Incoloy 800 vs 800H vs 800HT – What's the Difference, and Which to Choose?
Incoloy 800 vs 800H vs 800HT – What's the Difference, and Which to Choose?
Incoloy 800, 800H, and 800HT are nickel-chromium alloys used in high-temperature environments. The main differences lie in the controlled content of carbon, aluminum (Al), and titanium (Ti), with 800HT being the alloy with the best performance: 800 is the basic model, 800H improves creep resistance by controlling the carbon content, while 800HT further strictly controls the content of carbon, aluminum, and titanium (total content of 0.85-1.20%), resulting in superior high-temperature strength, stress rupture resistance, and grain stability. This makes 800H/HT perform better than the basic 800 model at temperatures above 650°C (1200°F). For general high-temperature applications, 800 can be chosen; for applications requiring higher creep/rupture resistance, 800H is recommended; and for extreme high-temperature, high-stress environments (such as furnace components), 800HT should be selected to obtain optimal creep resistance.
What is the temperature range of Incoloy 800?
INCOLOY 800 alloy exhibits high mechanical strength over a wide temperature range. Typically, the 800 alloy is widely used for its strength characteristics at operating temperatures up to approximately 1500°F (816°C). At these temperatures, equipment design is usually based on its tensile properties.
High-temperature environments cause most metals to wear down, especially when combined with factors such as pressure, oxidation, carburizing gases, and prolonged heating cycles. Therefore, many industries rely on high-temperature nickel alloys. Among these, the Incoloy 800 series alloys are among the most trusted materials for heaters, reformers, steam pipes, chemical equipment, and other high-temperature components subject to continuous thermal stress.
At first glance, Incoloy 800, 800H, and 800HT appear almost identical. They have similar names and overlapping basic compositions. However, each alloy has subtle chemical modifications that ultimately result in significant differences in performance and stability in high-temperature environments.
This article from Gnee Steel will detail the differences between these three grades, how their chemical compositions affect performance, and how to choose the most suitable alloy for your application. Additionally, this article will briefly compare Incoloy 800 and Incoloy 825, as this question frequently arises when buyers compare corrosion and heat resistance. Whether you are working with an Incoloy 800 supplier or an Incoloy 800H exporter, this information will help you make a more informed decision.
1. Introduction to Incoloy 800
Incoloy 800 is the original version of this alloy. It was designed to provide practical performance at high temperatures while resisting oxidation and carburization. This balance makes it suitable for many industrial systems where the ambient temperature is high, but not high enough to require specialized high-temperature creep-resistant materials.
Incoloy 800 Chemical Composition
| Element | Incoloy 800 (UNS N08800) |
|---|---|
| Nickel (Ni) | 30.0 – 35.0 % |
| Chromium (Cr) | 19.0 – 23.0 % |
| Iron (Fe) | ≥ 39.5 % |
| Carbon (C) | ≤ 0.10 % |
| Aluminum (Al) | 0.15 – 0.60 % |
| Titanium (Ti) | 0.15 – 0.60 % |
| Manganese (Mn) | ≤ 1.5 % |
| Silicon (Si) | ≤ 1.0 % |
| Copper (Cu) | ≤ 0.75 % |
| Sulfur (S) | ≤ 0.015 % |
| Phosphorus (P) | ≤ 0.045 % |
| Al + Ti | 0.30 – 1.20 % |
These elements work together to keep the alloy stable during prolonged heating. The alloy is resistant to deformation, which is crucial for equipment that needs to maintain dimensional stability for thousands of hours.
Applications of Incoloy 800
Heat exchangers
Medium-temperature furnace components
Heating tubes
Petrochemical piping
Steam equipment under moderate stress levels
If your project involves repeated heating, requires reliable oxidation resistance, and operates in the medium temperature range of high-temperature service, Incoloy 800 generally performs well.
2. How is Incoloy 800H Different?
Incoloy 800H was developed to address a specific problem: creep failure at high temperatures. Creep is the slow deformation of a material over time under high temperature and stress. When equipment is subjected to high temperatures for extended periods, materials with insufficient creep strength will expand, sag, or crack.
Improvements in 800H?
The main difference lies in tighter control over carbon content and heat treatment. These subtle changes improve the alloy's resistance to deformation. Incoloy 800H features:
A narrower carbon content range
Grain size requirements that promote high-temperature performance
Enhanced long-term stability in high-stress areas
Applications of 800H
Steam reformers
Hydrocarbon heaters
High-temperature piping
Superheater tubes
Heat treatment equipment
If your equipment operates at higher temperatures and under greater loads, 800H is stronger and safer than standard 800.
3. Incoloy 800HT: The highest-performing alloy in this series
Incoloy 800HT retains the improvements of 800H while tightening the ranges of aluminum, titanium, and carbon content. It undergoes a special high-temperature annealing treatment designed to better adjust and stabilize the alloy's structure.
Reasons for 800HT's superior performance
The excellent chemical composition allows for the formation of stronger, more heat-resistant precipitates within the metal. These precipitates help slow creep and improve long-term service life. Even after prolonged exposure to extremely high temperatures, 800HT maintains its shape and integrity better than the other two grades.
Typical Applications
Demanding furnace applications
High-temperature reactors
Reforming equipment
Components operating at high temperatures for extended periods
Heat treatment fixtures
If your equipment operates at the highest temperature range that the 800 series alloys can withstand, then 800HT is a safe choice.
Summary of Key Differences
Incoloy 800 (UNS N08800): The basic alloy, suitable for moderate high-temperature environments, but lacks the enhanced creep strength of the H/HT alloys.
Incoloy 800H (UNS N08810): Higher carbon content (0.05-0.10%) and controlled aluminum/titanium content (0.30-1.20%), along with controlled grain size, resulting in superior creep/rupture properties compared to the 800 alloy.
Incoloy 800HT (UNS N08811): Even stricter control: higher minimum carbon content (0.06-0.10%) and tighter aluminum + titanium content control (0.85-1.20%), providing optimal creep performance and stability at extreme temperatures (up to 925°C/1700°F).
How to Choose
For general heating applications (below approximately 650°C/1200°F): Incoloy 800 may be sufficient, but 800H/HT usually offers better long-term value.
For enhanced high-temperature strength: Choose 800H. It is ideal for process piping, heat exchangers, and carburizing fixtures requiring higher performance than the basic 800 alloy.
For extreme temperatures and creep resistance (above approximately 650°C/1200°F): Choose 800HT. Its tightly controlled composition provides superior stress rupture strength in furnace components, electric heating element sheaths, and demanding conditions.
Dual Certification: 800H and 800HT are often supplied with dual certification (800H/HT) because the 800HT specifications meet the 800H specifications, so you get the best performance in one product.
Why Choose Gnee as Your Nickel-Based Alloy Supplier
✅ Over 18 years of export experience, products sold to more than 80 countries
✅ Certified by ISO, SGS, and BV
✅ Global inventory of Inconel, Hastelloy, Incoloy, and Monel alloy tubing, plates, and bars
✅ Custom processing services available – including cutting, polishing, CNC machining, and packaging
✅ Fast delivery within 7-15 days, supported by global logistics partners
📦 Packaging and Shipping
All stainless steel products are packaged using the following methods:
Wooden pallets or crates
Moisture-proof packaging
Labels with furnace number, standard, and size labels
Shipped worldwide by sea, air, or express
Gnee Steel is a supplier of incoloy 800HT alloy, offering a wide range of products including: seamless pipe (sizes: 4-219 mm; thickness: 0.5-20 mm); welded pipe (sizes: 5.0-1219.2 mm; thickness: 0.5-20 mm); plates (thickness: 0.1 to 100 mm; width: 10-2500 mm); strips; alloy round bars (diameter: 3-800 mm); flat bars (thickness: 2-100 mm; width: 10-500 mm); hexagonal bars (size: 2-100 mm); wire rods; and extruded profiles. We collaborate with steel mills to provide our customers with incoloy 800HT alloy products that meet or exceed numerous leading industry standards, including ASTM, ASME, SAE, AMS, ISO, DIN, EN, and BS standards.
Gnee Steel stocks and sells incoloy 800HT, pipes, plates, strips, round bars, flat bars, forged billets, hexagonal steel, wire rods, and extruded profiles. Please feel free to contact us at ss@gneesteel.com for a quote.
