Views: 3 Author: Monica Publish Time: 2025-09-10 Origin: Site
718 Inconel is a nickel alloy renowned for its high strength, corrosion resistance, and fabricability, maintaining its integrity from cryogenic temperatures up to 1300°F. Its unique hardenability and resistance to post-weld cracking make it suitable for aerospace, oil and gas, power generation, and chemical processing.
718 inconel has a comprehensive range of product forms, including plate, sheet, bar, wire, pipe, tube, fittings, and forgings. Sourcing the right Inconel 718 product requires knowing its specifications, equivalents, properties, and procurement details.
While "Inconel 718" is the widely recognized trade name, the alloy is standardized under several international systems. Its Unified Numbering System designation is N07718, serving as the universal identifier. However, different countries and regions still use names that belong to their national standards.
Within the European EN standard, it is NiCr19Fe19Nb5Mo3, sometimes seen as 2.4668.
Other common proprietary or national equivalents include Nicrofer 5219 Nb (VDM Metals), Haynes 718 (Haynes International), Alloy 718, W.Nr. 2.4668 (German Werkstoffnummer), GH4169 (Chinese GB standard), and NC19FeNb (French AFNOR).
Crucially, while these names are chemically similar alloys centered around 718, minor variations in exact composition limits, impurity controls, and especially the detailed thermal processing mandated by different specifications can significantly influence the final microstructure and mechanical properties, particularly strength and creep resistance at elevated temperatures.
Therefore, specifying the exact material standard, such as AMS 5663M, is always preferred over relying on the trade name or UNS number when you are procuring.
An Inconel 718 data has 3 categories:
The following are AMS 5662 and AMS 5663 718 Inconel (UNS N07718) chemical compositions.
Nickel 50.0 - 55.0: Ni provides austenitic matrix, corrosion resistance, and toughness.
Chromium 17.0 - 21.0: Cr is for oxidation and corrosion resistance.
Iron 17-19%: lowers cost, stabilizes structure. Significant Fe content is a key feature.
Niobium + Tantalum 4.75 - 5.50: Forms the γ'' strengthening phase.
Molybdenum 2.80 - 3.30: Mo is a solid solution strengthener; it enhances high-temp strength and corrosion resistance.
Titanium 0.65 - 1.15: It forms the γ' phase and helps secondary hardening.
Aluminum 0.20 - 0.80: Al contributes to secondary hardening and oxidation resistance.
Carbon 0.08 max: It affects strength, weld ability, and carbide formation.
Manganese 0.35 max: Mn can affect hot work ability.
Silicon 0.35 max: Si affects oxidation resistance and fluidity in casting.
Copper 0.30 max: Cu can reduce hot work ability and corrosion resistance.
Cobalt 1.00 max: Co restricted in nuclear applications.
Phosphorus 0.015 max: P can embrittle grain boundaries.
Sulfur 0.015 max: S forms low-melting sulfides and harms hot work ability and ductility.
Boron 0.006 max: B strengthens grain boundaries but excess harms ductility.
718 inconel density: 8.19 g/cm³ (0.296 lb/in³)
718 inconel melting point: 1260-1340 ℃
718 inconel specific heat capacity: 435 J/kg·K at 20°C
718 inconel thermal expansion coefficient: 13.0 μm/m·°C (7.2 μin/in·°F) from 20 to 100°C
718 inconel themal conductivity: 11.4 W/m·K at 100°C
718 inconel electrical resistivity: 128 μΩ·cm at 20°C
718 inconel magnetism: very low (<1.01) in the annealed condition
Typical room-temperature mechanical properties:
Tensile Strength: ≥ 1350 MPa (195 ksi)
Yield Strength: ≥ 1170 MPa (170 ksi)
Elongation: ≥ 12%
Reduction in Area: ≥ 15%.
Hardness: 35-45 HRC.
High-Temperature Strength: Inconel 718 has exceptional strength at elevated temperatures, particularly up to approximately 650°C, primarily from the precipitation of the coherent, ordered gamma double prime (γ'') phase (Ni₃Nb) during age hardening.
Creep and Stress Rupture Resistance: The γ'' precipitates, combined with solid solution strengthening from elements like molybdenum, confer excellent creep resistance and stress rupture life to Inconel 718 at temperatures below its phase stability limit (~650°C). It maintains useful load-bearing capability under prolonged exposure to high stresses at elevated temperatures, a critical requirement for rotating parts in gas turbines.
Excellent Fabricability and Weldability: Its relatively high iron content contributes to good hot workability, allowing successful forging, rolling, and extrusion. Crucially, it exhibits outstanding weldability by various processes without requiring post-weld heat treatment to avoid cracking.
Good Corrosion and Oxidation Resistance: Inconel 718 possesses good general corrosion resistance due to its high chromium content. It also exhibits good resistance to a wide range of corrosive media, including acids, salts, and seawater, particularly when fully hardened.
High Fatigue Strength and Fracture Toughness: 718 Inconel has high fatigue strength across a wide range of temperatures. Furthermore, it maintains good fracture toughness in both the solution-annealed and precipitation-hardened conditions.
Microstructural Stability: Below its critical temperature limit of approximately 650°C, 718 Inconel exhibits good microstructural stability over extended periods. The γ'' precipitates remain fine and coherent, providing stable strengthening. This long-term stability is essential for components designed with long service lives, ensuring predictable mechanical property retention.
Outstanding Cryogenic Toughness: Inconel 718 retains excellent ductility and fracture toughness at cryogenic temperatures down to liquid helium. Its face-centered cubic austenitic nickel-chromium matrix does not undergo a ductile-to-brittle transition. This property, combined with its high strength, makes it a preferred material for cryogenic applications such as pressure vessels, pumps, valves, and structural components in rocket engines and superconducting magnet systems.
Below is a price form for Inconel 718 (UNS N07718) across common product forms, reflecting 2024 market estimates in both USD/kg and USD/lb.
Product Form | inconel 718 price per kg (USD/kg) | inconel 718 price per pound (USD/lb) |
Inconel 718 Ingot | 35–55 | 16–25 |
Inconel 718 Bar | 45–75 | 20–34 |
Inconel 718 Plate (≥6mm thick) | 50–85 | 23–39 |
Inconel 718 Sheet (0.5–5mm) | 70–120 | 32–55 |
Inconel 718 Forging Fittings | 60–100 | 27–45 |
Inconel 718 Wire | 80–140 | 36–64 |
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Getting an accurate and timely quote for 718 Inconel requires providing suppliers with precise information. Here’s what you need to specify:
Exact Alloy and Specification: Clearly state "Inconel 718" and material specification, such as AMS 5663 for bar, AMS 5596 for sheet, ASTM B637 for bar, and ASTM B670 for plate.
Product Form and Dimensions: Specify the form, like Plate, Sheet, Bar, Wire, Tube, Pipe, Forging, fitting and provide precise dimensions (e.g., Thickness x Width x Length for plate/sheet, Diameter x Length for bar, or OD x Wall x Length for tube/pipe). Include tolerances if critical.
Quantity: Provide the required quantity, such as number of pieces, total weight, or total length/area.
Heat Treatment Condition: Specify the required condition, such as solution annealed, solution annealed and aged per AMS 5662/5663, annealed, or stress relieved. For aged conditions, ensure it matches the chosen spec.
Additional Testing/Special Requirements: State any requirements beyond the standard spec, such as ultrasonic testing (UT), dye penetrant inspection (DPI), eddy current (ET), grain size control, special surface finish, or traceability needs.
Delivery Requirements: Provide your delivery location and time frame.
