Incoloy Alloys
Incoloy 800HT (UNS N08811) — Composition, Properties & Supply
Incoloy 800HT (UNS N08811) has the highest creep-rupture strength in the 800 series. By restricting Al+Ti to 0.85–1.20% and guaranteeing a coarse solution-annealed grain structure it performs best in long-term stressed service above 815 °C.
What is the chemical composition of Incoloy 800HT?
| Element | Symbol | Content (wt%) |
|---|---|---|
| Ni | Ni | 30.0–35.0 |
| Cr | Cr | 19.0–23.0 |
| Fe | Fe | ≥ 39.5 |
| Al+Ti | Al+Ti | 0.85–1.20 |
| C | C | 0.06–0.10 |
| Cu | Cu | ≤ 0.75 |
| Mn | Mn | ≤ 1.50 |
| Si | Si | ≤ 1.00 |
Values are typical specification limits. Actual heat analysis is reported on the EN 10204 3.1 mill test certificate supplied with each shipment.
What are the mechanical properties of Incoloy 800HT?
| Property | Value | Note |
|---|---|---|
| Tensile strength | ≥ 450 MPa | Room temperature |
| Yield strength (0.2% offset) | ≥ 170 MPa | Room temperature |
| Elongation | ≥ 30 % | Gauge length 50 mm / 4D |
| Hardness | ≤ 180 HB | Brinell / Rockwell |
What are the physical properties of Incoloy 800HT?
| Property | Value |
|---|---|
| Density | 7.94 g/cm³ |
| Melting range | 1357–1385 °C |
| Thermal conductivity | 11.5 W/m·K |
| Elastic modulus | 196 GPa |
| Maximum service temperature | 1100 °C |
What are the key characteristics of Incoloy 800HT?
- Better creep-rupture strength than 800 and 800H above 815 °C
- Resists carburisation, oxidation and nitriding
- Good high-temperature microstructural stability
- Covered by ASME allowable stress data
Where is Incoloy 800HT used?
- Ethylene cracking furnace tubes and pigtails
- Reformer manifolds and outlet headers
- High-temperature nuclear heat exchangers
- Heat-treat rollers and radiant tubes
Which standards and specifications cover Incoloy 800HT?
What product forms are available?
Frequently asked questions
Why must 800HT keep Al+Ti between 0.85 and 1.20%?
Aluminium and titanium form the γ′ strengthening phase, but in 800HT's target range (above 815 °C) γ′ coarsens quickly and loses effect. Holding Al+Ti at 0.85–1.20% ensures strength comes from solid solution plus coarse grain, producing predictable, stable creep behaviour and higher allowable stresses.
Need Incoloy 800HT bar, tube, plate or forgings?
Send the grade, dimensions, standard and quantity. We answer within 10 minutes on working days and quote within 24 hours, with EN 10204 3.1 certification.
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