even transport stress can substantially degrade permeability, so post-anneal deformation is controlled and final magnetic verification is defined for the part. Stress-annealed sheet, fully annealed foil and finished shields are different conditions.
Do you supply Permalloy pipe, and can you certify a finished shield?
The verified range is magnetic strip, sheet, bar, wire, laminations and formed/tubular shields — not pressure pipe, and we do not publish a generic schedule chart as a Permalloy standard. A tubular magnetic shield is specified by diameter, wall, seam, anneal and magnetic acceptance. Raw-material certification (A753 chemistry and magnetic test) is separate from finished-shield qualification, which needs the installed geometry’s attenuation vs frequency and field — a coupon does not certify the assembly.
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