Steel 4-79 Mo-Permalloy H2-Anneal
Heat-treated state
H2-Anneal = dry-hydrogen magnetic anneal, 1100–1180 °C, controlled slow cool
Final state for shields and high-permeability cores — pick after all forming/welding is finished; handle with care, any strain destroys the magnetics.
Values for the H2-Anneal condition
Other 4-79 Mo-Permalloy tempers and conditions
4-79 Mo-Permalloy is listed in 7 conditions; see the grade overview at 4-79 Mo-Permalloy.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
H2-AnnealThis page Dry-hydrogen magnetic anneal, 1100–1180 °C, controlled slow cool | Final state for shields and high-permeability cores — pick after all forming/welding is finished; handle with care, any strain destroys the magnetics. | 220 | 500 | 45 | 110 HB | 3.1 % IACS |
magnetic-field (transverse or longitudinal) anneal after hydrogen anneal | Choose when a flat (constant-permeability, sheared) or square hysteresis loop is required, e.g. current transformers and pulse cores. | 220 | 500 | 45 | 110 HB | 3.1 % IACS |
Hot rolled/forged plate, bar and rod, annealed | Heavy-section supply form for machined shield housings and large cores; softer and coarser-grained than cold-worked product. | 250 | 560 | 40 | 125 HB | 3.1 % IACS |
AnnealedDefault mill soft anneal (strip/sheet as supplied) | Standard stocked soft strip/sheet: formable, moderate permeability; final magnetic anneal is done after forming. | 260 | 550 | 40 | 120 HB | — |
Half hard | Compromise temper for parts needing some spring/stiffness during handling before the final magnetic anneal. | 560 | 760 | 12 | 13 HRC | 3.1 % IACS |
Cold drawn | Straight, dimensionally accurate rod/wire for machined pole pieces and shield hardware; anneal parts after machining. | 620 | 800 | 15 | 17 HRC | 3.1 % IACS |
Cold rolled | Springy as-rolled strip for thin gauges, laminations and parts that will be annealed later; magnetically poor as-is. | 850 | 1,000 | 3 | 25 HRC | 3 % IACS |
What is 4-79 Mo-Permalloy H2-Anneal?
4-79 Mo-Permalloy H2-Anneal is 4-79 Mo-Permalloy heat treated to H2-Anneal — final state for shields and high-permeability cores — pick after all forming/welding is finished; handle with care, any strain destroys the magnetics. 4-79 Mo-Permalloy H2-Anneal has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 98% of steel grades. Elongation at break is 45% and the elastic modulus is 205 GPa (29.7 Msi). 4-79 Mo-Permalloy H2-Anneal has a density of 8.74 g/cm³ (0.316 lb/in³), heavier than 100% of steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; H2-Anneal is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 45%, better than 100% of steel grades
- Good corrosion resistance — 45/100, better than 98% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- High embodied carbon — 10 kg CO₂/kg, worse than 100% of steel grades
- Low strength — 220 MPa (31.9 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
- Difficult to machine — 25/100, worse than 93% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
4-79 Mo-Permalloy H2-Anneal properties
Typical room-temperature values for 4-79 Mo-Permalloy H2-Anneal; 22 are specific to this condition. Other listed values are 4-79 Mo-Permalloy reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4-79 Mo-Permalloy H2-Anneal has a density of 8.74 g/cm³ (0.316 lb/in³), heavier than 100% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical12
4-79 Mo-Permalloy H2-Anneal has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 98% of steel grades. Elongation at break is 45% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal5
4-79 Mo-Permalloy H2-Anneal 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
4-79 Mo-Permalloy H2-Anneal conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), better than 98% of steel grades.
Sustainability4
Producing a kilogram of 4-79 Mo-Permalloy H2-Anneal takes about 140 MJ of energy and emits 10 kg of CO₂ — more than 100% of steel grades. Typical recycled content is 20%.
Manufacturability8
4-79 Mo-Permalloy H2-Anneal's machinability is poor (25/100, worse than 93% of steel grades); weldability good (60/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4-79 Mo-Permalloy H2-Anneal
Is 4-79 Mo-Permalloy easy to machine?
Gummy and work-hardening — use sharp positive-rake carbide, rigid setups, low speed with heavy feed and flood coolant; leave a finishing pass and anneal after machining to restore magnetics.
Can 4-79 Mo-Permalloy be welded?
TIG/laser/electron-beam weldable with matching or Ni-Fe filler and low heat input; every weld and its HAZ must be re-annealed in dry hydrogen to recover permeability.
Can 4-79 Mo-Permalloy be formed, bent or molded?
Excellent deep-drawability in the soft temper (shield cans drawn in several stages with interstage anneals); any residual strain, dent or hard clamping raises coercivity dramatically.
What surface finishes work on 4-79 Mo-Permalloy?
Not anodizable; deburr gently, then passivate, electroless-nickel, tin or zinc plate, or lacquer for humid environments — avoid abrasive blasting or hard stamping after final anneal.
4-79 Mo-Permalloy 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 |
|---|---|---|
| NiNi (+Co) per GB/T 14986 1J79 | 78.5 – 80 | 79 |
| Mosome producers/ASTM grades run 4.0–5.0 | 3.8 – 4.1 | 4 |
| Mn | 0.3 – 0.6 | 0.45 |
| Si | 0.15 – 0.3 | 0.22 |
| C | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| Febalance, ≈16–17 % | balance | — |
4-79 Mo-Permalloy H2-Anneal — frequently asked
What is 4-79 Mo-Permalloy H2-Anneal used for?
4-79 Mo-Permalloy H2-Anneal is typically used for pulse/audio transformer cores, magnetic shielding cans, current sensor cores and recording head laminations. In short: archetypal high-permeability permalloy; best low-field shielding strip; deep-draws in soft temper.
What is the yield strength of 4-79 Mo-Permalloy H2-Anneal?
4-79 Mo-Permalloy H2-Anneal has a typical yield strength of 220 MPa (31.9 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 98% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4-79 Mo-Permalloy H2-Anneal easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Gummy and work-hardening — use sharp positive-rake carbide, rigid setups, low speed with heavy feed and flood coolant; leave a finishing pass and anneal after machining to restore magnetics.
Can 4-79 Mo-Permalloy H2-Anneal be welded?
Yes — weldability is rated good (60/100). TIG/laser/electron-beam weldable with matching or Ni-Fe filler and low heat input; every weld and its HAZ must be re-annealed in dry hydrogen to recover permeability.
What surface finishes work on 4-79 Mo-Permalloy H2-Anneal?
Not anodizable; deburr gently, then passivate, electroless-nickel, tin or zinc plate, or lacquer for humid environments — avoid abrasive blasting or hard stamping after final anneal.
Can 4-79 Mo-Permalloy H2-Anneal be formed, bent or molded?
Excellent deep-drawability in the soft temper (shield cans drawn in several stages with interstage anneals); any residual strain, dent or hard clamping raises coercivity dramatically.
What is the maximum service temperature of 4-79 Mo-Permalloy H2-Anneal?
4-79 Mo-Permalloy H2-Anneal 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 4-79 Mo-Permalloy Annealed and 4-79 Mo-Permalloy-CR?
Annealed is the default condition — standard stocked soft strip/sheet: formable, moderate permeability; final magnetic anneal is done after forming. CR: springy as-rolled strip for thin gauges, laminations and parts that will be annealed later; magnetically poor as-is. Yield strength is 260 MPa in Annealed versus 850 MPa in CR.
Sources
- GB/T 14986 (1J79) — SAC (2018)
- ASTM A753 Standard Specification for Wrought Nickel-Iron Soft Magnetic Alloys — ASTM (2020)
- HyMu 80 Alloy technical datasheet — Carpenter Technology (2020)
- MAGNIFER 7904 / soft magnetic Ni-Fe alloys — VDM Metals (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (magnetically soft materials) — 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.