Incoloy 800 / 800H / 800HT: properties, composition, uses and standards
Incoloy 800 / 800H / 800HT is a nickel–iron–chromium alloy for high-temperature service, chosen for furnaces, petrochemical heaters and high-temperature piping. UNS N08800, W.Nr 1.4876, density 7.94 g/cm³.
What is Incoloy 800 / 800H / 800HT?
Incoloy 800 / 800H / 800HT is a nickel–iron–chromium alloy for high-temperature service. Engineers choose it for furnaces, petrochemical heaters and high-temperature piping. It is also known as Alloy 800, UNS N08800 / N08810 / N08811, W.Nr 1.4876, Incoloy 800H.
- UNS
- N08800 · N08810 (800H) · N08811 (800HT)
- W.Nr
- 1.4876 · 1.4958 · 1.4959
- EN
- X10NiCrAlTi32-21
- JIS
- NCF 800
- Trade names
- Incoloy 800 · Nicrofer 3220
- Density
- 7.94 g/cm³
- Melting range
- 1357 – 1385 °C
- Magnetic
- Non-magnetic
Chemical composition and what each element does
| Element | Weight % |
|---|---|
| Nickel | 30.0 – 35.0 |
| Chromium | 19.0 – 23.0 |
| Iron | 39.5 min |
| Carbon | 0.10 max (800) · 0.05 – 0.10 (800H) |
| Aluminium | 0.15 – 0.60 |
| Titanium | 0.15 – 0.60 |
| Copper | 0.75 max |
| Manganese | 1.5 max |
| Silicon | 1.0 max |
Per ASTM B409 for UNS N08800 / N08810.
Balanced nickel and chromium resist oxidation and carburisation in furnace atmospheres.
Controlled carbon and coarse grain give 800H/HT their creep-rupture strength above 600 °C.
Aluminium and titanium improve high-temperature strength.
For aqueous acid service choose 825 instead.
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength | 520 MPa · 75 ksi (800) · 450 MPa · 65 ksi (800H) |
| Yield strength 0.2% | 205 MPa · 30 ksi (800) · 170 MPa · 25 ksi (800H) |
| Elongation | 30% |
Annealed plate, minimum values. Values for pipe, bar and forgings differ slightly — see the product standard.
Where Incoloy 800 / 800H / 800HT is used
- Petrochemical. Steam-methane reformer and ethylene furnace piping. Industry →
- Heat treatment. Furnace components and retorts. Industry →
- Power. Superheater and reheater tubing. Industry →
- Chemical. Hot process piping and heat exchangers. Industry →
Welding 800
The matching filler is ERNiCr-3 (AWS A5.14). ERNiCrCoMo-1 for creep-critical joints.
Keep heat input moderate and interpass temperature low, clean joints thoroughly, and pickle or passivate after welding where the service is corrosive.
Incoloy 800 / 800H / 800HT compared with similar grades
| Grade | PREN | Choose it for |
|---|---|---|
| Incoloy 800 / 800H / 800HT | — | Furnaces, petrochemical heaters and high-temperature piping |
| SS 310 / 310S | ≈ 25 | Furnaces, burners and heat treatment at high temperature |
| Inconel 600 | — | High-temperature oxidation, caustic and nuclear service |
| Inconel 825 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
Incoloy 800 / 800H / 800HT standards by product
Buying Incoloy 800 / 800H / 800HT: what to specify
- The product standard and the UNS or designation — for example ASTM B409 UNS N08800.
- Size, thickness or schedule, and quantity in pieces and kg or metres.
- Heat-treatment condition where the standard offers a choice.
- Certificate: EN 10204 3.1 as standard, 3.2 if a third party must witness.