UNS N07718 Alloy 718 Seamless Pipe Hard-deformable Nickel-base Alloy Hot-extruded Seamless Tube

UNS N07718 Alloy 718 Seamless Pipe Hard-deformable Nickel-base Alloy Hot-extruded Seamless Tube 

Material Standard: ASTM B637 / ASME SB637 / AMS 5596 (Aerospace)
UNS Designation: N07718
Common Names: Inconel 718, Alloy 718, Nickel-Chromium Superalloy

1. Key Composition (Weight %)

2. Manufacturing Process

• Seamless Pipe Production:

  • Hot Extrusion: Billet heated to ~1100°C and extruded through a die to form hollow shells.

  • Cold Drawing/Pilgering: Further precision sizing for tight tolerances (OD ±0.1mm, WT ±5%).

  • Solution Annealing: 955-1010°C + rapid cooling (water or air) to dissolve precipitates.

  • Aging Treatment: Dual-stage (720°C ±10°C for 8h → furnace cool to 620°C ±10°C for 8h) to precipitate γ″/γ′ phases.

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3. Properties

4. Applications

• Aerospace: Turbine blades, combustion chambers (up to 700°C).

• Oil & Gas: Downhole tubing, subsea risers (resists sulfide stress cracking).

• Nuclear: Reactor coolant pipes (neutron irradiation resistance).

• Chemical Processing: Valves, reactors handling chlorides/acidic media.

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• 5. Advantages Over Alternatives

• vs. Alloy 625: Higher strength (but lower ductility) due to γ″ hardening.

• vs. Stainless Steel (e.g., 316L): 3x higher yield strength at 500°C.

• Weldability: Unlike many superalloys, Alloy 718 can be welded via TIG/GTAW without post-weld cracking (low Al/Ti content).

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6. Compliance & Testing

• Certifications: NACE MR0175 (sulfide stress cracking resistant), PED 2014/68/EU.

• Testing:

  • NDT: 100% ultrasonic testing (ASTM E213) for defects.

  • PMI: XRF verification of composition.

  • Mechanical Tests: Per ASTM E8/E21.

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