Incoloy 800 vs 840 – What’s the Difference

Incoloy 800 vs 840

Incoloy is a family of nickel-chromium-based superalloys highly resistant to corrosion and oxidation at high temperatures. They are commonly used in various industrial applications, including chemical processing, oil and gas exploration, and aerospace. Two popular types of Incoloy are Incoloy 800 and Incoloy 840. In this blog post, we will discuss the differences between Incoloy 800 and 840 and determine which is better for use in different applications.

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Difference Between Incoloy 800 and 840

Composition and Characteristics

Incoloy 800 and 840 contain nickel, iron, and chromium, but Incoloy 800 also contains small amounts of titanium and aluminium, while Incoloy 840 has more aluminium and a small amount of carbon added. Incoloy 800 is the most commonly used Incoloy alloy and can withstand high temperatures of up to 1100°C. It also has good resistance to acidic and alkaline environments.

On the other hand, Incoloy 840 is a unique alloy with a higher nickel content than Incoloy 800, making it more corrosion-resistant. It has excellent high-temperature strength and can operate at temperatures up to 1000°C.


Incoloy 800 is a weldable alloy, and it can be welded using various techniques, including gas tungsten arc welding (GTAW), shielded metal arc welding (SMAW), and gas metal arc welding (GMAW). However, Incoloy 840 is less weldable than Incoloy 800 and requires different welding techniques.

Machinability and Formability

Incoloy 800 is more machinable and formable than Incoloy 840. It can easily form into various shapes, including tubes, sheets, and plates. It is also perfect for deep-drawing applications. In contrast, Incoloy 840 is more challenging to machine and form due to its higher nickel content.


Incoloy 800 is suitable for numerous applications, including furnace components, heat exchangers, the petrochemical industry, and power generation. Its resistance to sulfidation, carburization, and oxidation makes it ideal for high-temperature applications. Incoloy 840, on the other hand, is commonly used in applications requiring high-temperature strength and resistance to corrosion, such as incineration plants and gas turbines.


In conclusion, both Incoloy 800 and 840 are two popular Incoloy alloys with unique properties. Incoloy 800 is more commonly used for high-temperature applications due to its excellent resistance to oxidation and carburization. However, Incoloy 840 is an excellent choice for applications requiring high-temperature strength and resistance to corrosion. When choosing between the two, you must consider the specific application requirements, including the temperature, pressure, and environment, to ensure you pick the right alloy for the job.



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