Haynes263 Alloy

Haynes263 (UNS N07263) is a high-performance age-hardenable nickel-chromium-cobalt (Ni-Cr-Co) based superalloy, specifically engineered for medium-temperature applications (550-650℃) requiring exceptional resistance to gas turbine exhaust environments, cyclic thermal stress, and thermal fatigue. Unlike Haynes242 (Ni-Mo-Cr, strengthened by long-range ordering), Haynes263 achieves its core performance through γ’ phase (Ni₃(Al,Ti)) precipitation strengthening—a classic yet highly effective mechanism that delivers balanced strength, ductility, and fabricability. This makes it a staple material for gas turbine hot-section components subjected to intermittent operation (e.g., aircraft engine start-stop cycles) and aggressive combustion gas atmospheres, spanning aerospace, power generation, and industrial turbomachinery.

1. Chemical Composition (Mass Fraction, %)

Haynes263’s composition is precisely tailored to promote γ’ phase formation, enhance oxidation/corrosion resistance, and maintain processability—critical for manufacturing complex-shaped hot-section components.

2. Physical Properties

Haynes263’s physical properties are optimized for compatibility with adjacent gas turbine materials (e.g., nickel-based turbine blades, titanium casings) and efficient heat management in cyclic operation.

2.1 Core Physical Parameters

• Density: 8.47 g/cm³ (room temperature, 25℃)

Lower than Haynes242 (9.05 g/cm³) due to lower Mo content—advantageous for weight-sensitive aerospace components (e.g., aircraft engine combustors).

• Melting Temperature Range: 1290-1350℃ (liquidus: 1350℃; solidus: 1290℃)

Narrow range ensures uniform casting and welding; compatible with standard superalloy processing workflows.

• Thermal Expansion Coefficient (CTE):

◦ 25-538℃: 12.5×10⁻⁶/℃

◦ 25-650℃: 13.0×10⁻⁶/℃

Slightly higher than Haynes242 (12.1×10⁻⁶/℃ at 25-871℃) but matched to turbine blade alloys (e.g., Inconel 718: 13.1×10⁻⁶/℃), minimizing thermal mismatch in hot-section assemblies.

• Thermal Conductivity (λ):

◦ 100℃: 15.1 W/(m·K)

◦ 500℃: 18.3 W/(m·K)

◦ 650℃: 20.5 W/(m·K)

Higher than Haynes242 (18.9 W/(m·K) at 760℃), facilitating faster heat dissipation in cyclic operation (reduces thermal fatigue).

• Electrical Resistivity (ρ):

◦ Room temperature: 125 μΩ·cm

◦ 650℃: 145 μΩ·cm

Moderate resistivity balances eddy current loss control and heat generation in high-frequency environments (e.g., turbine electromagnetic sensors).

2.2 Magnetic Properties

• Magnetic Permeability (μ): ~1.003-1.006μ₀ (room temperature, H=800A/m)

Essentially non-magnetic, avoiding interference with aircraft navigation systems and turbine magnetic bearings.

• Curie Temperature (Tc): ~350℃

Remains non-magnetic above 350℃—critical for maintaining performance in hot-section components (operating ≥550℃).

3. Mechanical Properties (After Standard Heat Treatment)

Haynes263’s mechanical performance is defined by γ’ phase strengthening, with properties tailored for medium-temperature cyclic loading. The standard heat treatment cycle is:

Solution Annealing: 1120℃ (2050℉) for 1 hour, air cooling → Aging: 845℃ (1550℉) for 2 hours + 760℃ (1400℉) for 16 hours, air cooling.

Key Mechanical Performance Notes

• Superior Low-Cycle Fatigue (LCF) Strength: At 650℃, LCF life (10⁴ cycles, Δε=0.5%) is ≥1200 cycles—outperforming solid-solution alloys (e.g., Haynes230: 800 cycles) and making it ideal for start-stop applications (e.g., aircraft engines, industrial gas turbines).
• Balanced Creep-Ductility: At 650℃, 1000-hour creep rupture strength (≥220MPa) combined with 18% elongation avoids brittle failure—critical for components like turbine transition ducts subjected to sustained stress and thermal shocks.
• Post-Aging Ductility Retention: Even after long-term service (10,000h at 600℃), elongation remains ≥15%, ensuring repairability (e.g., welding of cracked combustor liners).

4. Environmental Resistance (Core Application Advantage)

Haynes263 is engineered for gas turbine combustion environments, with targeted resistance to oxidation, thermal corrosion, and combustion gas erosion—key for long service life in harsh atmospheres.

5. Application Products & Industry Scenarios

Haynes263’s unique blend of γ’ strengthening, cyclic fatigue resistance, and gas environment compatibility makes it the material of choice for medium-temperature hot-section components in turbomachinery.

5.1 Aerospace Gas Turbine Industry

• Combustor Liners & Transition Ducts: Operate at 550-650℃, withstanding cyclic heating (200-650℃) and combustion gas erosion. Haynes263’s LCF strength extends service life to 5,000+ flight cycles (vs. 3,000 cycles for Hastelloy X).
• Turbine Mid-Casings: In high-bypass turbofan engines, resist thermal expansion mismatch with titanium outer casings; low density (8.47g/cm³) reduces engine weight by 8-10% vs. Inconel 718.
• Afterburner Components: Flame holders and spray bars in military jet engines, enduring intermittent high-temperature (650℃) operation and fuel-rich combustion environments.
• Industrial Gas Turbine (IGT) Hot Sections: Transition pieces and vane platforms in 50-100MW IGTs (e.g., GE Frame 6), resisting thermal corrosion from natural gas/heavy fuel combustion. Service intervals extended to 12,000 hours (vs. 8,000 hours for Haynes214).
• Waste Heat Recovery Boilers: Tube sheets and headers in combined-cycle power plants (600-650℃), withstanding flue gas corrosion and thermal cycling. Corrosion resistance reduces maintenance costs by 40%.
• Marine Gas Turbine Combustors: In naval vessels (e.g., destroyers), resist salt-laden combustion gas (high Cl⁻ content) and cyclic operation. Haynes263’s Cr₂O₃-ZrO₂ film reduces salt-induced pitting by 60% vs. 310S stainless steel.
• Locomotive Turbine Exhaust Casings: Endure diesel fuel combustion byproducts (sulfur, soot) at 550-600℃; creep resistance ensures dimensional stability for 8,000+ operating hours.

5.2 Industrial Power Generation

5.3 Marine & Locomotive Turbines

6. Processing & Heat Treatment Guidelines

Haynes263’s processability is a key advantage for manufacturing complex components (e.g., curved combustor liners), requiring careful control to preserve γ’ phase potential.

6.1 Hot Working

• Forging Temperature Range: 1050-1150℃ (1920-2100℉)

◦ Initial forging: ≥1100℃ (to dissolve coarse γ’ phases and ensure recrystallization).

◦ Final forging: ≥1050℃ (to avoid work hardening and premature γ’ precipitation).

• Hot Rolling: Reduction ratio per pass: 25-35%; intermediate annealing (1100℃, 30min, air cooling) after 50-60% total deformation to restore ductility. Ideal for producing thin sheets (0.5-5mm) for combustor liners.
• Cold Rolling/Drawing: Total deformation up to 40% (for sheets/wires). Intermediate annealing (1080℃, 1h, air cooling) after 15-20% deformation to prevent cracking. Cold forming feasible for simple shapes (e.g., flanges).
• Precision Forming: Stamping and bending at room temperature; minimum bend radius: 2× thickness (to avoid grain boundary cracking in aged material).
• Recommended Methods: Gas Tungsten Arc Welding (GTAW), Laser Beam Welding (LBW); avoid submerged arc welding (risk of boron segregation).
• Filler Metal: Haynes263 matching alloy wire (Ni-20Cr-20Co-3Ti-2Al-6Mo); preheating (150-200℃) required for thick sections (>6mm) to reduce residual stress.
• Post-Weld Heat Treatment (PWHT): Mandatory for strength restoration—1120℃ solution anneal (1h, air cool) + full aging cycle. PWHT restores 95% of base metal tensile strength.
• Solution Annealing: For thick components (>20mm), extend hold time to

6.2 Cold Working

6.3 Welding

6.4 Heat Treatment Optimization