Alloy 800H/800HT® are two individual solid solution strengthened, iron-nickel-chromium alloys typically offered as one, dual certified alloy meeting the chemical composition requirements of both alloys. The primary difference between Alloys 800H and 800HT® is the restricted aluminum and titanium content in 800HT®, which results in higher creep and stress rupture properties. Both Alloy 800H and 800HT® are generally considered to be superior to the base Alloy 800 (UNS N08800) because of greater creep and stress rupture properties and a more restrictive C wt% range.
With its high nickel and chromium content, Alloy 800H/800HT® provides excellent resistance to oxidation, carburization and sulfidation and is commonly used in applications that involve long-term exposure to high temperatures. Heat treatment and power generation are two common industries where Alloy 800 H/HT® is used with typical applications found in superheater and reheater tubing, headers, pigtails, outlet manifolds and sheathing for heating elements. Alloy 800H/800HT® also has excellent resistance to nitric acid at concentrations up to 70% and has good resistance to organic media like formic, acetic and propionic acids.
INCOLOY® and 800HT® are registered trademarks of Special Metals Corporation.
Nickel Alloy 800 H/HT® Chemical Composition
Chemical Composition (wt%)
| Iron | 39.5 min | Aluminum | 0.15 to 0.60 |
| Nickel | 30.0 to 35.0 | Titanium | 0.15 to 0.60 |
| Chromium | 19.0 to 23.0 | Carbon | 0.06 to 0.10 |
| Manganese | 1.5 max | Phosphorus | 0.045 max |
| Silicon | 1.0 max | Sulfur | 0.015 max |
| Copper | 0.75 max | Other | Al + Ti = 0.85 to 1.20 |
*Maximum, unless range is indicated
Nickel Alloy 800 H/HT® Physical Properties
| Density, lb/in3 | 0.287 |
| Melting Temperature | 2475°F to 2525°F |
| Specific Heat, Btu/lb ˚F | 0.11 |
| Permeability @ 70°F for Annealed Material | 1.014 (200 Oersted) |
| Curie Temperature | -175°F |
| Elastic Modulus @ 75°F (Tension) | 28.50 X 103 ksi |
| Elastic Modulus @ 1600°F (Tension) | 19.20 X 103 ksi |
| Electrical Resistivity @ 70°F | 595 Ω•circ mil/ft |
| Electrical Resistivity @ 1800°F | 776 Ω•circ mil/ft |
Nickel Alloy 800 H/HT® Mechanical Properties
All properties in this table are for material in the solution annealed condition (hot worked and cold worked) and are from the governing ASTM specification.
| 0.2% Yield Strength, min. (ksi) | 25 |
| Tensile Strength, min. (ksi) | 65 |
| Elongation, min. (%) | 30 |
Your Source for Nickel Alloy 800 H/HT®
At Double Eagle Alloys, we supply Nickel Alloy 800 H/HT® in long bar, flanges, pipe, sheet, gaskets, fittings and header plugs engineered for these demanding services. Contact our team to learn how Nickel Alloy 800 H/HT® can support long-term performance and reliability.
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Data shown are typical and provided for informational purposes only. Values should not be considered minimums or maximums for specification or final design. Actual product data may vary, and information may be revised without notice.