Incoloy alloys are characterised by high-temperature strength, oxidation and corrosion resistance, thus finding applications in many sectors. Of these, Incoloy Alloy 800 and Incoloy 800H are two of the most popular types of this material. While they share several similarities, their differences make them suitable for specific applications. In this blog, we’ll explore the key differences between Incoloy Alloy 800 and 800H, focusing on their composition, properties, and ideal uses.
What is Incoloy Alloy 800?
Incoloy Alloy 800 is a nickel-iron-chromium alloy designed for high-temperature applications. Its composition offers excellent resistance to oxidation, carburisation, and other forms of corrosion at elevated temperatures. Incoloy 800 pipes & tubes are commonly used in industries such as chemical processing, heat exchangers, and power plants, where exposure to high temperatures is a concern.
What is Incoloy 800H?
Incoloy 800H is a modified version of Incoloy Alloy 800, with a higher carbon content (approximately 0.05–0.10%) and tighter control over its composition. This modification enhances the alloy’s creep strength and resistance to stress rupture at higher temperatures. Incoloy 800H is often used in applications where materials are subjected to extreme heat and stress over extended periods.
Key Differences Between Incoloy Alloy 800 and 800H
Carbon Content
The primary difference between Incoloy Alloy 800 and 800H is their carbon content. Incoloy 800 has a lower carbon content, typically around 0.05%, while Incoloy 800H contains a higher carbon concentration of 0.05-0.10%. This higher carbon content in 800H increases strength and makes it more suitable for high-temperature applications.
Creep Strength
Incoloy 800H is specifically designed for higher creep strength at elevated temperatures. The higher carbon content and precise control over other alloying elements give 800H superior resistance to creep, which is the gradual deformation of materials under constant stress. As a result, Incoloy 800H is often preferred for applications where the material is exposed to continuous high temperatures and stresses.
Stress Rupture Resistance
Due to its enhanced composition, Incoloy 800H has better stress rupture resistance than Incoloy Alloy 800. This makes 800H ideal for industries where components are under long-term exposure to high pressure and temperature, such as in furnace components, petrochemical plants, and thermal processing equipment.
Applications
While both alloys are used in similar industries, Incoloy Alloy 800 is more common in applications where temperature and corrosion resistance are required but not at extreme or high temperatures. Incoloy 800H, on the other hand, is better suited for high-stress, high-temperature environments where materials need to maintain structural integrity over long periods.
Welding and Fabrication
Incoloy Alloy 800 and 800H are known for their ease of fabrication and welding. However, due to its higher carbon content, Incoloy 800H requires more careful control during welding, which can lead to the formation of carbides that may affect its properties.
Conclusion
In conclusion, while Incoloy Alloy 800 and 800H share many similarities, the primary difference lies in the carbon content and the resulting improvements in creep strength and stress rupture resistance. Incoloy 800H is designed for more demanding applications with constant high temperatures and stress, making it the better option for power generation, chemical processing, and heat exchangers.
Both alloys offer excellent resistance to oxidation and corrosion, and Incoloy 800 pipes & tubes remain a reliable solution for high-temperature environments. However, for applications where material performance under long-term high stress and elevated temperatures is critical, Incoloy 800H is often the preferred choice.