GH2907 Alloy

GH2907 is a premium iron-nickel-cobalt (Fe-Ni-Co) based precipitation-hardening wrought superalloy, upgraded from GH2901 to meet higher-temperature service demands in harsh thermal-mechanical-corrosion coupling environments. It achieves strengthening primarily through the coherent precipitation of high-stability γ’ phase (Ni₃Al, Ti, Nb) — with a γ’ phase content optimized to 22-27% — and is supplemented by synergistic solid solution strengthening from chromium (Cr), molybdenum (Mo), and tungsten (W). Unlike GH2901 (focused on 680-900℃ service), GH2907 incorporates tungsten to enhance ultra-high-temperature strength and adjusts the Ni-Co ratio to improve matrix stability, enabling reliable long-term operation in extreme conditions ranging from 720℃ to 950℃.

Notably, GH2907 forms a dense, multi-layer protective oxide film (Cr₂O₃-Al₂O₃-WO₃-Nb₂O₅) at ultra-high temperatures, providing superior resistance to sulfur-containing flue gas, high-pressure steam, and molten salt corrosion (even in chloride-rich environments). It retains excellent hot workability for manufacturing large-scale complex load-bearing components (e.g., advanced industrial gas turbine high-pressure disks, ultra-supercritical power plant boiler cores) and is widely used in next-generation thermal power generation, heavy-duty industrial gas turbines, and coal-to-chemical industries, where material performance under ultra-high-temperature and high-stress conditions is 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℃), slightly higher than GH2901 (8.10g/cm³) due to W addition, but 6-8% lower than high-Ni superalloys such as GH4738 (8.45g/cm³). This low-density advantage is critical for weight-sensitive ultra-high-temperature load-bearing components (e.g., industrial gas turbine high-pressure disks), reducing equipment overall weight by 2-7% compared to high-alloyed alternatives like Inconel 718.
• Magnetic Properties: Weakly magnetic at room temperature (magnetic permeability μᵣ ≈ 1.007-1.015); magnetic property gradually fades as temperature rises, becoming nearly non-magnetic (μᵣ ≈ 1.001-1.002) in the service temperature range (720-950℃). This makes it suitable for applications near general electromagnetic equipment, though caution is needed for high-precision magnetic sensors (e.g., gas turbine speed sensors, nuclear reactor magnetic control systems).
• Melting Temperature Range: 1350-1410℃ (liquidus: ~1410℃; solidus: ~1350℃). The narrow and stable melting range ensures uniform solidification during casting and consistent deformation during forging, reducing internal defects (e.g., shrinkage porosity, segregation) and improving structural integrity—critical for high-stress ultra-high-temperature parts like turbine rotors.
• Thermal Expansion Coefficient (CTE):

2.2 Thermal Properties

◦ 20-100℃: ~12.1×10⁻⁶/℃

◦ 20-600℃: ~13.6×10⁻⁶/℃

◦ 20-800℃: ~14.9×10⁻⁶/℃

◦ 20-900℃: ~15.3×10⁻⁶/℃

◦ 20-950℃: ~15.6×10⁻⁶/℃

The more gradual CTE increase (vs. GH2901) minimizes thermal stress during frequent temperature cycling (e.g., gas turbine start-stop, ultra-supercritical boiler load adjustment), reducing thermal fatigue cracking risk by 55-65% compared to Fe-Ni-Co alloys like GH2901.

• Thermal Conductivity (λ):

◦ 100℃: ~15.2W/(m·K)

◦ 500℃: ~18.5W/(m·K)

◦ 800℃: ~21.8W/(m·K)

◦ 900℃: ~22.6W/(m·K)

◦ 950℃: ~23.3W/(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 40-45% compared to GH2901.

2.3 Mechanical Properties (After Standard Heat Treatment: 1120-1160℃ solid solution for 1h, water cooling + 760-790℃ aging for 8h, air cooling)

Key Notes:

• The ultra-high room-temperature strength (σᵦ ≥980MPa) meets the load-bearing requirements of industrial gas turbine high-pressure disks and ultra-supercritical boiler valves, with strength 3-5% higher than GH2901;
• At 820℃ (a typical service temperature for coal-to-chemical cracking furnace internals), the creep rupture strength (≥450MPa) is 7-10% higher than that of GH2901, ensuring long-term structural stability under ultra-high-temperature load;
• Even at 950℃ (near its upper service limit), the retained elongation (≥9%) and creep rupture strength (≥220MPa) prevent brittle fracture during emergency shutdowns, making it suitable for components with extreme thermal cycling (e.g., advanced metallurgical furnace rolls, gas turbine combustion chamber liners).

3. Application Products & Industry Scenarios

3.1 Advanced Industrial Gas Turbine Field

As a core material for ultra-high-temperature components in next-generation industrial gas turbines, GH2907 is used for:

• High-pressure Turbine Disks: Disks (rotational speed up to 20,000 rpm) in combined cycle power generation turbines (turbine inlet temperature: 1300-1400℃), operating in 850-900℃ high-temperature gas environments; the alloy’s creep resistance ensures a service life of up to 150,000 hours;
• Combustion Chamber Liners: Hot-zone liners in combustion chambers, resisting 900-950℃ high-temperature gas 冲刷 and thermal fatigue; its thermal stability reduces deformation risks by 45-55% compared to GH2901;
• Turbine Blades (Medium-Pressure Stages): Blades in stages 2-4 of turbines, withstanding 780-850℃ gas erosion and centrifugal forces; its low density reduces turbine rotational inertia and energy consumption by 5-8%.

3.2 Ultra-supercritical (A-USC) Thermal Power Generation Field

In advanced ultra-supercritical power plants (steam parameters: 650-700℃, 35-40MPa), GH2907 is applied to:

• Boiler Core Components: Final superheater headers (operating temperature: 720-760℃) and steam collection boxes, where its excellent weldability allows for large-diameter header manufacturing (maximum diameter ≥1600mm) without welding defects;
• Steam Turbine Rotor Parts: High-pressure turbine rotor shafts and integral disks, withstanding 680-730℃ high-pressure steam and cyclic thermal stress; the alloy’s creep resistance extends maintenance intervals by 36-42 months compared to GH2901;
• Superheater Tube Supports: High-temperature support brackets for superheater tubes, resisting 750-800℃ steam oxidation and mechanical wear; its corrosion resistance reduces scaling by 60-70%.

3.3 Coal-to-Chemical & Petrochemical Field

In large-scale coal-to-olefins and heavy oil hydrogenation units (operating temperature: 800-920℃), GH2907 is used for:

• Cracking Furnace Tubes: Core furnace tubes in coal-to-olefins cracking furnaces, resisting hydrocarbon gas pyrolysis corrosion and high-temperature sulfur/chloride-containing media; compared to GH2901, it extends service life by 60-70% and reduces maintenance costs by 50-55%;
• High-pressure Hydrogenation Reactor Internals: Catalyst support grids and reactor inner liners in heavy oil hydrogenation reactors (pressure: 25-30MPa, temperature: 850-900℃), resisting hydrogen embrittlement and severe corrosion;
• Waste Heat Boiler Tubes: Tubes in coal gasification waste heat boilers, resisting 820-880℃ flue gas corrosion (containing H₂S, HCl) and improving heat recovery efficiency by 22-28%.
• Metallurgical Industry: High-temperature furnace rolls (working temperature: 820-920℃) for nickel-based superalloy continuous annealing lines, withstanding high-temperature air oxidation and metal melt splashing; the alloy’s wear resistance extends roll service life by 80-90% compared to 310S stainless steel;
• Vacuum Heat Treatment Equipment: Heating element supports and furnace liners in ultra-high-temperature vacuum annealing furnaces (operating temperature: 900-950℃), ensuring uniform temperature distribution and avoiding contamination of heat-treated workpieces (e.g., high-precision aerospace superalloy components);
• High-temperature Test Equipment: Sample holders for ultra-high-temperature creep testing (720-950℃) and high-load fixture components in material performance testing machines, providing stable support for long-term tests (up to 12,000 hours) and ensuring accurate test data for next-generation superalloy research.
• Hot Working: Forging temperature range: 1160-1220℃; initial forging temperature should not exceed 1220℃ to avoid γ’ phase dissolution and grain coarsening, and final forging temperature should not be lower than 1020℃ (higher than GH2901) to prevent work hardening and cracking;
• Cold Working: Cold working is limited to light deformation (≤12%) such as precision machining and grinding; cold rolling or stamping is not recommended due to ultra-high room-temperature strength; intermediate annealing (1060-1100℃, 1h) is required after any cold deformation to restore ductility—annealing temperature is 20-40℃ higher than GH2901 to ensure full recrystallization;
• Heat Treatment: The two-step process (solid solution + aging) must be strictly controlled—over-aging (above 820℃) will cause γ’ phase coarsening (particle size >0.3μm) and significant strength degradation, while under-aging (below 740℃) will result in insufficient precipitation strengthening and reduced ultra-high-temperature creep resistance.

3.4 Metallurgical & High-end Industrial Fields

4. Processing & Heat Treatment Recommendations

This comprehensive performance and application profile makes GH2907 an advanced, high-reliability superalloy for ultra-high-temperature high-end manufacturing, perfectly balancing thermal corrosion resistance, ultra-high-temperature strength, and processability for the most demanding large-scale, complex-shaped components in next-generation energy, aerospace, and chemical industries.