Incoloy 800, Incoloy 800H and Incoloy 800HT are nickel-iron-chromium alloys developed for high-temperature service. They share a common alloy family but are designed for different performance priorities.

Incoloy 800 is widely used for general high-temperature corrosion resistance, while 800H and 800HT are designed for improved high-temperature strength and creep or stress-rupture performance under specified conditions.

The correct grade depends on temperature, stress, design life and the governing material specification.

1. Common Alloy Characteristics

All three grades contain nickel, iron and chromium. Chromium contributes to oxidation resistance, while nickel supports structural stability and corrosion resistance at elevated temperatures.

The differences between the grades involve chemical controls, carbon and aluminum-titanium requirements, grain structure and specified mechanical properties. These differences influence their performance in long-term high-temperature service.

2. Incoloy 800

Incoloy 800 is commonly used where resistance to oxidation, carburization and nitridation is important, together with adequate mechanical performance at elevated temperatures.

Typical applications include:

• Industrial furnace components
• Heat exchangers
• Petrochemical processing equipment
• Heating elements and process equipment
• High-temperature piping and structural components

It is often selected when the primary requirement is high-temperature corrosion resistance rather than the most demanding creep-strength design.

3. Incoloy 800H

Incoloy 800H is designed for improved high-temperature mechanical performance compared with standard 800 in relevant product forms and specifications.

It is frequently considered for equipment operating under sustained stress at elevated temperatures, where creep and stress-rupture properties become important design factors.

Potential applications include:

• High-temperature heat exchangers
• Chemical and petrochemical processing equipment
• Industrial furnaces
• High-temperature piping
• Process equipment requiring long-term dimensional stability

4. Incoloy 800HT

Incoloy 800HT is a further controlled version of the alloy family, intended to provide specified high-temperature mechanical properties through tighter chemistry and processing requirements.

It is commonly evaluated for demanding high-temperature applications where creep strength, stress-rupture performance and long service life are critical.

Applications may include:

• High-temperature process equipment
• Petrochemical furnaces
• Heat-transfer systems
• Industrial heating equipment
• Components subject to sustained thermal and mechanical loading

5. Selection Factors

6. Important Procurement Note

The designations 800, 800H and 800HT should not be selected based only on nominal chemical composition. Product specifications, heat treatment, grain size and mechanical-property requirements matter significantly.

For pressure equipment or long-term high-temperature service, buyers should confirm the exact standard and required test certificates before placing an order.

Conclusion

Incoloy 800, 800H and 800HT belong to the same high-temperature alloy family but serve different engineering needs. Incoloy 800 is suitable for many high-temperature corrosion applications, while 800H and 800HT are considered when elevated-temperature mechanical performance is more demanding.

AlloysFactory can assist with grade selection, product forms and technical quotation requirements.

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