Inconel 718 IN718 (UNS N07718)

spore: profile
id: inconel-718
spore_version: 0.2
family: nickel-alloys
name: Inconel 718
abbreviation: IN718 (UNS N07718)
role: structural superalloy
category: metals
type: nickel-superalloys
summary: |
  Inconel 718 is an age-hardenable nickel-chromium superalloy with iron, niobium and molybdenum. Its strength comes from gamma double prime and gamma prime precipitates formed during heat treatment. The Special Metals datasheet gives a room temperature yield strength of 171 ksi and 133 ksi at 1300 F, and a tensile strength of 237 ksi at -320 F. It is used for liquid-fuel rocket parts, such as the main combustion chamber shell of the RS-25 engine, and for cryogenic tankage, turbine casings and fasteners.
best_for: Hot and cryogenic structural parts that must keep strength and fatigue resistance, such as rocket engine shells, rings, casings and fasteners
weakest_at: The datasheet service limit is 1300 F, and long exposure between about 700 and 1000 C lets delta phase form and weaken the alloy
identity:
  formula: 'Nickel-chromium-iron superalloy: 50.00 to 55.00 Ni (plus Co), 17.00 to 21.00 Cr, 4.75 to 5.50 Nb (plus Ta), 2.80 to 3.30 Mo, 0.65 to 1.15 Ti, 0.20 to 0.80 Al, balance Fe (wt%)'
  source: sm718
  where: Table 1, Limiting Chemical Composition (Special Metals datasheet); UNS N07718 and W.Nr. 2.4668 from the introduction
  designations:
    - system: UNS
      code: N07718
      source: sm718
      where: Introduction, first paragraph (UNS N07718/W.Nr. 2.4668)
    - system: UNS
      code: N07719
      source: sm718
      where: Available Products and Specifications, first paragraph (designated at UNS N07718, UNS N07719 and Werkstoff Nr. 2.4668)
    - system: EN
      code: '2.4668'
      source: sm718
      where: Introduction, first paragraph (W.Nr. 2.4668)
    - system: EN name
      code: NiCr19Fe19NbMo3
      source: haynes718
      where: Specifications and Codes table, DIN row (printed NiCr19Fe19NbMo3)
    - system: DIN
      code: '17742'
      source: haynes718
      where: Specifications and Codes table, DIN row (17742 No. 2.4668)
    - system: DIN
      code: '17744'
      source: sm718
      where: Available Products and Specifications, Others list
    - system: DIN
      code: '17750'
      note: plate, sheet and strip
      source: sm718
      where: Available Products and Specifications, plate, sheet and strip list
    - system: DIN
      code: '17751'
      note: pipe and tube
      source: sm718
      where: Available Products and Specifications, pipe and tube list
    - system: DIN
      code: 17752-17754
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: ASTM
      code: B637
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: ASME
      code: SB 637
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: ASTM
      code: B670
      note: plate, sheet and strip
      source: sm718
      where: Available Products and Specifications, plate, sheet and strip list
    - system: ASME
      code: SB 670
      note: plate, sheet and strip
      source: sm718
      where: Available Products and Specifications, plate, sheet and strip list
    - system: ASTM
      code: B906
      note: plate, sheet and strip
      source: sm718
      where: Available Products and Specifications, plate, sheet and strip list
    - system: ASME
      code: SB 906
      note: plate, sheet and strip
      source: sm718
      where: Available Products and Specifications, plate, sheet and strip list
    - system: ASTM
      code: B983
      note: seamless pipe and tube
      source: haynes718
      where: Specifications and Codes table, Seamless Pipe and Tube row
    - system: AMS
      code: '5589'
      note: seamless tubing
      source: sm718
      where: Heat Treating and Mechanical Properties, 1700 to 1850 F anneal table ('AMS 5589, Seamless Tubing')
    - system: AMS
      code: '5590'
      note: seamless tubing
      source: sm718
      where: Heat Treating and Mechanical Properties, 1900 to 1950 F anneal table ('AMS 5590, Seamless Tubing')
    - system: AMS
      code: '5596'
      note: sheet, strip and plate
      source: sm718
      where: Heat Treating and Mechanical Properties, 1700 to 1850 F anneal table ('AMS 5596, Sheet, Strip, & Plate')
    - system: AMS
      code: '5597'
      note: sheet, strip and plate
      source: sm718
      where: Heat Treating and Mechanical Properties, 1900 to 1950 F anneal table ('AMS 5597, Sheet, Strip, & Plate')
    - system: AMS
      code: '5662'
      note: bars, forgings and rings
      source: sm718
      where: Heat Treating and Mechanical Properties, 1700 to 1850 F anneal table ('AMS 5662 and 5663, Bars, Forgings, & Rings')
    - system: AMS
      code: '5663'
      note: bars, forgings and rings
      source: sm718
      where: Heat Treating and Mechanical Properties, 1700 to 1850 F anneal table ('AMS 5662 and 5663, Bars, Forgings, & Rings')
    - system: AMS
      code: '5664'
      note: bars, forgings and rings
      source: sm718
      where: Heat Treating and Mechanical Properties, 1900 to 1950 F anneal table ('AMS 5664, Bars, Forgings, & Rings')
    - system: AMS
      code: '5832'
      note: wire
      source: ati718
      where: Specifications list ('AMS 5832 - Wire')
    - system: AMS
      code: '5914'
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: AMS
      code: '5962'
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: ISO
      code: '6208'
      note: plate, sheet and strip
      source: sm718
      where: Available Products and Specifications, plate, sheet and strip list
    - system: ISO
      code: '9723'
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: ISO
      code: '9724'
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: ISO
      code: '9725'
      note: rod, bar, wire and forging stock
      source: sm718
      where: Available Products and Specifications, rod, bar, wire and forging stock list
    - system: Trade name
      code: INCONEL alloy 718
      source: sm718
      where: Page header ('INCONEL alloy 718')
    - system: Trade name
      code: ATI 718
      source: ati718
      where: Page header ('ATI 718 Alloy') and General paragraph ('ATI 718 alloy (UNS N07718)')
    - system: Trade name
      code: HAYNES® 718
      source: haynes718
      where: Page heading ('HAYNES ® 718 alloy')
tags:
  environments:
    - launch
  stresses: []
  applications:
    - propulsion-and-tanks
    - cryogenic-fuel
    - structures
    - mechanisms
properties:
  - benchmark: density
    value: 0.297
    unit: lb/in3
    scope: material
    conditions:
      basis: annealed and aged material (annealed alone is 0.296 lb/in3)
    method: Table 2, Physical Constants, printed in lb/in3 and kept as printed; the importer converts to g/cm3
    status: ground
    source: sm718
    where: Table 2, Density, Annealed and Aged
  - benchmark: melting_point
    value: 1260
    value_high: 1336
    unit: °C
    scope: material
    conditions:
      basis: melting range as printed in Table 2 (2300 to 2437 F)
    method: Table 2, printed in C as 1260-1336
    status: ground
    source: sm718
    where: Table 2, Melting Range
  - benchmark: specific_heat
    value: 435
    unit: J/kg °C
    scope: material
    conditions:
      basis: at 70 F (21 C); printed as 0.104 Btu/lb F
    method: Table 2, metric value in parentheses as printed
    status: ground
    source: sm718
    where: Table 2, Specific Heat at 70 F
  - benchmark: curie_temperature
    value: -112
    unit: °C
    scope: material
    conditions:
      basis: annealed and aged material (printed as -170 F)
    method: Table 2, metric value in parentheses as printed
    status: ground
    source: sm718
    where: Table 2, Curie Temperature, Annealed and Aged Material
  - benchmark: thermal_conductivity
    value: 79
    unit: BTU·in/ft²·h·°F
    scope: material
    conditions:
      basis: annealed and aged, at 70 F
    method: Table 5, column Ann. + Aged at 70 F, as printed
    status: ground
    source: sm718
    where: Table 5, Thermal Conductivity, row 70
  - benchmark: thermal_conductivity
    value: 148
    unit: BTU·in/ft²·h·°F
    scope: material
    conditions:
      basis: annealed and aged, at 1200 F
    method: Table 5, column Ann. + Aged at 1200 F, as printed
    status: ground
    source: sm718
    where: Table 5, Thermal Conductivity, row 1200
  - benchmark: cte
    value: 8.91
    unit: ppm/°F
    scope: material
    conditions:
      basis: mean linear expansion from 70 F to 1400 F, annealed and aged
    method: Table 5 prints 8.91 in/in/F x 10^-6; 10^-6 in/in/F is the same as ppm/F, so the number is unchanged
    status: ground
    source: sm718
    where: 'Table 5, Mean Linear Expansion, row 1400 (footnote b: from 70 F to temperature shown)'
  - benchmark: electrical_resistivity
    value: 725
    unit: ohm circ mil/ft
    scope: material
    conditions:
      basis: annealed and aged, at 70 F
    method: Table 5, column Ann. + Aged, as printed
    status: ground
    source: sm718
    where: Table 5, Electrical Resistivity, row 70
  - benchmark: elastic_modulus
    value: 29
    unit: ksi x 10^3
    scope: material
    conditions:
      basis: Young's modulus at 70 F, hot-rolled flat heat treated 1800 F/1 hr, A.C. plus 1325 F/8 hr, F.C.
      unit_in_source: ksi x 10^3 (printed 29.0, the column header)
    method: Table 4 prints 29.0 in ksi x 10^3; recorded as printed, in ksi x 10^3
    status: ground
    source: sm718
    where: Table 4, Modulus of Elasticity, Young's Modulus, row 70
  - benchmark: elastic_modulus
    value: 23
    unit: ksi x 10^3
    scope: material
    conditions:
      basis: Young's modulus at 1300 F, same heat treatment as Table 4
      unit_in_source: ksi x 10^3 (printed 23.0, the column header)
    method: Table 4 prints 23.0 in ksi x 10^3; recorded as printed, in ksi x 10^3
    status: ground
    source: sm718
    where: Table 4, Modulus of Elasticity, Young's Modulus, row 1300
  - benchmark: poissons_ratio
    value: 0.294
    unit: '-'
    scope: material
    conditions:
      basis: at 70 F
    method: Table 4, Poisson's Ratio column, computed by the datasheet from E and G as printed
    status: ground
    source: sm718
    where: Table 4, Poisson's Ratio, row 70
  - benchmark: ultimate_tensile_strength
    value: 201
    unit: ksi
    scope: material
    conditions:
      basis: room temperature, hot-rolled 0.625-in diameter bar, annealed 1800 F/1 hr and aged 1325 F/8 hr (typical, not a specification minimum)
    method: Table 22, Hot-Rolled 0.625-in-Diam., Room row
    status: ground
    source: sm718
    where: Table 22, High-Temperature Tensile Properties, Hot-Rolled 0.625-in-Diam., Room
  - benchmark: yield_strength
    value: 171
    unit: ksi
    scope: material
    conditions:
      basis: 0.2 percent offset, room temperature, same bar as the row above
    method: Table 22, same row as above
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., Room row, Yield Strength
  - benchmark: ultimate_tensile_strength
    value: 164.5
    unit: ksi
    scope: material
    conditions:
      basis: 1200 F, same bar and heat treatment
    method: Table 22, same bar, 1200 F row
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., 1200 F row
  - benchmark: yield_strength
    value: 145
    unit: ksi
    scope: material
    conditions:
      basis: 0.2 percent offset, 1200 F, same bar
    method: Table 22, same bar, 1200 F row
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., 1200 F row, Yield Strength
  - benchmark: ultimate_tensile_strength
    value: 145.5
    unit: ksi
    scope: material
    conditions:
      basis: 1300 F, same bar and heat treatment
    method: Table 22, same bar, 1300 F row
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., 1300 F row
  - benchmark: yield_strength
    value: 133
    unit: ksi
    scope: material
    conditions:
      basis: 0.2 percent offset, 1300 F, same bar
    method: Table 22, same bar, 1300 F row
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., 1300 F row, Yield Strength
  - benchmark: elongation
    value: 26
    unit: '%'
    scope: material
    conditions:
      basis: room temperature, elongation in 2 in., same bar
    method: Table 22, same bar, Room row
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., Room row, Elongation
  - benchmark: elongation
    value: 22
    unit: '%'
    scope: material
    conditions:
      basis: 1300 F, same bar
    method: Table 22, same bar, 1300 F row
    status: ground
    source: sm718
    where: Table 22, Hot-Rolled 0.625-in-Diam., 1300 F row, Elongation
  - benchmark: ultimate_tensile_strength
    value: 237
    unit: ksi
    scope: material
    conditions:
      basis: '-320 F, hot-rolled 5/8-in diameter round, annealed 1800 F/1 hr and aged (a different test set from Table 22)'
    method: Table 20, Effect of Temperature on Tensile Properties, -320 F row
    status: ground
    source: sm718
    where: Table 20, Effect of Temperature, -320 F row, Tensile Strength
  - benchmark: yield_strength
    value: 173.5
    unit: ksi
    scope: material
    conditions:
      basis: '-320 F, 0.2 percent offset, same test set as Table 20'
    method: Table 20, same row as above
    status: ground
    source: sm718
    where: Table 20, Effect of Temperature, -320 F row, Yield Strength
  - benchmark: min_service_temp
    value: -423
    unit: °F
    scope: material
    conditions:
      basis: temperature range stated for use in the datasheet introduction
    method: Introduction, printed as used at -423 to 1300 F; a typical service range, not a specification limit
    status: ground
    source: sm718
    where: Introduction, first paragraph
  - benchmark: max_service_temp
    value: 1300
    unit: °F
    scope: material
    conditions:
      basis: temperature range stated for use in the datasheet introduction
    method: Introduction, printed as used at -423 to 1300 F; a typical service range, not a specification limit
    status: ground
    source: sm718
    where: Introduction, first paragraph
corrosion:
  - environment: Air oxidation between about 973 K and 1573 K (700 to 1300 C)
    headline: Below 1173 K (900 C) the oxide film slows the oxidation rate with time, and above that the rate follows a diffusion-controlled parabolic law.
    effect: Brookhaven National Laboratory weighed Inconel 718 samples in air and found that below 1173 K the oxidation rate fell with time, which the authors attribute to the oxide film passivating the surface and slowing oxygen transport. From 1173 K to 1573 K the mass gain was parabolic, which means the oxide growth was limited by diffusion through the scale. The report gives the rate coefficients in its tables, but the printed exponents in the text extract were not clear enough to copy, so only the qualitative result is recorded here.
    rating: low
    conditions:
      temperature: 973 K to 1573 K in air (BNL report title range)
      test: mass gain of samples heated in air, weighed after cooling
    source: bnl-52620
    where: Summary of results; Parabolic Oxidation Rate (24-hour tests) series, 1173 K to 1573 K
  - environment: General oxidation and corrosion service
    headline: The datasheet rates the oxidation and corrosion resistance as superior, but it gives no corrosion rates.
    effect: Special Metals says Inconel 718 combines good mechanical properties over a wide temperature range with superior oxidation and corrosion resistance, which is why it is specified for many fastener applications. Wikipedia attributes the oxidation and corrosion resistance to the gamma double prime and gamma prime precipitates that form during age hardening, mainly from niobium.
    rating: unknown
    conditions:
      basis: qualitative statements, no test medium or exposure time given
    source: sm718
    where: Bolting section; Wikipedia Inconel 718 introduction (see wiki718)
  - environment: Oil-field tubular service under NACE MR0175
    headline: Oil-field material is made to a maximum hardness of 40 HRC so that it meets the NACE MR0175 limit.
    effect: Special Metals produces Inconel 718 for oil-field use under NACE MR0175, which requires solution annealing and aging to a maximum hardness of 40 Rockwell C. The usual route is a solution treatment at 1850 to 1900 F and aging at 1450 F for six to eight hours. The bulletin gives mechanical properties for this material but no corrosion test result.
    rating: unknown
    conditions:
      standard: NACE MR0175, maximum 40 HRC
      heat_treatment: solution treated 1850 to 1900 F, aged 1450 F for 6 to 8 hours (typical)
    source: sm718
    where: Other Heat Treatments; Table 6
risks:
  hazards:
    - text: PubChem's aggregated GHS record for nickel (from 4,778 company reports) lists H317 in 99.9 percent of the reports that give a hazard code, H351 in 72.9 percent, H372 in 99.7 percent and H350 in 22.5 percent. It also lists H341, H360F, H334 and H412 at lower ratios. The record is for nickel metal, not for the alloy, and nickel is about 50 to 55 percent of Inconel 718.
      ghs:
        - H317
        - H351
        - H372
        - H350
        - H341
        - H360F
        - H334
        - H412
      source: pubchem-nickel
      where: GHS Classification, aggregated ECHA C&L notifications (CID 935)
    - text: No safety data sheet for the finished alloy was read in this run. The hazards above are the nearest sourced record.
      ghs: []
      source: pubchem-nickel
      where: Not applicable (gap)
  failure_risks:
    - mode: Delta phase precipitation
      trigger: Exposure between about 700 and 1000 C, with peak precipitation near 900 C
      consequence: Delta phase (Ni3Nb, orthorhombic) forms. Because it is more stable than gamma double prime, the gamma double prime is lost and the alloy weakens.
      severity: moderate
      source: wiki718
      where: Deleterious Phases
    - mode: Laves phase formation
      trigger: Temperatures above about 1000 C
      consequence: Laves phase, (Ni, Fe, Cr)2(Nb, Mo, Ti), forms in large globular aggregates richer in niobium than the strengthening phases. This depletes gamma prime and gamma double prime, which weakens the material significantly.
      severity: high
      source: wiki718
      where: Deleterious Phases
  side_effects: []
  handling:
    - text: Special Metals says the material is usually bought in the mill-annealed or stress-relieved condition, fabricated in that condition, and then heat treated to the specification. Solution anneal at 1700 to 1850 F, then age at 1325 F for 8 hours, furnace cool to 1150 F and hold for 18 hours in total.
      source: sm718
      where: Heat Treating and Mechanical Properties, first two paragraphs
    - text: Special Metals says the alloy's resistance to postweld cracking is outstanding.
      source: sm718
      where: Introduction, first paragraph
  mitigations:
    - text: Use the 1700 to 1850 F anneal when rupture life, notch rupture life and fatigue strength are the main concern; use the 1900 to 1950 F anneal when tensile-limited ductility and low-temperature notch strength matter more, though it can cause notch brittleness in stress rupture.
      source: sm718
      where: 1700 to 1850 F Anneal and Age; 1900 to 1950 F Anneal and Age
uses:
  - application: propulsion-and-tanks
    device: Main combustion chamber shell of the RS-25 (Space Shuttle main engine and SLS core-stage engine)
    example: The main combustion chamber comprises a structural shell made of Inconel 718, lined with NARloy-Z copper alloy. The chamber reaches about 3300 C in flight, per Wikipedia.
    source: wiki-rs25
    where: Engine description, main combustion chamber paragraph
  - application: cryogenic-fuel
    device: Cryogenic tankage
    example: Special Metals lists cryogenic tankage among the uses for Inconel 718, and the material keeps a tensile strength of 237 ksi at -320 F in the Table 20 test.
    source: sm718
    where: Introduction, first paragraph; Table 20
  - application: structures
    device: Rings, casings and formed sheet metal parts for aircraft and land-based gas turbine engines
    example: Special Metals lists rings, casings and formed sheet parts for aircraft and land-based gas turbine engines, as well as components for liquid-fuelled rockets.
    source: sm718
    where: Introduction, first paragraph
  - application: mechanisms
    device: Fasteners, bolting and springs
    example: Special Metals says the excellent relaxation resistance of Inconel 718 supports its use for springs up to 1100 F, and that the alloy is specified for many fastener applications.
    source: sm718
    where: Bolting section; Spring Properties section
supply:
  - subject: Nickel
    producers:
      - country: Indonesia
        share_percent: 66.7
        year: 2025
      - country: Philippines
        share_percent: 6.9
        year: 2025
      - country: Russia
        share_percent: 5.1
        year: 2025
      - country: Canada
        share_percent: 3.6
        year: 2025
    recycling: 'USGS: nickel recovered from scrap accounted for about 60 percent of apparent consumption in 2025. Most secondary nickel is in the form of stainless-steel scrap.'
    substitutes:
      - 'USGS: low-nickel, duplex or ultrahigh-chromium stainless steels replace austenitic grades in some uses; titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments.'
    source: usgs-mcs2026-nickel
    where: World Mine Production and Reserves table (2025e); shares calculated by Space Mushroom against the printed world total of 3,900,000 t (not printed as a share); Recycling; Substitutes; Domestic Production and Use (stainless, alloy steel and nickel-containing alloys are more than 85 percent of U.S. consumption)
  - subject: Chromium
    producers:
      - country: South Africa
        share_percent: 45.1
        year: 2025
      - country: Turkey
        share_percent: 17.6
        year: 2025
      - country: Kazakhstan
        share_percent: 13.7
        year: 2025
      - country: India
        share_percent: 5.9
        year: 2025
    substitutes:
      - 'USGS: chromium has no substitute in stainless steel, the leading end use, or in superalloys, the major strategic end use.'
    source: usgs-mcs2026-chromium
    where: World Mine Production and Reserves table (2025e, thousand t); shares calculated by Space Mushroom against the printed world total of 51,000 thousand t; Substitutes
  - subject: Niobium
    producers:
      - country: Brazil
        share_percent: 92.9
        year: 2025
      - country: Canada
        share_percent: 5.4
        year: 2025
    recycling: 'USGS: niobium was recycled with niobium-bearing steels and superalloys, but scrap recovery was negligible; the recycled amount may have been as much as 20 percent of apparent consumption.'
    substitutes:
      - 'USGS: ceramic matrix composites, molybdenum, tantalum and tungsten can replace niobium in high-temperature superalloy applications, with a performance loss or higher cost.'
    source: usgs-mcs2026-niobium
    where: World Mine Production and Reserves table (2025e, niobium content); shares calculated by Space Mushroom against the printed world total of 112,000 t (rounded); Recycling; Substitutes; Domestic Production and Use (superalloys about 23 percent of U.S. consumption)
media: []
documents:
  - title: Special Metals INCONEL alloy 718 datasheet, publication SMC-045
    type: datasheet
    url: https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-718.pdf
    year: 2007
  - title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Niobium (Columbium)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf
    year: 2026
  - title: 'PubChem: Nickel (CID 935), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    year: 2026
  - title: Greene and Finfrock, Oxidation of Inconel 718 in Air at Temperatures from 973 K to 1620 K, BNL-52620
    type: report
    url: https://www.osti.gov/servlets/purl/777719
    year: 2000
  - title: ATI 718 Alloy technical data sheet, NI-105 version 2
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/nickel-cobalt/nickel-based/ati_718_allvac_version_tds_en_v1.pdf
    year: 2011
  - title: HAYNES 718 alloy datasheet
    type: datasheet
    url: https://haynesintl.com/en/datasheet/haynes-718-alloy/
    year: 2026
gaps:
  - No flight or flight-qualified test of Inconel 718 was read in this run beyond the RS-25 engine description; the datasheet gives typical, not qualified, values.
  - Falcon engine use was not sourced in this run, so it is left out of uses.
  - Oxidation rate coefficients from the BNL report were not copied because the text extract shows the exponents unclearly; only the qualitative passivation result is recorded.
  - No quantitative corrosion test (salt spray, sour-service, stress corrosion or pitting) for Inconel 718 was read; corrosion entries are qualitative.
  - Turbine disc use is not stated in any source read in this run; the datasheet and Wikipedia name gas turbine engine components and parts in general.
  - Critical-mineral list status for nickel, chromium and niobium was not read in the USGS excerpts used here, so no critical_lists entries are given.
  - The Special Metals datasheet is a 2007 publication; the USGS production figures are 2025 estimates and are shares calculated from printed tonnages, not printed shares.
  - No safety data sheet for the finished alloy was read; hazards come from PubChem's nickel record.
  - Table 20 and Table 22 are from different test sets, so their room-temperature values differ (190.5 ksi and 201.0 ksi UTS); both are kept with their sources.
  - No images were added; no photograph or diagram with a verified licence was read in this run.
  - Long-term creep and rupture data (Figures 6 and 7 of the datasheet) are graphical and were not read.
  - Hardness, fatigue and low-temperature impact values are present in the datasheet tables but were not added in this pass.
  - 'ASTM B966: looked for, not printed by the Special Metals, ATI, Haynes or Carpenter pages. ASTM B906 (plate, sheet and strip) is printed by Special Metals and is listed instead.'
  - 'NiCr19Fe19Nb5Mo3: looked for, not printed by the pages read. Haynes prints NiCr19Fe19NbMo3 for W.Nr. 2.4668, and that spelling is listed.'
  - 'Allvac 718: looked for, not printed by the ATI 718 datasheet, which names the grade ATI 718. Allvac appears there only in the company footer and trademark line.'
  - Stockist grade pages for alloy 718 were not reached. Carpenter's 718 page and safety data sheet print UNS N07718, AMS 5662, AMS 5663 and DIN 2.4668, which are already listed; they also print API 6A718 and NACE MR0175, which are left out.
  - AMS 5950 is printed in the Special Metals plate, sheet and strip list, but the datasheet says it defines the requirements for alloy 718SPF, a related grade, so it is left out.
  - NACE MR0175, ISO 15156, API 6A718, AWS A5.14 and ASME Code Cases are service or code standards printed for this alloy rather than grade designations, so they are left out. AECMA PrEN drafts are left out because AECMA is not a designation system.
sources:
  sm718:
    title: INCONEL alloy 718 datasheet, publication SMC-045
    id: Special Metals Corporation, copyright 2007
    url: https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-718.pdf
    year: 2007
    kind: datasheet
    license: Special Metals terms (cited, not reproduced)
  usgs-mcs2026-nickel:
    title: 'Mineral Commodity Summaries 2026: Nickel'
    id: USGS, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: US Government work (public domain)
  usgs-mcs2026-chromium:
    title: 'Mineral Commodity Summaries 2026: Chromium'
    id: USGS, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: US Government work (public domain)
  usgs-mcs2026-niobium:
    title: 'Mineral Commodity Summaries 2026: Niobium (Columbium)'
    id: USGS, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf
    year: 2026
    kind: report
    license: US Government work (public domain)
  pubchem-nickel:
    title: Nickel, PubChem CID 935, GHS classification (aggregated ECHA C&L notifications)
    id: PubChem CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    year: 2026
    kind: database
    license: PubChem (NIH, public domain)
  bnl-52620:
    title: Oxidation of Inconel 718 in Air at Temperatures from 973 K to 1620 K
    id: Greene and Finfrock, Brookhaven National Laboratory, BNL-52620 (October 2000)
    url: https://www.osti.gov/servlets/purl/777719
    year: 2000
    kind: report
    license: US Department of Energy report (public)
  wiki718:
    title: Inconel 718
    id: Wikipedia, English article (checked 2026-10-19)
    url: https://en.wikipedia.org/wiki/Inconel_718
    year: 2026
    kind: web
    license: CC BY-SA 4.0
  wiki-rs25:
    title: RS-25
    id: Wikipedia, English article (checked 2026-10-19)
    url: https://en.wikipedia.org/wiki/RS-25
    year: 2026
    kind: web
    license: CC BY-SA 4.0
  ati718:
    title: ATI 718 Alloy technical data sheet, NI-105 version 2
    id: ATI Allvac, Monroe NC, NI-105 version 2 (2/25/2011)
    url: https://www.atimaterials.com/Products/Documents/datasheets/nickel-cobalt/nickel-based/ati_718_allvac_version_tds_en_v1.pdf
    year: 2011
    kind: datasheet
    license: ATI terms (cited, not reproduced)
  haynes718:
    title: HAYNES 718 alloy datasheet
    id: Haynes International, datasheet page for HAYNES 718 alloy (checked 2026-10-24)
    url: https://haynesintl.com/en/datasheet/haynes-718-alloy/
    year: 2026
    kind: datasheet
    license: Haynes International terms (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-19'
review:
  status: draft
  method: assistant
  checked_values: 23
  unreachable: 1
  caveats: 2
  note: Written by an AI assistant on 2026-10-19 from the Special Metals datasheet (Tables 2, 4, 5, 20, 22 and text), the USGS 2026 nickel, chromium and niobium summaries (production shares calculated from printed tonnages), PubChem nickel GHS and the BNL oxidation report. The Springer intergranular oxidation paper could not be opened; the Wikipedia RS-25 and Inconel 718 pages were read as raw text. Values are copied from those pages; none from search snippets.
story:
  recipe:
    line: 'Inconel 718 is an iron-based nickel-chromium superalloy. Its composition is set by the Special Metals limiting chemical composition table (UNS N07718): about 50 to 55 percent nickel plus cobalt, 17 to 21 percent chromium, 4.75 to 5.5 percent niobium plus tantalum, 2.8 to 3.3 percent molybdenum, and balance iron. It is solution annealed and then age hardened, which forms gamma prime and gamma double prime precipitates.'
    parts:
      - name: Nickel
        symbol: Ni
        share_percent: 50
        share_high: 55
        role: The matrix of the alloy. Cobalt, up to 1.00 percent, is counted with nickel in the datasheet table.
      - name: Chromium
        symbol: Cr
        share_percent: 17
        share_high: 21
        role: Chromium is the element that gives the alloy its oxidation and corrosion resistance, which the datasheet rates as superior.
      - name: Iron
        symbol: Fe
        share_note: balance (the rest)
        role: The balance of the alloy, forming the austenitic matrix with nickel and chromium.
      - name: Niobium plus tantalum
        symbol: Nb
        share_percent: 4.75
        share_high: 5.5
        role: Main age-hardening element. Niobium forms the gamma double prime precipitate, which gives most of the strength.
      - name: Molybdenum
        symbol: Mo
        share_percent: 2.8
        share_high: 3.3
        role: Molybdenum is part of the composition that the datasheet specifies for this alloy.
      - name: Titanium
        symbol: Ti
        share_percent: 0.65
        share_high: 1.15
        role: Forms part of the gamma prime precipitate with aluminium.
      - name: Aluminium
        symbol: Al
        share_percent: 0.2
        share_high: 0.8
        role: Forms part of the gamma prime precipitate with titanium.
  risk_groups:
    - title: For people
      level: 0
      verdict: Not classified as a hazard on its own; the nickel record
      lead: The alloy is a solid metal. The sourced hazard record is PubChem's entry for nickel, and no safety data sheet for the finished alloy was read in this run. Not classified as a hazard on its own; the nickel record carries the hazard flags
      points:
        - label: The metal
          line: PubChem's aggregated record for nickel lists skin sensitisation (H317, 99.9 percent of reports that give a code), suspected cancer (H351, 72.9 percent) and organ damage from repeated exposure (H372, 99.7 percent).
        - label: Dust and fume
          line: Nickel is about half of this alloy, so grinding, cutting and welding fume should be controlled. The datasheet does not give fume limits.
    - title: If a part is held in the wrong temperature range
      lead: These results come from the datasheet and from the Wikipedia summary of phase stability, not from field incidents.
      points:
        - label: Delta phase
          line: Between about 700 and 1000 C, delta phase (Ni3Nb) forms and takes niobium away from the strengthening gamma double prime, which weakens the alloy.
        - label: Laves phase
          line: Above about 1000 C, Laves phase forms in large aggregates and depletes the strengthening phases significantly.
    - title: Handling and heat treatment
      points:
        - label: Fabrication
          line: Special Metals says the material is usually bought in the mill-annealed or stress-relieved condition, fabricated in that condition, and then heat treated to specification.
        - label: Weld cracking
          line: The datasheet describes the alloy's resistance to postweld cracking as outstanding, so welding before the final age is a standard route.
  why: Inconel 718 is a nickel-chromium superalloy designed to hold strength over a wide temperature range. Its strength comes from fine gamma prime and gamma double prime precipitates, formed by a solution anneal followed by an aging treatment. Niobium is the main age-hardening element. The datasheet describes good tensile, fatigue, creep and rupture strength combined with easy fabrication, which explains its use in rocket engine parts, cryogenic tanks and gas turbine casings.
  uses:
    - where: Rocket engines
      line: The main combustion chamber of the RS-25 engine has a structural shell made of Inconel 718, lined with a copper-silver-zirconium alloy called NARloy-Z. Special Metals lists components for liquid-fuelled rockets among the alloy's uses.
    - where: Cryogenic tanks
      line: Special Metals lists cryogenic tankage among the uses, and the datasheet gives a tensile strength of 237 ksi at -320 F for one hot-rolled bar.
    - where: Gas turbines and aircraft
      line: Rings, casings and formed sheet parts for aircraft and land-based gas turbine engines are named in the datasheet.
    - where: Fasteners and springs
      line: The datasheet says the alloy is specified for many fastener applications, and that its relaxation resistance supports its use for springs up to 1100 F.
  can_do:
    - label: Strength when hot
      benchmark: yield_strength
      line: The yield strength of one hot-rolled bar is 171 ksi at room temperature, 145 ksi at 1200 F and 133 ksi at 1300 F (Table 22).
    - label: Cold toughness
      benchmark: ultimate_tensile_strength
      line: The same family of heat treatments gives a tensile strength of 237 ksi at -320 F in Table 20, so the strength rises when cold.
    - label: Stiffness
      benchmark: elastic_modulus
      line: Young's modulus is 29.0 x 10^3 ksi at 70 F and 23.0 x 10^3 ksi at 1300 F (Table 4).
    - label: Density
      benchmark: density
      line: Density is 0.297 lb/in3 for the annealed and aged material (Table 2).
  compare: Inconel 718 is the nickel-based alloy in this collection. Its datasheet gives tensile data from -320 F to 1300 F and rates its oxidation resistance as superior. Cost and machining difficulty are not covered by the sources read here.
  compare_rows:
    - scope: material
      label: Density
      benchmark: density
    - scope: material
      label: Stiffness
      benchmark: elastic_modulus
    - scope: material
      label: Melting range
      benchmark: melting_point
  handling:
    - Buy it in the mill-annealed or stress-relieved condition for machining, forming or welding, then heat treat it to specification (Special Metals).
    - Keep the heat treatment on the printed schedule; the 1700 to 1850 F anneal gives the best rupture and fatigue life (Special Metals).
    - Avoid holding the alloy in the 700 to 1000 C range for long periods, where delta phase forms (Wikipedia).
    - Control dust and fume from grinding and welding, because nickel is about half of the alloy (PubChem).
  good_for:
    - Strength at high temperature. Yield strength is 133 ksi at 1300 F for one hot-rolled bar, against 171 ksi at room temperature.
    - Cryogenic structures. Tensile strength is 237 ksi at -320 F in the Table 20 test.
    - Welded and aged hardware. The datasheet describes outstanding resistance to postweld cracking.
  watch_out:
    - The datasheet service limit is 1300 F, and its main tensile tables stop at 1300 F (Special Metals).
    - Long exposure between about 700 and 1000 C forms delta phase, which removes the strengthening phase (Wikipedia).
    - Above about 1000 C, Laves phase forms and weakens the alloy significantly (Wikipedia).
    - The sources read here give no corrosion rates; the corrosion entries are qualitative.
  verdict: Inconel 718 is the default nickel superalloy for hot and cryogenic structural hardware. Its strength and stability are well documented up to about 1300 F, and the main risks are phase changes above that range.