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Alloy 800H (UNS N08810): High-Temperature Corrosion Resistance and Mechanical Properties

Alloy 800H (UNS N08810) is a nickel-iron-chromium alloy known for its exceptional high-temperature strength and resistance to oxidation and carburization. This material is widely used in industries such as petrochemical, power generation, and heat treatment due to its ability to withstand extreme environments.

Composition and Key Features

The chemical composition of Alloy 800H includes approximately 30-35% nickel, 19-23% chromium, and a controlled carbon content (0.05-0.10%) that enhances its creep rupture strength at elevated temperatures. The alloy also contains small amounts of aluminum and titanium for improved stability.

High-Temperature Corrosion Resistance

Alloy 800H demonstrates outstanding resistance to various forms of high-temperature corrosion:

  • Oxidation resistance up to 1100°C (2012°F)

  • Excellent resistance to carburizing environments

  • Good performance in sulfidizing atmospheres

  • Resistance to chloride stress corrosion cracking

Mechanical Properties

The mechanical properties of Alloy 800H make it particularly suitable for high-temperature applications:

Property Value
Tensile Strength ≥450 MPa (65 ksi)
Yield Strength ≥170 MPa (25 ksi)
Elongation ≥30%
Creep Rupture Strength (700°C) Approx. 100 MPa (14.5 ksi) for 10,000 hours

Applications

Due to its unique combination of properties, Alloy 800H is commonly used in:

  • Furnace components and heat exchangers

  • Petrochemical processing equipment

  • Power generation systems

  • Nuclear reactor components

  • Industrial heating elements

Conclusion

Alloy 800H (UNS N08810) offers an excellent balance of high-temperature strength, corrosion resistance, and fabricability, making it a preferred material for demanding industrial applications. Its controlled carbon content provides enhanced creep resistance compared to standard Alloy 800, while maintaining good weldability and formability characteristics.