# Alloy 800H (UNS N08810) High-Temperature Corrosion Resistance and Mechanical Properties
## Introduction to Alloy 800H
Alloy 800H (UNS N08810) is an austenitic nickel-iron-chromium alloy designed for high-temperature applications. This material offers exceptional resistance to oxidation and carburization at elevated temperatures, making it a preferred choice for various industrial applications.
## Chemical Composition
The chemical composition of Alloy 800H plays a crucial role in its performance characteristics:
- Nickel (Ni): 30-35%
- Chromium (Cr): 19-23%
- Iron (Fe): Balance
- Carbon (C): 0.05-0.10%
- Aluminum (Al): ≤ 0.15-0.60%
- Titanium (Ti): ≤ 0.15-0.60%
## High-Temperature Corrosion Resistance
Oxidation Resistance
Alloy 800H demonstrates excellent oxidation resistance up to 1100°C (2012°F) due to its high chromium content. The formation of a protective chromium oxide layer on the surface prevents further oxidation at elevated temperatures.
Carburization Resistance
The alloy’s resistance to carburization makes it suitable for applications in hydrocarbon processing environments. The balanced nickel and chromium content helps maintain stability in carburizing atmospheres.
Sulfidation Resistance
While not as resistant as some specialty alloys, Alloy 800H offers moderate resistance to sulfidation in certain environments, particularly when sulfur partial pressures are controlled.
## Mechanical Properties
Room Temperature Properties
At ambient temperatures, Alloy 800H typically exhibits:
- Tensile Strength: 500-700 MPa
- Yield Strength: 200-300 MPa
- Elongation: 30-45%
Elevated Temperature Properties
The mechanical properties of Alloy 800H at high temperatures are particularly noteworthy:
Temperature (°C) | Tensile Strength (MPa) | Yield Strength (MPa) |
---|---|---|
600 | 380-450 | 150-200 |
800 | 250-300 | 100-150 |
1000 | 120-180 | 50-80 |
Creep and Rupture Strength
Alloy 800H is specifically designed for creep resistance applications. Its controlled carbon content and grain structure contribute to excellent creep-rupture properties at temperatures up to 815°C (1500°F).
## Applications
The combination of high-temperature corrosion resistance and mechanical strength makes Alloy 800H suitable for:
- Petrochemical processing equipment
- Heat treatment furnaces
- Power generation components
- Nuclear reactor components
- Industrial heating elements</li