If you are sourcing Inconel 718 precipitation‑hardening nickel‑base superalloy for aerospace gas turbine parts, oil‑gas downhole hardware, boiler superheater components or high‑strength fasteners, its primary ASTM designation is UNS N07718. Different ASTM specifications apply depending on product shape, while multiple international grades serve as close cross‑reference equivalents. Always verify material certificates to confirm compliance for your critical‑service project.
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Products Description
What is Inconel 718 alloy?
Inconel 718 (UNS N07718) is a widely‑used niobium‑strengthened precipitation‑hardening nickel‑iron‑chromium superalloy. It delivers high tensile strength, creep‑rupture performance and corrosion resistance for continuous service up to 650 ℃. Its balanced weldability and formability make it the preferred material for demanding high‑temperature and corrosive‑environment components across multiple industries.
What is the ASTM equivalent of Inconel 718 alloy?
| Country / System | Grade | ISC / W‑Nr. | Standard Document |
|---|---|---|---|
| USA UNS | Inconel 718 | N07718 | Base UNS number |
| USA ASTM‑Bar & Forging | Alloy 718 | N07718 | ASTM B637 / ASME SB637 |
| USA ASTM‑Sheet & Plate | Alloy 718 | N07718 | ASTM B670 |
| USA ASTM‑Seamless Tube | Alloy 718 | N07718 | ASTM B983 |
| USA AMS(Aerospace) | Inconel 718 | N07718 | AMS 5662, AMS 5596 |
| China GB | GH4169(GH169) | H41690 | GB/T 14992 |
| Europe EN / DIN | NiCr19Fe19Nb5Mo3 | 2.4668 | EN 10095 |
| Japan JIS | NCF718 | - | JIS G 4902 |
| France AFNOR | NC19FeNb | - | NF standard |
Can GH4169 be substituted for Inconel 718 alloy?
Yes. GH4169 is the Chinese domestic counterpart grade for Inconel 718 (UNS N07718). Under GB/T 14992 specification, GH4169 shares nearly identical chemical limits with Inconel 718.
One key note: While chemical composition ranges align, aerospace‑critical projects often require AMS standard certification with strict melting‑process controls (VIM‑VAR double melting). For general industrial high‑temperature applications, GH4169 can be adopted; for aviation or NADCAP‑required components, AMS‑certified Inconel 718 material is strongly recommended.
Inconel 718 Alloy Chemical Composition
| Element (wt.%) | ASTM UNS N07718 |
|---|---|
| Ni | 50.00‑55.00 |
| Cr | 17.00‑21.00 |
| Fe | Balance |
| Nb+Ta | 4.75‑5.50 |
| Mo | 2.80‑3.30 |
| Ti | 0.65‑1.15 |
| Al | 0.20‑0.80 |
| C | ≤0.08 |
| Mn | ≤0.35 |
| Si | ≤0.35 |
| P | ≤0.015 |
| S | ≤0.015 |
| B | ≤0.006 |
Inconel 718 Alloy Typical delivery condition & mechanical properties
| Delivery Condition | Rp0.2 MPa | Rm MPa | Elongation A (%) | Hardness |
|---|---|---|---|---|
| Solution‑annealed | 450‑650 | 850‑1000 | 25‑35 | ≤28 HRC |
| Solution + Double‑Aging | ≥1035 | ≥1240 | ≥12 | 36‑42 HRC |
Note: Mechanical values apply to standard heat‑treated bar stock. Actual results are affected by section thickness and forging process. Special mechanical requirements can be agreed via purchase order.
Physical Properties of Inconel 718 (UNS N07718)
| Item | Value |
|---|---|
| Density | 8.23 g/cm³ |
| Melting Range | 1260‑1335 ℃ |
| Modulus of Elasticity | 200 GPa |
| Thermal Conductivity (20℃) | 11.6 W/(m·K) |
| Coefficient of Thermal Expansion (20‑650℃) | 12.8×10⁻⁶ /℃ |
Main Application of Inconel 718 Alloy
- Aerospace & Gas turbine: Turbine disks, combustion chamber components, high‑temperature fasteners, compressor shafts.
- Oil & gas industry: Downhole safety valves, packer assemblies, high‑pressure mandrels for deep corrosive wells.
- Power‑generation equipment: Boiler superheater straight tubes, U‑bend tubes, flue‑gas desulfurization spray nozzles.
- Chemical processing: Heat‑exchanger tubing, pressure vessel parts resisting high‑temperature corrosive media.
- Precision hardware: High‑strength bolts, custom forgings and machined blanks for extreme‑condition service.
Common Product Forms and Delivery Standards for Inconel 718 Alloy
- Round Bar / Rod Hot‑rolled / peeled bar (ASTM B637): large‑diameter blanks for forging and heavy‑section machining. Cold‑drawn / centerless‑ground bar (ASTM B637): tight tolerance for shafts, aerospace fasteners.
- Sheet & Plate (ASTM B670) Cold‑rolled thin sheet for forming parts; saw‑cut heavy plate for valve blocks and structural components.
- Seamless Tube & Pipe (ASTM B983) Standard seamless tube and precision capillary tube for heat‑exchanger and aerospace instrument circuits.
- Forgings & Forging Stock (ASTM B637) Custom ring forgings, disc preforms, shaft forgings produced according to customer drawings.
Delivery Condition: Solution‑annealed or solution‑annealed plus double‑age‑hardened upon customer requirements.
If you are currently sourcing this nickel superalloy or planning component manufacturing, GNEE can provide material cross‑reference checking, dimension tolerance confirmation and full MTC documentation support. Send your drawing and standard requirements for quotation.
FAQ:
Q: Is UNS N07718 equal to Inconel 718?
A: Yes. UNS N07718 is the unified numbering system designation for Inconel 718 nickel‑base superalloy. Different ASTM / AMS specifications reference this same UNS grade for different product forms.
Q: Can Inconel 718 be used for seawater offshore service?
A: Inconel718 offers good chloride stress‑corrosion‑cracking resistance compared with ordinary stainless steel. For long‑term immersion seawater service, full corrosion testing is still recommended to match real‑world operating environment.
Q: What documents should I require while buying Inconel 718 equivalent grades?
A: Request mill test certificates including chemical analysis, heat‑lot traceability, mechanical test data, PMI and NDT records. Specify ASTM or AMS version on purchase order for your project acceptance criteria.
