Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
Alloy 800H is an austenitic, solid-solution iron–nickel–chromium alloy — the high-temperature, high-creep-strength variant of the 800 series. This datasheet presents the material within the American (ASTM / ASME / SAE-AMS / UNS) standard system.
It has nearly the same base composition as alloy 800 but with a controlled carbon content of 0.05–0.10% and a coarse grain structure (ASTM grain size 5 or coarser), produced by a high-temperature anneal at approximately 1150 °C (2100 °F). This combination of controlled chemistry and coarse grain gives significantly higher creep and stress-rupture strength than alloy 800, particularly in the 593–980 °C (1100–1800 °F) range. The chromium provides oxidation and corrosion resistance; iron resists internal oxidation; and the high nickel content maintains a ductile, stable austenitic structure with strong resistance to chloride-ion stress-corrosion cracking.
It is widely used where long-term strength at elevated temperature is essential: petrochemical furnace cracker tubes, pigtails, headers and reformer tubing; ethylene and ethylene-dichloride process equipment; power-plant superheater and reheater tubing; gas-cooled-reactor heat exchangers; and industrial-furnace radiant tubes, muffles, retorts and heat-treating fixtures. Where even higher rupture strength is required, alloy 800HT (UNS N08811) is used.
Values per Special Metals official datasheet, solution-annealed (coarse-grain) condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.94 | g/cm³ |
| Melting range | 1357–1385 | °C |
| Young's modulus (20 °C) | 196.5 | GPa |
| Shear modulus (20 °C) | 73.4 | GPa |
| Poisson's ratio (20 °C) | 0.339 | — |
| Specific heat capacity (0–100 °C) | 460 | J/kg·K |
| Coefficient of thermal expansion (20–100 °C) | 14.4 | µm/m·°C |
| Magnetic permeability (21 °C, annealed) | 1.014 | Essentially non-magnetic |
| Curie temperature | –115 | °C |
| Maximum service temperature | ~980 | °C |
Limiting composition per ASTM B408 (UNS N08810).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | 39.5 | balance | Base element; resistance to internal oxidation |
| Nickel | Ni | 30.0 | 35.0 | Ductile austenitic structure; chloride-SCC resistance |
| Chromium | Cr | 19.0 | 23.0 | Oxidation + corrosion resistance |
| Carbon | C | 0.05 | 0.10 | Controlled higher range — key for creep/rupture strength |
| Aluminium | Al | 0.15 | 0.60 | High-temperature stability |
| Titanium | Ti | 0.15 | 0.60 | High-temperature stability; carbide/nitride former |
| Aluminium + Titanium | Al+Ti | 0.30 | 1.20 | Combined limit |
| Manganese | Mn | — | 1.50 | Deoxidiser |
| Copper | Cu | — | 0.75 | Residual |
| Silicon | Si | — | 1.0 | Deoxidiser |
| Sulphur | S | — | 0.015 | Residual impurity |
Special requirement: ASTM grain size 5 or coarser (high-temperature anneal), required for creep-rupture performance.
Typical room-temperature properties, solution-annealed (coarse-grain) condition.
| Property | Value | Notes |
|---|---|---|
| Ultimate tensile strength | ~450–500 MPa | Solution-annealed |
| 0.2% proof strength (yield) | ~170–205 MPa | Solution-annealed |
| Elongation at break | ~30 % min | Solution-annealed |
| Hardness | ~120–184 HB | Solution-annealed |
The coarse-grain structure gives lower room-temperature strength than fine-grain alloy 800 but markedly superior creep and stress-rupture strength at 593–980 °C — the primary reason for selecting 800H. The alloy is solid-solution and not age-hardenable. Values are typical; confirm against the mill test certificate for each delivery.
| Environment | Performance | Notes |
|---|---|---|
| Creep / stress-rupture (593–980 °C) | Outstanding | Coarse grain + controlled carbon; main advantage over alloy 800 |
| High-temperature oxidation | Excellent | Protective Cr₂O₃ scale |
| Carburisation | Good | Resists carburising furnace atmospheres |
| Nitridation | Good | Resists nitriding atmospheres |
| Chloride stress-corrosion cracking | Excellent | High Ni content |
| Nitric / organic acids | Very Good | Good aqueous resistance |
| Sulphuric / hydrochloric acid | Limited | Not recommended for strong reducing acids |
| Metallurgical stability | Excellent | Stable austenite over full service range |
An austenitic solid-solution alloy; not age-hardenable. The defining treatment is a high-temperature solution anneal to develop coarse grain.
Solution Anneal (defining treatment) Temperature: ~1150 °C (2100 °F) Result: ASTM grain size 5 or coarser — required for optimum creep and stress-rupture strength.
This higher anneal temperature (versus ~980 °C for basic alloy 800) is what distinguishes 800H. Cool rapidly through 540–760 °C where aqueous corrosion resistance is required, to limit sensitisation.
Good weldability by all common processes, similar to alloy 800. Welded fabrications for high-temperature service should use fillers matched to the application.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / GMAW | Excellent | RA 82 (AWS ERNiCr-3); RA330-04 for closer thermal-expansion match |
| SAW (submerged-arc) | Good | ERNiCr-3 wire + compatible flux |
| SMAW / stick | Good | ENiCrFe-type electrode |
For maximum strength, alloy 617 (ERNiCrCoMo-1) wire or 117 (ENiCrCoMo-1) electrodes are suggested. Post-weld stress-relief at ~900 °C may be used to avoid grain-boundary cracking above 540 °C.
Machining Guidelines
| Tooling | Cutting Speed | Feed |
|---|---|---|
| Coated carbide | 33.5–57.9 m/min | 0.20–0.89 mm/rev |
| High-speed steel | 10.7–29.0 m/min | 0.20–0.89 mm/rev |
Machining behaviour is the same as alloy 800; the alloy work-hardens during machining.
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | 870–1200 °C; heavy forging 1010–1200 °C; avoid 650–870 °C (cracking risk) |
| Cold forming | Similar to alloy 600 / stainless |
| Re-anneal | ~1150 °C to restore coarse grain after heavy cold work |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Petrochemical | Furnace cracker tubes, pigtails, headers, reformer tubing | High creep-rupture strength at 593–980 °C |
| Chemical processing | Ethylene / ethylene-dichloride / acetic-anhydride / nitric-acid equipment | Strength + corrosion resistance |
| Power generation | Superheater / reheater tubing; gas-cooled-reactor heat exchangers | Long-term elevated-temperature strength |
| Industrial furnaces | Radiant tubes, muffles, retorts, heat-treating fixtures | Creep strength + oxidation resistance |
| Petroleum refining | Steam/hydrocarbon reformers, hydrodealkylation units | High-temperature stability |
| Product Form | ASTM Standard | ASME Code | AMS |
|---|---|---|---|
| Rod and bar | ASTM B408 | ASME SB-408 | AMS 5871 |
| Forgings | ASTM B564 | ASME SB-564 | — |
| Plate, sheet and strip | ASTM B409 / B906 | ASME SB-409 | AMS 5871 / 5877 |
| Seamless pipe and tube | ASTM B407 / B829 | ASME SB-407 | — |
| Welded pipe / tube | ASTM B514 / B515 | ASME SB-514 / SB-515 | — |
| Fittings | ASTM B366 | ASME SB-366 | — |
| Welding consumables | RA 82 (AWS ERNiCr-3) · alloy 617 (ERNiCrCoMo-1) for max strength | — | — |
ASME Boiler and Pressure Vessel Code Case 1325; approved for high-temperature service. Designation UNS N08810 (dual-certifiable considerations apply for N08811).
| Alloy | Ni % | Cr % | Other | Best Used For |
|---|---|---|---|---|
| Alloy 800H | 30–35 | 19–23 | C 0.05–0.10, grain ≥ASTM5 | High creep/rupture strength 593–980°C |
| Alloy 800 | 30–35 | 19–23 | C ≤0.10, fine grain | General heat + corrosion to 816°C |
| Alloy 800HT | 30–35 | 19–23 | C 0.06–0.10, Al+Ti 0.85–1.20 | Highest creep-rupture strength |
| Alloy 600 | ≥72 | 14–17 | Ni-base | Higher Ni; full chloride-SCC immunity |
| Alloy 330 | 34–37 | 18–20 | Si 1.0–1.5 | Carburisation + thermal shock to 1148°C |
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