# 1.3912 Forgings (Invar 36 / Alloy 36 / FeNi36 / UNS K93600)

**Source:** https://www.steelforgepieces.com/Nickel-Alloy/1.3912.html
**Manufacturer:** Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
**Address:** No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
**Telephone:** +86 189 2135 9659
**Email:** sales@steelforgepieces.com
**Revision date:** 5 August 2026

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## Summary

1.3912 is the European material number (Werkstoff Nr.) for the binary iron-nickel low-expansion alloy containing 35 to 37 % nickel. It is sold commercially as Invar 36, Alloy 36, FeNi36 or Nilo 36, and is listed as UNS K93600 in the United States. The coefficient of thermal expansion is about 1.3 x 10-6 /K near room temperature, roughly one tenth that of 304 stainless steel. It stays low from cryogenic temperatures up to about 260 degrees C (500 degrees F).

Jiangyin Jiangnan Metal Co., Ltd. forges 1.3912 to customer drawings as rings, seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings, tube sheets, bored pipes and valve components. Material is melted by EAF plus VOD with ESR remelting, annealed, ultrasonically tested and supplied with EN 10204 3.1 or 3.2 certificates.

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## Equivalent grades and standards

| System / region | Designation | Notes |
|---|---|---|
| EN / DIN (Werkstoff Nr.) | 1.3912 | European material number |
| EN / DIN (name) | FeNi36, NiFe36 | Chemical-symbol designation |
| UNS (USA) | K93600, K93601, K93603 | Varies with product form and purity |
| ASTM | F1684 Alloy 36 | Wrought low-expansion alloys |
| ASTM (sheet, strip, wire) | B388, B753 | Applies to non-forged product forms |
| AFNOR (France) | NF A54-301 | Chemistry only |
| GB (China) | 4J36 | Chinese precision alloy designation |
| Trade names | Invar 36, Nilo 36, Pernifer 36, Vacodil 36 | Trademarks of their owners, used for identification only |
| Military | MIL-S-16598, MIL-I-23011 Cl. 7 | Where invoked by the purchaser |

Equivalences are given for identification. The governing specification is the one named on the purchase order.

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## Chemical composition

Weight percent, as supplied by Jiangyin Jiangnan Metal for 1.3912 forgings.

| Element | C | Si | Mn | P | S | Cr | Mo | Ni |
|---|---|---|---|---|---|---|---|---|
| wt. % | max 0.10 | max 0.50 | max 0.50 | max 0.025 | max 0.025 | max 0.50 | max 0.50 | 35.0-37.0 |

| Element | V | W | Ti | Cu | Al | Nb | Co | Fe |
|---|---|---|---|---|---|---|---|---|
| wt. % | not specified | not specified | not specified | not specified | not specified | not specified | max 1.00 | 60.00-65.00 |

Nickel is the controlling element and iron is the balance. Delivered chemistry is reported per heat on the EN 10204 certificate.

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## Mechanical properties

### Typical tensile strength by temper

| Condition | Tensile strength, psi | Tensile strength, MPa |
|---|---|---|
| Annealed | 85,000 max | 586 max |
| 1/4 hard | 90,000 to 115,000 | 620 to 793 |
| 1/2 hard | 105,000 to 125,000 | 724 to 862 |
| Hard | 120,000 min | 827 min |

Open-die forgings are normally supplied annealed. The harder tempers apply to cold-worked bar and strip.

### Typical room-temperature properties, annealed forged condition

| Property | Metric | Imperial |
|---|---|---|
| Ultimate tensile strength | 490 MPa | 71 ksi |
| Yield strength, 0.2 % offset | 240 MPa | 35 ksi |
| Elongation in 50 mm | 42 % | 42 % |

Typical values for guidance, not guaranteed minima. Section size, forging reduction and heat-treatment cycle all affect the result.

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## Physical properties

| Property | Value | Condition / note |
|---|---|---|
| Density | 8.1 g/cm3 (0.293 lb/in3) | Room temperature |
| Melting point | 1,429 degrees C (2,605 degrees F) | Approximate |
| Coefficient of thermal expansion | 1.3 x 10-6 /K | 20 to 100 degrees C, annealed |
| Low-expansion service range | cryogenic to 260 degrees C | Expansion rises above this range |
| Magnetic response | Ferromagnetic | At room temperature and throughout the low-expansion range |
| Annealing temperature | 830 to 900 degrees C | Slow cool. Cycle depends on section and stability requirement |
| Welding filler | CF36 bare wire | GTAW and GMAW |

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## Thermal expansion compared with other materials

Coefficient of linear thermal expansion, 20 to 100 degrees C, in units of 10-6 per kelvin.

| Material | Coefficient |
|---|---|
| 1.3912 / Invar 36 | 1.3 |
| Carbon steel (1.0038) | 12.0 |
| 304 stainless (1.4301) | 17.3 |
| Aluminium 6061 | 23.4 |

Worked example: raise a 1,000 mm forged shaft by 80 degrees C. In 1.3912 it grows about 0.10 mm. The same shaft in 304 stainless grows about 1.38 mm, roughly thirteen times more. This is the reason 1.3912 is used for composite moulds, laser benches, metrology frames and LNG containment.

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## Forged product forms

All shapes are produced by open-die forging or ring rolling from ESR ingot, then heat treated and rough machined.

| Product form | Size range |
|---|---|
| Forged rings and seamless rolled rings | OD 200 to 3,000 mm, height to 800 mm |
| Forged flanges | WN, SO, BL, LJ, orifice. To ASME B16.5 / B16.47 or drawing |
| Forged round bars | Diameter 30 to 800 mm, length to 6,000 mm |
| Forged discs and disks | Diameter 150 to 2,000 mm, thickness 20 to 500 mm |
| Forged shafts and spindles | Stepped, eccentric, hollow. Length to 6,000 mm |
| Forged sleeves and bushings | OD 100 to 1,500 mm, bored and rough machined |
| Forged tube sheets | Diameter to 3,000 mm, drilled to layout on request |
| Forged pipes and tubes | Bored from solid, heavy wall, short length |
| Valve components | Bodies, stems, seat rings, blocks. Ball, gate, globe, check, plug |
| Custom open-die forgings | Blocks, nozzles, manifolds, rolls. Made entirely to drawing |

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## Manufacturing route

1. **Melting, EAF plus VOD.** Electric arc furnace melting followed by vacuum oxygen decarburisation, which brings carbon, sulphur and dissolved gases down.
2. **Remelting, ESR.** Electroslag remelting refines the ingot structure, reduces segregation and improves inclusion cleanliness.
3. **Open-die forging or ring rolling.** The ingot is upset and drawn on the press, or pierced and rolled on the ring mill, to break down the cast structure and develop grain flow that follows the part contour.
4. **Heat treatment.** Annealing at 830 to 900 degrees C with slow cooling. Where maximum dimensional stability is specified, a stabilising cycle is added after rough machining.
5. **Rough machining.** Turned or milled to the agreed allowance.
6. **Non-destructive testing.** Ultrasonic examination to EN 10228-3, SEP 1921 or ASTM A388 as specified. PT and hardness survey on request.
7. **Certification and release.** EN 10204 3.1 mill certificate as standard, or 3.2 with third-party witness.

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## Applications

**Cryogenic and LNG.** Containment and membrane components for LNG tankers. Transfer lines and pipe supports for liquefied gas. Forged flanges and tube sheets for cryogenic heat exchangers. Valve bodies and seat rings sealing from ambient down to -196 degrees C.

**Aerospace composite tooling.** Forged blocks and plates for composite lay-up moulds. Mould frames that hold tolerance through the autoclave cycle. Jigs and fixtures where CTE has to match the cured laminate.

**Precision instruments and optics.** Optical and laser bench structures. Metrology frames, length standards, gauge bodies. Positioning devices and stages for photonic equipment. Seals, spacers and rigid instrument housings.

**Electronics and control.** Bimetal thermostat elements paired with a high-expansion alloy. Cavity resonators for radar and microwave equipment. Magnetic shielding and small transformer cores. Clock balance wheels and pendulum rods.

**Pressure equipment.** Forged flanges and tube sheets for shell-and-tube exchangers. Nozzles and forged shells for air receivers and pressure vessels. Heavy-wall bored forgings replacing seamless pipe in short lengths.

**Rotating and mechanical parts.** Shafts, spindles and eccentric shafts in precision drives. Forged gears and rolls where centre distance has to stay fixed. Bushings and sleeves running against dissimilar metals.

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## Testing, inspection and certification

**Non-destructive testing**

- Ultrasonic testing to EN 10228-3, SEP 1921, ASTM A388, or the acceptance class named on the order
- Penetrant testing to ASTM E165 on machined surfaces where specified
- Dimensional inspection reported against the customer drawing before release

**Documentation**

- EN 10204 3.1: mill certificate issued by the factory quality department, supplied as standard
- EN 10204 3.2: certificate countersigned by an independent inspection body such as SGS, BV, TUV or Lloyd's
- Reported data: heat number, chemistry, mechanical results, heat-treatment record, NDT report

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## Frequently asked questions

**What is 1.3912 material?**

1.3912 is the European material number for a binary iron-nickel alloy containing 35 to 37 % nickel with iron as the balance. It is a low-expansion alloy, sold commercially as Invar 36, Alloy 36, Nilo 36 or FeNi36, and designated UNS K93600 in the United States. Its defining characteristic is a coefficient of thermal expansion near 1.3 x 10-6 /K around room temperature.

**Is 1.3912 the same as Invar 36?**

Yes. 1.3912 and Invar 36 describe the same alloy. 1.3912 is the European material number and Invar 36 is a trade name. Alloy 36, Nilo 36, Pernifer 36, FeNi36, 4J36 and UNS K93600 all refer to the same nominal composition. Minor limits on residual elements can differ between the governing standards, so the specification named on the purchase order still controls acceptance.

**What is the chemical composition of 1.3912?**

Nickel 35.0 to 37.0 %, iron 60.00 to 65.00 %, carbon max 0.10 %, silicon max 0.50 %, manganese max 0.50 %, phosphorus max 0.025 %, sulphur max 0.025 %, chromium max 0.50 %, molybdenum max 0.50 % and cobalt max 1.00 %. Jiangyin Jiangnan Metal reports the actual heat chemistry on the EN 10204 certificate supplied with every forging.

**What is the thermal expansion coefficient of 1.3912?**

About 1.3 x 10-6 per kelvin between 20 and 100 degrees C in the annealed condition, roughly one tenth that of 304 stainless steel. The coefficient stays low from cryogenic temperatures up to about 260 degrees C (500 degrees F), then rises steadily above that. Exact values depend on heat treatment and prior cold work.

**Can 1.3912 be forged, and what forged shapes are available?**

Yes. 1.3912 forges readily using practices similar to austenitic stainless steel. Jiangyin Jiangnan Metal produces 1.3912 as open-die forged rings, seamless rolled rings, flanges, round bars, discs, shafts, spindles, sleeves, bushings, tube sheets, bored pipes and tubes, valve bodies, seat rings, blocks and nozzles, all made to customer drawings.

**Is 1.3912 magnetic?**

Yes. 1.3912 is ferromagnetic at room temperature and throughout the temperature range where it shows its low-expansion behaviour. If an application requires a non-magnetic low-expansion material, this alloy is not suitable and a different grade should be selected.

**Is 1.3912 weldable?**

Yes. 1.3912 is welded by GTAW and GMAW using CF36 bare filler wire. Surfaces must be free of oil, oxide and marking materials before welding. Where dimensional stability is critical, a post-weld stress-relief cycle is normally applied before finish machining.

**How does 1.3912 resist corrosion?**

1.3912 resists corrosion adequately in dry air at room temperature but will rust in moist air, because it is an iron-nickel alloy with no deliberate chromium addition. Parts held in storage or shipped by sea should be oiled or otherwise preserved. Painting or plating is common where the alloy will be exposed in service.

**What certificates come with 1.3912 forgings?**

EN 10204 3.1 mill certificates are supplied as standard, covering heat number, chemical analysis, mechanical test results, heat-treatment record and NDT report. EN 10204 3.2 certificates witnessed by SGS, BV, TUV, Lloyd's or a nominated inspector are available on request. Ultrasonic testing is performed to EN 10228-3, SEP 1921 or ASTM A388 as specified on the order.

**Who supplies 1.3912 open-die forgings?**

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It manufactures 1.3912 (Invar 36) forgings to customer drawings and ships worldwide. Enquiries: +86 189 2135 9659 or sales@steelforgepieces.com.

**How do I get a price for a 1.3912 forging?**

Send a drawing or a dimensioned sketch to sales@steelforgepieces.com. Include the shape, finished or rough-machined size, quantity, delivery condition and any testing or certification requirements. A quotation normally follows within one working day. If only a finished-part drawing is available, Jiangyin Jiangnan Metal will propose the forging envelope and machining allowance.

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## Related grades

Low-expansion and controlled-expansion alloys: Invar 36, Invar 42, Kovar, Alloy 42-6, Alloy 45, Alloy 46, Alloy 48, Alloy 52, Alloy 475, Ni-Span-C Alloy 902.

Nickel alloys: Incoloy A-286, A286, Inconel 625, Incoloy 800H, Monel 400, Hastelloy C-276, Haynes 230, Nimonic 80A, Waspaloy.

Full grade index: https://www.steelforgepieces.com/Nickel-Alloy/

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## Contact

Jiangyin Jiangnan Metal Co., Ltd.
Open-die forging factory
No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone: +86 189 2135 9659
Email: sales@steelforgepieces.com
Website: https://www.steelforgepieces.com/

Capability: open-die forging, ring rolling, heat treatment, machining, non-destructive testing.
Materials: nickel alloy, stainless steel, tool steel, alloy steel, carbon steel.

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Technical data on this page is provided for engineering guidance and is not a warranty. Invar, Nilo, Pernifer and other trade names are registered trademarks of their respective owners and are used here only to identify alloy grades.