Power Generation Turbines
Turbine discs, compressor blades, nozzle vanes, guide rings, labyrinth seal rings, and rotor end rings in gas and steam turbines. Continuous service up to 600 °C under high centrifugal and thermal cyclic loading.
Introduction — Why 2.4650 Stands Apart from Other Nickel Alloys
When engineers designing gas turbines, industrial compressors, or critical valve assemblies push past the performance limits of conventional stainless steels and standard nickel alloys, they often converge on the same answer: 2.4650. Registered under the European material numbering system as W.Nr. 2.4650 and compositionally described as NiCo20Cr20MoT (sometimes abbreviated NiCoCr20Mo), this is a precipitation-hardened nickel-cobalt-chromium superalloy engineered for demanding environments where sustained mechanical performance at temperatures up to 600 °C is non-negotiable.
Unlike workhorse grades such as Inconel 718 or 316L stainless steel, 2.4650 carries a deliberate cobalt addition of approximately 20 wt.% that substantially raises the alloy's solid-solution strengthening baseline — before any age-hardening treatment is applied. The result is a material delivering exceptionally high yield strength (≥ 900 MPa), superior creep resistance, and outstanding resistance to oxidation and hot corrosion, all within a single precision-forged component.
This guide provides a complete technical reference on 2.4650: its chemical composition, precipitation-hardening metallurgy, mechanical properties, heat treatment cycle, forging product forms, industrial applications, international standard designations, and quality inspection requirements. Where relevant, we reference open-die forging and ring-rolling capabilities for 2.4650 for specifications and custom quotation.
Key Takeaway
2.4650 is not a general-purpose nickel alloy. It is a high-cobalt precipitation-hardened superalloy selected specifically for applications demanding high yield strength, creep resistance, and oxidation resistance at elevated temperatures where lighter-duty alloys would deform or fail.
Chemical Composition of 2.4650 (NiCo20Cr20MoT)
The designation NiCo20Cr20MoT is itself a compositional shorthand that immediately communicates the principal elements: nickel (Ni) as the base matrix, cobalt (Co) at approximately 20 wt.%, chromium (Cr) at approximately 20 wt.%, molybdenum (Mo) for solid-solution strengthening and corrosion resistance, and titanium (T) — together with aluminium — which drives the precipitation-hardening response.
| Element | Nominal Content (wt.%) | Primary Function in 2.4650 |
|---|---|---|
| Nickel (Ni) | Balance (~35–40%) | Austenitic matrix — foundation for ductility and toughness |
| Cobalt (Co) | ~20% | Solid-solution strengthening; raises γ' solvus temperature — the key differentiator |
| Chromium (Cr) | ~20% | Oxidation and hot corrosion resistance via Cr₂O₃ protective scale |
| Molybdenum (Mo) | ~5–6% | Solid-solution strengthening; pitting and crevice corrosion resistance |
| Titanium (Ti) | ~2–3% | Primary hardener — forms γ' Ni₃(Al,Ti) precipitates during aging |
| Aluminium (Al) | ~1–2% | Co-forms γ' precipitates; improves high-temperature oxidation resistance |
| Carbon (C) | ≤ 0.08% | Controlled carbide formation at grain boundaries |
| Boron (B) | Trace | Grain-boundary cohesion; creep rupture life improvement |
The ~20% cobalt content is the single most distinctive feature of 2.4650 relative to other nickel superalloys. Cobalt raises the melting point of the matrix phase, delays stacking-fault formation at high temperatures, and — critically — increases the maximum volume fraction of γ' precipitates that can be stabilised, amplifying the age-hardening response without exotic refractory additions.
MetallurgyHow Precipitation Hardening Works in 2.4650
To understand why 2.4650 achieves its remarkable elevated-temperature strength, you need to understand the γ' (gamma prime) phase — the nanoscale crystallographic feature responsible for most of the alloy's mechanical capability above 400 °C.
The γ' Strengthening Mechanism
In the solution-annealed condition, titanium and aluminium atoms are dissolved uniformly within the nickel-cobalt matrix. When the alloy is aged at controlled temperatures, these atoms diffuse and precipitate as a coherent ordered intermetallic compound — Ni₃(Al,Ti). This compound forms as nanometre-scale cuboidal particles (the γ' phase) crystallographically aligned with the surrounding matrix. These particles block dislocation movement far more effectively than solid-solution strengthening alone, maintaining strength long after conventional alloys have softened.
The 4-Stage Heat Treatment Cycle for 2.4650 Forgings
Solution Anneal — approx. 1,050–1,100 °C
The 2.4650 forging is heated until all γ' precipitates fully dissolve into the matrix, removing prior microstructural heterogeneity. Quenching locks in this supersaturated state, ready for aging.
Primary Age — approx. 845 °C / 8–16 hours
Controlled nucleation and growth of the primary γ' precipitate population. Larger, more widely spaced particles form, establishing the creep resistance distribution for elevated-temperature service.
Secondary Age — approx. 760 °C / 8–16 hours
A finer secondary population of γ' particles nucleates between the primary precipitates. This bimodal distribution simultaneously maximises tensile strength and creep rupture life.
Air Cool to Room Temperature
The bimodal γ' structure is locked in at peak-aged condition. The forging is ready for final machining and inspection. Furnace charts are archived as part of the EN 10204 3.1 Mill Test Certificate documentation package.
Critical Buyer Warning
Incorrect aging temperature or hold time can irreversibly coarsen γ' particles in 2.4650, reducing tensile strength by 10–20% and creep rupture life significantly. Always request furnace temperature charts AND thermocouple calibration certificates alongside the EN 10204 3.1 MTC. These records distinguish capable manufacturers from distributors reselling reprocessed material.
Mechanical and Physical Properties of 2.4650
The data below represents typical minimum values for 2.4650 in the fully heat-treated condition (solution annealed + double aged). Actual values depend on forging size, section thickness, geometry, and the exact heat treatment cycle applied.
Tensile Strength (UTS)
≥1,100 MPa
Room temperature, fully aged
0.2% Yield Strength
≥900 MPa
Room temperature, peak-aged
Elongation at Break
≥15%
Good ductility retained after aging
Hardness
38–44 HRC
Vickers equivalent ~375–430 HV
Max Service Temp.
600 °C
Continuous, oxidising environments
Density
~8.2 g/cm³
Typical for NiCo superalloys
Elevated-Temperature Strength Retention
Conventional austenitic stainless steels lose roughly 40–50% of their room-temperature yield strength by 500 °C. 2.4650, by contrast, retains approximately 70–75% of its room-temperature yield strength at 500 °C — due to the thermal stability of the γ' precipitate structure enabled by its high cobalt content. Creep rupture testing at 600 °C confirms that 2.4650 forgings can sustain stresses of 400–500 MPa for periods exceeding 1,000 hours without rupture. Jiangsu Liangyi Co., Limited produces 2.4650 in forged ring diameters up to 6 metres and bar stock up to 2 metres, covering the full range of turbine and valve component sizes.
Oxidation and Corrosion Resistance
The ~20% chromium content produces a dense Cr₂O₃ surface oxide providing excellent protection in oxidising atmospheres up to approximately 950 °C — well above the alloy's mechanical service limit. The molybdenum addition also provides resistance to crevice corrosion and pitting in environments containing chlorides or sulphur dioxide.
Alloy Comparison2.4650 vs. Other Superalloys — A Technical Comparison
The table below summarises key differentiators across the alloys most commonly specified for similar applications. Note that proprietary trademarked grade names referenced for comparison purposes remain the intellectual property of their respective owners.
| Property | 2.4650 NiCo20Cr20MoT | 2.4668 (Inconel 718 type) | 2.4632 (Nimonic 90 type) | Waspaloy type |
|---|---|---|---|---|
| Base chemistry | Ni-Co-Cr-Mo | Ni-Cr-Fe-Nb | Ni-Cr-Co | Ni-Co-Cr-Mo |
| Max service temp. | 600 °C | 650 °C | 920 °C | 800 °C |
| 0.2% Yield strength | ≥900 MPa | ≥1,035 MPa | ≥800 MPa | ≥860 MPa |
| Creep resistance @ 500 °C | Excellent | Very good | Good | Excellent |
| Oxidation resistance | Excellent | Good | Excellent | Excellent |
| Forging difficulty | Medium-High | Medium | Medium-High | High |
| Typical applications | Turbine discs, valve seats, compressor parts | Aerospace structures, fasteners, casings | Turbine blades, exhaust valves, springs | Aerospace turbine discs, high-temp rings |
Trademark notice: "Inconel" is a registered trademark of Special Metals Corporation. "Nimonic" is a registered trademark of Special Metals Corporation. "Waspaloy" is a registered trademark of United Technologies Corporation. These names are used in this article solely for technical comparison and identification purposes. Jiangsu Liangyi Co., Limited is not affiliated with, endorsed by, or authorised by the trademark holders. We produce forgings to the European W.Nr. material specifications (2.4650, 2.4668, 2.4632) only.
Forging Forms2.4650 Forging — Available Product Forms and Manufacturing Capabilities
Forging — rather than casting — is the preferred manufacturing route for 2.4650 components that carry structural loads. Open-die forging and seamless ring-rolling refine the alloy's grain structure, align crystallographic flow with principal stress directions, and eliminate the porosity and segregation risks inherent to cast ingots.
At Jiangsu Liangyi Co., Limited, 2.4650 is available in the following custom forged product forms:
- Forged round bars and square bars — up to 2 metres in diameter; turbine blade blanks, valve spindle bar stock, fastener billets
- Seamless rolled rings — up to 6 metres outer diameter, 30 tonnes single-piece weight; turbine casings, guide rings, labyrinth seal rings, flange blanks
- Forged discs and plates — up to 3 metres diameter; turbine disc blanks, compressor stage blanks
- Hollow components — hubs, housings, shells, sleeves, thick-walled hollow bars up to 3,000 mm OD
- Custom near-net-shape forgings — manufactured to customer drawings: turbine blades, valve seats, valve spindles, nozzle bodies, compressor impellers
Manufacturing Capability
Single-piece weights from 30 kg to 30,000 kg. All 2.4650 forgings produced in-house at our 80,000 m² Jiangyin facility using 2,000–6,300 tonne hydraulic presses and 1–5 metre seamless rolling machines. No subcontracting. Full traceability from steel melting to final inspection. Annual capacity: 120,000 tonnes.
Industrial Applications of 2.4650 (NiCo20Cr20MoT) Forgings
Aerospace Components
Compressor stage discs, structural fasteners, engine casing rings, and afterburner structural parts where weight-to-strength ratio and temperature stability are simultaneously critical.
Industrial Valve Components
Main steam valve (MSV) and governor valve (GV) seats, cores, sleeves, spindles, and bonnets. Control valve (CV/CRV) internals in power plant turbine inlet and bypass systems.
Oil & Gas Equipment
Wellhead components, downhole tool bodies, high-pressure valve seats, and compressor impellers requiring combined corrosion resistance and high mechanical strength under demanding service conditions.
Chemical Processing
Pump housings, impellers, reaction vessel internals, and agitator shafts in high-temperature chemical environments involving sulphur compounds, acidic media, or mixed oxidising-reducing conditions.
Test Equipment & Instrumentation
High-temperature test fixtures, precision load frames, and instrumentation housings requiring dimensional stability at elevated temperature combined with corrosion resistance.
International Designations and Standard Cross-References for 2.4650
| Standard / System | Designation | Notes |
|---|---|---|
| European W.Nr. | 2.4650 | Primary reference for European procurement, drawings, and purchase orders |
| Compositional name (full) | NiCo20Cr20MoT | Used on EN 10204 mill test certificates and technical drawings |
| Compositional name (abbrev.) | NiCoCr20Mo | Common abbreviation omitting the titanium hardener suffix |
| EN 10302 | NiCo20Cr20MoT | Creep-resisting steels, nickel and cobalt alloys — the governing EN standard |
| Comparable grades (verify composition) | See trademark notice above | Proprietary grades may have different composition limits — always confirm against W.Nr. 2.4650 chemistry before substituting |
When ordering 2.4650 forgings, always specify the W.Nr. 2.4650 or NiCo20Cr20MoT designation explicitly in your purchase order and request EN 10204 3.1 mill test certificates covering full chemical composition and mechanical property test results from the actual forging heat.
Quality & InspectionQuality Inspection for 2.4650 Forgings — What Buyers Should Require
A comprehensive inspection programme for 2.4650 forgings should include all of the following as a minimum:
- Chemical composition analysis — OES or ICP to verify all specified elements meet EN 10302 limits for W.Nr. 2.4650
- Mechanical property testing — tensile test (UTS, 0.2% proof stress, elongation) and hardness survey (Brinell or Vickers) as minimum; Charpy impact testing where the application demands it
- Ultrasonic Testing (UT) — full volumetric scan per EN 10228-3 or ASTM A388 to detect internal porosity, laminations, or inclusions
- Dye Penetrant Inspection (DPI/PT) — surface crack detection on all finished machined faces per EN ISO 3452 or ASTM E165
- Dimensional inspection — CMM or manual verification of all critical dimensions against the approved customer drawing
- Heat treatment records — furnace temperature charts, thermocouple calibration certificates, and soak time logs for every heat treatment cycle
Our Certification & Documentation — What We Provide
Jiangsu Liangyi Co., Limited holds ISO 9001:2015 quality management system certification. As standard, we supply EN 10204 3.1 Mill Test Certificates covering full chemical composition and mechanical test results for every order. EN 10204 3.2 certificates (requiring third-party witness inspection) are available upon customer request — the customer appoints and bears the cost of the independent inspection body. Third-party inspection can be coordinated with internationally recognised bodies such as SGS, Bureau Veritas, TÜV, DNV, ABS, Lloyd's Register, and others upon request. We do not claim to hold API 6A product approval, NACE MR0175 material certification, or PED CE marking independently — our forgings can be produced to meet the material requirements of these standards, but final compliance certification for a specific application remains the responsibility of the project engineer and system integrator.
How to Source 2.4650 Forgings — Practical Procurement Checklist
2.4650 is a speciality superalloy that requires a manufacturer with direct Ni-Co superalloy forging experience, precise in-house heat treatment capability, and calibrated inspection equipment. When evaluating suppliers, the following criteria are most critical:
- Direct forging capability — confirm the manufacturer operates their own hydraulic presses and ring-rolling machines; outsourced forging operations introduce process variables and break the traceability chain
- In-house heat treatment — precipitation hardening requires accurate, calibrated furnaces; outsourced aging treatment introduces temperature uniformity and traceability risks
- Superalloy-specific experience — general carbon steel forging shops lack the process knowledge for Ni-Co superalloys: die design for narrow hot working temperature windows and microstructure development require decades of specialised experience
- ISO 9001:2015 certification — verify the certificate scope explicitly covers forging manufacturing operations, not just trading or distribution activities
- EN 10204 3.1 MTC as standard — full chemical composition and mechanical property test certificates should be supplied with every order as a standard deliverable
- Export experience — confirm the manufacturer has established experience with international shipping documentation, customs classification, and export packaging requirements
Jiangsu Liangyi Co., Limited has over 25 years of experience manufacturing 2.4650 and related nickel superalloy forgings at its 80,000 m² Jiangyin, Jiangsu Province facility. ISO 9001:2015 certified, operating its own in-house metallurgical laboratory, with verified export records to more than 50 countries. check available 2.4650 dimensions and request a custom quote
Related Product Pages & Technical Resources
Frequently Asked Questions About 2.4650 (NiCo20Cr20MoT)
2.4650 (NiCo20Cr20MoT) is a precipitation-hardened nickel-cobalt-chromium-molybdenum superalloy registered under the European material number W.Nr. 2.4650. It contains approximately 20% cobalt and 20% chromium, providing outstanding yield strength (≥900 MPa), creep resistance, and oxidation resistance at service temperatures up to 600 °C.
2.4650 has a maximum continuous mechanical service temperature of 600 °C under load. Its Cr₂O₃ protective oxide layer provides oxidation resistance up to approximately 950 °C, but the creep and fatigue performance limits at 600 °C govern the practical service rating for structural components.
In the fully heat-treated condition, 2.4650 achieves a minimum 0.2% yield strength of ≥900 MPa and an ultimate tensile strength (UTS) of ≥1,100 MPa at room temperature, with elongation at break of ≥15%. At 500 °C, the yield strength typically retains 70–75% of the room-temperature value.
2.4650 undergoes a four-stage heat treatment: (1) Solution anneal at 1,050–1,100 °C; (2) Primary age at approximately 845 °C for 8–16 hours; (3) Secondary age at approximately 760 °C for 8–16 hours; (4) Air cool to room temperature. This produces a bimodal γ' precipitate distribution that maximises both tensile strength and creep rupture life.
2.4650 is a Ni-Co-Cr-Mo system hardened by γ' precipitates, optimised for creep resistance at 400–600 °C in turbine disc and valve applications. W.Nr. 2.4668 (the grade commonly associated with the Inconel 718 type composition) is a Ni-Cr-Fe-Nb system with higher room-temperature yield strength (≥1,035 MPa) and a 650 °C max service temperature, most often specified for aerospace structural parts and fasteners. Note: "Inconel" is a registered trademark of Special Metals Corporation and is used here only for technical reference.
We produce custom 2.4650 forgings from 30 kg to 30,000 kg per piece. Available forms include: forged round bars up to 2 m diameter; seamless rolled rings up to 6 m outer diameter (up to 30 t per ring); forged discs up to 3 m diameter; hollow components up to 3,000 mm OD; and custom near-net-shape forgings to customer drawings.
Jiangsu Liangyi Co., Limited holds ISO 9001:2015 quality management system certification. We supply EN 10204 3.1 Mill Test Certificates as standard with all orders. EN 10204 3.2 certificates (with third-party witness inspection) are available on request, coordinated with customer-appointed inspection bodies. We do not independently hold API 6A product approval or PED CE marking — our forgings are produced to meet the applicable material specifications, and compliance certification for specific applications is determined at the project level.
2.4650 forgings are primarily used in: gas and steam turbine discs, compressor blades, guide rings, and labyrinth seal rings; aerospace compressor discs and structural fasteners; industrial main steam valve (MSV) and control valve (CV) seats, spindles, and bonnets; oil and gas wellhead components; chemical processing pump housings and impellers; and high-temperature test fixtures. The alloy is appropriate for any application requiring ≥900 MPa yield strength and creep resistance at continuous service temperatures of 400–600 °C.
Summary — Is 2.4650 (NiCo20Cr20MoT) Right for Your Project?
2.4650 (NiCo20Cr20MoT, W.Nr. 2.4650) is the optimal material choice when your application simultaneously requires:
- Continuous service temperatures between 400 °C and 600 °C under mechanical stress
- High yield strength (≥ 900 MPa) combined with adequate ductility (≥ 15% elongation at break)
- Resistance to creep deformation and stress-rupture failure at elevated temperature
- Oxidation resistance and moderate corrosion resistance in industrial gas or mildly acidic environments
- A forged — not cast — component for grain structure integrity, complete material traceability, and superior fatigue performance
It is not the optimum specification if your primary requirement is temperature capability above 700 °C (where grades such as 2.4632 become more appropriate), or if cost is the primary driver for a moderate-temperature application where austenitic stainless steel could adequately perform.
For technical consultation, custom forging specifications, or to request a competitive quotation with a response within 24 hours, visit the the Jiangsu Liangyi Co., Limited product page at www.jnmtforgedparts.com/24650-nicocr20mo-forging-parts.html.