NC6949 Nimonic C-263 Plate

Nimonic C-263 Plates Description

Nimonic C-263 Plates exhibit a γ-austenitic microstructure strengthened by 25–30 vol% γ' precipitates (Ni₃[Al, Ti], 20–50 nm diameter) after solution treatment (1150°C) and ageing (800°C/8h). Grain boundaries are decorated with discontinuous M₂₃C₆ carbides (<1 vol%), while intragranular MC carbides (Ti/Mo-rich) provide dispersion hardening. The alloy exhibits an anisotropic mechanical behaviour: the yield strength in the rolling direction (∥RD) attains 750–850 MPa, compared with 650–700 MPa in the transverse direction, attributable to a 〈110〉 texture.

Thermomechanical properties include directional thermal expansion (∥RD CTE: 14.2 μm/m·°C, ⊥RD: 14.9 μm/m·°C at 20–800°C) and thermal conductivity (∥RD: 12.1 W/m·K, ⊥RD: 10.8 W/m·K at 500°C). Creep resistance is derived from γ' coherency strains, sustaining >100 MPa stress at 800°C for 100 hours without tertiary creep. Oxidation kinetics follow parabolic scaling (kₚ=3×10⁻¹⁴ g²/cm⁴·s at 900°C) via adherent Cr₂O₃ scales doped with TiO₂.

Surface characteristics feature controlled roughness (Ra ≤1.6 μm for cold-rolled, ≤3.2 μm for hot-rolled) and chromium-depletion zones <0.3 μm after pickling. Electrochemically, passive films exhibit high impedance (>10⁶ Ω·cm²) in 3.5% NaCl at 600°C, with pitting potentials >+800 mV_SCE. Phase instability initiates at 900°C: σ-phase formation exceeds 0.3 vol% after 1 000 hours, reducing impact toughness by 35%. Fatigue strength at 800°C remains >300 MPa (10⁷ cycles) due to γ'-mediated slip homogenisation, while residual stresses from rolling are maintained below 15% of the yield strength via stress-relief annealing. Degradation is dominated by γ' coarsening (>100 nm) above 850°C, thereby accelerating dislocation climb.

Nimonic C-263 Plates Applications

Nimonic C-263 plates are utilised in extreme thermomechanical environments, where high-temperature strength, oxidation resistance and fabricability are required. Their primary application is in aerospace combustion chambers and afterburner liners, where γ'-precipitate hardening maintains creep strength above 100 MPa at 800°C and mitigates thermal fatigue during rapid thermal cycles. The alloy’s controlled Al/Ti ratio permits welded fabrication without strain-age cracking, which is critical for complex gas turbine hot-section assemblies.

In power generation, these plates are employed as transition ducts and combustor seals in land-based turbines operating at 815–870°C, given that the stability of the chromium oxide scale (parabolic rate constant kₚ=3×10⁻¹⁴ g²/cm⁴·s at 900°C) counteracts oxidation-carburisation degradation. In advanced ultra-supercritical (A-USC) plants, they are used to construct boiler headers and steam piping operating at 700–750°C under 35 MPa pressure, where cobalt solid-solution strengthening retains a yield strength above 450 MPa after 100 000 hours.

Industrial applications include catalytic reactor vessels in petrochemical processing, where the material resists sulfidation at 750°C; heat exchanger plates for geothermal brine systems, which withstand H₂S/CO₂ corrosion at 300°C; and containment liners in nuclear fuel reprocessing, which are immune to nitric acid oxidation under gamma irradiation. The cold-rolled surface finish (Ra ≤1.6 μm) ensures sealing integrity in pressurised systems, while the anisotropic thermal expansion (14.2 μm/m·°C ∥RD vs. 14.9 μm/m·°C ⊥RD) is compensated in welded layouts through tailored preheating protocols.

Emerging applications include hypersonic vehicle thermal protection systems, which endure aerodynamic heating of up to 900°C, and fusion reactor first-wall shielding, where the alloy’s radiation damage tolerance exceeds 50 dpa neutron flux. Performance is validated under thermal cycling (600°C→room temperature, >10⁴ cycles) with less than 5% loss in impact toughness, attributable to the stability of the γ' precipitates.

Nimonic C-263 Plates Packaging

Our products are packaged in customised cartons of various sizes based on the material dimensions. Small items are securely packed in PP boxes, while larger items are placed in custom wooden crates. We ensure strict adherence to packaging customisation and the use of appropriate cushioning materials to provide optimal protection during transportation.

Packaging: Carton, Wooden Box, or Customized.

Kindly review the packaging details provided for your reference.

Manufacturing Process

1.       Brief Manufacturing Process Flow

2.       Testing Method

(1)    Chemical Composition Analysis – Verified using techniques such as GDMS or XRF to ensure compliance with purity requirements.

(2)    Mechanical Properties Testing – Includes tensile strength, yield strength and elongation tests to assess material performance.

(3)    Dimensional Inspection – Measures thickness, width and length to ensure adherence to specified tolerances.

(4)    Surface Quality Inspection – Checks for defects such as scratches, cracks or inclusions through visual and ultrasonic examination.

(5)    Hardness Testing – Determines material hardness to confirm uniformity and mechanical reliability.

Please refer to the SAM testing procedures for detailed information.

Nimonic C-263 Plates FAQs

Q1. What maximum continuous service temperature avoids significant γ' coarsening?

γ' precipitates maintain an optimal sub-50 nm size below 850°C; prolonged exposure above this temperature accelerates coarsening (>100 nm after 1 000 hours), which reduces creep strength by 25–30%. For service above 850°C, durations should be limited to <500 hours.

Q2. How does welding thermal cycling affect the aged microstructure?

HAZ temperatures exceeding 1 020°C (γ' solvus) dissolve the precipitates. On cooling, reprecipitation induces strain-age cracking unless the interpass temperature is maintained below 100°C and subsequent post-weld ageing at 800°C for 8h restores 95% of the HAZ strength.

Q3. Are there specific machining parameters to avoid work hardening?

Yes:

Turning: Use carbide tools, 25–35 m/min speed and a feed of ≥0.15 mm/rev.

Drilling: Employ a 70° point angle with peck drilling at intervals equal to twice the diameter.

Coolant must be sulphur-free to prevent the initiation of stress corrosion.

Related Information

1.       Common Preparation Methods

Nimonic C-263 plates are manufactured through an integrated thermomechanical process initiated with vacuum induction melting (VIM) of high-purity electrolytic nickel, chromium pellets, cobalt granules, molybdenum powder and aluminium–titanium master alloys under an argon atmosphere, to achieve precise compositional targets (Ni-bal., Cr-20±0.5%, Co-20±0.5%, Mo-6±0.2%, Ti-2.2±0.1%, Al-0.4±0.1%). The molten alloy undergoes secondary refining via electroslag remelting (ESR) or vacuum arc remelting (VAR) to reduce interstitial elements (O≤30 ppm, N≤80 ppm) and eliminate macro-segregation. Homogenisation at 1200°C for 12–24 hours dissolves primary carbides, after which the ingot is hot-forged at 1150–1200°C with a minimum 5:1 reduction to disrupt the as-cast structure. Hot rolling proceeds in the γ-austenite stability range (1100–1150°C), progressively reducing thickness from 300 mm to 3–100 mm using reversing mills and employing controlled strain rates (0.05–0.5 s⁻¹) to prevent edge cracking resulting from aluminium/titanium segregation zones.

A solution treatment at 1150±10°C for 2–4 hours per 25 mm thickness dissolves the γ' precipitates and M₂₃C₆ carbides, followed by rapid water quenching to retain a supersaturated solid solution. Cold rolling is applied with a 20–50% thickness reduction via tandem mills for sheets ≤10 mm, generating a pronounced 〈110〉∥ rolling direction texture and dislocation densities >10¹⁴ m⁻². Subsequent intermediate solution annealing at 1150°C restores workability after a 30–40% reduction. Final ageing employs a two-stage protocol: primary ageing at 800±10°C for 8 hours precipitates fine γ' (Ni₃[Al, Ti], 20–50 nm, 25–30 vol%), followed by secondary ageing at 700±10°C for 16 hours to stabilise grain boundary M₂₃C₆ carbides without compromising γ' coherency. Critical microstructural control includes rapid cooling through 750–950°C (with a dwell time of <15 minutes) to suppress the formation of topologically close-packed (TCP) phases (σ, μ) and isothermal holds at 850°C to dissolve Laves phases. Surface finishing involves abrasive belt grinding (Ra ≤1.6 μm for cold-rolled) or pickling in HNO₃/HF solutions (for hot-rolled), while non-destructive validation utilises ultrasonic testing (detecting internal flaws >1.5 mm), eddy current inspection (identifying surface defects >100 μm) and metallographic verification of the γ' distribution via scanning electron microscopy. Thermomechanical performance qualification includes stress rupture testing (>100 MPa at 800°C for 100 h) and Charpy V-notch impact assessment (>40 J at 20°C).