GH3128 Superalloy
GH3128 is a nickel-based superalloy strengthened by solid solution and precipitation (primarily with chromium, tungsten, molybdenum, and titanium). It is widely recognized for its excellent high-temperature strength, oxidation resistance, and thermal stability, making it a critical material in high-temperature industrial applications. Below is a detailed overview of its key properties, composition, processing, and applications:
1. Chemical Composition
The chemical composition of GH3128 is carefully formulated to balance strength, oxidation resistance, and processability. Key elements and their typical ranges include:
Element Content Range (%) Role in the Alloy
Nickel (Ni) Base element (~55-61) Serves as the matrix, providing a stable structure and high-temperature stability.
Chromium (Cr) 19.0-22.0 Enhances oxidation and corrosion resistance by forming a dense protective oxide film at high temperatures.
Tungsten (W) 7.5-9.5 Improves high-temperature strength and creep resistance through solid-solution strengthening.
Molybdenum (Mo) 1.8-2.3 Further enhances solid-solution strengthening and resistance to high-temperature deformation.
Titanium (Ti) 0.4-0.8 Promotes grain refinement and precipitation strengthening, improving room and high-temperature strength.
Carbon (C) ≤0.05 Controls grain growth and improves carbide formation for enhanced creep resistance.
Iron (Fe) ≤1.5 Minor impurity or additive to adjust alloy properties.
2. Physical Properties
GH3128 exhibits physical properties tailored for high-temperature environments:
Density: Approximately 8.80 g/cm³, making it suitable for structural components where weight efficiency is important.
Melting Point: 1370-1400°C, ensuring stability in extreme heat conditions.
Thermal Conductivity: Increases with temperature, ranging from ~11.6 W/(m·℃) at 100°C to ~25.1 W/(m·℃) at 1000°C, facilitating heat dissipation.
Coefficient of Linear Expansion: 12.8×10⁻⁶/℃ (20-100°C) and 16.5×10⁻⁶/℃ (20-1000°C). Compatibility with other materials must be considered to avoid thermal stress during temperature cycles.
Magnetic Property: Non-magnetic, ideal for applications requiring magnetic neutrality (e.g., aerospace electronics).
3. Mechanical Properties
The alloy’s mechanical performance is optimized for high-temperature strength and durability:
High-Temperature Strength:
Tensile strength (Rm) ≥ 750 MPa at room temperature.
At 800°C, tensile strength remains ≥ 550 MPa, with yield strength (Rp0.2) ≥ 300 MPa.
Elongation (A5) ≥ 35% at room temperature, ensuring ductility for forming and assembly.
Creep Resistance: Excellent resistance to creep deformation under long-term high-temperature stress (e.g., <0.2% creep strain after 1000 hours at 850°C under 200 MPa load). Fatigue Resistance: Good resistance to cyclic loading, critical for components like turbine blades and combustion chambers subjected to repeated thermal and mechanical stress. Oxidation Resistance: Maintains structural integrity in oxidizing atmospheres up to 1000°C, thanks to the protective chromium oxide layer. 4. Processing Performance GH3128 can be processed using various methods, though careful control is required due to its high alloying content: Hot Working: Suitable for hot forging, rolling, and extrusion. Optimal temperature range: 1100-1200°C. Slow cooling after hot working is recommended to avoid residual stress. Cold Working: Can be cold-rolled, drawn, or stamped, but work hardening occurs rapidly. Intermediate annealing (at 1050-1100°C) is needed to restore ductility. Welding: Compatible with welding processes such as gas tungsten arc welding (GTAW) and electron beam welding. Pre-weld cleaning and post-weld annealing (1050-1100°C) are advised to prevent oxidation and reduce residual stress. Heat Treatment: Standard treatment: Solution annealing at 1150-1200°C (held for 1-2 hours) followed by air cooling, optimizing grain structure and mechanical properties. 5. Application Fields GH3128’s combination of high-temperature performance and processability makes it indispensable in several industries: Aerospace: Components of aero-engines, including combustion chambers, afterburners, and turbine casings. Rocket engine nozzles and heat shields for spacecraft. Energy Sector: Hot-end components of industrial gas turbines (e.g., transition pieces, flame holders). High-temperature heat exchangers and reactor parts in petrochemical and nuclear industries. Metallurgy and Manufacturing: Furnace fixtures, radiant tubes, and high-temperature rollers for heat treatment and glass production. Tools and dies for high-temperature forming processes. In summary, GH3128 is a versatile nickel-based superalloy designed to excel in extreme high-temperature environments, where its strength, oxidation resistance, and processability make it a material of choice for critical industrial and aerospace applications.