GH4033 Alloy

GH4033 is a high-performance nickel-based precipitation-hardening wrought superalloy, specifically designed for ultra-high-temperature service scenarios requiring exceptional creep resistance and microstructural stability. It achieves strengthening primarily through the coherent precipitation of γ’ phase (Ni₃Al, Ti) — the core strengthening phase — and is supplemented by solid solution strengthening from chromium (Cr). Unlike solid solution alloys such as GH3034, GH4033 maintains outstanding mechanical properties at higher temperatures, enabling reliable long-term operation in harsh environments ranging from 800℃ to 1050℃.

Notably, GH4033 exhibits excellent resistance to high-temperature oxidation (forming a dense Al₂O₃-Cr₂O₃ composite oxide film) and thermal corrosion from sulfur-containing media, while retaining good hot workability for manufacturing complex load-bearing components. It is widely used in core hot-end parts of advanced aero-engines, industrial gas turbines, and high-end energy equipment, where material ultra-high-temperature strength and long-term reliability are critical. 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 8.20g/cm³ at room temperature (25℃), which is slightly higher than solid solution alloy GH3034 (8.10g/cm³) due to Ti/Al addition, but 6-8% lower than high-W nickel-based superalloys such as GH3128 (8.70g/cm³). This low-density advantage is critical for weight-sensitive ultra-high-temperature load-bearing components (e.g., aero-engine turbine blades), reducing equipment overall weight by 4-9% compared to high-alloyed nickel-based alternatives.
• Magnetic Properties: Non-magnetic across the entire service temperature range (room temperature to 1050℃) (magnetic permeability μᵣ ≈ 1.000-1.001). This makes it highly suitable for applications near precision magnetic sensors (e.g., aero-engine turbine speed sensors, nuclear reactor magnetic control systems), as it does not interfere with magnetic field distribution or sensor accuracy.
• Melting Temperature Range: 1360-1420℃ (liquidus: ~1420℃; solidus: ~1360℃). The narrow and stable melting range ensures uniform solidification during investment casting (for turbine blades) and consistent deformation during forging, reducing internal defects (e.g., shrinkage porosity, segregation) and improving component structural integrity—critical for high-stress ultra-high-temperature parts.
• Thermal Expansion Coefficient (CTE):

2.2 Thermal Properties

◦ 20-100℃: ~12.5×10⁻⁶/℃

◦ 20-600℃: ~14.0×10⁻⁶/℃

◦ 20-800℃: ~15.3×10⁻⁶/℃

◦ 20-1000℃: ~16.0×10⁻⁶/℃

◦ 20-1050℃: ~16.3×10⁻⁶/℃

The gradual CTE increase minimizes thermal stress during frequent temperature cycling (e.g., aero-engine start-stop, gas turbine load adjustment), reducing thermal fatigue cracking risk by 45-55% compared to conventional nickel-based alloys (e.g., Inconel 625).

• Thermal Conductivity (λ):

◦ 100℃: ~15.0W/(m·K)

◦ 500℃: ~18.5W/(m·K)

◦ 800℃: ~21.8W/(m·K)

◦ 1000℃: ~23.5W/(m·K)

◦ 1050℃: ~24.2W/(m·K)

The temperature-dependent conductivity improvement promotes efficient heat dissipation in ultra-high-temperature components, avoiding localized overheating (a major cause of γ’ phase coarsening and creep acceleration) and extending part service life by 30-35% compared to GH3034.

2.3 Mechanical Properties (After Standard Heat Treatment: 1080-1120℃ solid solution for 1h, water cooling + 700-720℃ aging for 16h, air cooling)

Key Notes:

• The ultra-high room-temperature strength (σᵦ ≥950MPa) meets the load-bearing requirements of aero-engine turbine blades and high-pressure fasteners, with strength 70-80% higher than solid solution alloy GH3034;
• At 900℃ (a typical service temperature for industrial gas turbine hot-end parts), the creep rupture strength (≥250MPa) is 25-30% higher than that of GH3128, ensuring long-term structural stability under high-temperature cyclic load;
• Even at 1050℃ (near its upper service limit), the retained elongation (≥6%) and creep rupture strength (≥60MPa) prevent brittle fracture during emergency shutdowns, making it suitable for components with extreme thermal cycling (e.g., aero-engine combustion chamber liners).

3. Application Products & Industry Scenarios

3.1 Aerospace Field

As a core material for advanced aero-engine hot-end parts, GH4033 is used for:

• Aero-engine Turbine Blades: Low-pressure and medium-pressure turbine blades (rotational speed up to 18,000 rpm) in large bypass ratio turbofan engines (thrust ≥180kN), operating in 900-1000℃ high-temperature gas environments; the alloy’s creep resistance ensures a service life of up to 35,000 flight hours;
• Turbine Disks: Medium-pressure turbine disks, withstanding centrifugal forces up to 40,000g and 850-900℃ gas erosion; its fine-grained structure (grain size 5-8 ASTM) ensures uniform strength distribution;
• Combustion Chamber Liners: Hot-zone liners in aero-engine combustion chambers, resisting 1000-1050℃ high-temperature gas 冲刷 and thermal fatigue, reducing liner replacement frequency by 40-50% compared to GH3128.

3.2 Energy Field

3.2.1 Industrial Gas Turbines

In heavy-duty industrial gas turbines (turbine inlet temperature: 1200-1300℃) for power generation and mechanical drive, GH4033 is applied to:

• Turbine Rotor Blades: Medium-pressure turbine blades (stage 3-5), withstanding 900-950℃ high-pressure gas and cyclic thermal stress; the alloy’s creep resistance improves gas turbine efficiency (up to 58% for combined cycle power generation);
• Combustion Chamber Support Rings: High-temperature support rings around combustion chambers, resisting radiant heat and ensuring structural stability for over 100,000 hours of operation.

3.2.2 Advanced Nuclear Energy

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

• Heat Exchanger Tubes: High-temperature heat exchanger tubes in MSRs, resisting corrosion by molten fluoride salts (e.g., LiF-BeF₂) and weak radiation;
• Reactor Core Structural Parts: Auxiliary structural parts in HTGRs, withstanding 750-800℃ high-temperature helium gas erosion.

3.3 Petrochemical Field

In large-scale coal-to-olefins and ethylene cracking units (operating temperature: 950-1050℃), GH4033 is used for:

• Ultra-high-temperature Cracking Furnace Tubes: Core furnace tubes in coal-to-olefins cracking furnaces, resisting hydrocarbon gas pyrolysis corrosion and creep deformation; compared to GH3034, it extends furnace tube service life by 60-70% and reduces maintenance costs by 45-50%;
• High-pressure Valve Stems: Valve stems in high-temperature syngas pipelines (pressure: 20-25MPa, temperature: 900-950℃), resisting hydrogen embrittlement and ensuring valve sealing reliability.
• Metallurgical Industry: High-temperature furnace rolls (working temperature: 900-950℃) for nickel-based superalloy hot rolling, withstanding alloy melt splashing and mechanical wear; its oxidation resistance extends roll service life by 80-90% compared to 310S stainless steel;
• Vacuum Heat Treatment Equipment: Heating elements and furnace liners in vacuum annealing furnaces (operating temperature: 1000-1050℃), ensuring uniform temperature distribution and avoiding contamination of heat-treated workpieces;
• High-temperature Test Equipment: Sample holders for ultra-high-temperature creep testing (800-1050℃) and high-load fixture components in material performance testing machines, providing stable support for long-term tests (up to 10,000 hours) and ensuring accurate test data for superalloy research.
• Hot Working: Forging temperature range: 1120-1180℃; initial forging temperature should not exceed 1180℃ to avoid γ’ phase dissolution and grain coarsening, and final forging temperature should not be lower than 1000℃ to prevent work hardening and cracking;
• Cold Working: Cold working is limited to light deformation (≤15%) such as precision machining and grinding; cold rolling or stamping is not recommended due to high room-temperature strength; intermediate annealing (1050-1080℃, 1h) is required after any cold deformation to restore ductility;
• Heat Treatment: The two-step process (solid solution + aging) must be strictly controlled—over-aging (above 750℃) will cause γ’ phase coarsening (particle size >0.5μm) and significant strength degradation, while under-aging (below 680℃) will result in insufficient precipitation strengthening and reduced high-temperature creep resistance.

3.4 Metallurgical & High-end Industrial Fields

4. Processing & Heat Treatment Recommendations

This comprehensive performance and application profile makes GH4033 an advanced, high-reliability nickel-based superalloy for ultra-high-temperature high-end manufacturing, perfectly balancing ultra-high-temperature strength, oxidation resistance, and processability for the most demanding hot-end components in aerospace, energy, and petrochemical industries.