1. Introduction of Incoloy Grades
Incoloy 800 series alloys are a group of nickel-iron-chromium alloys known for their excellent strength and resistance to oxidation and carburization at high temperatures. Incoloy 800 grades includes 800, 800H, 800HT etc. These alloys are widely used in various industries, including chemical processing, power generation, and heat treatment, because of their ability to maintain structural integrity in extreme environments. The high nickel and chromium content in these alloys contributes significantly to their performance.
2. Incoloy 800 (Alloy 800)
Incoloy 800, also known as Alloy 800, is the base alloy in the 800 series. It is composed primarily of nickel (30-35%), iron (39.5% minimum), and chromium (19-23%), with small amounts of other elements such as aluminum and titanium. This alloy is known for its excellent resistance to oxidation, sulfidation, and carburization, making it ideal for use in high-temperature applications.
2.1 Key Features and Benefits:
- High resistance to oxidation and carburization
- Good mechanical properties at elevated temperatures
- Excellent corrosion resistance in acidic environments, including nitric acid
2.2 Common Applications:
- Heat exchangers
- Furnace components
- Chemical and petrochemical processing equipment
3. Incoloy 800H
Incoloy 800H is a modified version of Incoloy 800, designed to provide improved performance at higher temperatures. The primary difference between 800 and 800H is the higher carbon content (0.05-0.10%) and the addition of up to 1.20% aluminum and titanium. These modifications enhance the alloy’s creep and stress rupture properties. The grain size of Incoloy 800H is also controlled to improve its high-temperature strength.
3.1 Enhanced Features:
- Improved creep and stress rupture strength
- Better performance at temperatures above 600°C (1112°F)
- Enhanced structural stability
3.2 Typical Uses:
- Superheater and reheater tubing in power plants
- Industrial furnaces
- Heat-treating equipment
4. Incoloy 800HT
Incoloy 800HT is another variant of the 800 series, offering even greater high-temperature strength than 800H. This alloy has a similar composition to 800H but with tighter control on the carbon, aluminum, and titanium content. The result is an alloy that provides superior performance in the most demanding high-temperature environments.
4.1 Differences from Incoloy 800H:
- Higher creep and stress rupture strength
- Enhanced stability at temperatures up to 982°C (1800°F)
- Better resistance to thermal fatigue and cyclic heating
4.2 Applications:
- Ethylene furnace quench boilers
- Hydrocarbon cracking
- Heat exchangers in chemical and petrochemical industries
5. Comparison: 800 vs 800HT
When comparing Incoloy 800 and 800HT, several key differences emerge, primarily in their high-temperature performance and mechanical properties.
5.1 Chemical Composition:
- Both alloys contain similar amounts of nickel, iron, and chromium.
- 800HT has more tightly controlled levels of carbon, aluminum, and titanium.
5.2 Mechanical Properties:
- Incoloy 800HT offers superior creep and stress rupture strength compared to 800.
- 800HT maintains better structural stability at higher temperatures.
5.3 Suitability for Applications of Incoloy 800 series:
- Incoloy 800 is suitable for applications requiring good corrosion resistance and moderate high-temperature strength.
- Incoloy 800HT is preferred for more demanding high-temperature applications where enhanced mechanical properties are critical.
6. Conclusion of Incoloy Grades
The Incoloy 800 grades, including Incoloy 800, 800H, and 800HT, are essential materials in industries that operate under extreme conditions. Each variant offers unique benefits, making them suitable for specific applications. As technology advances, the demand for materials that can withstand higher temperatures and more aggressive environments will continue to grow, ensuring the ongoing relevance of the Incoloy 800 series.
For further reading and detailed technical specifications, such as comprehensive information on the properties, applications, and performance of Incoloy 800 series alloys, will be in the next post.
