Nickel Alloy Alloy 42
UNS K94100 · ASTM F30 Alloy 42
Alloy 42 (K94100, ASTM F30) is a low-expansion iron-nickel controlled-expansion alloy whose thermal expansion is matched to silicon and borosilicate glass, and it is the standard lead-frame material for semiconductor packages.
Reference datasheet — Alloy 42 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 Annealed condition
Alloy 42 tempers and conditions
Alloy 42 is supplied in 9 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Rolled + Annealed plate / forged bar | Heavy-section condition for machined fixtures, molds and large glass-to-metal seal bodies. | 250 | 500 | 38 | 140 HB | 2.5 % IACS |
Lead-frame strip | Ultra-clean, tight-gauge, low-carbon surface strip specified for semiconductor lead frames and stamped hermetic parts. | 260 | 510 | 38 | 138 HB | 2.5 % IACS |
AnnealedDefault bright/hydrogen annealed strip, sheet and bar (soft) | Default stocked condition: maximum ductility for deep drawing, stamping and glass sealing; stable low expansion. | 270 | 520 | 35 | 145 HB | — |
Strain hardened, half hard | Choose when stamped parts need more stiffness/springback control but still moderate bending ductility. | 480 | 620 | 15 | 10 HRC | 2.5 % IACS |
Cold drawn | Standard bar and wire condition for machined glass-sealing pins, eyelets and headers. | 500 | 640 | 18 | 12 HRC | 2.5 % IACS |
Stress relieved | Pick when stamped or machined parts must hold dimensional stability and flatness after forming, with strength retained. | 560 | 680 | 12 | 13 HRC | 2.5 % IACS |
Strain hardened and partially annealed, half hard | Typical temper for stamped lead frames and shields needing flatness and edge stiffness. | 590 | 700 | 8 | 16 HRC | 2.4 % IACS |
Hardened | Highest strength flat product; use where stiffness dominates and only gentle forming is required. | 720 | 800 | 3 | 22 HRC | 2.4 % IACS |
Spring hard | For contact springs and diaphragms where low expansion must be combined with high elastic limit. | 830 | 900 | 2 | 28 HRC | 2.4 % IACS |
What is Alloy 42?
Alloy 42 (K94100, ASTM F30) is a low-expansion iron-nickel controlled-expansion alloy whose thermal expansion is matched to silicon and borosilicate glass, and it is the standard lead-frame material for semiconductor packages. Annealed stock gives about 270 MPa yield, 520 MPa tensile, 35% elongation and 145 HB (78 HRB) with a formability rating of 90, and it is supplied mainly as thin strip, foil and fine wire in annealed, H14, H24, spring and cold-drawn tempers. Maximum service temperature is 400 °C, machinability is poor (rated 28), and the alloy has no inherent corrosion resistance, so plating is normally required. Alloy 52 is the choice when a higher expansion match to hard glasses is needed. Alloy 42 has a density of 8.12 g/cm³ (0.293 lb/in³), lighter than 76% of nickel alloy grades. It melts at 1,425°C (2,597 °F). Alloy 42 has a yield strength of 270 MPa (39.2 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 84% of nickel alloy grades. Elongation at break is 35% and the elastic modulus is 145 GPa (21 Msi).
What is Alloy 42 used for?
- IC lead frames
- glass-to-metal seals
- TO-can transistor packages
- electronic component leads
Advantages
- Low embodied carbon — 6.5 kg CO₂/kg, better than 99% of nickel alloy grades
- Forms and bends easily — 90/100, better than 98% of nickel alloy grades
- High electrical conductivity — 2.5 % IACS, better than 85% of nickel alloy grades
Limitations
- Needs corrosion protection — 32/100, worse than 98% of nickel alloy grades
- Low stiffness — 145 GPa (21 Msi), worse than 96% of nickel alloy grades
- Limited service temperature — 400°C (752 °F), worse than 94% of nickel alloy grades
- Low strength — 270 MPa (39.2 ksi), worse than 84% of nickel alloy grades
Alloy 42 properties
Typical room-temperature values for Alloy 42-Annealed; bars are the position among nickel alloy grades.
Physical3
Alloy 42 has a density of 8.12 g/cm³ (0.293 lb/in³), lighter than 76% of nickel alloy grades. It melts at 1,425°C (2,597 °F).
Mechanical15
Alloy 42 has a yield strength of 270 MPa (39.2 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 84% of nickel alloy grades. Elongation at break is 35% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
Alloy 42 is rated for continuous service to 400°C (752 °F). It conducts heat at 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 73% of nickel alloy grades. Thermal expansion is 4.9 µm/m·K (2.72 µin/in·°F).
Electrical3
Alloy 42 conducts electricity at 2.5 % IACS, better than 85% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 98% of nickel alloy grades.
Sustainability4
Producing a kilogram of Alloy 42 takes about 85 MJ of energy and emits 6.5 kg of CO₂ — less than 100% of nickel alloy grades. Typical recycled content is 25%.
Manufacturability7
Alloy 42's machinability is poor (28/100, better than 82% of nickel alloy grades); weldability very good (70/100); formability excellent (90/100).
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 nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. Alloy 42 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Alloy 42
Is Alloy 42 easy to machine?
Gummy and work-hardening like austenitic stainless — use sharp positive-rake carbide, rigid setups, heavy positive feeds, and flood coolant; avoid dwelling.
Can Alloy 42 be welded?
Readily GTAW, EB, laser and resistance welded with matching Alloy 42 filler; keep joints free of carbon, sulphur and oil to preserve expansion behaviour and avoid hot cracking.
Can Alloy 42 be formed, bent or molded?
Excellent deep-drawing and stamping response in the annealed temper; interstage anneal at 800–900 °C in dry hydrogen for heavy reductions.
Alloy 42 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 |
|---|---|---|
| NiGB 4J42 narrows to 41.5–42.5 | 40.5 – 43.5 | 42 |
| C | ≤ 0.05 | 0.03 |
| Mn | ≤ 0.8 | 0.4 |
| Si | ≤ 0.3 | 0.15 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | ≤ 0.25 | |
| Co | ≤ 0.5 | |
| Aldeoxidiser residual | ≤ 0.1 | |
| Mgdeoxidiser residual | ≤ 0.1 | |
| Ti | ≤ 0.1 | |
| Cu | ≤ 0.2 | |
| Febalance, ≈57–58% | balance |
What surface finishes work on Alloy 42?
Not anodizable — glass-sealing parts are wet-hydrogen decarburised/oxidised, then Ni, Ag, Sn or Au plated for solderability and corrosion protection.
Surface treatments FabDigit runs on nickel alloy 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).
Plating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Nickel Alloy Alloy 42 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K94100
- ASTM
- F30 Alloy 42
- Other
- F30
How much does Alloy 42 cost?
Alloy 42 is a high-cost nickel alloy ($$$$), 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.
Alloy 42 — frequently asked
What is Alloy 42 used for?
Alloy 42 is typically used for IC lead frames, glass-to-metal seals, TO-can transistor packages and electronic component leads. In short: standard lead-frame alloy; matched to silicon and borosilicate; excellent deep-drawing strip.
What is the yield strength of Alloy 42?
Alloy 42 has a typical yield strength of 270 MPa (39.2 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 84% of nickel alloy grades. Strength varies by condition: see the 9 listed tempers.
Is Alloy 42 easy to machine?
Not especially — machinability is rated poor (28/100, better than 82% of nickel alloy grades). Gummy and work-hardening like austenitic stainless — use sharp positive-rake carbide, rigid setups, heavy positive feeds, and flood coolant; avoid dwelling.
Can Alloy 42 be welded?
Yes — weldability is rated very good (70/100). Readily GTAW, EB, laser and resistance welded with matching Alloy 42 filler; keep joints free of carbon, sulphur and oil to preserve expansion behaviour and avoid hot cracking.
What surface finishes work on Alloy 42?
Not anodizable — glass-sealing parts are wet-hydrogen decarburised/oxidised, then Ni, Ag, Sn or Au plated for solderability and corrosion protection.
Can Alloy 42 be formed, bent or molded?
Excellent deep-drawing and stamping response in the annealed temper; interstage anneal at 800–900 °C in dry hydrogen for heavy reductions.
What is the maximum service temperature of Alloy 42?
Alloy 42 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 Alloy 42 Annealed and Alloy 42 Spring?
Annealed is the default condition — default stocked condition: maximum ductility for deep drawing, stamping and glass sealing; stable low expansion. Spring: for contact springs and diaphragms where low expansion must be combined with high elastic limit. Yield strength is 270 MPa in Annealed versus 830 MPa in Spring.
How much does Alloy 42 cost?
Alloy 42 is a high-cost nickel alloy ($$$$), 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
- ASTM F30 — Standard Specification for Iron-Nickel Sealing Alloys — ASTM International (2018)
- GB/T 15018 / YB/T 5241 — 4J42 (2019)
- Alloy 42 (UNS K94100) controlled-expansion alloy datasheet — Carpenter Technology / Ed Fagan (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Low-Expansion Alloys) — ASM International (1990)
- ASM Specialty Handbook: Nickel, Cobalt and Their Alloys — ASM International (2000)
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.