Nickel alloys 800 (UNS N08800, 1.4876), 800H (UNS N08810, 1.4958), and 800HT (UNS N08811, 1.4959) are variations of the same family of materials, distinguished by their respective chemical compositions and mechanical properties. While they share similarities, each alloy offers distinct characteristics tailored to specific applications and operating conditions.
Alloys 800/800H/800HT • UNS N08800/N08810/N08811
1. Nickel Alloy 800 (UNS N08800):
- Incoloy Alloy 800 is a solid solution strengthened nickel-iron-chromium alloy with good strength and excellent resistance to oxidation and carburization at elevated temperatures.
- It is typically used in applications requiring high-temperature strength and resistance to corrosion and oxidation, such as furnace components, petrochemical processing, and heat treating equipment.
- Alloy 800 exhibits good creep and rupture strength at temperatures up to approximately 1100°C (2000°F), making it suitable for prolonged exposure to high-temperature environments.
2. Nickel Alloy 800H (UNS N08810):
- Incoloy Alloy 800H is a modified version of Alloy 800 with higher carbon content and controlled grain size for improved creep and rupture properties at high temperatures.
- The higher carbon content in Alloy 800H promotes enhanced creep resistance, particularly at temperatures above 700°C (1290°F), while maintaining good resistance to oxidation and corrosion.
- It is commonly utilized in applications involving thermal processing, industrial furnaces, and chemical processing where elevated temperatures and prolonged exposure to aggressive environments are prevalent.
3. Nickel Alloy 800HT (UNS N08811):
- Incoloy Alloy 800HT is another modification of Alloy 800, distinguished by its higher creep and rupture strength at temperatures above 700°C (1290°F) compared to Alloy 800H.
- In addition to the higher carbon content present in Alloy 800H, Alloy 800HT incorporates aluminum and titanium additions to further enhance its high-temperature mechanical properties.
- Alloy 800HT offers superior creep resistance and thermal stability, making it well-suited for demanding applications such as steam methane reforming, coal gasification, and power generation.
Incoloy 800/N08800 Vs 800H/N08810 Vs 800HT/N08811
1. Chemical Composition:
- Nickel Alloy 800 typically consists of approximately 32-37% nickel, 19-23% chromium, and 30-35% iron, with small amounts of other elements such as manganese, sulfur, silicon, and copper.
- Nickel Alloy 800H has a similar composition to Alloy 800 but with increased carbon content, typically ranging from 0.05% to 0.10%, which enhances its high-temperature mechanical properties.
- Nickel Alloy 800HT incorporates higher levels of carbon (approximately 0.06-0.10%), as well as additions of aluminum (0.15-0.60%) and titanium (0.15-0.60%) for improved creep strength and thermal stability.
2. Mechanical Properties:
- 1.4876 Alloy 800 exhibits good tensile strength, yield strength, and elongation properties at room temperature, with adequate resistance to stress corrosion cracking and intergranular corrosion.
- 1.4958 Alloy 800H demonstrates enhanced creep and rupture properties compared to Alloy 800, particularly at elevated temperatures exceeding 700°C (1290°F), making it suitable for applications requiring prolonged exposure to high stresses.
- 1.4959 Alloy 800HT offers the highest creep and rupture strength among the three alloys, with superior resistance to deformation under high temperatures and prolonged service life in aggressive environments.
3. Applications:
- Nickel Alloy 800 UNS N08800 is commonly utilized in a wide range of applications requiring resistance to oxidation, carburization, and high-temperature corrosion, such as heat exchangers, furnace components, and chemical processing equipment.
- Nickel Alloy 800H UNS N08810 finds applications in refining and petrochemical industries, power generation, and thermal processing where elevated temperatures and mechanical stresses are prevalent.
- Nickel Alloy 800HT UNS N08811 is preferred for demanding applications involving steam methane reforming, coal gasification, and power generation due to its exceptional creep resistance and thermal stability at temperatures exceeding 700°C (1290°F).
4. Processing and Fabrication:
All three alloys can be readily hot worked, cold worked, and welded using conventional methods. However, due to their high-temperature applications, careful consideration must be given to post-weld heat treatment to maintain mechanical properties and minimize susceptibility to sensitization and intergranular corrosion.
Nickel alloys 800, 800H, and 800HT PRODUCT FORMS
1. Pipe and Tubing:
Seamless and welded pipes and tubes are available in a range of sizes and wall thicknesses to suit diverse industrial applications.
2. Plate and Sheet:
Nickel alloy 800, 800H, and 800HT are available in plate and sheet forms, offering versatility in fabricating components such as heat exchangers, reactors, and furnace parts.
3. Bar and Wire:
Round bars, square bars, and wire rods made from Nickel alloys 800, 800H, and 800HT are utilized in various applications requiring high-temperature strength, corrosion resistance, and excellent surface finish.
4. Fittings and Flanges:
Pipe fittings, flanges, and forged components are available in Nickel alloys 800, 800H, and 800HT to facilitate the construction and assembly of piping systems in corrosive and high-temperature environments.
5. Welding Consumables:
Welding electrodes, filler wires, and flux-cored wires specifically designed for Nickel alloys 800, 800H, and 800HT are available to facilitate the joining of components and structures.
6. Forgings and Castings:
Forged and cast components such as valves, fittings, and pressure vessels can be manufactured from Nickel alloys 800, 800H, and 800HT to meet specific design requirements and performance criteria.
7. Heat Exchanger Tubes:
Seamless and welded heat exchanger tubes made from Nickel alloys 800, 800H, and 800HT are utilized in the fabrication of heat transfer equipment for chemical processing, power generation, and oil refining industries.
