GH2132 Superalloy
GH2132 is a nickel-iron-based superalloy strengthened by precipitation (primarily with chromium, nickel, and titanium-aluminum intermetallics), belonging to the Inconel 718 family of alloys. It is renowned for its exceptional high-temperature strength, creep resistance, and oxidation resistance, making it a critical material in applications requiring reliable performance under extreme thermal and mechanical stress. Below is a detailed overview of its composition, properties, processing, and applications:
1. Chemical Composition
GH2132’s composition is carefully formulated to balance precipitation strengthening, oxidation resistance, and processability. Key elements and their typical ranges are as follows:
Element Content Range (%) Role in the Alloy
Nickel (Ni) 24.0-27.0 Forms the matrix with iron, providing high-temperature stability and enabling precipitation of strengthening phases.
Iron (Fe) Base element (~38-46) Reduces alloy cost while maintaining high-temperature performance; works with nickel to form a stable matrix.
Chromium (Cr) 13.5-16.0 Enhances oxidation and corrosion resistance by forming a protective chromium oxide film at high temperatures.
Molybdenum (Mo) 1.0-1.5 Improves solid-solution strengthening and creep resistance at elevated temperatures.
Titanium (Ti) 2.4-2.8 Critical for precipitation strengthening, forming γ’ (Ni₃Ti) phases that enhance high-temperature strength.
Aluminum (Al) 0.4-0.8 Aids in forming γ’ phases and improves oxidation resistance by stabilizing the protective oxide layer.
Carbon (C) ≤0.08 Forms carbides at grain boundaries, enhancing creep resistance and preventing grain boundary sliding.
2. Physical Properties
GH2132 exhibits physical properties optimized for high-temperature structural applications:
Density: Approximately 7.93 g/cm³, lighter than many nickel-based superalloys, making it suitable for weight-sensitive components.
Melting Point: 1364-1427°C, ensuring stability in extreme heat conditions without structural breakdown.
Thermal Conductivity: Increases with temperature, ranging from ~15.1 W/(m·℃) at 100°C to ~22.7 W/(m·℃) at 800°C, facilitating effective heat dissipation.
Coefficient of Linear Expansion: 12.8×10⁻⁶/℃ (20-100°C) and 17.3×10⁻⁶/℃ (20-800°C). Compatibility with mating materials is critical to minimize thermal stress during temperature cycles.
Magnetic Property: Non-magnetic in the solution-annealed condition, ideal for applications requiring magnetic neutrality (e.g., aerospace electronics).
3. Mechanical Properties
GH2132’s mechanical performance is characterized by exceptional strength and creep resistance at high temperatures:
Tensile Strength:
At room temperature: Tensile strength (Rm) ≥ 930 MPa; yield strength (Rp0.2) ≥ 620 MPa.
At 650°C: Tensile strength remains ≥ 830 MPa; yield strength ≥ 590 MPa, ensuring robust load-bearing capacity in high-temperature service.
Ductility: Elongation (A5) ≥ 15% at room temperature and ≥ 12% at 650°C, providing sufficient formability for fabrication.
Creep Resistance: Excellent resistance to creep deformation under long-term high-temperature stress (e.g., creep rupture strength ≥ 620 MPa for 100 hours at 650°C), critical for extended service life in hot components.
Fatigue Resistance: Good resistance to cyclic loading, essential for components like turbine blades and bolts subjected to repeated thermal and mechanical stress.
Oxidation Resistance: Maintains structural integrity in oxidizing atmospheres up to 800°C, with minimal weight loss from oxidation after prolonged exposure.
4. Processing Performance
GH2132 can be processed using various methods, though precipitation strengthening requires precise heat treatment control:
Hot Working:
Suitable for hot forging, rolling, and extrusion. Optimal temperature range: 1100-1180°C, where the alloy exhibits good plasticity.
Slow cooling after hot working is recommended to avoid residual stress and facilitate subsequent heat treatment.
Cold Working:
Can be cold-rolled, drawn, or stamped, but work hardening is significant. Intermediate annealing (at 980-1050°C) restores ductility for further processing.
Welding:
Compatible with welding processes such as gas tungsten arc welding (GTAW) and electron beam welding.
Post-weld heat treatment (solution annealing + aging) is necessary to restore full strength and corrosion resistance.
Heat Treatment:
Standard treatment: Solution annealing at 980-1050°C (held for 1-2 hours) followed by air cooling, then aging at 700-720°C (held for 16 hours) and air cooling. This process precipitates γ’ phases for maximum strength.
5. Application Fields
GH2132’s combination of high strength, creep resistance, and cost-effectiveness (due to iron content) makes it widely used in:
Aerospace:
High-temperature fasteners, turbine disks, and blade retainers in aero-engines, where strength at 650-700°C is critical.
Structural components for rocket engines and spacecraft thermal systems.
Energy Sector:
Hot-end components of industrial gas turbines, such as turbine casings, bolts, and heat shields.
High-pressure valves and pipes in nuclear power plants and petrochemical reactors.
Industrial Manufacturing:
High-temperature springs, dies, and furnace fixtures for heat treatment processes.
Wear-resistant and corrosion-resistant parts in high-temperature mechanical equipment.
In summary, GH2132 is a high-performance nickel-iron-based superalloy valued for its exceptional high-temperature strength, creep resistance, and cost-effectiveness. Its versatility makes it a key material in critical applications across aerospace, energy, and industrial sectors where reliability under extreme conditions is paramount.