Nickel Alloy Alloy 42 Spring
Heat-treated state
UNS K94100 · ASTM F30 Alloy 42
Spring = spring hard
For contact springs and diaphragms where low expansion must be combined with high elastic limit.
Values for the Spring condition
Other Alloy 42 tempers and conditions
Alloy 42 is listed in 9 conditions; see the grade overview at Alloy 42.
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 |
SpringThis page 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 Spring?
Alloy 42 Spring is Alloy 42 heat treated to Spring — for contact springs and diaphragms where low expansion must be combined with high elastic limit. Alloy 42 Spring has a yield strength of 830 MPa (120 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 88% of nickel alloy grades. Elongation at break is 2% and the elastic modulus is 150 GPa (21.8 Msi). Alloy 42 Spring 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). Annealed is the default condition FabDigit quotes; Spring is available on request or by drawing note.
Advantages
- Low embodied carbon — 6.5 kg CO₂/kg, better than 99% of nickel alloy grades
- Easy to machine — 36/100, better than 98% of nickel alloy grades
- High strength — 830 MPa (120 ksi), better than 88% of nickel alloy grades
- High electrical conductivity — 2.4 % IACS, better than 84% of nickel alloy grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 99% of nickel alloy grades
- Needs corrosion protection — 32/100, worse than 98% of nickel alloy grades
- Low stiffness — 150 GPa (21.8 Msi), worse than 95% of nickel alloy grades
- Limited ductility — 2%, worse than 95% of nickel alloy grades
Alloy 42 Spring properties
Typical room-temperature values for Alloy 42 Spring; 21 are specific to this condition. Other listed values are Alloy 42 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Alloy 42 Spring 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 Spring has a yield strength of 830 MPa (120 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 88% of nickel alloy grades. Elongation at break is 2% and the elastic modulus is 150 GPa (21.8 Msi).
Thermal6
Alloy 42 Spring is rated for continuous service to 300°C (572 °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 Spring conducts electricity at 2.4 % IACS, better than 84% 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 Spring 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 Spring's machinability is fair (36/100, better than 98% of nickel alloy grades); weldability good (55/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Alloy 42 Spring
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.
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.
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 | — |
Alloy 42 Spring — frequently asked
What is Alloy 42 Spring used for?
Alloy 42 Spring 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 Spring?
Alloy 42 Spring has a typical yield strength of 830 MPa (120 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 88% of nickel alloy grades. Strength varies by condition: see the 9 listed tempers.
Is Alloy 42 Spring easy to machine?
Not especially — machinability is rated fair (36/100, better than 98% 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 Spring be welded?
Yes — weldability is rated good (55/100). 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 Spring?
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 Spring 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 Spring?
Alloy 42 Spring is rated for continuous use to about 300°C (572 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.