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Alloy 718
ISO S (heat-resistant alloys & titanium)Precipitation hardening nickel-base superalloy. Number: UNS N07718. Standard: ASTM B637 (bar, forgings) / ASTM B670 (plate) / SAE AMS 5662, 5663, 5664 (bar, forgings, rings) / AMS 5596, 5597 (plate).
🌐JIS and international equivalents
“Close” means composition or properties are not exactly the same. Before substituting, check the values in each standard.
| System | Designation | Number | Relation | Confidence |
|---|---|---|---|---|
| UNS | Alloy 718 | UNS N07718 | — | |
| EN | NiCr19Fe19Nb5Mo3 | 2.4668 | equivalent | Agrees in 2+ sources[2][6][1] |
| JIS | NCF718 | JIS G 4901 (bar) | equivalent | One source / reference[7][8] |
| GB | — | — | Not confirmed |
Differences between the equivalents (from the sources)
- EN NiCr19Fe19Nb5Mo3: VDM and voestalpine give material number 2.4668 and NiCr19Fe19Nb5Mo3. Special Metals also lists W.Nr. 2.4668. VDM's table gives ISO symbol NiCr19Nb5Mo3 and AFNOR NC19FeNb
- JIS NCF718: The creep data sheet of the National Institute for Materials Science (NIMS) covers "19Cr-18Fe-3Mo-5Nb-Ti-Al corrosion-resisting and heat-resisting superalloy bar (JIS NCF 718-B)". The composition is basically the same as Alloy 718, but no Japanese primary source explicitly stating the correspondence between NCF718 and UNS N07718 was found, and the JIS composition ranges are not confirmed. The existence of the 2023 revision of JIS G 4901 (April 20, 2023) was confirmed in the JSA preview, but the preview has no table of steel grades
- GB : Material giving GH4169 is only from distributors' and trading companies' pages, and no primary source from Chinese manufacturers or standards bodies was found
📄Related specifications (AMS, ASTM etc.)
Specifications called up on purchase orders and drawings. AMS are SAE aerospace material specifications, split by product form (bar, plate, forging), melting practice and heat treatment. Standard texts are paid, so only titles and scopes checked on the publishers’ public pages are shown.
| Spec | Scope | Confidence |
|---|---|---|
| ASTM B637 | Standard Specification for Precipitation-Hardening and Cold Worked Nickel Alloy Bars, Forgings, and Forging Stock for Moderate or High Temperature ServiceBar, forgings and stock for forging (hot and cold worked) of precipitation hardening nickel alloys. Includes alloys other than 718 | Agrees in 2+ sources[10][1] |
| ASTM B670 | Standard Specification for Precipitation-Hardening Nickel Alloy Plate, Sheet, and Strip for High-Temperature ServiceRolled plate, sheet and strip of N07718. Delivered in the annealed (solution treated) condition | Agrees in 2+ sources[11][1] |
| AMS 5662 | ALLOY BARS, FORGINGS, AND RINGS, CORROSION AND HEAT RESISTANT Nickel Base - 19Cr - 3.1Mo - 5.1(Cb + Ta) - 0.90Ti - 0.50Al Consumable Electrode or Vacuum Induction Melted, Solution TreatedBar, forgings and rings. Delivered as solution treated (premised on aging after machining) | Agrees in 2+ sources[12][1] |
| AMS 5663 | ALLOY BARS, FORGINGS, AND RINGS, CORROSION AND HEAT RESISTANT Nickel Base - 19Cr - 3.1Mo - 5.1(Cb + Ta) - 0.90Ti - 0.50Al Solution and Precipitation Heat Treated Consumable Electrode or Vacuum Induction MeltedBar, forgings and rings. Solution treated + precipitation hardened (aged) condition | Agrees in 2+ sources[13][1] |
| AMS 5596 | Plate, strip and sheet. Delivered in the annealed (solution treated) condition | One source / reference[14][1][3][15] |
All ASTM standards on Kezuriba: ASTM standards quick reference.
✈Main aerospace uses (as stated in the sources)
- Rings, casings and various formed sheet metal parts for aircraft and land-based gas turbine engines, liquid-fuel rocket parts, fasteners, instrumentation parts[1]
- Originally developed and used for stationary and rotating parts of aircraft turbines (housings, mounting parts, turbine disks)[2]
- High-strength parts of jet engines (from forgings, castings and bar), welded and sheet metal parts, fasteners, parts of liquid rockets used at cryogenic temperatures[3]
- Aircraft engines and gas turbines as applications of AMS-compliant products[6]
⚗Chemical composition (mass %)
Ranges differ between specifications, so each one has its own column (dark figures agree in several sources, light figures come from one source).
| Element | Spec ① | Spec ② |
|---|---|---|
| Ni | 50 – 55[1][2] | — |
| Cr | 17 – 21[1][2] | — |
| Fe | —[1][2] | — |
| Nb | 4.75 – 5.50[1][2] | — |
| Ta | — | ≤ 0.05[2] |
| Mo | 2.8 – 3.3[1][2] | — |
| Ti | 0.65 – 1.15[1][2] | — |
| Al | 0.2 – 0.8[1][2] | — |
| Co | ≤ 1[1][2] | — |
| C | ≤ 0.08[1][2] | — |
| Mn | ≤ 0.35[1][2] | — |
| Si | ≤ 0.35[1][2] | — |
| P | ≤ 0.015[1][2] | — |
| S | ≤ 0.015[1][2] | — |
| B | ≤ 0.006[1][2] | — |
| Cu | ≤ 0.3[1][2] | — |
- Spec ① AMS/ASTM (Special Metals writes it as Ni+Co and states it follows AMS. VDM states the values are per ASTM and SAE AMS)
- Spec ② ASTM/SAE AMS (VDM's table)
⚖Density
8.19 g/cm³
Value for solution treated material. Special Metals 0.296 lb/in³ (converted to 8.19 g/cm³) and ATI 8.19 g/cm³ agree. For aged material, Special Metals 0.297 lb/in³ and Haynes 8.23 g/cm³. VDM gives 8.26 g/cm³ and voestalpine 8.2 g/ccm, slightly different depending on the source
Calculate weight in Alloy 718 →💪Mechanical properties
“Reference” values are not specified minimums from the standard but figures published by makers and others.
| Condition | Tensile MPa | Yield MPa | Elong. % | Hardness | Type of value |
|---|---|---|---|---|---|
| Bar, forgings and rings: solution treated (927–1010℃ = 1700–1850°F) + two-step aging (AMS 5663) | ≥ 1275 | ≥ 1034 | ≥ 12 | HB 331 min (or equivalent) | AMS 5663 specified value (room temperature, longitudinal. Minimum values quoted in manufacturer material) Agrees in 2+ sources[1][6][2] |
| Plate and strip (AMS 5596. Solution treated + aged) | ≥ 1241 | ≥ 1034 | ≥ 12 | HRC 36 min (or equivalent) | AMS 5596 specified value (room temperature. Minimum values quoted in manufacturer material) Agrees in 2+ sources[1][2] |
| Bar, forgings and rings: solution treated (1038–1066℃ = 1900–1950°F) + two-step aging (AMS 5664) | ≥ 1241 | ≥ 1034 | ≥ 10 (bar) / >=12 (forgings) | HB 341 min (or equivalent) | AMS 5664 specified value (room temperature, transverse. Minimum values quoted in Special Metals material) One source / reference[1] |
| Bar: as solution treated (AMS 5662) | — | — | — | HB less than 277 | AMS 5662 specified value (quoted in VDM material) One source / reference[2] |
| As solution treated / after aging | — | — | — | Solution treated about HRC 20–25, after aging about HRC 36–44 | Typical value (ATI datasheet) One source / reference[3] |
1 MPa ≈ 145 psi (0.145 ksi). Hardness conversion · unit converter
🔧Machinability notes (as stated in the sources)
- Special Metals: it can be machined, but because of its high strength and tendency to work harden, care is needed in selecting tool grade, tool geometry, cutting speed and cutting fluid. Aged material gives a slightly better surface finish and better chip control with chip breakers, but annealed (solution treated) material machines more easily and gives longer tool life[1]
- VDM: solution treated material machines easily with low tool load, but aged material gives a better surface finish. It is best to rough before aging and finish after aging. Because it work hardens readily, use a low cutting speed and an appropriate feed, and keep the tool continuously engaged. A depth of cut reaching below the work-hardened layer is important[2]
- ATI: can be machined readily in either the solution treated or aged condition[3]
- Sandvik Coromant cites Inconel 718 as an example of an ISO S precipitation hardening nickel-base alloy and states that it has high strength even at high temperature, large fluctuations in cutting force from serrated chips, work hardening and built-up edge hardening, and notch wear at the depth-of-cut line[4]
- Sumitomo Electric's general catalog shows an evaluation example of a PVD grade for turning difficult-to-cut materials with Inconel 718 (44HRC), CNMG120408, vc=40m/min, f=0.1mm/rev, ap=1.5mm, wet (these are the tool's evaluation conditions, not recommended conditions)[9]
📚Sources
Primary sources (public documents from makers, industry associations and standards bodies), numbered where each value is cited. Many are in Japanese.
- specialmetals.com https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-718.pdf
- vdm-metals.com https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Data_Sheets/Data_Sheet_VDM_Allo…
- atimaterials.com https://www.atimaterials.com/Products/Documents/datasheets/nickel-cobalt/nickel-based/ati_…
- sandvik.coromant.com https://www.sandvik.coromant.com/en-us/knowledge/materials/workpiece-materials
- kyocera.co.jp https://www.kyocera.co.jp/prdct/tool/wp-content/uploads/2014/07/2024-2026_A.pdf
- voestalpine.com https://www.voestalpine.com/specialtymetals/eu/app/uploads/sites/251/2025/05/Alloy-718-EN-…
- mdr.nims.go.jp https://mdr.nims.go.jp/datasets/be87ce61-cb43-4d00-951c-35ab69e125e8
- webdesk.jsa.or.jp https://webdesk.jsa.or.jp/preview/pre_jis_g_04901_000_000_2023_j_ed10_ch.pdf
- sumitool.com https://www.sumitool.com/downloads/cutting-tools/general-catalog/assets/pdf/a.pdf
- store.astm.org https://store.astm.org/standards/b637
- store.astm.org https://store.astm.org/standards/b670
- sae.org https://www.sae.org/standards/content/ams5662/
- sae.org https://www.sae.org/standards/content/ams5663/
- sae.org https://www.sae.org/standards/content/ams5596/
- saemobilus.sae.org https://saemobilus.sae.org/standards/ams5596-alloy-sheet-strip-plate-corrosion-heat-resist…
Other materials
Nickel alloy