Inconel 600 is a nickel-chromium-iron superalloy known for its excellent corrosion resistance, high-temperature stability, and good mechanical properties across a wide temperature range. It is one of the earliest developed nickel-based superalloys and remains widely used in various industrial applications requiring reliability in harsh environments. Below is a detailed overview:
Chemical Composition
Nickel (Ni): 72.0% minimum
Chromium (Cr): 14.0-17.0%
Iron (Fe): 6.0-10.0%
Carbon (C): 0.15% maximum
Manganese (Mn): 1.0% maximum
Silicon (Si): 0.5% maximum
Copper (Cu): 0.5% maximum
Sulfur (S): 0.015% maximum
Physical Properties
Density: Approximately 8.47 g/cm³
Melting Point: 1370-1425°C
Thermal Conductivity: 15.1 W/m·°C at 100°C; increases to 23.0 W/m·°C at 800°C
Coefficient of Linear Expansion: 13.3×10⁻⁶/°C (20-100°C); 17.0×10⁻⁶/°C (20-800°C)
Electrical Resistivity: 72.0 μΩ·cm at 20°C
Magnetic Property: Non-magnetic in all heat-treated conditions
Mechanical Properties
Tensile Strength: Minimum 550 MPa at room temperature
Yield Strength (0.2% offset): Minimum 240 MPa at room temperature
Elongation: Minimum 30% at room temperature
Hardness: Maximum 150 HB in the annealed condition
High-Temperature Performance: Maintains good strength up to 800°C, with tensile strength remaining above 345 MPa at 650°C
Performance Characteristics
Corrosion Resistance: Excellent resistance to various corrosive environments, including:
Oxidizing media (e.g., nitric acid, high-temperature air) due to its chromium content.
Neutral and alkaline solutions, making it suitable for chemical processing.
Moderate resistance to chloride-induced pitting and crevice corrosion.
High-Temperature Stability: Resistant to oxidation in air up to 1000°C, forming a protective chromium oxide film.
Ductility and Toughness: Maintains good ductility even after long-term exposure to elevated temperatures, reducing the risk of brittle fracture.
Processing Performance
Hot Working: Can be hot-forged, rolled, or extruded in the temperature range of 1100-1200°C, with good plasticity and formability.
Cold Working: Suitable for cold rolling, drawing, and stamping, with moderate work hardening. Intermediate annealing (1010-1120°C followed by water quenching) restores ductility.
Welding: Easily weldable using common methods such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW). Filler metals like ERNiCr-3 are recommended to match the alloy’s properties.
Heat Treatment: Typically solution-annealed at 1010-1120°C for 30-60 minutes followed by water or air cooling to achieve optimal corrosion resistance and mechanical properties.
Application Fields
Chemical Processing: Reactors, heat exchangers, and piping for handling acids, alkalis, and organic compounds.
Nuclear Industry: Components in pressurized water reactors (PWRs) and nuclear fuel processing systems, thanks to its corrosion resistance in high-temperature water.
Aerospace: Combustion chamber liners, turbine exhaust components, and heat shields in gas turbine engines.
Heat Treatment: Furnace fixtures, radiant tubes, and baskets for high-temperature annealing and sintering processes.
Marine Engineering: Valves, pumps, and fasteners in seawater environments, where corrosion resistance is critical.
In summary, Inconel 600 is a versatile superalloy valued for its balanced combination of corrosion resistance, high-temperature stability, and processability. Its long-standing use across chemical, nuclear, aerospace, and industrial sectors underscores its reliability in demanding environments.