Soft Magnetic Alloy 1J79 (Permalloy 80) · UNS K94840 · GB 1J79
Soft Magnetic Alloy 1J79 (Permalloy 80) (K94840): composition, properties, fittings and flanges
Soft Magnetic Alloy 1J79 (Permalloy 80) (K94840, GB 1J79) is High-permeability nickel-iron-molybdenum soft magnetic alloy. Soft Magnetic Alloy 1J79 (Permalloy 80) is specified at Nickel 78.0 - 80.0, Molybdenum 3.80 - 4.50. 1J79 is the high-permeability end of the permalloy range: 80 % nickel plus molybdenum gives initial…
- UNS
- K94840
- W. Nr.
- -
- Density
- 8.60 g/cm³ (0.311 lb/in³)
- Key strength
- 550 MPa / 80 ksi
Identification and standards
| Short form | Soft Magnetic Alloy 1J79 (Permalloy 80) · UNS K94840 · GB 1J79 |
|---|---|
| Classification | High-permeability nickel-iron-molybdenum soft magnetic alloy |
| UNS | K94840 |
| Werkstoff number | - |
| Material family | Precision Alloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Iron (Fe) | Balance | Matrix |
| Nickel (Ni) | 78.0 - 80.0 | Very high permeability |
| Molybdenum (Mo) | 3.80 - 4.50 | Raises permeability and resistivity |
| Manganese (Mn) | 0.60 - 1.10 | Processing |
| Silicon (Si) | 0.30 - 0.50 | Resistivity |
| Carbon (C) | 0.03 max | Kept low - carbon degrades permeability |
| Phosphorus (P) | 0.020 max | - |
| Sulphur (S) | 0.020 max | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed) | 550 MPa / 80 ksi |
|---|---|
| 0.2 % yield strength, min | 240 MPa / 35 ksi |
| Elongation in 2 in, min | 30 % |
| Typical hardness, annealed | 120 - 160 HB |
| Saturation flux density, typical | About 0.75 T |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 8.60 g/cm³ (0.311 lb/in³) |
|---|---|
| Melting range | 1440 °C (2625 °F) |
| Modulus of elasticity | 160 GPa (23.2 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 13.0 W/m·K |
| Curie temperature | About 400 °C |
| Electrical resistivity | About 55 µΩ·cm |
Specifications by product form
| Forgings & flanges | To order against GB/T 15018 (1J79) |
|---|---|
| Butt weld fittings | Not normally supplied |
| Seamless pipe & tube | Not normally supplied |
| Plate / sheet / strip | GB/T 15018 / ASTM A753 family |
| Bar / rod | GB/T 15018 |
| Welding consumables | Welding degrades magnetic properties |
| UNS / EN / China | UNS K94840 · GB 1J79 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Current transformers, instrument transformers and sensors
- Magnetic shields, mu-metal enclosures and recording heads
- High-sensitivity relays and pulse transformers
- Aerospace and precision instrumentation magnetic circuits
Welding, forming and machining
- Welding
- Not fusion welded in magnetic service. Any cold work or welding must be followed by the full high-temperature hydrogen anneal to restore permeability.
- Heat treatment
- Magnetic anneal at 1100 - 1200 °C in dry hydrogen with a controlled cooling rate; mechanical shock after annealing degrades the properties.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Soft Magnetic Alloy 1J79 (Permalloy 80) from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.
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