Alloy 800HT UNS N08811: Properties, Applications, and Performance Guide

Alloy 800HT UNS N08811 is a nickel-iron-chromium superalloy renowned for its exceptional high-temperature strength and oxidation resistance. This advanced material is stabilized with titanium and aluminum, offering superior performance in extreme environments. Engineers and manufacturers favor it for critical applications where reliability under thermal stress is non-negotiable.

High-Temperature Mechanical Properties

This alloy maintains excellent creep and rupture strength at temperatures up to 1500°F (815°C). Its controlled carbon content and solution annealing treatment ensure optimal microstructural stability, preventing embrittlement during prolonged exposure to heat. These characteristics make it indispensable for components subjected to thermal cycling.

Corrosion Resistance Capabilities

Alloy 800HT demonstrates remarkable resistance to oxidation, carburization, and sulfidation. It performs exceptionally well in corrosive atmospheres containing sulfur compounds and molten salts, outperforming standard stainless steels in aggressive chemical processing environments.

Primary Industrial Applications

The unique combination of properties makes Alloy 800HT UNS N08811 ideal for demanding sectors:

Petrochemical Processing Equipment

Used in steam methane reformer components, pyrolysis furnace tubing, and catalyst support systems where high temperature and pressure conditions prevail.

Power Generation Systems

Essential for nuclear steam generator tubing, heat exchangers, and superheater components in conventional and advanced power plants.

Aerospace and Thermal Processing

Employed in gas turbine components, combustion chambers, and heat treatment fixtures requiring sustained performance at elevated temperatures.

Frequently Asked Questions

What distinguishes Alloy 800HT from standard Alloy 800?

The HT variant features tighter controls on aluminum and titanium content, along with specific heat treatment requirements, resulting in enhanced high-temperature mechanical properties.

Can Alloy 800HT be welded effectively?

Yes, it demonstrates good weldability using matching filler metals and proper procedures, though post-weld heat treatment may be necessary for optimal performance in high-temperature service.

What are the maximum service temperatures?

Alloy 800HT performs reliably at temperatures up to 1500°F (815°C) for extended durations, with short-term capability to 1800°F (980°C) in oxidizing atmospheres.

Optimizing Component Performance

Proper material selection and fabrication techniques are crucial for maximizing the alloy’s capabilities. Consider thermal expansion characteristics, environmental compatibility, and mechanical loading conditions during design phases. Partner with experienced material suppliers who provide certified stock and technical support.

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