Incoloy 800H (UNS N08810): A Nickel-Iron-Chromium Alloy Offering Stability at High Temperature
Technical Description
Incoloy 800H is a nickel-iron-chromium based super alloy developed to offer superior oxidation and creep resistance in long-term high temperature applications. Its basic chemical composition contains approximately 30-35% nickel, 19-23% chromium, 0.05-0.10% carbon, up to 39.5% iron, up to 1.0% aluminium and up to 1.0% titanium.
This alloy is derived from the original Incoloy 800 (UNS N08800) composition and has been made durable against high temperature conditions with a controlled carbon (minimum 0.05%) and aluminium + titanium (0.85% minimum) content. It therefore exhibits strong mechanical stability against both oxidative atmospheres and creep in the 600–1100 °C temperature range.
Incoloy 800H is subjected to solution annealing and can mostly be used in heat resistant parts without disturbing the grain structure of the material. Typically its tensile strength is 450–600 MPa and its yield strength in the range of 200–250 MPa. Its real advantage, however, is that it can largely preserve these values even in long-term high temperature applications.
Incoloy 800H Relevant Standards
Incoloy 800H can be used in different sectors thanks to its compliance with various international standards. The relevant ASTM and AMS norms are given below:
- ASTM B409 – Sheet, plate and strip products
- ASTM B408 – Bar and wire products
- ASTM B564 – Forged and flange parts
- ASTM B366 – Welded fittings
- ASME SB-409 / SB-564 – Suitability for pressure vessel applications
- AMS 5871 – Aerospace standard for high temperature structural parts
- EN 1.4958 / X8NiCrAlTi32-21 – European standard
- UNS N08810 – Unified Numbering System designation
The supply of material compliant with these standards is, especially in fields such as energy, petrochemicals and heat exchanger systems, the basis of quality control processes.
Incoloy 800H Trade Names and Equivalents
- Incoloy® 800H – Registered trade name of Special Metals Corporation
- Alloy 800H – Common technical designation
- UNS N08810 – Chemical designation
- W.Nr. 1.4958 – German standard number
- VDM Alloy 800H, ATI 800H, ThyssenKrupp 800H – Commercial producer designations
These equivalent designations are of critical importance for technical alignment in international supply processes.
Incoloy 800H Application Areas
Incoloy 800H is an alloy specially preferred for industrial systems operating at high temperature. Its principal areas of use are presented below:
- Petrochemical and Refinery Equipment*Reformer tubes, catalytic cracker systems
*Ethane, propane and methane steam reforming systems
*Heater tubes, manifold systems - Power Plants and Thermal Facilities*Heat exchangers
*Flue gas cleaning systems
*In-boiler support elements - Nuclear Energy Systems*In-reactor equipment
*Burner parts
*Mechanical parts in contact with radiation - Chemical and Process Industry*Equipment operating with acidic and basic solutions at high temperature
*In-reactor coil systems - Heat Treatment Furnaces*Furnace atmosphere tubes
*Carrier pallet and rail systems
*Heater burner components
- Petrochemical and Refinery Equipment*Reformer tubes, catalytic cracker systems
In these fields Incoloy 800H reduces total operating costs by providing long life, a low maintenance requirement and high reliability.
Incoloy 800H Advantages
- High Temperature Strength and Creep Resistance: Especially in the 600–1100 °C range the material preserves its durability against deformation under high load.
- Oxidation and Carburisation Resistance: It provides protection against degradation such as surface oxidation or internal carbon transfer in environments worked at high temperature.
- Microstructural Stability: By preserving its structural stability after solution annealing it offers a long service life.
- Weldability: It can be joined successfully by methods such as TIG, MIG and coated electrode welding.
- Stress Corrosion Resistance in Chlorinated Environments: Crack formation under stress is minimal in atmospheres containing sulphur and chlorine.
Incoloy 800H Disadvantages
- Cost: Because of the high nickel ratio its price is quite high compared with commercial steels. For this reason it is used only in long-life and critical applications.
- Machinability Difficulties: Tool wear in machining can be high, especially in the hardened or cold formed conditions.
- Non-Magnetic Structure:It may not be suitable for situations requiring magnetic identification or non-destructive testing applications.
- Medium Level Mechanical Strength: Although its high temperature strength is high, its mechanical properties at room temperature are limited and it does not offer as much strength as steel.
Conclusion and Industrial Evaluation
Incoloy 800H is a versatile alloy developed for equipment operating under high temperature, offering a long service life and stability. Used across a broad spectrum from petrochemical plants to nuclear reactors, this alloy promises, thanks to properties such as creep resistance and oxidation stability, high reliability and low maintenance cost.
Although it has limitations such as cost and machining difficulties, in applications requiring critical temperature strength Incoloy 800H shows superior performance compared with similar alloys. In this respect it holds an important place in industrial materials engineering solutions.
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| Chemical Composition (X10NiCrAlTi32-20) | | Room Temperature Mechanical Properties | | ||
|---|---|---|---|---|---|
| Grade | Incoloy 800 (UNS N08800, 1.4876) | Incoloy 800H (UNS N08810, 1.4958) | Incoloy 800HT (UNS N08811, 1.4959) | Properties | Values |
| Ni | 30.0-35.0% | 30.0-35.0% | 30.0-35.0% | Density (Specific Gravity) | 7940 kg/m³ |
| Cr | 19.0-23.0% | 19.0-23.0% | 19.0-23.0% | Melting Point | 1357-1385°C |
| Fe | min 39.5% | min 39.5% | min 39.5% | Specific Heat | 460 J/kg•°C |
| Cu | max 0.75% | max 0.75% | max 0.75% | Curie Point | -115 °C |
| C | max 0.10% | 0.05-0.10% | 0.06-0.10% | | |
| Mn | max 1.50% | max 1.50% | max 1.50% | | |
| Si | max 1.00% | max 1.00% | max 1.00% | | |
| S | max 0.015% | max 0.015% | max 0.015% | | |
| Al | 0.15-0.60% | 0.15-0.60% | 0.25-0.60% | | |
| Ti | 0.15-0.60% | 0.15-0.60% | 0.25-0.60% | | |
| Ti+Al | 0.30-1.2% | 0.30-1.2% | 0.85-1.2% | |
We supply this material
We supply Incoloy 800H (1.4876) — to AMS 5871, AMS 5766 standards, in the dimensions and forms required. For stock availability and pricing:
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