Nickel Alloy 800 /H/HT
These nickel steel alloys are identical except for the higher level of carbon in alloy 800H, and the addition of up to 1.20 % aluminum and titanium in alloy 800HT
Alloy 800, 800H, and 800HT are nickel-iron-chromium alloys having high resistance to carburization and oxidation in high-temperature exposure and with good strength.
Alloy 800 was the first of these alloys and it was slightly modified into Alloy 800H. The modification made was to control carbon (.05.10%) and grain size to optimize stress rupture properties. Alloy 800HT has more modifications to the combined aluminum and titanium levels (.851.20%) to ensure optimum high temperature properties.
The nickel alloy is dual certified (800H/HT) and combines the properties of both forms. Alloy 800H/HT alloy was actually meant for hightemperature structural applications. These alloys are resistant to embrittlement from precipitation of sigma phase and chloride stresscorrosion cracking due to the nickel content. The corrosion resistance is quite high.
In the solution annealed condition, alloys 800H and 800HT have excellent creep and stress rupture properties.
Alloy 800 is mainly used in applications with temperatures up to 1100° F, while alloys 800H and 800HT are normally used in temperatures above 1100° F where resistance to creep and rupture is required. The chemical balance allows the nickel steel alloy to exhibit excellent resistance to carburization, oxidation and nitriding atmospheres.
- Chemical process equipment handling mixed acids both oxidizing and reducing
- Flue gas desulfurization scrubbers
- Evaporators for wetprocess phosphoric acid containing H2SO4, HF and ferric salts
- Weld Overlay
The nickel alloy is dual certified (800H/HT) and combines the properties of both forms. Alloy 800H/HT alloy was actually meant for high temperature structural applications. These alloys are resistant to embrittlement from precipitation of sigma phase and chloride stress corrosion cracking due to the nickel content. The corrosion resistance is quite high.
In the solution annealed condition, alloys 800H and 800HT have excellent creep and stress rupture properties.
Resistance to embrittlement
Alloy 800 is mainly used in applications with temperatures up to 1100° F, where alloys 800H and 800HT are normally used in temperatures above 1100° F where resistance to creep and rupture is required. The chemical balance allows the nickel steel alloy to exhibit excellent resistance to carburization, oxidation and nitriding atmospheres.
Alloy 800HT will not become embrittled even after long periods of usage in the 1200 1600° F range where many stainless steels become brittle.
Cold forming properties
Superior cold forming properties associated with the nickelchromium alloys are exhibited with 800HT. When cold forms extensively, the grain size produces a visibly undulated surface called “orange peel”. Alloy 800HT can be welded by the common techniques used on stainless steels.
| Element | 800 | 800 H | 800HT |
| Nickel | 30.0-35.0 | 30.0-35.0 | 30.0-35.0 |
| Chromium | 19.0-23.0 | 19.0-23.0 | 19.0-23.0 |
| Iron | 39.5 min | 39.5 min | 39.5 min |
| Carbon | 0.1 max | 0.05-0.10 | 0.06-0.10 |
| Aluminium | 0.15-0.60 | 0.15-0.60 | 0.25-0.60 |
| Titanium | 0.15-0.60 | 0.15-0.60 | 0.25-0.60 |
| Al + Ti | 0.3-1.2 | 0.3-1.2 | 0.85-1.2 |
Physical Properties
| Metric | Imperial | |
| Density | 8.05 g/cm3 | 0.291Metric lb/in3 |
Mechanical Properties
| Property | |
| Tensile strength* | 75-100 ksi |
| 2% Yield* | 30-60 ksi |
| Elongation* | 60-30% |
*Annealed
- Tube
- Pipe
- Fittings
- Flanges
- Special Sections
- Sheet
- Plate
- Flat Bar
- Round Bar
- Hollow Bar
- I Beam
- U Channel
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