Stainless pipe fitting,stainless fitting,duplex stainless,31803,32750,32760,we are one of largest sour service stainless fitting supplier according to ISO 10156.
Alloy 718 (UNS N07718), also commonly known as Inconel 718 is a premium precipitation-hardening nickel-chromium-iron superalloy complying with ASTM B637, B670, ASME SB-637, AMS 5662 and AMS 5664 industry specifications. Reinforced with niobium, molybdenum and titanium alloying elements, this age-hardenable superalloy balances ultra-high mechanical strength, outstanding fatigue resistance, creep performance and comprehensive corrosion resistance, covering cryogenic to medium-high temperature service conditions up to 650°C.
Different from conventional solid-solution nickel alloys, UNS N07718 achieves remarkable strength enhancement through controlled aging heat treatment, without sacrificing formability and welding performance. It features stable performance in H₂S/CO₂ oilfield environments, effectively resisting sulfide stress cracking and chloride corrosion failure and high-temperature oxidation, maintaining stable structural integrity under alternating mechanical load and thermal cycling environments. With reliable low-temperature toughness and high-pressure structural stability, Alloy 718 has become the most widely applied superalloy in aerospace, oil & gas, power generation and high-pressure industrial equipment worldwide.
We professionally supply forged fittings, seamless tubes, flanges, plates, round bars and custom precision forgings of Alloy 718, fully meeting high-standard industrial and aerospace procurement requirements.
2. Standard Chemical Composition (wt%)
The chemical composition strictly follows UNS registration and international superalloy standards, ensuring consistent precipitation hardening effect, structural stability and superior comprehensive performance:
| Element | C (max) | Si (max) | Mn (max) | P (max) | S (max) | Cr | Ni | Mo | Nb | Ti | Al | Fe |
| Specification | 0.08 | 0.35 | 0.35 | 0.015 | 0.015 | 17.00~21.00 | 50.00~55.00 | 2.80~3.30 | 4.75~5.50 | 0.65~1.15 | 0.20~0.80 | Balance |
Note: Niobium is the core strengthening element, forming stable γ” (Ni₃Nb) precipitates during aging treatment, while titanium and aluminum form auxiliary γ’ (Ni₃(Al,Ti)) phases, jointly delivering excellent tensile strength and creep resistance to greatly improve tensile strength and creep resistance. Molybdenum enhances structural stability and pitting corrosion resistance, while chromium provides excellent oxidation and general corrosion protection. he controlled carbon content reduces intergranular carbide precipitation tendency, ensuring excellent weldability and structural toughness, ensuring superior welding performance and structural toughness.
3. Heat Treatment & Mechanical Properties
All Alloy 718 (UNS N07718) products adopt standardized dual heat treatment processes: solution annealing followed by precise aging hardening. Standard solution treatment is performed at 950~980℃ with rapid cooling to homogenize microstructure and eliminate residual stress. ubsequent standardized two-step aging treatment: holding at 710~720℃ for 8 hours, then furnace cooling to 610~620℃ for 8 hours before air cooling, which allows full and stable precipitation of strengthening phases, maximizing mechanical strength and fatigue resistance. Each batch is equipped with complete heat treatment records, PMI spectral reports and authoritative mechanical test certificates.
3.2 Room-Temperature Mechanical Properties (Aged Condition)
- Tensile Strength: ≥1240 MPa
- Yield Strength (0.2% Offset): ≥1030 MPa
- Elongation: ≥12%
- Brinell Hardness: ≥320 HB
3.3 Physical & High-Temperature Characteristics
Density: 8.22 g/cm³; Average linear expansion coefficient (20~650℃): 14.2×10⁻⁶/℃. Alloy 718 maintains stable mechanical properties and creep resistance at temperatures up to 650℃, with excellent anti-fatigue performance under high-frequency alternating load. It retains reliable toughness at cryogenic temperatures, featuring minimal thermal deformation and outstanding structural dimensional stability in long-term cyclic service.
4. Core Performance Advantages
4.1 Ultra-High Mechanical Strength & Fatigue Resistance
Benefiting from precipitation strengthening mechanism, UNS N07718 achieves far higher tensile and yield strength than conventional nickel alloys. It exhibits exceptional resistance to high-cycle fatigue and mechanical creep, perfectly adapting to high-pressure, high-load and vibration-intensive working conditions, which is irreplaceable for aerospace and high-end pressure equipment.
4.2 Excellent Multi-Medium Corrosion Resistance
The chromium-molybdenum composite alloy system provides outstanding resistance to oxidation, pitting, crevice corrosion and stress corrosion cracking. It performs stably in seawater, neutral brine, acidic media and H₂S/CO₂ oilfield environments, effectively resisting sulfidation and chloride corrosion failure.
4.3 Superior Low & Medium Temperature Stability
Alloy 718 has no ductile-brittle transition at ultra-low temperatures and maintains excellent impact toughness. Meanwhile, it retains stable mechanical integrity and anti-creep performance under long-term service below 650℃, covering cryogenic storage, normal temperature and medium-high temperature multi-scene applications.
4.4 Excellent Weldability & Processability
Compared with other high-strength precipitation hardening superalloys, Alloy 718 features lower welding cracking sensitivity. It can be welded via GTAW and GMAW processes with matched professional filler wires. The solution-annealed base material presents excellent hot forging, cold machining and forming performance, supporting precision manufacturing of complex structural parts.
4.5 Reliable Thermal Structural Stability
With stable precipitated phase microstructure, Under long-term thermal cycling below 650℃, UNS N07718 will not undergo rapid strength attenuation or grain coarsening. It maintains consistent mechanical performance and dimensional accuracy, greatly extending the service life of key load-bearing components.
5. Product Range & Specifications
We supply full-series ASTM/ASME standard Alloy 718 UNS N07718 finished products and semi-finished materials for high-strength and corrosion-resistant 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-pressure 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
- High-Pressure Flanges & Custom Forgings: WN, SO, blind flanges and special-shaped high-strength structural forgings for extreme working conditions
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 & Aviation Industry: Gas turbine discs, blades, combustion chamber components, engine fasteners, high-temperature load-bearing structural parts
- Oil & Gas Offshore Engineering: High-pressure wellhead fittings, downhole tool components, offshore platform corrosion-resistant structural parts, pipeline connectors
- Power Generation Industry: Gas turbine hot-section components, boiler high-pressure fittings, generator rotor parts, thermal cycle key equipment
- Petrochemical & Chemical Industry: High-pressure reactor internals, high-strength heat exchanger tubes, acid and alkali corrosion-resistant process piping
- Cryogenic & Precision Equipment: Low-temperature storage vessel components, cryogenic pipeline fittings, high-precision mechanical structural parts
7. Quality Control & Product Marking
All Alloy 718 UNS N07718 products are manufactured under strict ISO 9001 quality management system. Our standardized production and inspection workflow covers raw material spectral recheck → hot forming & professional 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 718 / UNS N07718 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.
