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When mission-critical components must perform reliably from cryogenic temperatures up to 650°C (1200°F) while enduring extreme centrifugal loads and corrosive atmospheres, Inconel 718 (UNS N07718 / W.Nr. 2.4668 / GH4169) is the global industry standard. It is a precipitation-hardenable nickel-chromium-iron alloy strengthened primarily by niobium-bearing gamma double-prime (γ") precipitates. Unlike solution-strengthened alloys such as Inconel 600 or 625, Alloy 718 achieves very high yield strength (over 1000 MPa) after age hardening and retains excellent weldability—weld zones can be re-aged to recover near-parent-metal strength. Shanghai COCESS Special Alloys Co., Ltd supplies fully certified Inconel 718 bar, forging stock, plate, sheet, seamless tube, and welded pipe in strict accordance with ASTM B637, B670, AMS 5662/5663, and AMS 5596 to support aerospace, power generation, and oil & gas projects worldwide.
The unique precipitation behavior of Inconel 718 is driven by its niobium and molybdenum content, which form coherent γ" (Ni₃Nb) precipitates during aging. Typical composition limits per AMS 5662 / ASTM B637 are:
Nickel (Ni): 50.00 – 55.00 % (Matrix / Balance)
Chromium (Cr): 17.00 – 21.00 % (Oxidation & general corrosion resistance)
Iron (Fe): 16.00 – 20.00 % (Balance / Stabilizes austenite)
Niobium + Tantalum (Nb+Ta): 4.75 – 5.50 % (Primary γ" strengthener)
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 %
Phosphorus (P): ≤ 0.015 %
Sulfur (S): ≤ 0.015 %
Boron (B): ≤ 0.006 %
Copper (Cu): ≤ 0.30 %
Inconel 718 is usually supplied in the solution-annealed (soft) condition for machining/formability, then aged (typically 720°C + 620°C two-step) to develop full strength.
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 Temperature: Below –196 °C (non-magnetic in annealed condition)
Typical Mechanical Properties (Room Temp, Solution Treated + Aged per AMS 5663):
Tensile Strength (Rm): ≥ 1240 – 1275 MPa (180 – 185 ksi); typical 1310 – 1380 MPa
Yield Strength (Rp0.2): ≥ 1030 – 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 Temperature Range: –253 °C (cryogenic) to 650 °C continuous; short excursions to 700 °C acceptable depending on stress.
Elevated Temperature Reference (650 °C):
Tensile Strength: ~965 MPa (140 ksi)
Yield Strength: ~790 MPa (115 ksi)
100 h / 690 MPa Stress Rupture Life: typically ≥ 23 h
Precipitation Hardening with Good Weldability: Unlike some γ'-strengthened superalloys, Inconel 718 does not severely soften in the weld HAZ. Post-weld aging restores strength, making it ideal for large welded structures (engine cases, ducting).
Broad Temperature Capability: Maintains toughness at cryogenic temperatures (used in liquid oxygen/hydrogen rocket systems) and retains high strength to ~650°C.
Corrosion & SSC Resistance: Resists oxidizing and reducing acids, seawater, and sour-gas (H₂S/CO₂/Cl⁻) environments. Complies with NACE MR0175/ISO 15156 for sour service.
Creep & Fatigue Resistance: Excellent low-cycle fatigue (LCF) and creep-rupture performance in the 400–650°C range, critical for turbine disks and high-speed rotating parts.
Shanghai COCESS supplies Inconel 718 for the following sectors:
Aerospace & Defense: Turbine disks, compressor disks, blades, seals, cases, mounts, fasteners, and rocket engine turbopump components (NASA/SpaceX heritage alloys).
Power Generation: Industrial gas turbine (IGT) disks, bolts, and high-temp fasteners; nuclear reactor internals requiring radiation resistance and strength.
Oil & Gas / Subsea: High-strength wellhead components, packers, mandrels, and completion equipment in sour (H₂S-containing) environments; subsea bolting.
High-Performance Automotive / Racing: Turbocharger wheels, exhaust valves, and connecting rods where light weight and high-temp strength are required.
Cryogenic Systems: LOX/LH₂ tank structural members, valves, and fittings.
We stock and process Inconel 718 (UNS N07718) in compliance with major specifications:
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 (seamless), AMS 5589 / 5590
Welding Wire: AMS 5832 (ERNiFeCr-2)
Forgings / Custom Shapes: Per customer drawing, rough machined or as-forged
All material is shipped with EN 10204 3.1 Mill Test Reports documenting heat analysis and mechanical test results. Ultrasonic testing (UT per ASTM A388 / SEB 682), magnetic particle inspection, and third-party witness (SGS, TÜV, DNV, etc.) can be arranged on request.
For stock availability, Inconel 718 technical datasheets, or project-specific quotations, please contact Shanghai COCESS Special Alloys Co., Ltd. Our technical team is ready to support your material specification and compliance needs for aerospace, energy, and high-performance engineering applications.
