Permalloy 50 (1J50) Soft Magnetic Alloy | Industrial Application Guide
ZYTC Alloy, a professional Chinese supplier of precision soft magnetic alloys, provides high-quality Permalloy 50, also known as 1J50, Hy-Ra 49/50H, complying with ASTM A753 and UNS K94840 standards.
Unlike structural alloys valued for high hardness, Permalloy 50 is a soft magnetic alloy defined by its excellent magnetization and demagnetization performance. It preserves complete signal transmission without attenuation under weak magnetic fields, making it an indispensable material for high-precision magnetic circuit designs.
This nickel-iron alloy has a tightly controlled nickel content of 49%每51%. It delivers the highest saturation flux density (approximately 1.5 T) within the Permalloy family, together with superior magnetic permeability and low core loss compared with silicon steel. While ordinary silicon steel can meet basic transformer core requirements, Permalloy 50 is the ideal choice for precision magnetic circuits, signal coupling and weak current detection applications.
Who Needs Permalloy 50?
- Audio transformer engineers: Solve excessive core loss and overheating issues of silicon steel above several hundred hertz
- ELCB (Earth Leakage Circuit Breaker) manufacturers: Fabricate magnetic cores with sensitive response under leakage current of only a few milliamps
- Magnetic amplifier designers: Maintain stable magnetic gain under medium magnetic field strength
- Clock stator suppliers: Guarantee reliable stepping motion under microampere-level current
Chemical Composition of Permalloy 50 (1J50)
Magnetic properties of Permalloy 50 rely heavily on precise nickel content control within 49% to 51%. Even a 1% deviation in nickel percentage will greatly alter its magnetic characteristics.
| Element | C | P/S | Si | Ni | Mn | Cu | Fe |
|---|---|---|---|---|---|---|---|
| Content (wt%) | ≒0.03 | ≒0.020 | 0.15每0.30 | 49.5每50.5 | 0.30每0.60 | ≒0.20 | Balance |
Note: Standard Permalloy 50 contains no chromium. Adding chromium improves corrosion resistance but reduces saturation magnetization. For every 9 wt% chromium added, saturation magnetization drops by half. Confirm your working environment to decide whether a corrosion-resistant variant is required.
Core Physical & Mechanical Properties
| Property | Typical Value | Remarks |
|---|---|---|
| Electrical Resistivity | 45每60 米次﹞cm | Higher than pure iron, low eddy current loss |
| Curie Temperature | 450每500∼C | Loses magnetism above this temperature |
| Tensile Strength | 450每550 MPa (soft state) | Good workability |
| Elongation | ≡30% | Suitable for cold stamping, bending & shearing |
| Hardness | HV 150每200 | Depends on heat treatment and cold working |
Key Magnetic Properties (GB/T 15018)
Magnetic performance of Permalloy 50 is not inherent; it is tuned by dedicated heat treatment. Even with identical chemical composition, a 50∼C heat treatment difference or doubled cooling rate may double the initial permeability. This is a common overlooked risk during procurement.
| Performance Index | Cold Rolled Strip | Forged / Rolled Bar & Plate | Explanation |
|---|---|---|---|
| Initial Permeability (米₀) | ≡3.8 mH/m | ≡3.1 mH/m | Permeability under weak magnetic field, determines smooth signal transfer |
| Maximum Permeability (米ₘ) | ≡62.5 mH/m | ≡31.3 mH/m | Permeability at optimal working point for highest efficiency |
| Coercivity (Hc) | ≒9.6 A/m | ≒14.4 A/m | Lower value = less residual loss, higher sensitivity and efficiency |
| Saturation Magnetic Flux Density (Bs) | ~1.5 T | ~1.5 T | Highest Bs among Permalloy grades, supports higher flux without saturation |
With the same magnetic flux, transformers built from 1J50 can be smaller, generate less heat and have lower no-load current. It is widely used for medium & high frequency transformers (400每8000 Hz) with rated power below 100 W.
Material Selection & Application Guide
The main risk of Permalloy 50 comes not from chemical composition, but from delivery condition and properly executed heat treatment. Mechanical processing such as stamping, bending and turning introduces internal stress, which pins magnetic domain walls and sharply reduces permeability. Stress relief annealing is mandatory to restore magnetic performance.
Scenario 1: Transformer & Inductor Cores (Stacked Laminations)
- Recommended form: Cold rolled strip, thickness 0.1每0.5 mm (selected by operating frequency)
- Usage: Stamped into E/I laminations or toroidal cores
- Critical reminder: Stamping creates material stress. Stress relief annealing at 800每900∼C under hydrogen atmosphere is required after stamping. Without post-stamping heat treatment, initial permeability may drop to only 1/3 of the standard value.
Scenario 2: Magnetic Shielding Enclosures (Bent Sheet Metal Parts)
- Recommended form: Soft annealed strip or plate
- Usage: Bending and deep drawing to form shielding housings
- Critical reminder: Bending reduces local permeability. Low-temperature annealing at 400每500∼C can partially recover shielding performance if shielding effect fails to meet requirements.
Scenario 3: Precision Instrument Transformer Cores (Toroidal / Rectangular)
- Recommended form: Finished cores (stamped, wound and heat treated)
- Critical reminder: Toroidal cores need full heat treatment after winding. In-house heat treatment has high risks regarding furnace temperature uniformity and atmosphere control. Finished cores from ZYTC Alloy are fully tested for magnetic properties; customers only need coil winding and assembly. Request batch-specific measured magnetic data (米₀, Hc, Bs) instead of only reference standard values.
Scenario 4: Clock Stator Laminations & Relay Magnetic Components
- Recommended form: Cold rolled strip (in-house stress relief annealing after stamping) or precision blanked finished parts
- Critical reminder: Components require ultra-tight dimensional tolerance ㊣0.01 mm. ZYTC Alloy provides precision fine blanking service to save your mold development cost.
Available Product Forms from ZYTC Alloy
- Cold rolled thin strips & sheets
- Round bars and plates
- Precision stamped laminations & finished components
- Pre-heat-treated toroidal / rectangular magnetic cores
Why Choose ZYTC Alloy for Permalloy 50 (1J50)
✅ Strict nickel composition control to guarantee stable magnetic performance
✅ Complete in-house heat treatment service to restore magnetic properties after machining
✅ Precision stamping and fine blanking service for custom magnetic components
✅ Full batch traceability with test certificates including measured magnetic data
✅ Support prototype small orders and mass bulk supply
✅ Professional technical team to assist material grade selection and heat treatment consultation
Request A Quote
Contact ZYTC Alloy for Permalloy 50 (1J50, ASTM A753, UNS K94840). Share your operating frequency, magnetic circuit design and drawing requirements. Our alloy engineers will provide professional material recommendations and competitive quotation.
📧 dominic@zytc-steel.com
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