Permalloy or Carpenter HyMu 80 is a nickel-iron-molybdenum alloy providing great resistance to general corrosion and humidity. It has high magnetic permeability. It is basically a Nickel-IronMolybdenum alloy that provides high magnetic permeability with low hysteresis loss. It is commonly used in magnetic toroids, transformer cores, home theater systems and shielding applications. Permalloy (Nickel 80%) or Mumetal is a magnetic shielding material that is made from a nickel-iron alloy. It has high permeability and is an ideal material for shielding in constant or low frequency magnetic regions. Nominal hysteresis loss. Alloy 4, UNS N14080, Alloy HyMu 80, Permalloy 80, MIL N 14411C, Comp 1, alloy 4750, High Perm 49, Permenorm 5000 H2, Radiometal 4550, Superimphy T, Ultraperm 80, Ultravac 80 ®, Vac 80,Carpenter HyMu 80,UNS N14080Permalloy Specifications: ASTM A-753-78, , MIL-N-14411 B (MR).
Permalloy possesses high permeability and minimum coercive force, it is useful in the magnetic shielding operations. The annealed and deep drawn alloy can be formed into shields through bending, forging and spinning. Spot or tungsten inert gas welding methods are used including or excluding base metal filler rod.
The alloy shields are annealed up to 1900oF to obtain the suitable shielding properties after accomplishing the forging processes. Generally, high temperature yield strength and improved permeability are obtained.
In order to find the relative shielding competency of alloy HyMu 80, a specimen is assessed as an open ended cyinderical shield in a uniform magnetic field that is created by Helmholtz coil. When a pickup system is placed in coil, attenuation that is a ratio of finding no shield to that noticed when material is placed over the pickup having perpendicular axis on the field. It calculates the effect of shielding in the specific testing media and for provided specimen on the base of its thickness, length to diameter ratio and coil diameter.
| Grade | Chemical Composition WT % | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Mn | Si | P | S | Cr | Ni | Fe | Mo | Co | Cu | |
| Permalloy HyMu 80 | Max 0.02 | Max 0.5 | Max 0.35 | Max 0.025 | Max 0.025 | - | 80 | Bal | - | - | - |
| Alloy 1, UNS K94490 | Max 0.05 | Max 0.8 | Max 0.5 | Max 0.03 | Max 0.01 | Max 0.3 | 43.5-46.5 | Bal | Max 0.3 | Max 0.5 | Max 0.3 |
| Alloy 2, UNS K94840 | Max 0.05 | Max 0.8 | Max 0.5 | Max 0.03 | Max 0.01 | Max 0.3 | 47.0-49.0 | Bal | Max 0.3 | Max 0.5 | Max 0.3 |
| Alloy 3, UNS K14076 | Max 0.05 | Max 1.5 | Max 0.5 | Max 0.02 | Max 0.01 | 2.0-3.0 | 75.0-78.0 | Bal | Max 0.5 | Max 0.5 | 4.0-6.0 |
| Alloy 4, UNS K14080 | Max 0.05 | Max 0.8 | Max 0.5 | Max 0.02 | Max 0.01 | Max 0.3 | 79.0-82.0 | Bal | 3.5-6.0 | Max 0.5 | Max 0.3 |
| Density | 8.74 |
| Specific heat Capacity | 0.118 BTU/lb/of |
| Thermal conductivity | 240.1 BTU-in/hr/ft2/°F |
| Elastic modulus | 31.4 x 10(3) ksi after process annealing up to 871°C |
| 33.7 x 10 (3) ksi after cold drawing | |
| 33.3 x 10(3) ksi after hydrogen annealing at 1177°C | |
| Electrical resistivity | 349 ohm-cir-mil/ft at 70°F |
| Coefficient of electrical resistivity | 6.00 x 10-4 Ohm/Ohm/°F at 0 to 930°F |
| Curie temperature | 860°F |
| Melting point | 2650°F |
| Coercivity | 0.00800 to 0.0200 Oe |
| Permeability | 200000 |
| Residual induction | 3500 G |
| Hysteresis Loss | 1.80E-6 to 2.40E-6 J/cm3/cycle |
| Modulus of Elasticity | |
| Subsequent Process Annealing up to 871°C, In Tension | 31.4 x 103 ksi |
| Cold Drawn, In Tension | 33.7 x 103 ksi |
| Hydrogen Annealed at 1177°C, In Tension | 33.3 x 103 ksi |
| Temperature | in/in/°F |
|---|---|
| -103 °F to 77 °F | 6 x 10 (-6) in/in/°F |
| -58 oF to 77 °F | 5.94 x 10 (-6) in/in/°F |
| -11 oF to 77 °F | 5.78 x x 10 (-6) in/in/°F |
| 77 of to 122 °F | 6.83 x 10 (-6) in/in/°F |
| 77 of to 212 °F | 6.89 x 10 (-6) in/in/°F |
| 77 of to 392 °F | 7.09 x 10 (-6) in/in/°F |
| 77 of to 572 °F | 7.22 x 10 (-6) in/in/°F |
| 77 of to 752 °F | 7.39 x 10 (-6) in/in/°F |
It offers medium resistance to damped and atmospheric corrosive conditions.
Mean Critical temperature emissivity.
| -103 to 77°F | 6.00 x 10-6 in/in/°F |
| -58 to 77°F | 5.94 x 10-6 in/in/°F |
| -11 to 77°F | 5.78 x 10-6 in/in/°F |
| 77 to 122°F | 6.83 x 10-6 in/in/°F |
| 77 to 212°F | 6.89 x 10-6 in/in/°F |
| 77 to 392°F | 7.09 x 10-6 in/in/°F |
| 77 to 572°F | 7.22 x 10-6 in/in/°F |
| 77 to 752°F | 7.39 x 10-6 in/in/°F |
Annealing process, to remove deformation and regaining alloy in a soft form, drawing, spinning, forging, bending, annealing up to 1450 to 1850oF is done for less than 60 minutes. As alloy contains high content of nickel, high permeability alloys immediately soak carbon, sulfur, oxygen and other elements from burnt gases in the furnace. This annealing should be done in the presence of detached ammonia, vacuum or inert gas and hydrogen conditions.
To get utmost softness and suitable magnetic and electric features, the alloy is annealed in absence of oxygen with hydrogen at 1121oC to 1177oC for two to four hours. The furnace quenching up to 1100oF is done. From 1100oF to 700oF, quenching rate is between 350oF to 600oF per hour. Oil, grease, lacquer and pollutants should be eradicated prior to annealing. The component parts should be isolated through inert insulating powder like magnesium and aluminum oxide while hydrogen annealing.
Vacuum heat processing can be done. Normally, minor loss in magnetic features is noticed as compare to heat processing in arid hydrogen conditions.
Carpenter alloy HyMu 80 is readily weldable by implementing the common processes for ferrous alloy. If a filler metal is needed, the same methods are used. The end annealed alloys can be tender or tough soldered. The soldering is not preferred before heat processing.
For high blanking features, Carpenter HyMu 80 alloy should be kept in the cold treated conditions. For high forging features, alloy strip should be processed in the cold rolled and annealed conditions. For excellent drawing features, the alloy should be annealed and deep drawn.
Steel grade
Special steel