Incoloy® 800H / 800HT (UNS N08810 / N08811)
Incoloy 800 with controlled carbon and grain size for creep strength above 1100 °F — the furnace, reformer and heat-treatment fixture alloy, weldable and stable to 1800 °F.
What Incoloy 800H/HT is.
800H and 800HT are the high-temperature versions of Incoloy 800. Carbon is held in a narrow 0.05 to 0.10 percent range, the alloy is annealed at a higher temperature for a coarse grain, and 800HT adds a minimum aluminium-plus-titanium content. Together these give creep and rupture strength far above standard 800 at 1100 °F and beyond, while the nickel-iron-chromium base keeps its oxidation and carburization resistance to about 1800 °F.
We machine 800H/HT studs, bolts, nuts and fixtures from certified B408 bar, dual certified to both grades where the heat allows, with PMI on every lot.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.06 | 0.10 |
| Manganese | Mn | — | 1.5 |
| Silicon | Si | — | 1.0 |
| Sulfur | S | — | 0.015 |
| Phosphorus | P | — | 0.045 |
| Chromium | Cr | 19.0 | 23.0 |
| Nickel | Ni | 30.0 | 35.0 |
| Copper | Cu | — | 0.75 |
| Aluminium | Al | 0.25 | 0.60 |
| Titanium | Ti | 0.25 | 0.60 |
| Aluminium + titanium | Al+Ti | 0.85 | 1.20 |
| Iron | Fe | 39.5 | — |
Values per ASTM B408-22 Table 6 for UNS N08811 (verified against the specification); N08810 (800H) has carbon 0.05–0.10 %, Al and Ti 0.15–0.60 % each, and no Al + Ti minimum; the Al + Ti 0.85–1.20 % row applies to N08811 only.
Mechanical properties.
| Condition and nominal diameter (in.) | Tensile strength, min (ksi) | Yield strength 0.2% offset, min (ksi) | Elongation, min (%) | Reduction of area, min (%) | Hardness |
|---|---|---|---|---|---|
| Annealed, cold or hot worked — all | 65 | 25 | 30 | — | — |
Values per ASTM B408-22 Table 5 for annealed rod and bar (verified against the specification).
Specifications that apply.
How Incoloy 800H/HT ships from Houston.
- Studs and stud bolts
- Hex and heavy hex bolts
- Nuts and washers
- Socket head cap screws
- Machined components from certified bar
Incoloy 800H/HT fasteners we make.
Every item is manufactured to your drawing or standard in Incoloy 800H/HT, imperial or metric, with an EN 10204 3.1 certificate.
What are 800H and 800HT?
Standard Incoloy 800 is a good oxidation-resistant alloy but its creep strength at furnace temperatures is limited. 800H narrows the carbon range and requires a coarse-grain anneal, both of which slow creep; 800HT goes further by setting a minimum aluminium-plus-titanium content so that fine precipitates strengthen the grains. The two are usually dual certified, and ASME assigns them allowable stresses at temperatures where standard 800 has none.
Testing, certification and marking
- Tensile and hardness tested per heat-treat lot
- Grade or alloy symbol and manufacturer's identification on every piece
- EN 10204 3.1 material test report with heat number and chemistry; 3.2 witness available
- PMI verification standard on nickel alloys
Incoloy 800 / 800H / 800HT (UNS N08800 / N08810 / N08811)
The economical high-temperature alloy — 32 % nickel, 21 % chromium — for furnace, reformer and heat-exchanger hardware from 1000 to 1800 °F.
ASTM B166 barInconel 600 (UNS N06600)
The general-purpose nickel-chromium alloy — oxidation resistant to 2000 °F, immune to chloride stress-corrosion cracking, for furnace, heat-treat and nuclear hardware.
ASTM B572 rodHastelloy X (UNS N06002)
The combustion-zone alloy — oxidation resistant to 2200 °F with good creep strength — for gas-turbine, furnace and afterburner hardware.