Nickel Alloy Incoloy 800HT-ANN (Annealed)
Heat-treated state · default condition
UNS N08811 · EN 1.4959
Standard stocked condition for pressure vessels, furnace parts and formed components; best combination of ductility and creep strength.
Values for the ANN condition
Other Incoloy 800HT tempers and conditions
Incoloy 800HT is listed in 7 conditions; see the grade overview at Incoloy 800HT.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed 1150 °C | Choose for long-term service above 900 °C (cracking coils, reformer and radiant tubes) where creep-rupture life dominates over room-temperature strength. | 215 | 500 | 48 | 130 HB | 1.8 % IACS |
ANNDefaultThis page Annealed | Standard stocked condition for pressure vessels, furnace parts and formed components; best combination of ductility and creep strength. | 240 | 520 | 45 | 140 HB | — |
Hot-worked and annealed bar | Use for bar that must be code-qualified for elevated-temperature/creep service or heavily machined without distortion. | 240 | 520 | 45 | 145 HB | 1.8 % IACS |
Cold-worked and annealed | Standard condition for seamless heat-exchanger and furnace tubing: annealed properties with cold-finished dimensional accuracy and bright surface. | 250 | 540 | 43 | 150 HB | 1.8 % IACS |
Hot-worked | Economical bar/forging condition for machined furnace fixtures where slightly higher yield and lower ductility are acceptable. | 280 | 560 | 38 | 160 HB | 1.8 % IACS |
As-welded deposit | Reference condition for fabricated assemblies; joint strength approaches annealed base metal but creep strength of the weld is lower than 800HT base. | 300 | 550 | 33 | 165 HB | 1.7 % IACS |
Cold drawn | Pick for close-tolerance fasteners, pins and instrument tubing needing higher room-temperature strength; not for creep service without re-anneal. | 500 | 680 | 25 | 210 HB | — |
What is Incoloy 800HT-ANN?
Incoloy 800HT-ANN is Incoloy 800HT heat treated to ANN — standard stocked condition for pressure vessels, furnace parts and formed components; best combination of ductility and creep strength. Incoloy 800HT-ANN has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 90% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 196 GPa (28.4 Msi). Incoloy 800HT-ANN has a density of 7.94 g/cm³ (0.287 lb/in³), lighter than 88% of nickel alloy grades. It melts at 1,357°C (2,475 °F).
Advantages
- Low embodied carbon — 7.5 kg CO₂/kg, better than 96% of nickel alloy grades
- High service temperature — 1,100°C (2,012 °F), better than 88% of nickel alloy grades
- High electrical conductivity — 1.8 % IACS, better than 81% of nickel alloy grades
Limitations
- Low strength — 240 MPa (34.8 ksi), worse than 90% of nickel alloy grades
Incoloy 800HT-ANN properties
Typical room-temperature values for Incoloy 800HT-ANN; 12 are specific to this condition. Other listed values are Incoloy 800HT reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Incoloy 800HT-ANN has a density of 7.94 g/cm³ (0.287 lb/in³), lighter than 88% of nickel alloy grades. It melts at 1,357°C (2,475 °F).
Mechanical13
Incoloy 800HT-ANN has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 90% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
Incoloy 800HT-ANN is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), better than 57% of nickel alloy grades. Thermal expansion is 14.4 µm/m·K (8 µin/in·°F).
Electrical3
Incoloy 800HT-ANN conducts electricity at 1.8 % IACS, better than 81% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 77% of nickel alloy grades.
Sustainability4
Producing a kilogram of Incoloy 800HT-ANN takes about 110 MJ of energy and emits 7.5 kg of CO₂ — less than 93% of nickel alloy grades. Typical recycled content is 40%.
Manufacturability7
Incoloy 800HT-ANN's machinability is poor (28/100, better than 82% of nickel alloy grades); weldability very good (75/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Incoloy 800HT-ANN
Is Incoloy 800HT easy to machine?
Treat like a gummy austenitic Ni alloy: rigid setup, positive-rake carbide or ceramic, low speed with heavy feed, flood coolant and never dwell — it work-hardens instantly.
Can Incoloy 800HT be welded?
Readily welded by GTAW/GMAW/SMAW with ERNiCr-3 (Alloy 82) or ENiCrFe-3; no preheat or PWHT needed, keep heat input low and interpass clean to avoid hot cracking.
Can Incoloy 800HT be formed, bent or molded?
Formable hot (1150–900 °C) and cold, but springback and forming loads are high; intermediate anneals at ~980–1050 °C are usual, and final creep parts should be re-annealed at ≥1120 °C for coarse grain.
What surface finishes work on Incoloy 800HT?
Pickle/passivate or grit-blast plus pickling to remove the tenacious Cr-rich scale; can be mechanically polished, but no anodising — a service-formed adherent oxide is the working surface.
Incoloy 800HT chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Ni | 30 – 35 | 32.5 |
| Cr | 19 – 23 | 21 |
| Chigher C than 800H for creep strength | 0.06 – 0.1 | 0.08 |
| Al | 0.25 – 0.6 | 0.45 |
| Ti | 0.25 – 0.6 | 0.45 |
| Al+Tikey 800HT requirement | 0.85 – 1.2 | 1 |
| Mn | ≤ 1.5 | 0.8 |
| Si | ≤ 1 | 0.4 |
| Cu | ≤ 0.75 | 0.3 |
| S | ≤ 0.02 | 0 |
| Febalance, 39.5 % min per ASTM | ≥ 39.5 (balance) | — |
Incoloy 800HT-ANN — frequently asked
What is Incoloy 800HT-ANN used for?
Incoloy 800HT-ANN is typically used for ethylene furnace tubes, hydrogen reformer components and catalyst support baskets. In short: highest-creep 800-series grade; stable above 1000 °C; furnace tube standard.
What is the yield strength of Incoloy 800HT-ANN?
Incoloy 800HT-ANN has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 90% of nickel alloy grades. Strength varies by condition: see the 7 listed tempers.
Is Incoloy 800HT-ANN easy to machine?
Not especially — machinability is rated poor (28/100, better than 82% of nickel alloy grades). Treat like a gummy austenitic Ni alloy: rigid setup, positive-rake carbide or ceramic, low speed with heavy feed, flood coolant and never dwell — it work-hardens instantly.
Can Incoloy 800HT-ANN be welded?
Yes — weldability is rated very good (75/100). Readily welded by GTAW/GMAW/SMAW with ERNiCr-3 (Alloy 82) or ENiCrFe-3; no preheat or PWHT needed, keep heat input low and interpass clean to avoid hot cracking.
What surface finishes work on Incoloy 800HT-ANN?
Pickle/passivate or grit-blast plus pickling to remove the tenacious Cr-rich scale; can be mechanically polished, but no anodising — a service-formed adherent oxide is the working surface.
Can Incoloy 800HT-ANN be formed, bent or molded?
Formable hot (1150–900 °C) and cold, but springback and forming loads are high; intermediate anneals at ~980–1050 °C are usual, and final creep parts should be re-annealed at ≥1120 °C for coarse grain.
What is the maximum service temperature of Incoloy 800HT-ANN?
Incoloy 800HT-ANN is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Incoloy 800HT-ANN and Incoloy 800HT-CD?
ANN is the default condition — standard stocked condition for pressure vessels, furnace parts and formed components; best combination of ductility and creep strength. CD: pick for close-tolerance fasteners, pins and instrument tubing needing higher room-temperature strength; not for creep service without re-anneal. Yield strength is 240 MPa in ANN versus 500 MPa in CD.
Sources
- ASTM B409 — Ni-Fe-Cr Alloy Plate, Sheet and Strip — ASTM International (2021)
- ASTM B408 / B407 — Ni-Fe-Cr Alloy Rod & Bar / Seamless Pipe & Tube — ASTM International (2021)
- INCOLOY alloys 800H & 800HT publication SMC-047 — Special Metals Corporation (2004)
- ASME BPVC Section II Part D — allowable stresses and physical properties for N08811 — ASME (2023)
- EN 10095 / DIN 17742 material 1.4959 (X8NiCrAlTi32-21) — CEN / DIN (2018)
- ASM Handbook Vol. 1 — Heat-Resistant and Superalloys — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.