1J85 Plate
A 1J85 plate is a sheet or flat piece of a high-performance soft magnetic iron-nickel alloy,commonly referred to as Permalloy 80, Mumetal, or Ni80Mo5.It is primarily engineered for applications that require extreme magnetic permeability and excellent magnetic shielding in weak magnetic fields.
Key Performance Features
- High Magnetic Permeability:
It conducts magnetic flux up to 100,000 times more effectively than standard structural steel,making it incredibly sensitive to weak fields. - Low Coercivity & Hysteresis Loss:
It magnetizes and demagnetizes effortlessly with almost zero energy loss,ensuring high signal sensitivity. - Near-Zero Magnetostriction:
The material does not change its physical shape significantly when magnetized,keeping its magnetic properties stable under mechanical stress.
Applications of 1J85 Plate
- MRI Shielding
- Transformer Cores
- Aerospace Instruments
- Security Tags
- Circuit Shielding
- Recording Heads
- Signal Relays
- Sensor Protection
- Vehicle Sensors
- Lab Enclosures
We offer 1J85 plates and sheets in thicknesses of 1.0, 1.5 and 2.0.We offer not only plaques en acier inoxydable and sheets but also plates made of Hastelloy,Incoloy,Inconel,Monel,and other alloys.Our products comply with ASTM A240,EN 10204,ISO 9001,PED 2014/68/EU ,CE,and other standards.With over a decade of experience in manufacturing and import/export,we are your best wholesaler in China.
Chemical Composition of 1J85 Plate
The 1J85 plate is a high-permeability,soft magnetic iron-nickel alloy.Its composition is governed by Chinese standard GB/T 15018 or GB/T 32286.1.
| Ni | Mo | Fe | Mn | Si | Cu | C | P | S |
|---|---|---|---|---|---|---|---|---|
| 79.0 – 81.0 | 4.80 – 5.20 | Équilibre | 0,30 – 0,60 | 0.15 – 0.30 | ≤ 0.20 | ≤ 0.03 | ≤ 0.02 | ≤ 0.02 |
Key Metallurgical Characteristics
Understanding the chemical composition alone is not enough to master this material.The interactions between these elements dictate how the plate behaves during manufacturing and final application.
Post-Fabrication Heat Treatment Dependency
As delivered from the rolling mill,a 1J85 plate has a single-phase Austenitic structure,but its internal crystal lattice is heavily distorted by cold-working stress.At this stage,it possesses almost no magnetic shielding capability.
- High-Temperature Annealing:
Once the plate is stamped,bent,or welded into its final part geometry,it must undergo high-temperature annealing at 1100°C to 1150°C in a high-vacuum or pure dry-hydrogen atmosphere. This eliminates internal stresses and purges remaining trace oxygen. - Controlled Cooling Rate:
The cooling velocity between 600°C and 400°C must be strictly regulated.This allows the Ni and Fe atoms to fall into an optimal “short-range ordered” crystalline state,which unlocks the material’s maximum magnetic permeability.
The Multi-Faceted Role of Molybdenum
While a pure binary 79%Ni-21%Fe alloy yields excellent static magnetic traits,it fails in dynamic applications due to its low electrical resistivity.Adding 5% Molybdenum alters the lattice structure to achieve two vital engineering goals:
- Eddy Current Mitigation:
It drives up the material’s electrical resistivity to approximately 0.56 μΩ·m,restricting the generation of heat and energy loss under alternating currents. - Zero Magnetostriction:
It fine-tunes the crystal lattice spacing so the alloy doesn’t change its mechanical volume when magnetized.Consequently,it remains magnetically stable even under mild mechanical stresses or vibrations.
Ultra-Low Carbon and Impurity Control
1J85 is engineered to react to incredibly weak external magnetic fields.If interstitial elements like carbon,sulfur,or phosphorus exceed standard thresholds,they form microscopic,non-magnetic precipitates.These precipitates act as “pinning sites” that block the physical rotation and movement of magnetic domains,severely crushing the material’s magnetic permeability.Premium 1J85 is exclusively melted using VIM to strip out these trace gases and contaminants.
1J85 Plate Standards & Equivalent Designations
| 1J85 (High-Permeability Soft Magnetic Crystalline Alloy) | |||||
|---|---|---|---|---|---|
| Standard / System | Equivalent Designation | Forme du produit | GB / GB/T (China) | GJB (Military) | GOST (Russia) |
| Norme chinoise | 1J85 | Plates, Sheets & Strips | GB/T 32286.1 | GJB 5873 | GOST 10160 |
| Russian / CIS Standard | 79NM / 81NMA (79НМ / 81НМА) | Bars & Rods | GB/T 15018 | – | GOST 10994 |
| ISO Chemical Name | Ni80Mo5Fe / Ni79Mo5 | Seamless Pipes & Tubes | – | – | – |
| UNS System | UNS N14080 | Welded Pipes & Tubes | – | – | – |
| Aviation / Aerospace | Moly-Permalloy / Supermalloy | Forgings & Rings | – | – | – |
| European / ASTM Designation | ASTM A753 Alloy 4 / DIN 2.4504 | ||||
| Generic Trade Name | Permalloy 80, HyMu 80 | ||||
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Mechanical Properties of 1J85 Plate
The 1J85 plate is primarily optimized for its electromagnetic attributes,meaning its mechanical parameters fluctuate drastically depending on its structural state: Cold-Rolled (Hardened) vs. Post-Annealed (Softened).
The standard mechanical properties at room temperature (20°C) according to specifications like GB/T 15018 and ASTM A753 are detailed below:
| Mechanical Property Parameter | Cold-Rolled | Post-Hydrogen Annealed | Engineering Significance |
|---|---|---|---|
| Résistance à la traction | 980 – 1150 MPa | 540 – 620 MPa | Drops by nearly half post-annealing as internal strain crystal defects heal. |
| Limite d'élasticité | 880 – 1020 MPa | 150 – 240 MPa | Yield point is extremely low post-anneal; the material becomes highly malleable. |
| Élongation | 1% – 3% | 35% – 50% | High post-anneal ductility allows the metal to stretch without tearing. |
| Vickers Hardness | 280 – 320 HV | 110 – 130 HV | Softens remarkably, making the final components prone to physical denting. |
| Dureté Brinell | 265 – 305 HB | 105 – 123 HB | Reflects macro-structural softening across the plate thickness. |
| Module d'élasticité | ~210 GPa | ~190 GPa | Slight reduction in structural rigidity due to atomic lattice relaxation. |
Critical Engineering Insights into 1J85 Mechanical Behavior
Stamping vs. Magnetic Performance
- The Cold-Rolled State:
In its raw,unannealed sheet form,1J85 features high yield strength and minimal elongation.This state is perfect for high-speed automated stamping,blanking,laser cutting,and deep-drawing.It resists burring and holds precise dimensional tolerances. - The Structural Trap:
Machining or bending the plate introduces immense plastic deformation and dislocations into the crystal lattice.Mechanically,the part is sturdy.Magnetically,it is ruined because these dislocations block magnetic domains from rotating.Therefore,all severe structural mechanical forming must happen BEFORE the final magnetic annealing process.
Extreme Post-Anneal Softness & Vulnerability
- Yield Deformation Risk:
With a post-anneal yield strength as low as 150 MPa,the material can be plastically deformed by simple human handling,accidental dropping,or clamping forces inside an assembly. - The “Dead” Magnetic State:
If an annealed part undergoes even slight mechanical bending or dropping during installation,the localized stress re-introduces dislocations.This drastically reduces the magnetic shielding capability of that zone.Annealed 1J85 shields must be handled like fragile glassware.
Machining and Cutting Fluid Restrictions
- Work Hardening Tendency:
Due to its high nickel content,1J85 behaves similarly to austenitic stainless steels.It work-hardens rapidly under the cutting tool if the feed rate is too slow or the tool is dull.Sharp carbide tools with positive geometries and constant,deep feeds are mandatory. - Sulfur Contamination Ban:
Traditional cutting fluids containing heavy sulfur or chlorine additives must be strictly avoided.Residual sulfur can diffuse into the 1J85 grain boundaries during subsequent high-temperature annealing,causing intergranular embrittlement and ruining the alloy’s magnetic properties.
Our Advantages in Manufacturing 1J85 Plate
Vacuum Induction Melting
We utilize advanced Vacuum Induction Melting (VIM) systems to process our raw alloy.
This strictly eliminates interstitial trace gases like oxygen,nitrogen,and carbon,preventing the formation of micro-precipitates that block magnetic domain rotation.
Ultra-Low Impurity Controls
Our chemical metallurgical process maintains sulfur,phosphorus,and carbon levels far below traditional standard limits.
By removing these harmful elements from the grain boundaries,we guarantee a highly pure matrix that delivers maximum magnetic permeability and zero structural embrittlement.
Precision Gauge Consistency
We employ automated cold-rolling mills equipped with real-time Automatic Gauge Control (AGC) tracking.
This ensures uniform thickness tolerances across the entire plate surface,which is critical for maintaining stable magnetic shielding performance in thin-gauge electronic components.
Optimized Heat Treatment
We offer proprietary high-temperature dry-hydrogen and high-vacuum annealing protocols.
This perfects the cooling phase between 600°C and 400°C to achieve a flawless “short-range ordered” crystal lattice,releasing the absolute peak magnetic performance of the material.
FAQs About 1J85 Plate
They are essentially the same class of material with minor commercial variations.1J85 is the designation under the Chinese standard (GB/T 15018).Permalloy 80 and HyMu 80 are American commercial designations (ASTM A753 Alloy 4),while Mumetal historically refers to a similar British formulation.All are high-permeability iron-nickel alloys containing approximately 80% Nickel and 5% Molybdenum.
No,not if you need magnetic shielding.Raw 1J85 plates are delivered in a cold-rolled or work-hardened state to allow for clean stamping and cutting.In this state,internal mechanical stresses disrupt the crystal lattice,leaving the material with almost zero magnetic shielding capability.It must undergo a final high-temperature annealing process after it is shaped.
The shaped parts must be annealed at 1100°C to 1150°C for 2 to 4 hours in a high-vacuum or pure,dry hydrogen atmosphere (dew point below -40°C).Crucially,the cooling rate between 600°C and 400°C must be strictly controlled (usually around 100°C to 200°C per hour) to allow the nickel and iron atoms to form the optimal crystal order required for peak permeability.
You should strictly avoid this.Once final-annealed,1J85 becomes mechanically very soft (hardness drops to around 120 HV).Any subsequent bending,dropping,machining,or welding introduces plastic strain and dislocations into the grain structure.This will severely degrade or completely destroy the magnetic permeability in the deformed zone.All structural forming must happen before annealing.
Non.1J85 has an incredibly high initial permeability,meaning it is exceptionally good at redirecting weak magnetic fields (like the Earth’s magnetic field or ambient electronic noise).However,it has a relatively low saturation induction.In the presence of a strong magnetic field,a thin 1J85 plate will quickly become magnetically saturated and lose its ability to shield.For strong fields,a multi-layer shield combining a high-saturation material (like silicon steel or 1J50) on the outside and 1J85 on the inside is required.
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