Nickel Alloy Alloy 42-SR (Stress relieved)
Heat-treated state
UNS K94100 · ASTM F30 Alloy 42
Pick when stamped or machined parts must hold dimensional stability and flatness after forming, with strength retained.
Values for the SR 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 |
SRThis page 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-SR?
Alloy 42-SR is Alloy 42 heat treated to SR — pick when stamped or machined parts must hold dimensional stability and flatness after forming, with strength retained. Alloy 42-SR has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 81% of nickel alloy grades. Elongation at break is 12% and the elastic modulus is 147 GPa (21.3 Msi). Alloy 42-SR 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; SR 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 — 34/100, better than 96% of nickel alloy grades
- High electrical conductivity — 2.5 % IACS, better than 85% of nickel alloy grades
- High strength — 560 MPa (81.2 ksi), better than 81% of nickel alloy grades
Limitations
- Needs corrosion protection — 32/100, worse than 98% of nickel alloy grades
- Low stiffness — 147 GPa (21.3 Msi), worse than 96% of nickel alloy grades
- Limited service temperature — 400°C (752 °F), worse than 94% of nickel alloy grades
- Limited ductility — 12%, worse than 83% of nickel alloy grades
Alloy 42-SR properties
Typical room-temperature values for Alloy 42-SR; 22 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-SR 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-SR has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 81% of nickel alloy grades. Elongation at break is 12% and the elastic modulus is 147 GPa (21.3 Msi).
Thermal6
Alloy 42-SR 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-SR 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-SR 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-SR's machinability is poor (34/100, better than 96% of nickel alloy grades); weldability good (68/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Alloy 42-SR
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-SR — frequently asked
What is Alloy 42-SR used for?
Alloy 42-SR 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-SR?
Alloy 42-SR has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 81% of nickel alloy grades. Strength varies by condition: see the 9 listed tempers.
Is Alloy 42-SR easy to machine?
Not especially — machinability is rated poor (34/100, better than 96% 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-SR be welded?
Yes — weldability is rated good (68/100). 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-SR?
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-SR 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-SR?
Alloy 42-SR 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.
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.