ASTM B407 UNS N08810 Incoloy 800H Pipe High Temperature Service Alloy
UNS N08810 is a nickel-iron-chromium alloy specifically designed for high-temperature service requiring good creep and rupture strength above 600°C (1112°F). It is a controlled chemistry version of UNS N08800 (Alloy 800), with tighter limits on carbon (0.05-0.10%) and a coarse grain size requirement (ASTM 5 or coarser) to optimize high-temperature properties.
The alloy maintains an austenitic structure and offers excellent oxidation and carburization resistance, as well as good corrosion resistance in high-temperature environments. UNS N08810 is particularly valued for its superior creep-rupture strength compared to standard 800, making it the preferred choice for petrochemical furnaces, heat treating equipment, and power generation components operating in the 600-900°C range.
| Parameter | Details |
|---|---|
| Standard | ASTM B407 (Seamless Tube), ASTM B408 (Bar), ASTM B409 (Plate/Sheet), ASME SB407 |
| Grade / UNS | UNS N08810 |
| Type | Seamless tube / Welded tube (ERW / EFW) |
| Outer Diameter | 6.0 mm – 610 mm (1/8″ – 24″) |
| Wall Thickness | 0.5 mm – 50 mm (SCH 5S – XXS) |
| Length | 6 m / 9 m / 12 m, or random lengths |
| Process | Cold drawn / Cold rolled (seamless); Plate rolled (welded) |
| Finish | Annealed & pickled / Bright annealed / Solution annealed |
| Ends | Plain end / Beveled end / Threaded |
| Packaging | Hexagonal bundles + plastic end caps + seaworthy wooden crates or pallets |
| Marking | Grade + Size + Heat No. + Standard |
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | 30.0 | 35.0 |
| Chromium (Cr) | 19.0 | 23.0 |
| Iron (Fe) | Balance | Balance |
| Carbon (C) | 0.05 | 0.10 |
| Aluminum (Al) | 0.15 | 0.60 |
| Titanium (Ti) | 0.15 | 0.60 |
| Manganese (Mn) | — | 1.50 |
| Silicon (Si) | — | 1.00 |
| Sulfur (S) | — | 0.015 |
| Phosphorus (P) | — | 0.030 |
| Copper (Cu) | — | 0.75 |
Key requirement: Coarse grain size (ASTM 5 or coarser) for enhanced creep strength.
| Property | Value |
|---|---|
| Density | 7.94 g/cm³ (0.287 lb/in³) |
| Melting Range | 1350 – 1400 °C (2460 – 2550 °F) |
| Coefficient of Thermal Expansion | 14.4 μm/m·K (8.0 μin/in·°F) |
| Modulus of Elasticity | 196 kN/mm² (28,400 ksi) |
| Feature | Benefit |
|---|---|
| High creep-rupture strength | Superior to standard 800 at elevated temperatures |
| Controlled carbon content | 0.05-0.10% optimizes high-temperature properties |
| Coarse-grain structure | ASTM 5 or coarser for enhanced creep resistance |
| Oxidation resistance | Excellent up to 1100°C (2012°F) |
| Carburization resistance | Outstanding in hydrocarbon service |
| Austenitic structure | Retains ductility and strength at high temperatures |
UNS N08810 offers good weldability with important considerations:
| Property | Detail |
|---|---|
| Preheating | Generally not required |
| Post-weld heat treatment | Not required (solution annealed condition) |
| Recommended methods | TIG (GTAW), MIG (GMAW), SMAW, SAW |
| Filler metal | ERNiCr-3, ENiCrFe-2, or ENiCrFe-3 |
| Interpass temperature | Maintain below 150°C (300°F) |
| Important note | Avoid sulfur contamination during welding |
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