Inconel® 718 (UNS N07718) is a precipitation-hardenable nickel-based superalloy widely used in aerospace applications requiring high strength, fatigue resistance and reliable performance at elevated temperatures. Its combination of tensile strength, creep-rupture resistance, oxidation resistance and good weldability makes it suitable for aircraft engine components, gas turbine parts, high-temperature fasteners and other critical aerospace assemblies.
For aerospace procurement, however, selecting Inconel 718 involves more than confirming the alloy grade. Buyers must consider the applicable AMS specification, product form, heat-treatment condition, mechanical properties, inspection requirements and material traceability. These details determine whether the supplied material is suitable for the intended component and manufacturing process.
Why Is Inconel 718 Used in Aerospace Applications?
Aircraft engines and aerospace systems operate under demanding mechanical and thermal conditions. Components may experience high rotational speeds, cyclic loading, vibration, elevated temperatures and repeated thermal changes. Materials used in these environments must maintain sufficient strength and dimensional stability throughout their service life.
Inconel 718 is particularly suitable for applications requiring a combination of high strength and manufacturability. Unlike some nickel-based superalloys that are difficult to fabricate, Alloy 718 has a relatively slow precipitation-hardening response. This allows machining, forming and welding operations to be performed before final age hardening under properly controlled procedures.
Its main advantages include:
- High mechanical strength: Suitable for highly loaded components and fasteners.
- Creep and rupture resistance: Helps components maintain load-bearing capability at elevated temperatures.
- Fatigue resistance: Supports applications involving repeated loading and vibration.
- Oxidation and corrosion resistance: Helps protect components exposed to hot gases and demanding environments.
- Good fabrication characteristics: Can be forged, machined and welded using suitable procedures.
These characteristics make Inconel 718 a widely established material for aircraft and land-based gas turbine applications.
Chemical Composition of Inconel 718
The chemical composition of Inconel 718 is carefully controlled to achieve its mechanical and high-temperature properties. Nickel forms the main alloy matrix, while chromium contributes to oxidation and corrosion resistance. Niobium, molybdenum, titanium and aluminum support strengthening and other performance characteristics.
| Chemical Element | Composition (wt.%) | Main Function |
|---|---|---|
| Nickel (Ni) | 50.0–55.0 | Main alloy matrix and high-temperature performance |
| Chromium (Cr) | 17.0–21.0 | Oxidation and corrosion resistance |
| Niobium + Tantalum (Nb + Ta) | 4.75–5.50 | Precipitation strengthening |
| Molybdenum (Mo) | 2.80–3.30 | Solid-solution strengthening and corrosion resistance |
| Titanium (Ti) | 0.65–1.15 | Precipitation strengthening |
| Aluminum (Al) | 0.20–0.80 | Participates in precipitation strengthening |
| Iron (Fe) | Balance | Main balance element |
Note: These are commonly published composition limits. Buyers should verify the exact chemical requirements against the applicable material specification and revision.
One important feature of Inconel 718 is its precipitation-strengthening mechanism. During the specified heat-treatment process, fine strengthening phases, particularly γ″ (Ni₃Nb), form within the alloy matrix. These precipitates significantly increase the material's strength.
The balance of niobium, titanium and aluminum is therefore important. Incorrect chemical composition or unsuitable heat treatment can affect the resulting microstructure and mechanical properties.
Aerospace Components Manufactured from Inconel 718
Inconel 718 is used in several aircraft engine and aerospace component categories. The required product form depends on the component geometry, manufacturing process, load conditions and engineering specification.
GNEE STEEL
Inconel 718 for Aircraft Engine Discs and Rings
Typical application: high-strength forged components for turbine and compressor assemblies.
Engine discs and rings are exposed to rotational forces, thermal cycling and substantial mechanical loads. Forged Inconel 718 is used in selected engine applications where high strength and fatigue performance are required.
The forging process helps produce the required component geometry and mechanical structure. Buyers should confirm forging dimensions, material condition, heat-treatment requirements and applicable ultrasonic inspection criteria.
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Alloy 718 for Turbine and Compressor Components
Inconel 718 is used in selected turbine and compressor components, including rotating and structural parts. Its high strength and resistance to fatigue make it suitable for components subjected to repeated mechanical loading.
The actual operating temperature and stress conditions must be evaluated during material selection. Inconel 718 is not automatically suitable for every hot-section component. More demanding temperature environments may require other nickel-based superalloys.
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UNS N07718 for Aerospace Fasteners and High-Strength Bolts
Typical application: high-strength bolts, studs, screws and fastening components.
Aerospace fasteners must maintain clamping force under vibration, thermal changes and mechanical stress. Inconel 718 is used for selected bolts, studs and other fastening components because of its high strength after precipitation hardening.
For procurement, buyers should specify the required fastener standard, diameter, thread dimensions, mechanical properties, heat-treatment condition and surface requirements. Material certification alone does not replace finished-fastener inspection.
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Inconel 718 for Rocket Engine and Cryogenic Components
Inconel 718 can be used in selected engine casings, rings and structural assemblies. These components may require a combination of strength, weldability and resistance to thermal and mechanical loading.
Depending on the design, the material may be supplied as plate, sheet, bar or forged stock. The correct product form should be selected according to the component drawing and manufacturing route.
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Inconel 718 for Combustion Chamber Liners
Engine combustion chambers experience extreme thermal environments where materials are exposed to high-velocity hot gases and rapid thermal cycling. Inconel 718 is deployed for combustion liners, transition pieces, and flame holders due to its reliable high-temperature strength and excellent weldability. It effectively resists thermal fatigue and high-temperature oxidation, preventing premature cracking and structural failure in the most demanding hot-section zones of aerospace propulsion systems.
Common Aerospace Specifications for Inconel 718
Choosing the correct specification is one of the most important steps in aerospace material procurement. Different standards cover different product forms, delivery conditions and testing requirements.
| Standard | Main Product Form / Scope | Procurement Considerations |
|---|---|---|
| AMS 5662 | Bars, forgings and rings; solution heat-treated condition | Chemical composition, melting practice, grain structure and heat-treatment response |
| AMS 5663 | Bars, forgings and rings; precipitation-hardened condition | Tensile properties, hardness, heat treatment and other specified tests |
| AMS 5596 | Sheet, strip and plate | Product dimensions, condition and mechanical requirements |
| ASTM B637 | Nickel alloy bars, forgings and forging stock for moderate or high-temperature service | Chemical analysis, heat treatment, tensile, hardness and stress-rupture requirements |
AMS 5662 and AMS 5663 are frequently referenced in aerospace procurement. In general, AMS 5662 covers solution-treated material, while AMS 5663 covers precipitation-hardened material. The required condition must match the component manufacturer's processing route.
ASTM B637 is also relevant to Inconel 718 bars and forgings, but buyers should not assume that ASTM B637 automatically satisfies an aerospace drawing calling for a specific AMS specification.
Important: Always check the exact standard revision, product form, condition and supplementary requirements stated on the purchase order or engineering drawing.
Heat Treatment: AMS 5662 vs. AMS 5663
Heat treatment has a direct influence on the mechanical properties of Inconel 718. The alloy is commonly supplied in a solution-treated condition and subsequently precipitation hardened to develop its required strength.
| Item | AMS 5662 | AMS 5663 |
|---|---|---|
| General condition | Solution heat-treated | Solution heat-treated and precipitation hardened |
| Main purpose | Provides material for further processing and subsequent aging | Provides specified hardened mechanical properties |
| Typical procurement use | Material to be machined or processed before final aging | Material supplied in the required hardened condition |
| Important checks | Chemical composition, solution treatment and heat-treatment response | Tensile strength, yield strength, elongation, hardness and specified testing |
The correct condition depends on the component manufacturing process. For example, a manufacturer may purchase solution-treated bar, machine the component and then carry out the required precipitation-hardening treatment.
By contrast, purchasing material already aged to the required condition may be appropriate for certain finished-product or machining requirements. The choice should be confirmed with the engineering specification.
Buyers should never compare two quotations based only on the words "annealed" or "aged." The exact AMS specification and delivery condition must be checked.
Why Does Aerospace-Grade Inconel 718 Cost More?
Aerospace-grade Inconel 718 generally costs more than standard industrial material because the final product may require additional controls beyond basic alloy composition.
The main cost factors include:
- Raw material costs: High nickel content and other alloying elements influence the melting cost.
- Melting and refining: Required melting routes and process controls can increase production expenses.
- Forging and rolling: High deformation resistance and controlled processing conditions increase manufacturing time.
- Heat treatment: Solution treatment and precipitation hardening require controlled thermal processing.
- Inspection: Mechanical testing, ultrasonic inspection and other specified examinations add cost.
- Traceability and certification: Aerospace procurement may require more detailed documentation and quality controls.
The price difference between two Inconel 718 products can therefore be substantial, even when both carry the same UNS designation. Product form, dimensions, AMS specification, delivery condition and inspection requirements must all be considered when comparing quotations.
GNEE STEEL: Inconel 718 Supply for Aerospace Requirements
GNEE STEEL supports international procurement requirements for Inconel 718 (UNS N07718 / W.Nr. 2.4668) in multiple product forms, including round bars, plates, sheets, seamless tubes, forgings and forging stock.
We can review buyer requirements covering product dimensions, applicable standards, heat-treatment conditions, inspection and documentation. For aerospace-related orders, the exact specification and acceptance criteria should be confirmed before quotation to ensure that the proposed material matches the customer's technical requirements.
If you are sourcing Inconel 718 for aircraft engines, turbine components, aerospace fasteners or other high-strength applications, send us the following information:
- Product form and material specification
- Required dimensions and tolerances
- Heat-treatment condition
- Required mechanical properties
- Inspection and certification requirements
- Order quantity and delivery destination
Available Product Forms of Inconel 718 for Aerospace Procurement
Different aerospace components require different starting material forms. GNEE STEEL can discuss sourcing requirements for multiple Inconel 718 product forms according to the buyer's specification.
Available Product Forms of Inconel 718 for Aerospace Applications
| Product Form | Typical Aerospace Uses | Key Purchasing Specifications |
|---|---|---|
| Round Bar / Rod | Fasteners, shafts and machined components | Diameter, length, AMS specification and heat-treatment condition |
| Plate | Structural parts and machined components | Thickness, width, length and material condition |
| Sheet / Strip | Formed sheet-metal components | Thickness, width, surface condition and tolerances |
| Seamless Tube | Aerospace fluid lines, fuel and hydraulic system components, engine auxiliary lines and instrumentation tubing | Outside diameter, wall thickness, length, dimensional tolerances, applicable specification and NDT requirements |
| Forgings / Rings | Engine discs, rings and load-bearing components | Forging dimensions, process requirements and ultrasonic inspection |
| Billet / Forging Stock | Further forging and component manufacturing | Billet dimensions, chemical composition and required testing |
Note: The actual suitability of Inconel 718 seamless tubing depends on the system design, operating conditions and applicable aerospace specification. Buyers should confirm the required tube standard, delivery condition and inspection criteria before ordering.
Contact GNEE STEEL to discuss your Inconel 718 requirements and request a specification-based quotation.
FAQ:
Is Inconel 718 stronger than steel?
Yes, Inconel 718 is significantly stronger than standard and stainless steels at room temperature and retains its strength remarkably well at extreme high temperatures where most steels weaken or fail.
Is Inconel 718 suitable for aircraft engine applications?
Yes. Inconel 718 is widely used in selected aircraft engine components, including discs, rings, fasteners, casings and other parts requiring high strength and fatigue resistance. The specific application must be evaluated against operating temperature, stress and design requirements.
What is the UNS number of Inconel 718?
The correct UNS designation is N07718. Its common material number is W.Nr. 2.4668.
What is the difference between AMS 5662 and AMS 5663?
AMS 5662 generally covers solution-treated bars, forgings and rings, while AMS 5663 covers precipitation-hardened products. The required specification depends on the manufacturing process and final mechanical properties.
Can Inconel 718 be supplied as aerospace-grade round bar?
Yes. Round bar is a common procurement form for aerospace-related machining and component manufacturing. Buyers should specify the required AMS standard, diameter, length, heat-treatment condition and inspection requirements.
What documents should accompany aerospace Inconel 718?
Depending on the purchase specification, buyers may require a material test certificate, chemical analysis, mechanical test results, heat-treatment records, inspection reports and traceability documentation. The exact document package should be agreed before ordering.
