Properties
Alloy 800H (UNS N08810) is an austenitic high-strength solid-solution Ni-Fe-Cr alloy with controlled levels of carbon, aluminium, titanium, silicon and manganese and controlled content of (Al+Ti).
The analysis is similar to that of alloy 800, but a special solution treatment (with grain sizes ≥ 90μm/ASTM No.4) gives significantly increased creep-rupture strength above 600°C (1110°F).
For services below 600°C (1110°F) the use of soft annealed alloy 800 is
suggested.
These alloys are characterised by:
- Good creep-rupture properties at temperatures above 600°C (1110°F) without loss of ductility during long term use at temperatures below 700°C (1290°F), due to limitation of (Ti+Al) content to max 0.7%
- Good resistance to reducing, oxidising and nitriding atmospheres and to atmospheres which alternate between reducing and oxidising conditions
- Metallurgical stability in long-term application at high temperatures
Alloy 800HT (UNS N08811) is an austenitic high-strength solid-solution Ni-Fe-Cr alloy with controlled levels of carbon, aluminium, titanium, silicon and manganese and increased content of (Al+Ti).
A special solution treatment (with grain sizes ≥ 90μm/ASTM No.4) gives highest creep-rupture strength above 700°C (1290°F) due to the precipitation of TiC.
Below 700°C (1290°F), gamma prime (γ') precipitates combined with a loss of ductility.
Alloy 800HT is characterised by:
- Excellent creep strength at temperature above 700°C (1290°F)
- Good resistance to reducing, oxidising and nitriding atmospheres and to atmospheres which alternate between reducing and oxidising conditions
- Metallurgical stability in long-term application at high temperatures
- Where frequent excursions to temperatures lower than 700°C (1290°F) during service cannot be excluded or parts of the material with run permanently at a regime below 700°C (1290°F) the use of alloy 800H is recommended
Designation and Standards - Alloy 800H
| Country National Standards |
Material Designation |
Specification | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Chem. Compo- sition |
Tube & Pipe | Sheet & Plate |
Rod & Bar |
Strip | Forgings | ||||
| Seamless | Welded | ||||||||
| France AFNOR |
|||||||||
| Germany DIN (Provisional) VdTÜV |
W.-Nr .1.4958 X5NiCrAITi3120 |
17459/460 412/434 |
17459 412/434 |
17460 412/434 |
17460 412/434 |
17460 412/434 |
17460 412/434 |
||
| United Kingdom BS |
NA 15 (H) | 3074 | 3072 | 3076 | 3073 | ||||
| USA ASTM ASME |
UNS N08810 | B407 SB407 |
B163 B514/515 SB163/ 514/515 |
B409 SB409 |
B408 SB408 |
B409 SB409 |
B564 SB564 |
||
| ISO | MC-FeNi32Cr21AITi | ||||||||
Designation and Standards - Alloy 800HT
| Country National Standards |
Material Designation | Specification | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Chem. Compo- sition |
Tube & Pipe | Sheet & Plate |
Rod & Bar |
Strip | Forgings | ||||
| Seamless | Welded | ||||||||
| France AFNOR |
|||||||||
| Germany DIN (Provisional) VdTÜV |
W.-Nr .1.4959 X8NiCrAITi32 21 |
17459/460 | 17459 | 17460 | 17460 | 17460 | 17460 | ||
| United Kingdom BS |
|||||||||
| USA ASTM ASME |
UNS N08811 | B407 SB407 |
B163 SB163 |
B409 SB409 |
B408 SB408 |
B409 SB409 |
B564 SB564 |
||
| ISO | |||||||||
Chemical Composition (%)
| Alloy 800H | Ni | Cr | Fe | C | Mn | Si | Cu | P | S | Al | Ti | Al+Ti |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 30.0 | 19.0 | bal. | 0.06 | 0.5 | 0.2 | - | - | - | 0.20 | 0.20 | - |
| Max | 32.0 | 22.0 | 0.08 | 1.0 | 0.6 | 0.5 | 0.015 | 0.010 | 0.40 | 0.50 | 0.7 |
| Alloy 800HT | Ni | Cr | Fe | C | Mn | Si | Cu | P | S | Al | Ti | Al+Ti |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | 30.0 | 19.0 | bal. | 0.06 | 0.5 | 0.2 | - | - | - | 0.30 | 0.30 | 0.85 |
| Max | 32.0 | 22.0 | 0.10 | 1.0 | 0.6 | 0.5 | 0.015 | 0.010 | 0.60 | 0.60 | 1.2 |
Mechanical Properties
The following properties are applicable to the solution-treated condition and the indicated size ranges. Material outside these size ranges is subject to special enquiry. The values are valid for longitudinal and transverse specimens.
Sheet and strip up to 3mm 1/8"
Sheet and plate up to 50mm 2"
Tube up to 200mm dia 8" dia
Rod and bar , forgings up to 250mm 10"
| Temp. | Tensile Strength |
0.2% Yield Strength |
1.0% Yield Strength |
Elongation A5% |
||||
|---|---|---|---|---|---|---|---|---|
| °C | °F | N/mm2 | Ksi | N/mm2 | Ksi | N/mm2 | Ksi | |
| RT | RT | 500 | 72.5 | 170 | 24.7 | 200 | 29.0 | Transverse 30 Longitudinal 35 |
| 93 | 200 | - | - | 141 | 20.4 | 161 | 23.3 | |
| 100 | 212 | <425> | - | 140 | 20.3 | 160 | 23.2 | |
| 200 | 392 | <400> | - | 115 | 16.7 | 135 | 19.6 | |
| 204 | 400 | - | - | 113 | 16.4 | 133 | 19.3 | |
| 300 | 572 | <390> | - | 95 | 13.8 | 115 | 16.7 | |
| 316 | 600 | - | - | 93 | 13.5 | 113 | 16.4 | |
| 400 | 752 | <360> | - | 80 | 11.6 | 100 | 14.5 | |
| 538 | 1000 | - | - | 77 | 11.2 | 97 | 14.1 | |
| 593 | 1100 | - | - | 75 | 10.9 | 95 | 13.8 | |
| 600 | 1112 | <300> | - | 75 | 10.9 | 95 | 13.8 | |
170... according to VdTÜV no.412 and 434 and converted (N/mm2 x 0.145=ksi) 141... values determined by graphs/diagrams <> informative only minimum short-time mechanical properties of alloy 800H at room and elevated temperatures according to VdTÜV data sheets 412 and 434.
Please Note: The figures quoted are intended for guidance only. For further information, please refer to the standards listed or contact our sales or QA department.
Metallurgical Structure
Alloy 800H and alloy 800HT are austenitic, solid solution alloys containing small amounts of precipitated titanium nitride and carbide, carbonitrides and chromium carbide.
During long-term exposure of alloy 800H to temperatures below 700°C (1290°F) γ'-phase may be formed which lowers the ductility.
Alloy 800HT precipitates γ'-phase combined with a loss of ductility.
Corrosion Resistance
The high nickel and chromium contents of alloy 800H and alloy 800HT ensure excellent resistance to oxidation. The alloys are also very resistant to carburisation, nitriding and oxidising sulphur-bearing atmospheres. The protective oxide film which is formed is adherent in both static and cyclic conditions of heating and cooling, and resistance to carburisation is enhanced when a thin film of oxide is first formed on the alloy. Resistance to hydrogen is excellent and alloy 800H and alloy 800HT are standard materials used in the production of hydrogen in steam/hydrocarbon reforming processes.
Applications
Due to high strength during long periods of service and resistance to carburisation and nitriding, alloy 800H and 800HT have found many applications in steam/hydrocarbon reforming, for components such as: pigtails, headers/collectors/manifolds, transfer piping, catalyst tubes (in low-pressure processes) and quench-system piping.
Typical applications include:
- Ethylene pyrolysis tubing in convection and radiant sections - resistance to carburisation and good mechanical properties
- Ethylene dichloride cracking tubes - resistance to carburisation and to dry hydrogen chloride and chlorine
- Cracking tubes used in the production of acetic anhydride and ketene - high strength, resistance to carburisation and the formation of sigma phase
- Components, e.g. heat exchangers, piping systems etc, in coal conversion plants
- Steam generator tubing in helium cooled, high temperature reactor systems - high strength, resistance to helium and to steam.
