HyMu 80 Permalloy Bar
Product Introduction
HyMu 80 Permalloy is a high-permeability nickel alloy. Typically, rod stock of this material is procured for one of two purposes: either to manufacture solid components requiring magnetic permeability-such as magnetic cores, pole pieces, or relay cores-or to be precision-machined into magnetic shielding enclosures or sensor probes.
The raw material cost of permalloy is influenced by the market prices of nickel and molybdenum; specifically, fluctuations in LME nickel prices directly impact our quotations. The pricing for the bars we typically supply is calculated comprehensively based on factors such as diameter, length, quantity, delivery condition, and specific processing requirements. Smaller-diameter bars are generally more expensive than larger-diameter ones (due to the greater difficulty involved in processing), and cold-drawn bright bars command a higher price than "black" (as-rolled) bars. The market reference price for small-diameter bars is approximately $100–$140 per 100 kg (subject to Minimum Order Quantity); the exact price depends on the client's specific requirements regarding diameter, tolerance, and quantity.
Industry Standards and Procurement Specifications
1. Applicable Standards:
ASTM A753 Alloy 8: This serves as the core standard for nickel-iron soft magnetic alloys; HyMu 80 corresponds to the Alloy 8 designation. Note that this is *not* Alloy 4-Alloy 4 represents a distinct chemical composition.
MIL N-14411 C, Composition 1: A U.S. military standard, frequently encountered in defense or aerospace supply chain applications.
GB/T 15018: A domestic standard, corresponding to grades 1J79 or 1J85 (which share similar chemical compositions and performance characteristics).
Customer Drawings and Technical Specifications: In many instances, these precision materials are manufactured strictly according to specific engineering drawings, with the aforementioned standards serving primarily as references.
2. Dimensions and Specifications (Specific to Rods):
The typical diameter range for Permalloy rods is Φ6 mm to Φ500 mm. Small-diameter rods (≤20 mm) are typically cold-drawn to a bright finish, featuring a smooth surface and high dimensional precision; medium-to-large diameter rods are supplied as hot-rolled or forged "black" bars, which require subsequent turning operations. Length: Standard lengths range from 2 to 6 meters, though fixed-length specifications are also available upon request. We require confirmation regarding whether delivery is to be made in random lengths or fixed lengths.
Straightness: Slender rods are subject to specific straightness requirements; therefore, it is essential to clearly specify the maximum permissible deviation (in millimeters) per meter of length.
3. Sample Testing:
As a general principle, we recommend that customers "request samples for testing first"-particularly for experimental applications involving critical magnetic circuits. We suggest that customers initially purchase small samples to conduct magnetic performance tests, and only place a large-scale order once they have confirmed that the data meets the required standards.
Special reminder: The standard delivery condition for our bars is the annealed state; however, cold-drawn bars are also available. Based on our experience, if customers intend to process the material directly into finished parts for immediate use, the annealed state is generally preferred. Conversely, if customers plan to perform their own annealing treatment after processing, the cold-drawn state is acceptable.
Processing difficulty and key points
The magnetic properties of HyMu 80 are not inherent; rather, they are "activated" through heat treatment. If the purchased bar stock is already in the annealed state, it can be used directly. However, if the material was purchased in a cold-drawn state-or if it underwent significant deformation during processing-a final annealing treatment must be performed.
Heat Treatment (This is the lifeblood of HyMu 80):
Final Annealing Process (to Achieve Optimal Magnetic Properties):
The temperature must be controlled within the range of 1121–1177°C, with a holding time of 2–4 hours. It is mandatory to use dry, pure hydrogen with a dew point of <–40°C. This constitutes the standard process; vacuum annealing typically yields slightly inferior performance. The furnace is allowed to cool to 593°C, after which the cooling rate is controlled within the range of 194–334°C per hour as the temperature drops from 593°C to 371°C.
Strict Rule: Under no circumstances should annealing be performed in an atmosphere containing sulfur or oxygen. High-nickel alloys are highly susceptible to absorbing carbon, sulfur, and oxygen from the furnace atmosphere; once contaminated, their magnetic properties suffer a catastrophic decline from which they cannot be recovered.
For more information, please contact:
Email: susan@lorkgroup.com
WhatsApp: +86 19937075488
Chemical Composition
| Weight% | Permalloy Alloy |
| Ni | 79.0-81.0% |
| Mo | 3.8-5.0% |
| Fe | 14-16% |
| Si | ≤0.5% |
| C / Cu | trace amounts |
Mechanical Properties
(Annealed Condition, Typical Values for Rods)
| Material | Reference value |
| Tensile Strength | ≥690 MPa (100,000 psi) |
| Yield Strength (0.2%) | ≥303 MPa (44,000 psi) |
| Elongation | ≥40% |
| Hardness | ≤80 HRB |
In the annealed state, it is very soft, facilitating machining.
Physics and magnetic properties (this is the core)
| Performance Specification | Typical Values |
| Initial permeability (μi) | 20,000 - 50,000 |
| Maximum Permeability (μm) | 100,000 - 200,000 |
| Coercivity (Hc) | 0.637 - 1.59 A/m |
| Saturation Magnetic Induction (Bs) Approx | 0.75 - 0.8 T |
| Resistivity (ρ) | 55-58 μΩ·cm |
Important Reminder: Magnetic properties-rather than mechanical properties-constitute the primary basis for acceptance testing. We provide actual test reports detailing the measured magnetic properties; typically, these tests are conducted in accordance with ASTM A596 or A773 standards. If a supplier states, "We guarantee only the chemical composition, not the magnetic properties," we strongly advise exercising extreme caution before purchasing such materials.
Key Points of Quality Inspection Process
Acceptance criteria are the core of qualified delivery.
-
Dimensional Tolerances:
For HyMu 80 Permalloy turned bars, we measure the diameter using a micrometer to verify that the finished product complies with the specified order tolerances. For "black" (as-rolled) bars, particular attention is paid to negative diameter tolerances, which typically allow for a deviation of ±0.5 to 1.0 mm. Additionally, straightness is verified in accordance with applicable inspection standards or specific customer requirements; for slender bars, this is typically measured by placing the bar on a surface plate and using a feeler gauge.
- Magnetic Performance Testing:
We provide reports on DC magnetic properties tested in accordance with ASTM A596 or A773 standards, covering data such as initial permeability (μi), maximum permeability (μm), coercivity (Hc), and saturation magnetic induction (Bs). If you require such data reports to carry authoritative weight, please contact us for assistance in arranging third-party testing.
- Chemical Composition Report:
For the chemical composition analysis of permalloy, we typically utilize handheld spectrometers to perform compositional testing during quality inspections at the goods receipt stage.
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