Controlled-expansion nickel-iron alloy · Open-die forgings
1.3917 is the German Werkstoff number for a binary nickel-iron controlled-expansion alloy containing about 42 % nickel, balance iron. It is also designated Ni42, X10Ni42, UNS K94100 and 4J42, and sold as Alloy 42, NILO 42 and Invar 42. It is specified for its coefficient of thermal expansion, which holds at roughly 4.0–5.0 × 10−6/K over 20–300 °C and matches silicon, alumina ceramic and hard sealing glasses.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges 1.3917 to customer drawings: forged rings and seamless rolled rings, discs, shafts, flanges, round bars, sleeves, bushings, tubes and tube sheets. Material is melted by EAF + VOD + ESR, ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, and certified to EN 10204 3.1 or 3.2. Send a drawing to sales@steelforgepieces.com or call +86 189 2135 9659 for a quotation.
1.3917 is a binary iron-nickel alloy with controlled thermal expansion. In the iron-nickel system the expansion coefficient depends on nickel content. It reaches its minimum at 36 % nickel, which is Invar 36, then rises as nickel goes up. At 42 % nickel the expansion is still low, and it happens to sit close to that of silicon, alumina and hard glass. Alloy 42 is specified for that match. Where the lowest possible expansion is wanted instead, Invar 36 is the grade.
Expansion stays low and predictable to about 300 °C. Above the Curie point, roughly 360–380 °C, the alloy turns paramagnetic, the expansion curve inflects and the coefficient climbs quickly. That is the working ceiling of the grade, and it is why published data for 1.3917 stops at 300 °C.
Schematic only, not to scale. Actual expansion data for a specific heat is reported on the mill certificate.
| System | Designation | Notes |
|---|---|---|
| Werkstoff (Germany) | 1.3917 | Also written W.-Nr. 1.3917 |
| DIN | Ni42 / X10Ni42 | DIN 17745; SEW 385 |
| UNS (USA) | K94100 | Unified Numbering System |
| ASTM | F30, F29, B753, F1684 | F30 covers sheet, strip, rod, bar, tubing and wire; F29 covers wire |
| AFNOR (France) | NF A54-301 | FeNi42 |
| GB (China) | 4J42 | Precision expansion alloy series |
| Trade names | Alloy 42 · NILO 42 · Invar 42 · Dilaton 42 | NILO is a Special Metals trademark; Invar is an Aperam trademark |
Cross-references are given for identification only. State the exact specification and revision on your order. An ASTM F30 order and a DIN 17745 order are not always interchangeable.
The limits below are typical for 1.3917 / Alloy 42 supplied to ASTM F30. Jiangyin Jiangnan Metal melts the grade by EAF + VOD + ESR. The vacuum-oxygen decarburisation and electroslag remelting stages hold sulphur and phosphorus down, which helps both hot working and seal integrity in the finished part.
| Grade | Ni | C | Mn | P | S | Si | Cr | Al | Fe |
|---|---|---|---|---|---|---|---|---|---|
| 1.3917 | 41.0–43.0 | 0.05 max | 0.80 max | 0.025 max | 0.025 max | 0.30 max | 0.25 max | 0.10 max | Balance |
Typical limits for identification. The chemistry that governs your order is the one reported on the mill certificate for that heat.
1.3917 is supplied and used annealed. Annealing is what gives it the dimensional stability and the flat expansion curve. Cold work raises strength but disturbs expansion behaviour, so parts for sealing or metrology are annealed after forming.
| Grade | Condition | Tensile strength | Yield strength (0.2 % offset) | Elongation |
|---|---|---|---|---|
| 1.3917 | Annealed | 490 MPa / 71,000 psi | 250 MPa / 36,000 psi | 43 % |
| Property | Value | Condition |
|---|---|---|
| Coefficient of thermal expansion | 4.0–5.0 × 10⁻⁶/K | Mean, 20–300 °C |
| Density | ≈ 8.12 g/cm³ | 20 °C |
| Melting range | 1425–1435 °C | — |
| Curie temperature | ≈ 360–380 °C | Ferromagnetic below, paramagnetic above |
| Modulus of elasticity | ≈ 148 GPa | 20 °C |
| Thermal conductivity | ≈ 10.7 W/(m·K) | 20–100 °C |
| Crystal structure | FCC | Soft annealed |
Typical published values for the grade, given for design guidance. Where expansion behaviour is critical, Jiangyin Jiangnan Metal can arrange CTE testing over 20–300 °C on the delivered heat. State this on the enquiry.
1.3917 forges without much trouble. Furnace atmosphere is the thing to watch: sulphur and oxygen picked up during reheating cause hot shortness and can ruin a billet, so soak times are kept short.
| Operation | Parameter | Purpose |
|---|---|---|
| Melting | EAF + VOD + ESR | Low S and P, clean and homogeneous ingot structure |
| Forging heat | 1175–1205 °C | Heat quickly, soak briefly, to limit S and O pickup from the furnace atmosphere |
| Open-die forging | Upsetting, drawing, punching, ring rolling | Breaks down the cast structure and closes porosity |
| Annealing | 850–1000 °C, protective atmosphere | Restores dimensional stability and a low, constant expansion coefficient |
| Machining | Annealed condition, HSS or carbide-tipped tooling | Worked by methods similar to austenitic stainless steels |
Every 1.3917 part is made to the customer's drawing. There is no fixed catalogue. Controlled-expansion alloys are melted in limited heat sizes, so achievable diameter and piece weight depend on the heat available when the order is placed. Send the drawing and the size is confirmed with the quotation.
| Product form | Indicative range | Typical use |
|---|---|---|
| Forged rings / seamless rolled rings | OD 150–2,000 mm | Seal rings, retaining rings, instrument frames |
| Forged discs and disks | OD 100–1,500 mm | Blanks for machined precision components |
| Forged shafts and spindles | Ø 60–600 mm | Thermostat rods, positioning shafts |
| Forged flanges | To drawing | Vacuum devices, sealed housings |
| Forged round bars and blocks | Ø 40–500 mm | General machining stock |
| Forged sleeves and bushings | To drawing | Bearing housings, spacers |
| Forged tubes and tube sheets | To drawing | Heat exchanger and vacuum hardware |
| Forged valve parts | To drawing | Stems, seat rings, bodies, blocks |
| Forged nozzles, gears, wheels, manifolds | To drawing | Instrument and equipment components |
Supplied as-forged, rough-machined or finish-machined. State the condition on the enquiry. Rough-machined blanks usually work out cheapest if the part will be finished on your own machines.
In every case below the requirement is the same. A part has to hold its dimensions, or hold a seal against a material that barely moves, while the temperature changes.
The expansion of 1.3917 matches silicon, beryllia and alumina, so it can be sealed directly to them without the joint cracking on thermal cycling.
Lead frames · chip carriers · hermetic packages · special electronic housingsThe oldest use of the grade. Sealed into hard glass envelopes, where the joint has to survive both manufacture and service.
Vacuum devices · electric lamp bulbs · radio and television tubes · transformer and capacitor bushingsPaired against a high-expansion alloy, 1.3917 forms the low-expansion side of a bimetal element and provides the reference length in rod-type thermostats.
Thermostat rods · thermostatic bimetal strip · temperature regulators · clock balance wheelsMoulds that hold dimension through the autoclave cycle. A steel tool would grow enough to put the cured part out of tolerance.
Advanced composite moulds · tooling frames · forged plates and blocksLow expansion over a wide temperature swing reduces thermal stress in containment and transfer systems.
LNG tanker containment components · transfer line hardware · forged flanges and nozzlesResonant cavities detune if their dimensions drift, so the cavity body is made from a controlled-expansion alloy.
Radar and microwave cavity resonators · echo boxes and filters for mobile telephony · magnetic shieldingUsed where drift in the instrument itself would show up in the measurement.
Positioning devices · optical device frames · scientific instruments · metrology fixtures · seals and spacersForged valve components in 1.3917 where seat and stem clearances must hold through temperature cycling.
Ball, check, globe, gate and plug valves · stems · seat rings · bodies · blocks · strainersOther forms regularly produced in 1.3917 include forged crankshafts and eccentric shafts, forged wheels, manifolds and rolls, forging pipes and nozzles, precision condenser blades, and electrical circuit breaker components.
If you are not sure whether 1.3917 is the right grade, send the operating temperature range and what the part has to seal against or stay aligned with. Invar 36 or Alloy 48 is often the better match for a given job.
1.3917 is the German Werkstoff number for a binary nickel-iron controlled-expansion alloy containing about 42 % nickel, balance iron. It is also designated Ni42, X10Ni42, UNS K94100 and 4J42, and is sold under the trade names Alloy 42, NILO 42 and Invar 42. Its defining property is a low and nominally constant coefficient of thermal expansion of roughly 4.0–5.0 × 10⁻⁶/K over the range 20–300 °C, which matches silicon, alumina and many sealing glasses.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges 1.3917 (Alloy 42) to customer drawings. Product forms include forged rings, seamless rolled rings, discs, shafts, flanges, round bars, sleeves, bushings, tubes and tube sheets. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
Both are nickel-iron controlled-expansion alloys, but the nickel content differs. Invar 36 contains about 36 % nickel and has the lowest expansion of the family, roughly 1.2–2.0 × 10⁻⁶/K near room temperature, which suits dimensionally critical structures. 1.3917 / Alloy 42 contains about 42 % nickel and expands slightly more, roughly 4.0–5.0 × 10⁻⁶/K over 20–300 °C. That higher figure is deliberate: it matches silicon, alumina ceramic and hard sealing glasses, so Alloy 42 is preferred for glass-to-metal seals, lead frames and bimetal strip, while Invar 36 is preferred for tooling and cryogenic structures.
The commonly cited standards are ASTM F30 (sheet, strip, rod, bar, tubing and wire), ASTM F29 (wire), ASTM B753, ASTM F1684, DIN 17745, SEW 385 and AFNOR NF A54-301. The UNS number is K94100 and the German Werkstoff number is 1.3917. Jiangyin Jiangnan Metal supplies 1.3917 forgings certified to EN 10204 3.1, or EN 10204 3.2 with third-party witness.
Typical limits are: nickel 41.0–43.0 %, carbon 0.05 % max, manganese 0.80 % max, silicon 0.30 % max, chromium 0.25 % max, aluminium 0.10 % max, phosphorus 0.025 % max, sulphur 0.025 % max, with iron as the balance. The governing figures for any given order are those on the mill certificate for that heat.
In the annealed condition 1.3917 typically shows a tensile strength around 490 MPa (71,000 psi), a 0.2 % offset yield strength around 250 MPa (36,000 psi) and elongation around 43 %. Maximum dimensional stability is obtained in the annealed condition, with annealing carried out at 850–1000 °C in a protective atmosphere.
Forging stock is heated rapidly to approximately 1175–1205 °C and soaked only briefly, to limit sulphur and oxygen pickup from the furnace atmosphere. The alloy is then open-die forged or ring-rolled and annealed at 850–1000 °C in a protective atmosphere to restore dimensional stability and a low, constant expansion coefficient. Jiangyin Jiangnan Metal melts the material by EAF + VOD + ESR to keep sulphur and phosphorus low and to improve forgeability.
Jiangyin Jiangnan Metal produces 1.3917 forgings to individual drawings rather than to a fixed catalogue, covering forged rings and seamless rolled rings, discs, shafts, flanges, round bars, sleeves, bushings, tubes and tube sheets. Because 1.3917 is a controlled-expansion alloy melted in limited heat sizes, the achievable outside diameter and piece weight depend on the heat available. Send the drawing to sales@steelforgepieces.com to confirm the size and weight for your part.
Ultrasonic testing is performed to EN 10228-3, SEP 1921 or ASTM A388 according to the acceptance class stated on the order. Chemical analysis, tensile testing, hardness testing and dimensional inspection are supplied as standard. Coefficient of thermal expansion testing over 20–300 °C can be added on request, and is recommended when the part is used for a glass-to-metal or ceramic-to-metal seal.
Typical uses are semiconductor lead frames, glass-to-metal and ceramic-to-metal seals in microelectronic components, vacuum devices and lamp envelopes, thermostat rods and thermostatic bimetal strip, tooling for aerospace composites, precision instruments and optical devices, transformer and capacitor bushings, LNG containment and transfer hardware, and positioning devices where dimensional stability under temperature change is critical.
Yes, below its Curie temperature. 1.3917 is ferromagnetic at room temperature and becomes paramagnetic above the Curie point, which lies at roughly 360–380 °C. This is also the region where the expansion curve inflects and the coefficient of thermal expansion rises sharply, which is why the alloy is specified only up to about 300 °C.
Lead time depends on whether a suitable heat of 1.3917 is available and on the size of the forging. Quotations are normally returned within 24 working hours of receiving a drawing, and the quotation states the confirmed lead time for that specific part. Contact sales@steelforgepieces.com or +86 189 2135 9659.
About this datasheet. Compiled by the engineering team at Jiangyin Jiangnan Metal Co., Ltd. from the recognised published specifications for the grade (ASTM F30, ASTM F29, ASTM B753, DIN 17745, SEW 385 and AFNOR NF A54-301) together with the works' own forging and heat-treatment practice for 1.3917.
Accuracy. Values shown are typical for the grade and are published for design guidance and identification. They do not form a specification and are not a contractual commitment. The chemistry, mechanical properties and testing results that govern any given order are those reported on the mill certificate issued for that heat.
Last reviewed . Questions on the data: sales@steelforgepieces.com.