Quick Answer: NiCoCrMoAlTi is a precipitation-hardened nickel–cobalt–chromium superalloy (EN grade 2.4634, UNS N07734) rated for continuous service up to 700 °C. It achieves tensile strength ≥ 1,000 MPa and elongation ≥ 25% through gamma-prime (γ′, Ni₃(Al,Ti)) precipitation hardening. It is used for turbine discs, aerospace compressor components, oil & gas valve internals, and nuclear pump parts.
This complete technical reference covers the six-element chemistry, the γ′ strengthening mechanism, heat treatment process, mechanical property data, alloy comparison against Inconel® 718 and Waspaloy®, and real-world industrial applications — from a manufacturer with 25+ years of NiCoCrMoAlTi forging experience.
NiCoCrMoAlTi is a precipitation-hardened nickel–cobalt–chromium superalloy developed for sustained performance in extreme thermal and mechanical environments. Its name is a direct shorthand for its six principal elements: Nickel (Ni), Cobalt (Co), Chromium (Cr), Molybdenum (Mo), Aluminum (Al), and Titanium (Ti). The most widely used specific grade is 2.4634 per EN 10302.
Unlike conventional stainless steels or single-phase nickel alloys, NiCoCrMoAlTi derives its structural strength from a controlled age-hardening reaction. During heat treatment, aluminum and titanium precipitate as an ordered intermetallic compound — gamma-prime (γ′), Ni₃(Al,Ti) — within the nickel-rich austenitic matrix. This fine, coherent precipitate network delivers exceptional yield strength, creep resistance, and fatigue life at temperatures up to 700 °C.
The material occupies a unique engineering performance space: creep strength enhanced by cobalt solid-solution hardening, oxidation protection from a dual-layer Cr₂O₃ + Al₂O₃ scale, and ductility significantly superior to competing superalloys such as Inconel® 718. For engineers specifying turbine discs, aerospace compressor components, or oil-and-gas valve bodies, NiCoCrMoAlTi forgings deliver reliable long-service performance where maintenance is costly or structurally impossible.
NiCoCrMoAlTi is a compositional family name, not a single fixed trade name. The primary grade is 2.4634 (EN 10302). It also appears as NiCo15Cr17Mo4Ti3Al (DIN), UNS N07734 (ASTM/SAE), and AMS 5771/5772 (aerospace). Always specify the full grade and standard when ordering to lock in the correct Al:Ti balance for your application.
Every aspect of NiCoCrMoAlTi's performance is determined by its elemental balance. Each of the six primary elements plays a distinct and irreplaceable metallurgical role. Even small deviations from the specified ranges can significantly alter phase stability, precipitate morphology, and service life.
| Element | Symbol | Typical % | Primary Metallurgical Function |
|---|---|---|---|
| Nickel | Ni | Balance | Austenitic FCC matrix host; base ductility, corrosion resistance, and solvent for all alloying elements |
| Cobalt | Co | 15–20 | Raises γ′ solvus temperature; strengthens γ matrix by solid-solution hardening; inhibits dislocation climb (dominant creep mechanism above 600 °C) |
| Chromium | Cr | 18–22 | Forms dense Cr₂O₃ surface scale for oxidation, sulfidation, and hot-corrosion protection; contributes to solid-solution strengthening |
| Molybdenum | Mo | 4–6 | Increases lattice strain resistance in the γ matrix; enhances pitting and crevice corrosion resistance in Cl¹¯ environments |
| Aluminum | Al | 1.2–1.8 | Primary γ′ former (Ni₃Al); contributes to Al₂O₃ sub-scale beneath Cr₂O₃ for dual-barrier oxidation protection |
| Titanium | Ti | 2.8–3.5 | Primary γ′ former (Ni₃Ti); increases γ′ volume fraction to ~35% and coherency strain that provides the dominant strengthening contribution; stabilizes grain boundary carbides |
A higher Al:Ti ratio improves oxidation resistance but can slightly reduce ductility. Turbine blade grades tend toward higher Ti for maximum γ′ volume; structural disc and ring grades balance both. Specifying only "NiCoCrMoAlTi" without a full grade designation leaves this critical trade-off undefined — always reference EN 2.4634 or UNS N07734.
NiCoCrMoAlTi's engineering strength is manufactured into the alloy through a precisely controlled heat treatment. In the as-forged or solution-annealed condition the material is relatively soft and formable. All values below are achieved only after the full solution anneal plus aging cycle is completed.
| Property | Typical Value (Aged) | Test Condition |
|---|---|---|
| Tensile Strength Rm | ≥ 1,000 MPa | Room temperature, EN 10002 |
| Yield Strength Rp0.2 | ≥ 800 MPa | Room temperature, EN 10002 |
| Elongation A | ≥ 25% | Room temp, gauge L₀=5d |
| Reduction of Area Z | ≥ 35% | Room temperature |
| Hardness | 290–360 HB | Aged condition, EN ISO 6506 |
| Creep Rupture (100 h) | ~550 MPa | At 600 °C |
| Density | ~8.2 g/cm³ | — |
| Thermal Expansion (CTE 20–600°C) | ~14×10&sup6; /°C | Lower CTE than A-286; reduces thermal fatigue |
| Melting Range | 1,300–1,390 °C | DSC analysis |
| Thermal Conductivity | ~11 W/m·K | At 400 °C |
| γ′ Volume Fraction | ~30–40% | Fully aged; XRD and TEM |
All NiCoCrMoAlTi forgings must undergo a defined post-forging heat treatment sequence before meeting any engineering standard's mechanical property requirements. The process has four stages, each with a specific metallurgical purpose. Incorrect execution at any stage compromises final properties irreversibly.
The forging is heated above the γ′ solvus to completely dissolve all precipitates, creating a single-phase supersaturated solid solution. Rapid quenching suppresses precipitation during cooling. This stage also recrystallises the deformed grain structure from forging and homogenises chemical segregation from the original ingot.
Fine, uniformly distributed γ′ particles nucleate and grow coherently within the matrix. Their size, volume fraction (30–40%), and inter-particle spacing control yield and tensile strength. Insufficient aging leaves excess Al and Ti in solution; over-aging causes precipitate coarsening (Ostwald ripening) and measurable strength loss.
A lower-temperature step completes grain boundary precipitation, improving creep-rupture life and high-temperature ductility without significantly reducing room-temperature strength. Specified for turbine disc and blade applications with sustained service at 600–700 °C. For structural rings at moderate temperature where fatigue governs, it may be omitted per engineering agreement.
Test specimens are extracted from the forging body centre — not companion bars — to ensure reported properties represent the entire part cross-section. Testing includes tensile (Rm, Rp0.2, A, Z), hardness, UT (EN 10228-3 or ASTM A388), and MT or PT. EN 10204 3.1 MTC is standard; 3.2 with client-nominated TPI (SGS, BV, TÜV, DNV) is available on request.
Engineers shortlisting nickel superalloys most frequently compare NiCoCrMoAlTi against Inconel® 718, Waspaloy®®, and A-286. Each has a distinct performance profile and commercial trade-off. The comparison covers criteria that most commonly determine alloy selection in turbine, pressure vessel, and oil-and-gas applications.
| Selection Criterion | NiCoCrMoAlTi (2.4634) | Inconel® 718 | Waspaloy® | A-286 |
|---|---|---|---|---|
| Max service temperature | ~700 °C | ~650 °C | ~760 °C | ~650 °C |
| Hardening mechanism | γ′ (Al+Ti) | γ″ (Nb)+γ′ | γ′ (Al+Ti) | γ′ (Ti) |
| Elongation (%) | ≥ 25% | 12–18% | 15–20% | ~16% |
| Stability above 650 °C | High — no δ-phase risk | Risk of γ″→δ transform | High | Moderate |
| Creep resistance | Very high (Co addition) | Good | Excellent | Moderate |
| Thermal expansion (CTE) | Low — reduces thermal fatigue | Medium | Low-medium | Higher |
| Forgeability | Good | Excellent | Moderate | Good |
| Relative cost | Medium-high (Co content) | Medium | High | Lower |
Choose NiCoCrMoAlTi (2.4634) when you need: (1) sustained service between 550–700 °C without Inconel 718's γ″→δ instability risk; (2) higher ductility than Waspaloy® for complex thin-section forgings or multi-axial stress components; or (3) lower CTE than A-286 in assemblies exposed to repeated thermal cycling. When design temperatures consistently exceed 720 °C, Waspaloy® or directionally solidified alloys are more appropriate.
NiCoCrMoAlTi's combination of high-temperature strength, ductility, and microstructural stability makes it a first-choice material across four primary industries. Forgings are the preferred product form because the forging process refines the grain structure, eliminates internal porosity, and aligns grain flow with the principal stress direction — improving fatigue life by 30–60% over machined plate alternatives.
Beyond these primary sectors, NiCoCrMoAlTi forgings are also applied in industrial chemical reactors processing nitric acid and ammonium compounds at elevated temperature, in marine gas turbine propulsion systems where power-to-weight ratio is critical, and in hot-isostatic pressing (HIP) vessel internals and high-temperature sintering furnace components. Request a quote for any of these applications.
NiCoCrMoAlTi can be produced as castings, hot-rolled bar, or open die forgings. For most critical structural applications, open die forging and seamless ring rolling are the preferred manufacturing routes for three fundamental reasons.
High compressive force from heavy hydraulic presses breaks down the coarse as-cast dendritic structure, closes internal porosity and micro-shrinkage cavities, and produces a fine, equiaxed grain structure. A minimum forging reduction ratio of 4:1 is typically specified for NiCoCrMoAlTi to guarantee this improvement throughout the entire cross-section — increasing fatigue life by 30–60% versus plate-machined alternatives.
Unlike a component machined from bar stock, an open die forged part has grain flow that follows the final component geometry. In a turbine disc forged near-net-shape, grain flow wraps radially — parallel to the primary hoop stress in service. For seamless rolled rings, the ring rolling process aligns grain flow circumferentially, which is precisely the direction that resists the hoop stresses acting on turbine casings, bearing housings, and pressure-retaining flanges during thermal cycling.
Forging test specimens are extracted from the centre of the cross-section, ensuring reported mechanical properties represent the entire part. This is a fundamental certification requirement under ASME, EN, and API standards for safety-critical turbine discs and pressure-retaining components. Companion bar testing, common for castings and extrusions, does not provide this assurance.
We produce NiCoCrMoAlTi open die forgings from 30 kg to 30,000 kg per piece, with seamless rolled rings up to 6,000 mm outer diameter. All heat treatment is performed in-house across multiple fully automated furnaces, with EN 10204 3.1 MTC standard and 3.2 with client TPI. NiCoCrMoAlTi open die forgings and seamless rolled rings
NiCoCrMoAlTi appears under different names in different national standard systems. The table provides the most important cross-references that procurement and materials engineers encounter when reading purchase orders, inspection certificates, and engineering drawings.
| Standard System | Designation | Application Note |
|---|---|---|
| EN (European) | 2.4634 / NiCoCrMoAlTi | Primary designation per EN 10302; most widely used in European power and nuclear industries |
| DIN (German) | NiCo15Cr17Mo4Ti3Al | Legacy DIN designation appearing in older German plant specifications and historical drawings |
| UNS | N07734 | ASTM/SAE unified number — always verify by full chemistry table, not number alone |
| AMS (Aerospace US) | AMS 5771 / AMS 5772 | US aerospace forgings and bars; confirm applicable revision with the prime contractor |
| Trade Name (similar) | Nimonic® 263 | Proprietary designation; compositions may differ — always cross-reference by element ranges |
| API / NACE | API 6A & MR0175 | Sour service oil & gas requires NACE MR0175/ISO 15156 hardness requirements |
When ordering NiCoCrMoAlTi forgings, always specify: (1) exact standard and revision; (2) heat treatment condition; (3) required mechanical properties and test direction; (4) MTC level (EN 10204 3.1 or 3.2); and (5) NDT standard and acceptance criteria. Our engineering team reviews incoming drawings and specifications at no charge.
For full production capability, shape range (bars, rings, discs, hollow components), and factory-direct quotation, visit: NiCoCrMoAlTi forged bars, discs and seamless rings
NiCoCrMoAlTi (EN 2.4634, UNS N07734) is a precipitation-hardened nickel–cobalt–chromium superalloy rated for continuous service up to 700 °C. It achieves tensile strength ≥ 1,000 MPa, yield strength ≥ 800 MPa, and elongation ≥ 25% via gamma-prime (γ′, Ni₃(Al,Ti)) precipitation hardening. Used for turbine discs, aerospace compressor components, oil & gas valve internals, and nuclear pump parts.
The EN designation is 2.4634 per EN 10302. Equivalent designations: NiCo15Cr17Mo4Ti3Al (DIN), UNS N07734 (ASTM/SAE), AMS 5771/5772 (aerospace). Always verify by full chemical composition, not designation number alone.
NiCoCrMoAlTi outperforms Inconel 718 in: (1) Service temperature — 700 °C vs. ~650 °C, as Inconel 718's γ″ transforms to brittle δ phase above ~650 °C; (2) Ductility — elongation ≥ 25% vs. 12–18%; (3) Lower CTE reducing thermal fatigue. Inconel 718 has better forgeability and lower cost.
Two-stage heat treatment: (1) Solution Annealing at 1,080–1,150 °C, hold 2–4 hours, rapid quench to dissolve γ′ and recrystallise grain structure; (2) Primary Aging at 820–850 °C for 8–16 hours to nucleate γ′ precipitate network. Optional Secondary Aging at 700–750 °C for 16–24 hours maximises creep rupture life.
Jiangsu Liangyi produces NiCoCrMoAlTi forgings from 30 kg to 30,000 kg. Seamless rolled rings to 6,000 mm OD. Product forms: bars (to 2,000 mm diameter), discs, rings, hollow components, near-net-shape parts. EN 10204 3.1/3.2 MTC. Third-party inspection: SGS, BV, TÜV, DNV.
NiCoCrMoAlTi (2.4634) is rated for continuous service at temperatures up to approximately 700 °C. This exceeds Inconel 718's practical limit of ~650 °C (due to γ″→δ phase instability), making NiCoCrMoAlTi preferred for turbine disc and valve applications requiring sustained high-temperature service.
NiCoCrMoAlTi (2.4634) forgings serve four primary industries: (1) Power Generation — gas turbine discs, compressor blades, and seal rings rated to 700°C for 25,000+ hour service intervals; (2) Aerospace — HP compressor discs, turbine shafts, and blisks for commercial and military turbofan engines under AMS specifications; (3) Oil & Gas HPHT — valve bodies, wellhead bonnets, and subsea connectors to NACE MR0175 sour service standard; (4) Nuclear Power — RCP shaft seals, pump impellers, and valve internals for PWRs. Secondary applications include chemical reactors, marine gas turbines, and HIP vessel internals.
NiCoCrMoAlTi (2.4634) forgings from Jiangsu Liangyi comply with: EN 10302 (material), EN 10228-3 / ASTM A388 (UT), EN ISO 6892-1 (tensile), EN ISO 6506-1 (hardness), and NACE MR0175/ISO 15156 (sour service). Mill Test Certificates are issued to EN 10204 3.1 as standard; EN 10204 3.2 with third-party inspection by SGS, Bureau Veritas, TÜV, or DNV is available on request. The manufacturing facility holds ISO 9001:2015 certification. AMS 5771 / AMS 5772 apply for aerospace applications.
Jiangsu Liangyi has manufactured NiCoCrMoAlTi open die forgings and seamless rolled rings for clients across 50+ countries for over 25 years. Our ISO 9001:2015 certified process integrates VIM/ESR melting, open die forging, ring rolling, heat treatment, NDT, and finish machining entirely under one roof in Jiangyin, China.
Send us your drawing and specification for a factory-direct quotation within 24 hours. No minimum order quantity on standard grades. Engineering specification review at no charge.