Incoloy 800 Series Material Selection Guide: How To Choose Between 800, 800H, And 800HT?
Aug 28, 2026
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Foreword
In high-temperature industrial sectors, material selection directly impacts equipment safety, service life, and operational efficiency. Thanks to their excellent oxidation resistance, corrosion resistance, and high-temperature stability, Incoloy 800 series nickel-based alloys are widely used in petrochemical processing, energy equipment, heat treatment furnaces, the nuclear industry, and high-temperature heat exchange systems.
Although Incoloy 800, Incoloy 800H, and Incoloy 800HT belong to the same alloy family, they fulfill distinct roles in practical applications due to differences in chemical composition, heat treatment conditions, and performance characteristics. Consequently, selecting the appropriate material based on specific operating conditions is a critical consideration during equipment design and procurement.
Introduction to Incoloy 800 Series Materials
The Incoloy 800 series consists of nickel-iron-chromium-based heat-resistant alloys; they primarily utilize increased chromium content to enhance oxidation and corrosion resistance, while leveraging nickel to improve material stability in high-temperature environments.
Although the three materials share similar base compositions, they have been optimized for different temperature and load conditions:
Incoloy 800
The base grade, emphasizing corrosion resistance and high-temperature oxidation resistance.
Incoloy 800H
Features increased carbon content and specialized heat treatment to enhance high-temperature creep strength.
Incoloy 800HT
Builds upon the 800H grade by further controlling the ratio of aluminum and titanium to strengthen long-term high-temperature stability.
Consequently, these three materials do not simply serve as substitutes for one another based on performance; rather, they represent distinct grades tailored to specific high-temperature application environments.
Comparison of Chemical Compositions of Incoloy 800, 800H, and 800HT
| Element |
Incoloy 800 |
Incoloy 800H |
Incoloy 800HT |
| Ni | 30-35% | 30-35% | 30-35% |
| Cr |
19-23% |
19-23% |
19-23% |
| Fe | rest | rest | rest |
| C | max0.10% | 0.05-0.10% | 0.06-0.10% |
| 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% |
| Al+Ti | 0.30% – 1.20% | 0.30% – 1.20% | 0.85-1.20% |
In terms of chemical composition, the primary differences among the three materials lie in their carbon content and the control of aluminum and titanium levels.
As the base material, Incoloy 800 features relatively relaxed controls on carbon and strengthening elements, primarily meeting general requirements for high-temperature corrosion resistance.
Incoloy 800H incorporates a higher carbon content; the resulting carbide strengthening mechanism enhances the material's creep resistance during long-term high-temperature operation, making it better suited for equipment subjected to sustained loads.
Incoloy 800HT further adjusts the ratio of aluminum to titanium to intensify γ' phase strengthening, thereby improving high-temperature strength and microstructural stability; consequently, it meets the demands of higher operating temperatures and extended service life cycles.
Comparison of Performance Differences: Why Are 800H and 800HT Better Suited for High-Temperature Environments?
Temperature-induced strength variation
- Incoloy 800 is suitable for operating conditions involving temperatures below 600°C where corrosion resistance is the primary requirement.
- Incoloy 800H, by increasing the carbon content, enables the formation of a more stable carbide structure at grain boundaries and is typically used in the temperature range of 593-760℃.
- Incoloy 800HT further optimizes the proportions of strengthening elements, enabling stable, long-term operation under extremely high-temperature, high-pressure conditions ranging from 760°C to 982°C.
Differences in high-temperature creep performance
- Incoloy 800 is primarily used in environments with moderate creep resistance requirements.
- Incoloy 800H, featuring controlled grain size and optimized composition, exhibits superior creep resistance under high-temperature, high-pressure conditions.
- Due to its higher content of strengthening elements, Incoloy 800HT maintains a more stable microstructure during long-term high-temperature operation, making it one of the 800-series grades with the best high-temperature performance.
Comparison of application fields
Incoloy 800
Industrial heating furnace components
Electric heating tube sheaths
Heat exchangers
Chemical processing equipment
Food processing equipment
Key characteristics: High temperature requirements but low mechanical stress; the primary focus is on corrosion and oxidation resistance.
Incoloy 800H
Petrochemical cracking furnaces
Steam reforming equipment
High-temperature heat exchangers
Pressure vessels
Chemical reaction equipment
Key characteristics: The equipment requires long-term operation, and the materials must withstand specific pressures and mechanical loads.
Incoloy 800HT
High-temperature equipment for the nuclear industry
High-temperature gas-cooled reactor components
Large-scale chemical reaction units
High-temperature energy systems
Heat exchange equipment for long-cycle operation
Key characteristics: Higher operating temperatures, longer maintenance intervals, and stricter requirements for material reliability.
How do you choose from the Incoloy 800 series?
Followed Content
A choice balancing cost and overall performance.
The equipment operates continuously and is subjected to pressure.
Facing requirements for extremely high temperatures and ultra-long service life.
Common Misconceptions Regarding Material Selection for the 800 Series
1. 800HT is definitely better than 800.
Although 800HT offers superior high-temperature performance, it comes at a higher price and entails stricter processing requirements. If the equipment's operating temperatures and loads do not meet the necessary thresholds, selecting 800HT could result in wasted costs.
2. 800 and 800H are fully interchangeable.
Although their compositions are similar, there are differences in their high-temperature creep properties. Alloy 800H generally offers superior performance for equipment subjected to long-term high-temperature loading.
3. Consider only temperature, without regard for load.
Material selection depends not only on operating temperature but also requires consideration of pressure, media corrosivity, operating cycles, and maintenance requirements.
Summarize
Incoloy 800, 800H, and 800HT represent the evolution of the 800 series heat-resistant alloys across different performance grades. While Incoloy 800 is suitable for standard high-temperature, corrosion-resistant applications, Incoloy 800H is enhanced for long-term, high-temperature load-bearing environments, and Incoloy 800HT meets the demands of even more rigorous, long-term high-temperature operations.
When procuring these materials, decisions should be based on a comprehensive assessment of operating temperatures, pressures, the service environment, and the intended design life, rather than simply opting for the highest-grade material. Selecting the specific Incoloy 800 series alloy best suited to the operating conditions is essential to achieving the optimal balance between equipment safety, cost-effectiveness, and service life.
Lork Group
Marketing Operations Department
Email: claire@lorkgroup.com
WhatsApp: +86 199 3707 5488
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