Alloy 36—best known under the trade names Invar® 36 and Nilo® 36—is a low-expansion nickel-iron alloy containing approximately 36% nickel. Its key feature is an exceptionally low coefficient of thermal expansion around room temperature, which means parts made from Alloy 36 change dimension very little when temperatures fluctuate. This makes it a preferred choice for precision assemblies and tooling where dimensional stability is critical.
The alloy maintains nearly constant dimensions over the range of normal atmospheric temperatures and offers a low coefficient of expansion from cryogenic temperatures up to about 260°C. In addition, Alloy 36 retains good strength and toughness at cryogenic temperatures, which is why it is widely used in metrology and cryogenic engineering.
Alloy 36 is also designated as Werkstoff 1.3912 and UNS K93600. Steelinox B.V. supplies Alloy 36 in round bar, forgings, plates and plate cutting, with certification available according to EN 10204 / 3.1.
| Element | Typical range (wt. %) |
|---|---|
| Ni | 35.0 – 37.0 |
| Fe | Balance |
| C | ≤ 0.05 |
| Mn | ≤ 0.60 |
| Si | ≤ 0.40 |
| P | ≤ 0.02 |
| S | ≤ 0.02 |
| Cr | per standard / see EN 10204 3.1 certificate (if specified) |
| Property | Typical value (annealed) |
|---|---|
| Tensile strength (Rm) | per standard / see EN 10204 3.1 certificate |
| Yield strength (Rp0.2) | per standard / see EN 10204 3.1 certificate |
| Elongation (A5) | per standard / see EN 10204 3.1 certificate |
| Hardness | per standard / see EN 10204 3.1 certificate |
| Thermal expansion (CTE) | per standard / see EN 10204 3.1 certificate (temperature range dependent) |
Exact values are stated on the material certificate EN 10204 / 3.1.
Invar® 36 / Nilo® 36 / Alloy 36 (1.3912 / UNS K93600) is supplied in round bar, forgings, plates and plate cutting. For precision applications, the required material condition and any stress-relief requirements can be specified to support dimensional stability after machining or fabrication.
Round bar: 2 mm – 250 mm (bigger sizes on request)
Plates / plate cutting: thickness 1/4" (6.3 mm) – 4" (101.6 mm)
Forgings are available on request.
Centerless grinding available on request. Provide diameter, tolerance, straightness and surface finish requirements for precision shafts or instrument components.
Alloy 36 is used wherever low thermal expansion and stable geometry are essential, including:
Alloy 36 has a very low coefficient of thermal expansion around room temperature compared to most steels and nickel alloys. This minimizes dimensional change when temperature fluctuates, helping maintain alignment and accuracy in precision assemblies, fixtures and tooling.
The alloy maintains nearly constant dimensions over normal atmospheric temperatures and offers a low coefficient of expansion from cryogenic temperatures to about 260°C. For engineering calculations, the relevant temperature range should be specified, and the declared values should be taken from the applicable standard and the EN 10204 / 3.1 certificate (if CTE is specified).
No. Alloy 36 is a nickel-iron alloy and not a stainless steel, so it does not provide the same corrosion resistance as chromium-rich stainless grades. If corrosion exposure is expected, consider surface protection, controlled environments, or an alternative alloy—depending on the balance between expansion control and corrosion requirements.
Yes. Alloy 36 retains good strength and toughness at cryogenic temperatures, which is one reason it is used in cryogenic equipment and for transporting liquefied gases. The required condition and any testing requirements should be specified for critical cryogenic service.
Steelinox B.V. supplies Alloy 36 (Invar® 36 / Nilo® 36, 1.3912 / UNS K93600) in round bar, forgings, plates and plate cutting. Round bar is typically available from 2 mm to 250 mm (larger sizes on request). Plate cutting is available in thicknesses from 6.3 mm to 101.6 mm.
Yes. Certificates are available according to EN 10204 / 3.1, confirming the delivered batch details and test results as applicable.
Yes, precision round bar and centerless ground shafts can be supplied on request. This is common for instrument parts and assemblies requiring tight tolerances and good surface finish. Provide tolerance and surface requirements when requesting a quote.
Certificates: EN 10204 / 3.1
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