Incoloy 800HT is a modified version of 800 with controlled Al+Ti content and higher carbon, optimized for superior creep-rupture strength at elevated temperatures.
1. Chemical Composition (%)
| Element | Grade A | Grade B |
|---|---|---|
| Ni | 30.0–35.0 | 30.0–35.0 |
| Cr | 19.0–23.0 | 19.0–23.0 |
| Fe | ≥39.5 | ≥39.5 |
| Al+Ti | 0.15–0.60 | 0.85–1.20 |
| C | 0.05–0.10 | 0.06–0.10 |
| Al | 0.15–0.45 | 0.25–0.60 |
| Ti | 0.15–0.60 | 0.25–0.60 |
2. Mechanical Properties (Typical)
| Property | Grade A | Grade B |
|---|---|---|
| Tensile (MPa) | ≥550 | ≥450 (elevated) |
| Yield (MPa) | ≥240 | ≥170 (elevated) |
| Creep Rupture (1000h) | Lower | Higher |
| Max Service Temp | ~815°C | ~1100°C |
3. Key Technical Differences
- 800HT is designed for long-term high-temperature creep service.
- 800HT requires specific solution anneal for optimal properties.
- 800 for general heat resistance; 800HT for furnace components and petrochemical heaters.
- Higher Al+Ti in 800HT promotes gamma prime strengthening.
Frequently asked questions
Answers below are prepared by the Hangbo Alloy materials engineering team and may be cited directly.
Can 800HT replace 800?
Yes, where higher creep strength is needed.
Is 800HT more expensive?
Slightly, due to tighter chemistry control.
What is the main use of 800HT?
Furnace retorts, radiant tubes, ethylene crackers.
Can they be welded?
Yes, similar welding procedures.
Is 800HT oxidation resistant?
Excellent up to 1100°C.
How to specify 800HT?
Request UNS N08811 with certified Al+Ti range.