Nickel alloys / UNS N08811
Incoloy® 800HT further tightens carbon and aluminium + titanium (0.85–1.20%) within the 800H limits, maximising creep and rupture strength above about 700 °C.
- UNS N08811
- W.Nr. 1.4959
- Spec ASTM B409
- Density 7.94 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | N08811 |
| W.Nr. | 1.4959 |
| EN | X8NiCrAlTi32-21 |
| Also known as | Alloy 800HT, 1.4959 |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| Ni | 30.0 | 35.0 |
| Cr | 19.0 | 23.0 |
| Fe | 39.5 | — |
| C | 0.06 | 0.10 |
| Al | 0.25 | 0.60 |
| Ti | 0.25 | 0.60 |
| Al+Ti | 0.85 | 1.20 |
| Mn | — | 1.50 |
| Si | — | 1.0 |
| S | — | 0.015 |
| Cu | — | 0.75 |
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength (min) | 450 MPa (65.3 ksi) |
| Yield strength, 0.2% offset (min) | 170 MPa (24.7 ksi) |
| Elongation in 50 mm (min) | 30 % |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.94 g/cm³ | 0.287 lb/in³ |
| Magnetic response | Non-magnetic | — |
Available forms & specifications
| Form | Specification | Size range |
|---|---|---|
| Sheets & plates | ASTM B168, B443, B409, B424, B127, B162 | 0.3 mm – 6 mm |
| Seamless pipe & tube | ASTM B167, B444, B407, B423, B165, B161 | 1/8" – 24" NB |
| Bars & rods | ASTM B166, B446, B408, B425, B164, B160 | 3 mm – 500 mm |
| Flanges & forgings | ASTM B564 | 1/2" – 48" NB (larger on request) |
| Buttweld fittings | ASTM B366 | 1/2" – 48" NB |
Corrosion & temperature resistance
Nickel-based alloys resist caustic alkalis, chloride stress-corrosion cracking and many acids, and keep their strength and oxidation resistance at temperatures where stainless steels fail.
Applications
Incoloy® 800HT: Pyrolysis, reformer and high-temperature piping. Chemical and petrochemical plant, sour-gas and oilfield equipment, furnace and heat-treatment hardware, power generation, marine engineering and aerospace components.
Incoloy® 800HT vs Incoloy® 800H
| Incoloy® 800HT | Incoloy® 800H | |
|---|---|---|
| UNS | N08811 | N08810 |
| Key property | Optimised creep strength | Higher creep strength than 800 |
| Typical use | Pyrolysis, reformer and high-temperature piping | Reformer pipes, ethylene furnace, heaters |
| Cr (wt %) | 19.0–23.0 | 19.0–23.0 |
| Ni (wt %) | 30.0–35.0 | 30.0–35.0 |
| Mo (wt %) | — | — |
| C (wt %) | 0.06–0.10 | 0.05–0.10 |
| Tensile / yield (min, MPa) | 450 / 170 | 450 / 170 |
Frequently asked questions
What is the UNS number of Incoloy® 800HT?
Incoloy® 800HT is designated UNS N08811 (W.Nr. 1.4959, EN X8NiCrAlTi32-21).
What is Incoloy® 800HT used for?
Optimised creep strength. Typical uses: pyrolysis, reformer and high-temperature piping.
Is Incoloy® 800HT magnetic?
Non-magnetic.
In which forms can I buy Incoloy® 800HT from Rajkamal Metals?
Coils & Strips, Sheets & Plates, Pipes & Tubes, Round Bars & Rods, Flanges, Buttweld Fittings, Socket Weld & Threaded Fittings, Fasteners, Ferrule / Instrumentation Fittings, Dish Ends, Custom Orders. Sizes as per standard; other sizes on request.
Do you supply a Mill Test Certificate with Incoloy® 800HT?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
What is the difference between Incoloy® 800HT and Incoloy® 800H?
Incoloy® 800HT: optimised creep strength. Incoloy® 800H: higher creep strength than 800. See the comparison table on this page.
Last updated: 30 October 2026. Grade names identify the supply range; designations are not engineering equivalents. Availability, make, origin and documentation are confirmed at quotation.
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