Steel 1J85-MFA
Heat-treated state
GB 1J85
MFA = magnetic field anneal (longitudinal/transverse) for tailored B-H loop
Anneal in a magnetic field to tailor the B-H loop: longitudinal for square-loop magnetic amplifiers and pulse transformers, transverse for flat constant-permeability instrument transformers and chokes.
Values for the MFA condition
Other 1J85 tempers and conditions
1J85 is listed in 5 conditions; see the grade overview at 1J85.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Final magnetic anneal, 1100–1180 °C dry hydrogen, slow cool | Final state for finished cores and shields: a 1100–1180 °C dry hydrogen anneal with slow cool gives peak permeability (μm above 200,000) and lowest coercivity, but leaves soft, stress-sensitive metal. | 210 | 550 | 45 | 105 HB | 3.1 % IACS |
MFAThis page Magnetic field anneal (longitudinal/transverse) for tailored B-H loop | Anneal in a magnetic field to tailor the B-H loop: longitudinal for square-loop magnetic amplifiers and pulse transformers, transverse for flat constant-permeability instrument transformers and chokes. | 215 | 560 | 43 | 106 HB | 3.1 % IACS |
MDefault Thermomechanically controlled processed | Default supply form: soft mill-annealed strip and sheet for stamping and core winding, with the hydrogen magnetic anneal performed after forming to develop magnetic properties. | 250 | 600 | 40 | 115 HB | 3.1 % IACS |
Half hard cold rolled strip | Choose half hard cold rolled strip for shielding cans and brackets that need rigidity yet must still be bent; 620 MPa yield, with magnetic performance restored only by annealing. | 620 | 850 | 12 | 185 HB | 3 % IACS |
Cold rolled hard strip / foil | Pick as-rolled hard strip or foil for thin gauges and high winding tension; permeability is very low and only a final anneal develops magnetic properties, with elongation at 3%. | 950 | 1,100 | 3 | 23 HRC | 3 % IACS |
What is 1J85-MFA?
1J85-MFA is 1J85 heat treated to MFA — anneal in a magnetic field to tailor the B-H loop: longitudinal for square-loop magnetic amplifiers and pulse transformers, transverse for flat constant-permeability instrument transformers and chokes. 1J85-MFA has a yield strength of 215 MPa (31.2 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 98% of steel grades. Elongation at break is 43% and the elastic modulus is 190 GPa (27.6 Msi). 1J85-MFA has a density of 8.75 g/cm³ (0.316 lb/in³), heavier than 100% of steel grades. It melts at 1,400°C (2,552 °F). M is the default condition FabDigit quotes; MFA is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 43%, better than 100% of steel grades
- Good corrosion resistance — 55/100, better than 99% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- High embodied carbon — 11 kg CO₂/kg, worse than 100% of steel grades
- Low strength — 215 MPa (31.2 ksi), worse than 98% of steel grades
- Poor heat conductor — 19 W/m·K (11 BTU/hr·ft·°F), worse than 97% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
1J85-MFA properties
Typical room-temperature values for 1J85-MFA; 21 are specific to this condition. Other listed values are 1J85 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
1J85-MFA has a density of 8.75 g/cm³ (0.316 lb/in³), heavier than 100% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
1J85-MFA has a yield strength of 215 MPa (31.2 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 98% of steel grades. Elongation at break is 43% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
1J85-MFA is rated for continuous service to 200°C (392 °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
1J85-MFA conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), better than 99% of steel grades.
Sustainability4
Producing a kilogram of 1J85-MFA takes about 160 MJ of energy and emits 11 kg of CO₂ — more than 100% of steel grades. Typical recycled content is 25%.
Manufacturability7
1J85-MFA's machinability is poor (25/100, worse than 93% of steel grades); weldability fair (50/100); formability good (58/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1J85-MFA
Is 1J85 easy to machine?
In the soft condition the alloy smears and work-hardens rapidly: use sharp, high positive-rake tools, lower speeds with a heavier feed and flood coolant. Cutting stresses markedly reduce permeability, so rough machine with allowance and finish-anneal afterwards.
Can 1J85 be welded?
TIG, laser and electron-beam welding are possible with clean joint preparation and low heat input. A full dry-hydrogen magnetic anneal after welding is required to recover magnetic properties.
Can 1J85 be formed, bent or molded?
Soft strip blanks, deep-draws and winds very well (formability score 85), but all cold work sharply lowers permeability. Anneal formed parts at 1100–1180 °C in dry hydrogen with slow cooling, then protect them from impact and mechanical stress.
What surface finishes work on 1J85?
Not anodizable; use nickel or tin plating, or paint, for corrosion protection, and the alloy can be polished. Handle annealed shields carefully and do not re-bend them after the final anneal.
1J85 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 |
|---|---|---|
| Niincludes Co | 79 – 81 | 80 |
| Mo | 4.8 – 5.5 | 5 |
| Mn | 0.3 – 0.6 | 0.45 |
| Si | 0.15 – 0.3 | 0.22 |
| Clower carbon gives better magnetic properties | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| Febalance, about 14-15% | balance | — |
1J85-MFA — frequently asked
What is 1J85-MFA used for?
1J85-MFA is typically used for precision toroidal cores, magnetic shielding and sensitive relay cores. In short: highest-permeability Ni-Fe-Mo alloy; supermalloy-class shielding grade; very stress-sensitive; anneal last.
What is the yield strength of 1J85-MFA?
1J85-MFA has a typical yield strength of 215 MPa (31.2 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 98% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 1J85-MFA easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). In the soft condition the alloy smears and work-hardens rapidly: use sharp, high positive-rake tools, lower speeds with a heavier feed and flood coolant. Cutting stresses markedly reduce permeability, so rough machine with allowance and finish-anneal afterwards.
Can 1J85-MFA be welded?
With care — weldability is rated fair (50/100). TIG, laser and electron-beam welding are possible with clean joint preparation and low heat input. A full dry-hydrogen magnetic anneal after welding is required to recover magnetic properties.
What surface finishes work on 1J85-MFA?
Not anodizable; use nickel or tin plating, or paint, for corrosion protection, and the alloy can be polished. Handle annealed shields carefully and do not re-bend them after the final anneal.
Can 1J85-MFA be formed, bent or molded?
Soft strip blanks, deep-draws and winds very well (formability score 85), but all cold work sharply lowers permeability. Anneal formed parts at 1100–1180 °C in dry hydrogen with slow cooling, then protect them from impact and mechanical stress.
What is the maximum service temperature of 1J85-MFA?
1J85-MFA is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1J85-M and 1J85-Y?
M is the default condition — default supply form: soft mill-annealed strip and sheet for stamping and core winding, with the hydrogen magnetic anneal performed after forming to develop magnetic properties. Y: pick as-rolled hard strip or foil for thin gauges and high winding tension; permeability is very low and only a final anneal develops magnetic properties, with elongation at 3%. Yield strength is 250 MPa in M versus 950 MPa in Y.
Sources
- ASM Handbook Vol.2 — Properties of Soft Magnetic Ni-Fe Alloys — ASM International (1990)
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.