Alloy 800HT UNS N08811: Properties, Applications, and Performance Guide
Alloy 800HT UNS N08811 is a nickel-iron-chromium superalloy known for its exceptional high-temperature strength and oxidation resistance. This material is widely used in demanding industrial applications due to its stability and durability under extreme conditions.
Key Mechanical Properties
The alloy offers excellent tensile and creep rupture strength at temperatures up to 1500°F (815°C). Its controlled carbon content and titanium/aluminum ratios ensure optimal microstructural stability during prolonged high-temperature exposure.
Chemical Composition Analysis
With approximately 30-35% nickel, 19-23% chromium, and balanced iron content, Alloy 800HT maintains excellent resistance to carburization and oxidation. The precise composition meets UNS N08811 specifications for critical applications.
Industrial Applications
Petrochemical Processing Equipment
This alloy performs exceptionally well in reformer furnaces, heater tubes, and radiant coils where thermal stability and corrosion resistance are paramount.
Power Generation Systems
Alloy 800HT serves effectively in gas turbine components, heat exchangers, and nuclear steam generator tubing due to its reliable performance under thermal cycling conditions.
Performance Advantages
The material’s enhanced creep properties make it superior to standard 800/800H alloys for high-temperature structural applications. Its proven performance in aggressive environments has established it as a go-to solution for engineers.
Frequently Asked Questions
Temperature Limitations
Alloy 800HT maintains structural integrity up to 1500°F (815°C) continuously, with short-term capability to 1800°F (980°C) in specific applications.
Welding Compatibility
Standard welding techniques including GTAW and GMAW produce excellent results when using matching filler metals and proper procedures.
Material Selection Guidance
When considering high-temperature alloys, Alloy 800HT UNS N08811 provides the optimal balance of strength, fabrication characteristics, and cost-effectiveness for severe service conditions.
Comparative Performance Data
Independent testing confirms superior stress rupture properties compared to similar austenitic alloys, particularly in carburizing environments.
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