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Alloy X-750 (UNS N07750, W.Nr. 2.4669) also commonly known as Inconel X-750, is a premium precipitation-hardening nickel-chromium superalloy manufactured in accordance with ASTM B637, ASME SB-637, AMS 5542 and AMS 5667 specifications, Seamless Pipe ASTM B167 / ASME SB-167, Pipe Fittings & Flanges ASME B16.9、ASME B16.5. Developed as a strengthened upgrade based on Alloy 600, UNS N07750 incorporates precisely proportioned aluminum, titanium and niobium elements to achieve outstanding age-hardening effects, delivering superior high-temperature strength, creep rupture performance and thermal relaxation resistance compared with conventional solid-solution nickel alloys.
The alloy retains the excellent oxidation and corrosion resistance of nickel-chromium base materials, while obtaining remarkable high-temperature rigidity and fatigue resistance through controlled aging heat treatment. It maintains stable mechanical integrity and dimensional accuracy under continuous service up to 700°C, exhibiting exceptional resistance to stress relaxation, thermal fatigue, chloride stress corrosion and high-temperature scaling. Featuring reliable formability before aging and stable structural performance after hardening, Alloy X-750 is widely recognized as the preferred material for high-temperature fasteners, spring components and thermal cycling structural parts in aerospace, power generation and petrochemical industries worldwide.
We supply a full range of Alloy X-750 finished products including seamless pipes, forged fittings, flanges, plates, bars and custom precision forgings, fully compliant with international high-standard industrial procurement requirements.
2. Standard Chemical Composition (wt%)
The chemical composition strictly complies with UNS registration and international superalloy standards, ensuring stable precipitation hardening characteristics, consistent microstructure and reliable comprehensive performance:
| Element | C (max) | Si (max) | Mn (max) | P (max) | S (max) | Cr | Ni+Co | Fe | Ti | Al | Nb+Ta |
| Specification | 0.08 | 0.50 | 1.00 | 0.015 | 0.015 | 14.00~17.00 | 70.00 Min | 5.00~9.00 | 2.25~2.75 | 0.40~1.00 | 0.70~1.20 |
Note: Titanium and aluminum serve as the core precipitation-strengthening elements, forming stable gamma prime precipitates during aging treatment to significantly enhance high-temperature tensile strength and anti-relaxation performance. Niobium optimizes microstructure stability and inhibits grain coarsening. High nickel-chromium matrix provides excellent oxidation resistance and stress corrosion cracking resistance, enabling Alloy X-750 to balance superior processability and long-term high-temperature structural stability.
3. Heat Treatment & Mechanical Properties
All Alloy X-750 (UNS N07750) products adopt standardized solution annealing plus aging hardening dual heat treatment process. The standard solution treatment is performed at 980~1010℃ followed by rapid air cooling to homogenize microstructure, eliminate residual stress and retain sufficient forming toughness. Precision aging treatment at 700~730℃ promotes uniform precipitation of strengthening phases, maximizing high-temperature strength, creep resistance and stress relaxation resistance. Each production batch is equipped with complete heat treatment records, PMI spectral inspection reports and mechanical performance certification.
3.2 Room-Temperature Mechanical Properties (Aged Condition)
- Tensile Strength: ≥1100 MPa
- Yield Strength (0.2% Offset): ≥825 MPa
- Elongation: ≥12%
- Brinell Hardness: ≥300 HB
3.3 Physical & High-Temperature Characteristics
Density: 8.25 g/cm³; Average linear expansion coefficient (20~700℃): 13.8×10⁻⁶/℃. Alloy X-750 maintains stable mechanical properties and anti-creep performance under long-term service up to 700℃. It features extremely low stress relaxation rate and excellent dimensional stability under sustained high-temperature load, making it ideal for long-life fastening and elastic components in thermal cycling environments.
4. Core Performance Advantages
4.1 Outstanding High-Temperature Strength & Anti-Relaxation Performance
Benefiting from uniform gamma prime precipitation strengthening, UNS N07750 exhibits far superior high-temperature yield strength and stress relaxation resistance compared with conventional nickel alloys. It effectively avoids loosening and failure of fasteners and elastic components under long-term high-temperature continuous load, ensuring stable clamping force and structural reliability for thermal equipment.
4.2 Excellent Thermal Fatigue & Creep Resistance
Alloy X-750 resists grain coarsening and microstructural degradation after prolonged high-temperature exposure. It maintains stable creep rupture strength and thermal fatigue resistance under repeated heating and cooling cycles, effectively preventing structural deformation and fatigue cracking in frequent temperature fluctuation working conditions.
4.3 Superior Corrosion & Oxidation Resistance
The high nickel-chromium matrix forms a dense protective oxide scale at elevated temperatures, providing excellent anti-scaling and oxidation performance. It exhibits excellent resistance to chloride-induced stress corrosion cracking and exhibits reliable resistance to atmospheric corrosion, mild acidic and alkaline media, adapting to complex high-temperature and corrosive composite service environments.
4.4 Optimized Processability & Weldability
In solution-annealed state, Alloy X-750 delivers excellent hot forging, cold machining and precision forming performance. It can be welded via GTAW and GMAW processes with matched professional filler materials. It can be welded via GTAW and GMAW processes with matched low-heat-input filler materials, and post-weld aging treatment is recommended to restore full mechanical strength, facilitating customized processing and on-site assembly of complex components.
4.5 Stable Long-Term Structural Reliability
With stable precipitated phase microstructure, Under long-term service below 700℃, UNS N07750 will not experience rapid strength attenuation or grain coarsening. It maintains consistent mechanical performance and dimensional accuracy, greatly extending the service cycle of key load-bearing and fastening components for industrial high-temperature equipment.
5. Product Range & Specifications
We supply a full range of ASTM/ASME standard Alloy X-750 UNS N07750 finished products and semi-finished materials for high-temperature and high-strength industrial systems:
- Forged Pipe Fittings: Seamless elbows, equal/reducing tees, concentric/eccentric reducers, pipe caps; Size range: NPS 1/2 ~ NPS 48, Wall thickness: SCH10 ~ SCH160, customized heavy-wall high-temperature fittings available
- Seamless Alloy Pipes & Tubes: Hot-finished and cold-drawn seamless tubes; Outer diameter: 16mm ~ 720mm, Wall thickness: 3mm ~ 90mm, custom fixed-length cutting service supported
- Plates, Sheets & Bars: Thick plates, thin sheets, round bars and flat bars, supporting custom forging blanks and precision CNC machining for fastener and spring components
- High-Pressure Flanges & Custom Forgings: WN, SO, blind flanges and special-shaped high-temperature structural forgings
Factory Quality Assurance: Full-batch PMI spectral inspection, mechanical property testing, hardness detection, UT/PT non-destructive testing and dimensional verification. All products are supplied with EN 10204 3.1 mill test certificates.
- Aerospace & Gas Turbine Industry: Gas turbine hot-section fasteners, sealing components, thermal shielding parts, engine elastic structural components
- Power Generation Equipment: Boiler high-temperature fasteners, spring components, steam turbine thermal cycling parts, power plant high-pressure fixture components
- Petrochemical & Refining Industry: High-temperature reactor fasteners, heat exchanger elastic components, high-temperature process pipeline fixing parts
- Industrial Heat Treatment Furnace: High-temperature furnace fixtures, thermal cycling load-bearing parts, anti-relaxation fastening components
- High-End Precision Equipment: High-temperature resistant springs, precision mechanical fastening parts, long-service thermal stability structural components
7. Quality Control & Product Marking
Alloy X-750 UNS N07750 products are manufactured under strict ISO 9001 quality management system. Our standardized full-process quality control workflow covers raw material spectral recheck → hot forming & professional dual heat treatment → mechanical performance testing → non-destructive flaw detection → dimensional inspection → laser marking & vacuum packaging. Finished products are free from surface cracks, inclusions, laps and oxidation defects. Standard laser marking includes brand information, Alloy X-750 / UNS N07750 grade, applicable industry standards, heat batch number, product dimensions and wall thickness, fully compliant with international high-end industrial procurement and third-party inspection requirements
If you need more information about Alloy X-750 UNS N07750 products, contact us today!
