Nickel-based alloys are vital for industries that demand high strength, corrosion resistance, and the ability to withstand extreme temperatures. Two of the most widely used materials in this category are Alloy 600 and Alloy 800. Both are part of the Inconel and Incoloy families, respectively, and have been proven to perform under harsh industrial conditions.
Although Alloy 600 and Alloy 800 share similarities in nickel-chromium composition, they differ significantly in chemical balance, mechanical performance, and application suitability. Understanding these differences helps engineers, designers, and procurement specialists select the right material for their projects.
This article will explore in detail the differences between Alloy 600 and Alloy 800, their compositions, properties, advantages, and typical uses.
What is Alloy 600?
Alloy 600, also known as Inconel 600, is a nickel-chromium-iron alloy. It was developed for service requiring both heat and corrosion resistance.
Key Features of Alloy 600
-
Composition: Nickel (72%), Chromium (14–17%), Iron (6–10%), with trace amounts of manganese, silicon, and carbon.
-
Corrosion Resistance: Excellent resistance to chloride stress corrosion cracking and to oxidation in high-temperature environments.
-
Temperature Performance: Performs well from cryogenic temperatures up to 2000°F (1093°C).
-
Mechanical Strength: Retains strength under high stress and elevated temperatures.
-
Fabrication: Good workability and weldability.
Applications of Alloy 600
-
Furnace components
-
Heat-treating equipment
-
Nuclear reactor components
-
Chemical processing equipment
-
Aerospace engines and exhaust systems
What is Alloy 800?
Alloy 800, commonly known as Incoloy 800, is a nickel-iron-chromium alloy with controlled amounts of carbon, aluminum, and titanium. It was designed to resist oxidation and carburization in high-temperature service.
Key Features of Alloy 800
-
Composition: Nickel (30–35%), Chromium (19–23%), Iron (39.5% minimum), with titanium and aluminum additions.
-
High Temperature Strength: Excellent resistance to scaling and stress rupture up to 1100°C (2010°F).
-
Corrosion Resistance: Good resistance to many acidic environments and to high-temperature oxidation.
-
Stability: Maintains structural stability during prolonged exposure to high temperatures.
-
Variants: 800H and 800HT are modified versions with improved creep and stress rupture strength.
Applications of Alloy 800
-
Heat exchangers in petrochemical plants
-
Steam generator tubing
-
Superheater and reheater tubing in power plants
-
Industrial furnace components
-
Equipment in nitric acid and ethylene production
Chemical Composition Comparison
| Element | Alloy 600 | Alloy 800 |
|---|---|---|
| Nickel (Ni) | ~72% | 30–35% |
| Chromium (Cr) | 14–17% | 19–23% |
| Iron (Fe) | 6–10% | Balance (≥39.5%) |
| Carbon (C) | ≤0.15% | ≤0.10% |
| Titanium (Ti) | – | 0.15–0.60% |
| Aluminum (Al) | – | 0.15–0.60% |
Key Difference: Alloy 600 has a much higher nickel content, giving it outstanding resistance to a wide range of corrosive environments. Alloy 800 has lower nickel but is strengthened with aluminum and titanium for better high-temperature stability.
Mechanical Properties Comparison
| Property | Alloy 600 | Alloy 800 |
|---|---|---|
| Tensile Strength (MPa) | 655 | 520 |
| Yield Strength (MPa) | 310 | 205 |
| Elongation (%) | 40 | 30 |
| Hardness (HB) | ~150 | ~160 |
Observation: Alloy 600 offers higher strength and elongation, while Alloy 800 provides long-term stability at extreme temperatures.
Corrosion Resistance Comparison
-
Alloy 600: Excellent in chloride environments, alkaline solutions, and reducing conditions. Performs well in nuclear and chemical industries where resistance to caustic corrosion is critical.
-
Alloy 800: Outstanding resistance to carburization and oxidation at high temperatures, but less resistant to reducing acids compared to Alloy 600.
High Temperature Behavior
-
Alloy 600: Functions reliably up to 2000°F but may suffer from structural instability during prolonged exposure.
-
Alloy 800: Specifically designed for stability, making it superior in long-term, high-temperature service such as furnace tubes and petrochemical reactors.
Cost Considerations
-
Alloy 600: Generally more expensive due to its high nickel content.
-
Alloy 800: More cost-effective for high-temperature applications, offering a balance between performance and price.
Advantages of Alloy 600
-
Exceptional resistance to chloride stress corrosion cracking.
-
High strength across a wide temperature range.
-
Excellent oxidation resistance.
-
Good mechanical properties from cryogenic to elevated temperatures.
Advantages of Alloy 800
-
Excellent structural stability at prolonged high temperatures.
-
Resistant to oxidation and carburization.
-
More affordable than high-nickel alloys like 600.
-
Available in modified versions (800H, 800HT) for enhanced creep resistance.
Industrial Applications Comparison
-
Alloy 600: Best for environments involving chlorides, caustics, and high heat such as chemical processing and nuclear power systems.
-
Alloy 800: Best for applications involving long-term exposure to high heat and oxidation, including furnaces, petrochemical plants, and power generation systems.
Case Example
In a petrochemical refinery, engineers needed tubing for a furnace operating at 1000°C. While Alloy 600 provided initial corrosion resistance, Alloy 800 was chosen because of its superior stability at sustained high temperatures. On the other hand, for a nuclear power plant coolant system, Alloy 600 was preferred due to its excellent resistance to caustic and chloride corrosion.
Future Outlook
With increasing demands in energy, chemical processing, and environmental systems, both Alloy 600 and Alloy 800 will continue to play vital roles. Alloy 600 will dominate in highly corrosive environments, while Alloy 800 will remain the top choice for stable, high-temperature applications. Advances in alloy development may further enhance performance while reducing costs.
Why Source from sasaalloy
Selecting the right supplier is crucial when choosing nickel alloys for critical applications. sasaalloy offers Alloy 600, Alloy 800, and their variants in multiple forms such as plates, sheets, tubes, and bars, all manufactured to meet ASTM and ASME standards. With strict quality assurance, international certifications, and efficient global logistics, sasaalloy ensures customers receive reliable, high-performance materials for demanding industries.
Conclusion
The difference between Alloy 600 and Alloy 800 lies in their composition, strength, and suitability for specific applications. Alloy 600, with its higher nickel content, excels in chloride and caustic environments, while Alloy 800 provides superior stability and performance in prolonged high-temperature conditions.
By understanding these differences, industries can optimize their material choices, ensuring both efficiency and cost-effectiveness. Whether it is for chemical processing, nuclear power, or petrochemical applications, choosing between Alloy 600 and Alloy 800 is a matter of aligning material properties with service requirements.
Post time: Sep-05-2025