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, %)

 

Element

Carbon (C)

Chromium (Cr)

Nickel (Ni)

Cobalt (Co)

Molybdenum (Mo)

Tungsten (W)

Titanium (Ti)

Aluminum (Al)

Niobium (Nb)

Iron (Fe)

Manganese (Mn)

Silicon (Si)

Phosphorus (P)

Sulfur (S)

Boron (B)

Zirconium (Zr)

Content Range

≤0.06

19.0-22.0

35.0-39.0

10.0-12.0

3.5-4.5

1.5-2.5

2.5-3.0

0.4-0.9

0.9-1.4

Balance

≤0.30

≤0.30

≤0.012

≤0.008

≤0.010

≤0.10

Function Note

Precisely controls grain growth; forms fine MC carbides at grain boundaries to enhance intergranular strength and creep resistance (avoids brittle carbides)

Enhances high-temperature oxidation and thermal corrosion resistance; forms dense Cr₂O₃ outer film to isolate corrosive media

Forms stable γ' phase with Ti/Al/Nb; ensures alloy ductility and toughness at 720-950℃

Improves matrix stability; raises recrystallization temperature by 50-80℃ vs. GH2901; enhances high-temperature strength

Enhances medium-temperature (700-850℃) strength; improves resistance to hydrogen embrittlement in coal-to-chemical environments

Enhances ultra-high-temperature (850-950℃) strength; forms W-rich precipitates to inhibit creep deformation

Core element for γ' phase precipitation; increases γ' content vs. GH2901 to improve high-temperature creep resistance

Assists Ti in forming fine γ' phase; optimizes particle size (0.08-0.18μm) for balanced strength and ductility

Enhances γ' phase stability; raises γ' solvus temperature to 1000℃, extending upper service limit

Matrix element; balances alloy cost, density, and processability for large components

Improves hot workability; strictly controlled to avoid low-melting-point inclusions

Enhances deoxidation effect; strictly limited to avoid reducing high-temperature mechanical properties

Strictly limited to prevent intergranular corrosion in sulfur/chloride-containing environments

Strictly limited to avoid hot cracking during forging/welding; refines grain boundaries

Refines grain boundaries; improves intergranular strength and thermal fatigue resistance

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)

 

Property	Room Temperature (25℃)	720℃	820℃	900℃	950℃
Yield Strength (σ₀.₂, MPa)	≥780	≥710	≥630	≥480	≥390
Tensile Strength (σᵦ, MPa)	≥980	≥910	≥810	≥620	≥520
Elongation (δ₅, %)	≥17	≥15	≥13	≥11	≥9
Reduction of Area (ψ, %)	≥24	≥22	≥20	≥17	≥14
Creep Rupture Strength (1000h, MPa)	-	≥550	≥450	≥300	≥220

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.