Steel Supermalloy
Supermalloy (1J86) is a copper-modified Mo-Permalloy with the highest initial and maximum permeability of the Ni-Fe family, reserved for the most demanding low-noise shielding and toroidal cores.
Reference datasheet — Supermalloy is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the M condition
Supermalloy tempers and conditions
Supermalloy is supplied in 6 conditions, soft to hard. M is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Final hydrogen (magnetic) anneal, ~1100–1180 °C dry H₂, controlled cool | The condition in which the finished shield or core is used — maximum permeability, minimum coercivity, but the metal is very soft and strain-sensitive. | 180 | 500 | 45 | 100 HB | 3 % IACS |
MDefault Thermomechanically controlled processed | Standard as-supplied soft condition for stamping, drawing and winding; the part is hydrogen-annealed after forming to develop magnetic properties. | 230 | 560 | 40 | 115 HB | 2.9 % IACS |
Hot rolled | Semi-finished bar or slab stock for further hot/cold working or rough machining of cores and pole pieces. | 300 | 620 | 32 | 140 HB | 2.9 % IACS |
Half hard | Choose when the strip must hold shape or spring slightly during winding/assembly before the final magnetic anneal. | 600 | 750 | 12 | 180 HB | 2.8 % IACS |
Cold drawn | For fine wire cores, sensor elements and machined screw-machine parts requiring straightness and tolerance. | 780 | 880 | 6 | 19 HRC | 2.8 % IACS |
Hardened | Highest strength and thinnest gauges (down to foil) for wound cores and laminations that will be annealed after winding. | 850 | 950 | 4 | 21 HRC | 2.8 % IACS |
What is Supermalloy?
Supermalloy (1J86) is a copper-modified Mo-Permalloy with the highest initial and maximum permeability of the Ni-Fe family, reserved for the most demanding low-noise shielding and toroidal cores. It is selected where residual noise and coercivity must be minimised, and is available as thin strip and tape-wound core stock plus hot-rolled, medium, half-hard, hard and cold-drawn conditions. Typical values are 230 MPa yield, 560 MPa tensile, 40% elongation and 65 HRB, with service to 400 °C. Machinability is the lowest of the permalloys (score 28), saturation is low and cost is high, so use 4-79 Mo-Permalloy or Mu-metal where extreme permeability is not required. Supermalloy has a density of 8.77 g/cm³ (0.317 lb/in³), heavier than 100% of steel grades. It melts at 1,400°C (2,552 °F). Supermalloy has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 97% of steel grades. Elongation at break is 40% and the elastic modulus is 210 GPa (30.5 Msi).
What is Supermalloy used for?
- magnetic amplifier cores
- toroidal shielding
- SQUID/precision instrument shielding
- high-sensitivity transformer cores
Advantages
- Ductile — tolerates forming and impact — 40%, better than 99% of steel grades
- Good corrosion resistance — 45/100, better than 98% of steel grades
- Forms and bends easily — 85/100, better than 96% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- High embodied carbon — 10.5 kg CO₂/kg, worse than 100% of steel grades
- Low strength — 230 MPa (33.4 ksi), worse than 97% of steel grades
- Poor heat conductor — 19 W/m·K (11 BTU/hr·ft·°F), worse than 97% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Difficult to machine — 28/100, worse than 91% of steel grades
Supermalloy properties
Typical room-temperature values for Supermalloy-M; bars are the position among steel grades.
Physical3
Supermalloy has a density of 8.77 g/cm³ (0.317 lb/in³), heavier than 100% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical14
Supermalloy has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 97% of steel grades. Elongation at break is 40% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
Supermalloy is rated for continuous service to 400°C (752 °F). It conducts heat at 19 W/m·K (11 BTU/hr·ft·°F), worse than 97% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
Supermalloy conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), better than 98% of steel grades.
Sustainability4
Producing a kilogram of Supermalloy takes about 135 MJ of energy and emits 10.5 kg of CO₂ — more than 100% of steel grades. Typical recycled content is 25%.
Manufacturability8
Supermalloy's machinability is poor (28/100, worse than 91% of steel grades); weldability good (60/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. Supermalloy is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Supermalloy
Is Supermalloy easy to machine?
Gummy and strongly work-hardening — use sharp positive-rake carbide, heavy feed, low speed (20–40 m/min) and generous coolant; avoid dwelling, and leave stock for a stress-relief before the magnetic anneal.
Can Supermalloy be welded?
TIG, micro-plasma, laser and resistance welding all work with matching or Ni-Fe filler, but every weld and heat-affected zone destroys permeability locally, so the assembly must be hydrogen-annealed afterwards.
Can Supermalloy be formed, bent or molded?
Excellent deep drawing, stamping and spinning in the soft condition; design for a final free-standing hydrogen anneal because any residual cold work or clamping strain sharply lowers permeability.
Supermalloy chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Nihigh-purity vacuum-melted | 79 – 82 | 80.5 |
| Moraises resistivity and permeability | 5 – 6.5 | 5.7 |
| Mn | 0.3 – 0.7 | 0.5 |
| Si | 0.15 – 0.35 | 0.25 |
| Cusmall Cu addition used in some Cu-modified variants of this alloy family | ≤ 0.3 | |
| Ckept low for magnetic quality | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | |
| P | ≤ 0.02 | |
| Febalance, ≈12–14% | balance |
What surface finishes work on Supermalloy?
Do not anodize; protect with electroless nickel, tin plating, chromate-free passivation or clear lacquer applied after the final anneal, and never shot-blast or hard-brush a finished shield.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel Supermalloy in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 1J86
How much does Supermalloy cost?
Supermalloy is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Supermalloy — frequently asked
What is Supermalloy used for?
Supermalloy is typically used for magnetic amplifier cores, toroidal shielding, SQUID/precision instrument shielding and high-sensitivity transformer cores. In short: highest permeability Ni-Fe alloy; low-noise shielding grade; toughest permalloy to machine.
What is the yield strength of Supermalloy?
Supermalloy has a typical yield strength of 230 MPa (33.4 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 97% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is Supermalloy easy to machine?
Not especially — machinability is rated poor (28/100, worse than 91% of steel grades). Gummy and strongly work-hardening — use sharp positive-rake carbide, heavy feed, low speed (20–40 m/min) and generous coolant; avoid dwelling, and leave stock for a stress-relief before the magnetic anneal.
Can Supermalloy be welded?
Yes — weldability is rated good (60/100). TIG, micro-plasma, laser and resistance welding all work with matching or Ni-Fe filler, but every weld and heat-affected zone destroys permeability locally, so the assembly must be hydrogen-annealed afterwards.
What surface finishes work on Supermalloy?
Do not anodize; protect with electroless nickel, tin plating, chromate-free passivation or clear lacquer applied after the final anneal, and never shot-blast or hard-brush a finished shield.
Can Supermalloy be formed, bent or molded?
Excellent deep drawing, stamping and spinning in the soft condition; design for a final free-standing hydrogen anneal because any residual cold work or clamping strain sharply lowers permeability.
What is the maximum service temperature of Supermalloy?
Supermalloy is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Supermalloy-M and Supermalloy-H?
M is the default condition — standard as-supplied soft condition for stamping, drawing and winding; the part is hydrogen-annealed after forming to develop magnetic properties. H: highest strength and thinnest gauges (down to foil) for wound cores and laminations that will be annealed after winding. Yield strength is 230 MPa in M versus 850 MPa in H.
How much does Supermalloy cost?
Supermalloy is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- GB/T 14986 (1J85/1J86) (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Soft Magnetic Alloys) — ASM International (1990)
- ASTM A753 — Standard Specification for Wrought Nickel-Iron Soft Magnetic Alloys — ASTM International (2019)
- High-permeability 80% Ni-Fe-Mo alloy strip datasheets (mu-metal / supermalloy class) — Magnetic shielding alloy producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.