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In sectors where components must endure extreme centrifugal loads, corrosive media, and temperatures ranging from cryogenic to 650°C, material consistency is non-negotiable. Inconel 718 (UNS N07718 / W.Nr. 2.4668 / GH4169) is the world's most widely specified precipitation-hardening nickel-chromium superalloy, strengthened by gamma double-prime (γ") Ni₃Nb precipitates. Its unique combination of ultra-high yield strength, weldability, and post-weld age-hardening response sets it apart from solution-strengthened alloys like 600 or 625. Shanghai COCESS Special Alloys Co., Ltd supplies fully certified Inconel 718 bar, forging stock, plate, sheet, seamless tube, and custom forgings in strict accordance with ASTM B637, AMS 5662/5663, and AMS 5596, supporting aerospace OEMs, turbine overhaul shops, and sour-service oil & gas projects worldwide.
The performance of Alloy 718 is driven by a high niobium content that forms coherent γ" precipitates during aging, supported by molybdenum for solid-solution strengthening and chromium for environmental resistance.
Chemical Composition (Weight %, per AMS 5662 / ASTM B637):
Nickel (Ni): 50.00 – 55.00 % (Matrix / Balance)
Chromium (Cr): 17.00 – 21.00 % (Oxidation & general corrosion resistance)
Iron (Fe): 16.00 – 20.00 % (Austenite stabilizer / Balance)
Niobium + Tantalum (Nb+Ta): 4.75 – 5.50 % (Primary γ" (Ni₃Nb) former — main strengthening phase)
Molybdenum (Mo): 2.80 – 3.30 % (Solid-solution strengthening, pitting resistance)
Titanium (Ti): 0.65 – 1.15 % (Contributes to γ' co-precipitation)
Aluminum (Al): 0.20 – 0.80 % (Contributes to γ' co-precipitation)
Cobalt (Co): ≤ 1.00 %
Carbon (C): ≤ 0.08 %
Manganese (Mn): ≤ 0.35 %
Silicon (Si): ≤ 0.35 %
Sulfur (S): ≤ 0.015 %
Boron (B): ≤ 0.006 %
Copper (Cu): ≤ 0.30 %
Inconel 718 is typically supplied in the solution-annealed (soft) condition for machining/formability, then aged (standard two-step: 720°C × 8h + furnace cool to 620°C × 8h) to develop full properties.
Physical Constants:
Density: 8.19 – 8.24 g/cm³ (0.296 lb/in³)
Melting Range: 1260 – 1336 °C (2300 – 2437 °F)
Thermal Conductivity (21°C): ~11.4 W/m·K
Coefficient of Thermal Expansion (21–649°C): ~14.6 × 10⁻⁶ /°C
Curie Point: Below –196°C (non-magnetic in annealed condition)
Typical Mechanical Properties (Room Temp, Solution Treated + Aged per AMS 5663):
Tensile Strength (Rm): ≥ 1275 MPa (185 ksi); typical 1310 – 1380 MPa
Yield Strength (Rp0.2): ≥ 1035 MPa (150 ksi); typical 1100 – 1170 MPa
Elongation (A5): ≥ 12 – 15 %
Reduction of Area: ≥ 15 – 20 %
Hardness: 32 – 44 HRC (331 – 401 HB)
Service Temp Range: –253°C (cryogenic) to 650°C continuous; short excursions to 700°C possible depending on stress.
Elevated Temp Reference (650°C):
Tensile Strength: ~965 MPa (140 ksi)
Yield Strength: ~790 MPa (115 ksi)
100h / 690 MPa Stress Rupture Life: typically ≥ 23 h
Weldability with Re-Age Capability: Unlike γ'-hardened superalloys, the HAZ does not severely soften. Welded assemblies can be aged post-weld to recover near-base-metal strength—critical for large fabricated cases, ducts, and pressure vessels.
Broad Temperature Utility: Retains toughness at cryogenic temps (LOX/LH₂ systems) and high strength to 650°C, covering more application windows than most stainless steels or lower-alloyed Ni-Cr-Fe grades.
Sour Service Resistance: Resists sulfide stress cracking (SSC) in H₂S/CO₂/Cl⁻ environments per NACE MR0175 / ISO 15156, making it a standard for downhole tools and wellhead components.
Creep & Low-Cycle Fatigue (LCF): Excellent LCF performance in the 400–650°C range, essential for turbine disks and high-speed rotating parts.
Shanghai COCESS supplies Inconel 718 material for:
Aerospace & Defense: Turbine disks, compressor disks, blades, cases, mounts, fasteners, and liquid-fuel rocket engine turbopump components.
Power Generation: Industrial gas turbine (IGT) disks, bolts, and nuclear reactor internals requiring irradiation resistance and high-temp strength.
Oil & Gas / Subsea: High-strength packers, mandrels, wellhead components, and subsea bolting in sour (H₂S-containing) environments.
High-Performance Automotive: Turbocharger wheels, exhaust valves, and connecting rods.
Cryogenics: LOX/LH₂ tank structural members, valves, and fittings.
We stock and process Inconel 718 (UNS N07718) to the following key standards:
Bar, Rod, Forging Stock, Rings: ASTM B637 / ASME SB637; AMS 5662 (solution treated), AMS 5663 (aged)
Plate, Sheet, Strip: ASTM B670 / ASME SB670; AMS 5596 (sheet), AMS 5597 (strip)
Seamless & Welded Tubing: ASTM B983 / B829; AMS 5589 / 5590
Welding Wire: AMS 5832 (ERNiFeCr-2 / Inconel 718 filler)
Custom Forgings / Rings: Per customer drawing, rough machined or as-forged
All shipments include EN 10204 3.1 Mill Test Reports with full heat analysis and mechanical test data. Ultrasonic Testing (UT per ASTM A388 / SEB 682), Magnetic Particle Inspection (MPI), and third-party witness (SGS, TÜV, DNV, etc.) are available upon request.
For Inconel 718 stock availability, technical datasheets, or project-specific quotations, contact Shanghai COCESS Special Alloys Co., Ltd. Our technical team is ready to support your material specification and compliance needs across aerospace, energy, and high-performance engineering sectors.
Website: https://en.cocessalloys.com
Email: sales@cocessalloys.com
