GH5188 Alloy

GH5188 is a premium cobalt-chromium-nickel (Co-Cr-Ni) based solid solution strengthened wrought superalloy, specifically engineered for ultra-high-temperature service scenarios requiring exceptional oxidation resistance, thermal corrosion resistance, and structural stability under extreme heat. It achieves strengthening primarily through the synergistic solid solution effect of chromium (Cr), tungsten (W), and molybdenum (Mo) — without relying on precipitation phases (unlike Fe-Ni-Co based GH2907) — and incorporates cobalt as the matrix element to enhance high-temperature stability. This alloy excels in continuous ultra-high-temperature environments ranging from 1000℃ to 1200℃, making it a core material for components exposed to aerodynamic heating, high-temperature gas erosion, or molten salt corrosion.

Notably, GH5188 forms a dense, self-healing Cr₂O₃-Al₂O₃ composite oxide film at ultra-high temperatures, providing superior resistance to sulfur-containing flue gas, molten salt (e.g., nitrate, chloride), and high-pressure oxygen. It retains good hot workability and weldability for manufacturing thin-walled or complex-shaped components (e.g., combustion chamber liners, heat shields) and is widely used in hypersonic aircraft propulsion systems, advanced industrial furnaces, and next-generation nuclear energy equipment. The following is a comprehensive breakdown of its chemical composition, physical properties, and application products.

1. Chemical Composition (Mass Fraction, %)

2. Physical Properties

2.1 Basic Physical Parameters

• Density: Approximately 9.15g/cm³ at room temperature (25℃), higher than Fe-Ni-Co based GH2907 (8.20g/cm³) and Ni-based GH4738 (8.45g/cm³) due to high W and Co content. While denser, its exceptional ultra-high-temperature strength and corrosion resistance offset weight concerns for critical components (e.g., hypersonic heat shields), where performance takes priority over weight.
• Magnetic Properties: Weakly magnetic at room temperature (magnetic permeability μᵣ ≈ 1.010-1.018); magnetic property gradually fades as temperature rises, becoming nearly non-magnetic (μᵣ ≈ 1.002-1.003) in the service temperature range (1000-1200℃). This makes it suitable for applications near general electromagnetic equipment, though caution is needed for high-precision magnetic sensors (e.g., aerospace navigation systems).
• Melting Temperature Range: 1370-1430℃ (liquidus: ~1430℃; solidus: ~1370℃). The stable melting range ensures the alloy maintains structural integrity even in short-term ultra-high-temperature spikes (up to 1350℃), providing a reliable material foundation for components exposed to extreme heat (e.g., rocket engine nozzles).
• Thermal Expansion Coefficient (CTE):

2.2 Thermal Properties

◦ 20-100℃: ~12.8×10⁻⁶/℃

◦ 20-600℃: ~14.5×10⁻⁶/℃

◦ 20-1000℃: ~16.2×10⁻⁶/℃

◦ 20-1200℃: ~17.0×10⁻⁶/℃

The gradual CTE increase minimizes thermal stress during rapid temperature cycling (e.g., hypersonic aircraft ascent/descent, industrial furnace start-stop), reducing thermal fatigue cracking risk by 50-60% compared to Co-based alloys like Haynes 188.

• Thermal Conductivity (λ):

◦ 100℃: ~14.0W/(m·K)

◦ 500℃: ~17.5W/(m·K)

◦ 1000℃: ~21.0W/(m·K)

◦ 1200℃: ~23.5W/(m·K)

The temperature-dependent conductivity improvement promotes efficient heat dissipation in ultra-high-temperature components, avoiding localized overheating (a major cause of material softening) and extending part service life by 35-40% compared to conventional Co-Cr alloys.

2.3 Mechanical Properties (After Standard Heat Treatment: 1150-1200℃ solid solution for 1h, air cooling)

Key Notes:

• The high room-temperature ductility (δ₅ ≥20%) ensures excellent formability, allowing the alloy to be processed into ultra-thin-walled tubes (minimum wall thickness ≥0.3mm) or curved heat shields via rolling, bending, or stamping;
• At 1000℃ (a typical service temperature for industrial furnace components), the creep rupture strength (≥180MPa) is 25-30% higher than that of Ni-based GH3128, ensuring long-term structural stability under ultra-high-temperature load;
• Even at 1200℃ (near its upper service limit), the retained elongation (≥10%) prevents brittle fracture during emergency shutdowns, making it suitable for components with extreme thermal cycling (e.g., hypersonic aircraft exhaust nozzles).

3. Application Products & Industry Scenarios

3.1 Aerospace & Defense Field

As a core material for ultra-high-temperature components in aerospace and defense systems, GH5188 is used for:

• Hypersonic Aircraft Propulsion Parts: Combustion chamber liners and nozzle throat components in scramjet engines, resisting 1100-1200℃ aerodynamic heating and high-temperature gas erosion; the alloy’s oxide film stability ensures service life during long-duration hypersonic flights (Mach 5+);
• Rocket Engine Components: Thrust chamber liners and exhaust nozzles in liquid rocket engines, withstanding 1200-1300℃ high-temperature combustion gas and thermal shock; its creep resistance reduces deformation risks by 45-55% compared to Haynes 188;
• Aerospace Thermal Protection Systems: Heat shield panels and leading edges for reentry vehicles (e.g., space capsules), resisting 1000-1150℃ reentry heating and ensuring structural integrity during atmospheric reentry.

3.2 Advanced Industrial Furnace Field

In ultra-high-temperature industrial furnaces (operating temperature: 1000-1200℃) for metallurgy, ceramics, and materials processing, GH5188 is applied to:

• Furnace Liners & Muffle Tanks: Inner liners of vacuum sintering furnaces and muffle tanks for superalloy heat treatment, resisting high-temperature air oxidation and ensuring uniform furnace temperature distribution; compared to 310S stainless steel, it extends service life by 80-90% and reduces maintenance costs by 60-70%;
• Heating Element Supports: Support brackets for silicon carbide (SiC) or molybdenum disilicide (MoSi₂) heating elements, withstanding 1100-1200℃ radiant heat and mechanical load;
• High-temperature Conveyors: Conveyor belts and rollers for ceramic sintering furnaces, resisting 1000-1050℃ high-temperature wear and thermal fatigue.

3.3 Energy & Nuclear Field

3.3.1 Molten Salt Energy Storage

In next-generation molten salt energy storage systems (heat transfer fluid temperature: 565-600℃, molten salt type: nitrate), GH5188 is used for:

• Heat Exchanger Tubes: Tubes in molten salt-air heat exchangers, resisting molten salt corrosion and high-temperature oxidation; the alloy’s corrosion resistance reduces tube scaling by 70-80% and improves heat exchange efficiency;
• Molten Salt Storage Tank Internals: Agitators and temperature sensors in molten salt storage tanks, withstanding long-term molten salt immersion and ensuring system reliability.

3.3.2 Advanced Nuclear Energy

For molten salt reactors (MSRs) and high-temperature gas-cooled reactors (HTGRs) (coolant temperature: 700-850℃), the alloy is used for:

• Reactor Core Auxiliary Components: Fuel handling tools and coolant flow guides in MSRs, resisting molten fluoride salt corrosion and weak neutron radiation;
• High-temperature Gas Ducts: Ducts for transporting high-temperature helium gas in HTGRs, withstanding 800-850℃ gas erosion and thermal fatigue.
• Metallurgical Industry: High-temperature sample holders and crucibles for superalloy vacuum induction melting (VIM), resisting 1050-1150℃ molten alloy erosion and ensuring molten metal purity;
• High-temperature Material Testing: Sample frames and fixtures for ultra-high-temperature oxidation testing (1000-1200℃) and creep testing, providing stable support for long-term tests (up to 5,000 hours) and ensuring accurate test data for next-generation ultra-high-temperature materials.
• Hot Working: Forging temperature range: 1180-1250℃; initial forging temperature should not exceed 1250℃ to avoid grain coarsening, and final forging temperature should not be lower than 1050℃ to prevent work hardening and cracking; hot working should be performed with slow deformation rates to avoid cracking;
• Cold Working: Cold rolling or stamping can be performed at room temperature, but deformation should be limited to ≤15% per pass due to high work hardening rate; intermediate annealing (1100-1150℃, 1h, air cooling) is recommended after each cold working pass to restore ductility;
• Welding: Suitable for TIG welding, MIG welding, and electron beam welding. Welding filler metal recommended: Co-Cr-Ni-W-Mo alloy (matching GH5188 composition); preheating temperature: 200-300℃; post-weld heat treatment: 1150-1200℃ solid solution for 1h, air cooling, to eliminate welding stress and restore oxidation resistance.

3.4 Metallurgical & Materials Testing Field

4. Processing & Welding Recommendations

This comprehensive performance and application profile makes GH5188 an advanced, high-reliability superalloy for ultra-high-temperature manufacturing, perfectly balancing extreme-temperature oxidation resistance, thermal stability, and processability for the most demanding components in aerospace, energy, and industrial fields.