Steel Supermalloy-M
Heat-treated state · default condition
M = thermomechanically controlled processed
Standard as-supplied soft condition for stamping, drawing and winding; the part is hydrogen-annealed after forming to develop magnetic properties.
Values for the M condition
Other Supermalloy tempers and conditions
Supermalloy is listed in 6 conditions; see the grade overview at Supermalloy.
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 |
MDefaultThis page 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-M?
Supermalloy-M is Supermalloy heat treated to M — standard as-supplied soft condition for stamping, drawing and winding; the part is hydrogen-annealed after forming to develop magnetic properties. Supermalloy-M 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). Supermalloy-M 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).
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-M properties
Typical room-temperature values for Supermalloy-M; 20 are specific to this condition. Other listed values are Supermalloy reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Supermalloy-M 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-M 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-M 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-M 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-M 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-M'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. Confirm any required mill or lot documentation when quoting.
Working with Supermalloy-M
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.
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.
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 | — |
Supermalloy-M — frequently asked
What is Supermalloy-M used for?
Supermalloy-M 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-M?
Supermalloy-M 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-M 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-M 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-M?
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-M 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-M?
Supermalloy-M 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.