Steel FeNi42 Annealed
Temper · default condition
UNS K94200, K94100 · ASTM F30 · EN 1.3917 · GB 4J42 · also Alloy 42
Default stocked condition for lead frames, deep-drawn caps and glass-to-metal seal parts needing maximum ductility and stable CTE.
Values for the Annealed condition
Other FeNi42 tempers and conditions
FeNi42 is listed in 6 conditions; see the grade overview at FeNi42.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefaultThis page bright/hydrogen annealed, fully soft | Default stocked condition for lead frames, deep-drawn caps and glass-to-metal seal parts needing maximum ductility and stable CTE. | 300 | 540 | 33 | 140 HB | — |
Quarter hard | Pick when slightly stiffer strip is needed for stamping flatness while retaining useful bend ductility. | 450 | 620 | 18 | 170 HB | 2.5 % IACS |
Cold drawn | Standard bar/rod supply condition for machined seal bodies and headers; anneal after rough machining to restore CTE stability. | 560 | 690 | 12 | 14 HRC | 2.5 % IACS |
Half hard | Standard half-hard strip/wire for stamped lead frames, springy contacts and parts needing higher yield without final anneal. | 580 | 700 | 10 | 205 HB | — |
Full hard | Maximum strength/stiffness strip for flat springs, shims and diaphragms where formability is not required. | 780 | 860 | 3 | 28 HRC | 2.4 % IACS |
Spring hard | Choose for wire and thin strip springs where high elastic limit and dimensional stability are needed. | 880 | 950 | 2 | 31 HRC | 2.4 % IACS |
What is FeNi42 Annealed?
FeNi42 Annealed is FeNi42 in the Annealed temper — default stocked condition for lead frames, deep-drawn caps and glass-to-metal seal parts needing maximum ductility and stable CTE. FeNi42 Annealed has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 86% of steel grades. Elongation at break is 33% and the elastic modulus is 145 GPa (21 Msi). FeNi42 Annealed has a density of 8.12 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Ductile — tolerates forming and impact — 33%, better than 96% of steel grades
- Forms and bends easily — 85/100, better than 96% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- Readily welded — 72/100, better than 75% of steel grades
Limitations
- Poor heat conductor — 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 100% of steel grades
- High embodied carbon — 7 kg CO₂/kg, worse than 99% of steel grades
- Low stiffness — 145 GPa (21 Msi), worse than 98% of steel grades
- Low electrical conductivity — 2.5 % IACS, worse than 97% of steel grades
- Difficult to machine — 30/100, worse than 89% of steel grades
FeNi42 Annealed properties
Typical room-temperature values for FeNi42 Annealed; 16 are specific to this condition. Other listed values are FeNi42 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
FeNi42 Annealed has a density of 8.12 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
FeNi42 Annealed has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 86% of steel grades. Elongation at break is 33% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
FeNi42 Annealed is rated for continuous service to 350°C (662 °F). It conducts heat at 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 100% of steel grades. Thermal expansion is 5.3 µm/m·K (2.94 µin/in·°F).
Electrical3
FeNi42 Annealed conducts electricity at 2.5 % IACS, worse than 97% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of FeNi42 Annealed takes about 100 MJ of energy and emits 7 kg of CO₂ — more than 99% of steel grades. Typical recycled content is 30%.
Manufacturability8
FeNi42 Annealed's machinability is poor (30/100, worse than 89% of steel grades); weldability very good (72/100); 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 FeNi42 Annealed
Is FeNi42 easy to machine?
Gummy and work-hardening — use sharp, positive-rake carbide, rigid setups, heavy positive feed, low-to-moderate speed and generous sulphur-free coolant; avoid dwelling.
Can FeNi42 be welded?
Readily GTAW/laser/resistance welded to itself and to Kovar using matching or low-carbon Ni-Fe filler; keep joints free of C, S and Pb to avoid embrittlement and CTE shift.
Can FeNi42 be formed, bent or molded?
Annealed strip stamps and deep-draws like soft austenitic stainless; interstage anneal at 800–900 °C in dry H₂ and finish with a stabilising anneal to set the expansion curve.
What surface finishes work on FeNi42?
Not anodizable — protect with electroless/electrolytic Ni, then Sn, Ag or Au for soldering and corrosion resistance; oxidised (blued) surfaces are used before glass sealing.
FeNi42 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) content controls CTE | 41 – 42.5 | 42 |
| C | ≤ 0.05 | 0.02 |
| Mn | ≤ 0.6 | 0.35 |
| Si | ≤ 0.3 | 0.15 |
| P | ≤ 0.02 | — |
| S | ≤ 0.02 | — |
| Crresidual | ≤ 0.25 | — |
| Coresidual/optional | ≤ 0.5 | — |
| Aldeoxidiser residual | ≤ 0.1 | — |
| Fe | balance | — |
FeNi42 Annealed — frequently asked
What is FeNi42 Annealed used for?
FeNi42 Annealed is typically used for IC lead frames, semiconductor package caps, glass-sealing components for silicon devices and bimetal strip layers. In short: silicon-matched expansion; standard lead-frame alloy; higher CTE than Invar 36.
What is the yield strength of FeNi42 Annealed?
FeNi42 Annealed has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 540 MPa (78.3 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is FeNi42 Annealed easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% of steel grades). Gummy and work-hardening — use sharp, positive-rake carbide, rigid setups, heavy positive feed, low-to-moderate speed and generous sulphur-free coolant; avoid dwelling.
Can FeNi42 Annealed be welded?
Yes — weldability is rated very good (72/100). Readily GTAW/laser/resistance welded to itself and to Kovar using matching or low-carbon Ni-Fe filler; keep joints free of C, S and Pb to avoid embrittlement and CTE shift.
What surface finishes work on FeNi42 Annealed?
Not anodizable — protect with electroless/electrolytic Ni, then Sn, Ag or Au for soldering and corrosion resistance; oxidised (blued) surfaces are used before glass sealing.
Can FeNi42 Annealed be formed, bent or molded?
Annealed strip stamps and deep-draws like soft austenitic stainless; interstage anneal at 800–900 °C in dry H₂ and finish with a stabilising anneal to set the expansion curve.
What is the maximum service temperature of FeNi42 Annealed?
FeNi42 Annealed is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between FeNi42 Annealed and FeNi42 Spring?
Annealed is the default condition — default stocked condition for lead frames, deep-drawn caps and glass-to-metal seal parts needing maximum ductility and stable CTE. Spring: choose for wire and thin strip springs where high elastic limit and dimensional stability are needed. Yield strength is 300 MPa in Annealed versus 880 MPa in Spring.
Sources
- ASTM F30 — Standard Specification for Iron-Nickel Sealing Alloys — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (controlled-expansion alloys) — ASM International (1990)
- Alloy 42 / Nilo 42 controlled expansion alloy datasheets — specialty Fe-Ni strip producers (2022)
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.