Are Incoloy 800H/800HT the same as Incoloy 800?
What are the differences in their application scenarios?
Chemical composition restrictions
Incoloy 800H has stricter limits on carbon content (0.05%–0.10%, higher than the standard Incoloy 800) and requires controlled levels of aluminum and titanium (Al+Ti = 0.8%–1.6%). Incoloy 800HT further tightens the component range on the basis of 800H, with more precise control over impurity elements such as sulfur and phosphorus, and its aluminum-titanium ratio is optimized to enhance high-temperature creep resistance.
Mandatory heat treatment process
Incoloy 800 can be delivered in the annealed state without additional heat treatment requirements for general applications. In contrast, Incoloy 800H and 800HT must undergo a stabilization heat treatment (holding at 980–1150°C for a specified time and then cooling properly). This process promotes the precipitation of fine and uniform carbide phases at the grain boundaries, thereby improving high-temperature strength and structural stability.
Incoloy 800: Suitable for general high-temperature and corrosion-resistant environments where creep resistance requirements are not extremely strict. Typical applications include heat exchanger tubes in moderate-temperature chemical processing, furnace components for industrial heating, and pipeline systems for handling corrosive media at temperatures below 800°C. It is also used in nuclear power auxiliary systems and food processing equipment because of its good formability and weldability.
Incoloy 800H: Designed for long-term service under high-temperature conditions (up to 900°C) with moderate creep load. Its main applications cover petrochemical cracking furnace tubes, reformer tubes in hydrogen production units, and radiant tubes in heat treatment furnaces. It is also an ideal material for high-temperature flue gas ducts and thermal oil heater components in power generation systems.
Incoloy 800HT: The premium grade optimized for extreme high-temperature and high-stress environments (service temperature up to 1000°C). It excels in creep rupture strength and long-term structural stability, making it the material of choice for critical components such as gas turbine combustion chambers, nuclear power steam generator U-tubes, ethylene cracking furnace core tubes, and high-temperature pressure vessel liners. It is widely used in aerospace, advanced energy, and other high-end industrial fields with stringent performance requirements.
