spore: profile
id: inconel-x750
spore_version: 0.2
family: nickel-alloys
name: Inconel X-750
abbreviation: X-750 (UNS N07750)
role: age-hardenable spring and fastener alloy
category: metals
type: nickel-superalloys
summary: |
  Inconel X-750 (UNS N07750, W. Nr. 2.4669) is a precipitation-hardenable nickel-chromium alloy with about 70 % nickel by specification, strengthened by gamma-prime (Ni3(Al,Ti)) after heat treatment. The Special Metals datasheet gives a density of 8.28 g/cm3 and a melting range of 1393 to 1427 C. Aged rod meets a minimum of 165 ksi tensile and 105 ksi yield (AMS 5667), and spring-temper wire a minimum of 220 ksi tensile (AMS 5699). The datasheet says it is used for rocket-engine thrust chambers and for springs and fasteners from sub-zero temperatures to 1200 F, and that heat-treated material keeps useful strength up to 1800 F.
best_for: Springs and high-strength fasteners that must keep their load from sub-zero temperatures to 1200 F, where relaxation resistance matters
weakest_at: 'Weight (8.28 g/cm3), and the strength depends on the temper: the spring-temper wire relaxes about four times as much as the No. 1 temper at 800 F, and welding a precipitation-hardened part can crack the parent metal'
identity:
  formula: 'Nickel-chromium precipitation-hardening alloy. Specification (wt%): nickel 70.00 min (plus cobalt), chromium 14.0 to 17.0, iron 5.0 to 9.0, titanium 2.25 to 2.75, aluminium 0.40 to 1.00, niobium plus tantalum 0.70 to 1.20, manganese 1.00 max, silicon 0.50 max, copper 0.50 max, cobalt 1.00 max, carbon 0.08 max, sulphur 0.01 max. Nominal analysis printed by VDM (wt%): Ni 73.0, Cr 15.0, Fe 7.0, Ti 2.5, Nb 0.90, Al 0.90, Co 0.70'
  source: special-metals-x750
  where: Table 1 Limiting Chemical Composition, Special Metals datasheet (SMC-067); nominal analysis in the X-750 row of the VDM Nickel Alloys safety data sheet, section 3.2
  designations:
    - system: UNS
      code: N07750
      source: special-metals-x750
      where: Title line and Available Products and Specifications section (UNS N07750/W. Nr. 2.4669)
    - system: EN
      code: '2.4669'
      note: W. Nr. number
      source: special-metals-x750
      where: Available Products and Specifications section (W. Nr. 2.4669)
    - system: AMS
      code: '5542'
      note: sheet, strip and plate, annealed
      source: special-metals-x750
      where: Table 6, row Sheet, strip and plate, AMS 5542
    - system: AMS
      code: '5598'
      note: sheet, strip and plate
      source: special-metals-x750
      where: Table 6, row Sheet, strip and plate, AMS 5598
    - system: AMS
      code: '5667'
      note: rods, bars and forgings
      source: special-metals-x750
      where: Table 6, row Rods, bars and forgings, AMS 5667
    - system: AMS
      code: '5582'
      note: seamless tubing
      source: special-metals-x750
      where: Table 6, row Seamless tubing, AMS 5582
    - system: AMS
      code: '5699'
      note: wire, spring temper
      source: special-metals-x750
      where: Table 6, row Wire, spring temper, AMS 5699
    - system: ASTM
      code: B637
      note: rod, bar and forging stock
      source: alloysintl-nickel-list
      where: Inconel X-750 row, ASTM B637 column
    - system: Trade name
      code: INCONEL alloy X-750
      source: special-metals-x750
      where: Title line, INCONEL alloy X-750
tags:
  environments: []
  applications:
    - mechanisms
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Density, X-750
    value: 8.28
    unit: g/cm3
    scope: material
    conditions:
      grade: X-750 (UNS N07750)
      temperature: not stated
      unit_in_source: 0.299 lb/in3
    method: Value printed in a manufacturer datasheet, physical constants table
    status: ground
    source: special-metals-x750
    where: Table 2 Physical Constants, row Density g/cm3
  - benchmark: melting_point
    label: Melting range, X-750
    value: 1393
    value_high: 1427
    bound: range
    unit: °C
    scope: material
    conditions:
      grade: X-750
      unit_in_source: 2540 to 2600 °F
    method: Range printed in a manufacturer datasheet, physical constants table
    status: ground
    source: special-metals-x750
    where: Table 2 Physical Constants, row Melting Range °C
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 70 °F
    value: 83
    unit: Btu/in./hr/sq ft/°F
    scope: material
    conditions:
      temperature: 70 °F
      heat_treatment: 2100°F/3 hr, A.C., + 1550°F/24 hr, A.C., + 1300°F/20 hr, A.C. (triple heat treatment, Table 3 footnote a)
      unit_in_source: Btu/in./hr/sq ft/°F
    method: Value printed in a manufacturer datasheet, thermal properties table, unit as printed
    status: ground
    source: special-metals-x750
    where: Table 3 Thermal Properties, row 70, column Thermal Conductivity
  - benchmark: specific_heat
    label: Specific heat at 70 °F
    value: 0.103
    unit: Btu/lb/°F
    scope: material
    conditions:
      temperature: 70 °F
      heat_treatment: 2100°F/3 hr, A.C., + 1550°F/24 hr, A.C., + 1300°F/20 hr, A.C. (Table 3 footnote a)
      unit_in_source: Btu/lb/°F
    method: Value printed in a manufacturer datasheet, thermal properties table
    status: ground
    source: special-metals-x750
    where: Table 3 Thermal Properties, row 70, column Specific Heat
  - benchmark: cte
    label: Mean linear expansion, 70 to 200 °F
    value: 7
    unit: 10-6 in./in./°F
    scope: material
    conditions:
      temperature: mean from 70 °F to 200 °F
      heat_treatment: 2100°F/3 hr, A.C., + 1550°F/24 hr, A.C., + 1300°F/20 hr, A.C. (Table 3 footnote a)
    method: Value printed in a manufacturer datasheet, thermal properties table
    status: ground
    source: special-metals-x750
    where: Table 3 Thermal Properties, row 200, column Mean Linear Expansion from 70 °F
  - benchmark: cte
    label: Coefficient of thermal expansion, 68 to 212 °F
    value: 6.7
    unit: µin/in·°F
    scope: material
    conditions:
      temperature: 68 to 212 °F
      unit_in_source: µin/in °F
    method: Value printed in a distributor data sheet
    status: ground
    source: rolled-alloys-x750
    where: Physical Properties table, row Coefficient of Thermal Expansion (68°F - 212°F)
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 70 °F
    value: 731
    unit: ohm circ mil/ft
    scope: material
    conditions:
      temperature: 70 °F
      heat_treatment: 2100°F/3 hr, A.C., + 1550°F/24 hr, A.C., + 1300°F/20 hr, A.C. (Table 3 footnote a)
      unit_in_source: ohm/circ mil/ft
    method: Value printed in a manufacturer datasheet, thermal properties table
    status: ground
    source: special-metals-x750
    where: Table 3 Thermal Properties, row 70, column Electrical Resistivity
  - benchmark: elastic_modulus
    label: Modulus of elasticity, static tension at 80 °F
    value: 31
    unit: 10^3 ksi
    scope: material
    conditions:
      temperature: 80 °F
      test: static tension
      unit_in_source: 10^3 ksi
    method: Value printed in a manufacturer datasheet, modulus table
    status: ground
    source: special-metals-x750
    where: Table 5 Modulus of Elasticity, row 80, column Tension Static
  - benchmark: shear_modulus
    label: Modulus of rigidity, static torsion at 80 °F
    value: 11
    unit: 10^3 ksi
    scope: material
    conditions:
      temperature: 80 °F
      test: static torsion
      unit_in_source: 10^3 ksi
    method: Value printed in a manufacturer datasheet, modulus table
    status: ground
    source: special-metals-x750
    where: Table 5 Modulus of Elasticity, row 80, column Torsion Static
  - benchmark: poissons_ratio
    label: Poisson's ratio
    value: 0.29
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Value printed as a footnote to the modulus table in a manufacturer datasheet
    status: ground
    source: special-metals-x750
    where: Table 5 Modulus of Elasticity, footnote a (Poisson's ratio = 0.29)
  - benchmark: yield_strength
    label: Yield strength, rod and forgings, minimum
    value: 105
    bound: lower
    unit: ksi
    scope: material
    conditions:
      form: rod, bar and forgings, under 4.0 in
      temper: equalized plus precipitation-treated, 1625°F/24 hr, A.C., + 1300°F/20 hr, A.C. (AMS 5667)
      temperature: room temperature
      measure: 0.2 % offset
    method: Minimum value printed in a manufacturer datasheet for the AMS 5667 condition
    status: ground
    source: special-metals-x750
    where: Rods, Bars and Forgings section, equalized plus precipitation-treated table, row Under 4.0 in, column Yield Strength (0.2% offset)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, rod and forgings, minimum
    value: 165
    bound: lower
    unit: ksi
    scope: material
    conditions:
      form: rod, bar and forgings, under 4.0 in
      temper: equalized plus precipitation-treated, 1625°F/24 hr, A.C., + 1300°F/20 hr, A.C. (AMS 5667)
      temperature: room temperature
    method: Minimum value printed in a manufacturer datasheet for the AMS 5667 condition
    status: ground
    source: special-metals-x750
    where: Rods, Bars and Forgings section, equalized plus precipitation-treated table, row Under 4.0 in, column Tensile Strength
  - benchmark: elongation
    label: Elongation, rod and forgings, minimum
    value: 20
    bound: lower
    unit: '%'
    scope: material
    conditions:
      form: rod, bar and forgings, under 4.0 in
      temper: equalized plus precipitation-treated (AMS 5667)
      temperature: room temperature
      basis: in 4D
    method: Minimum value printed in a manufacturer datasheet for the AMS 5667 condition
    status: ground
    source: special-metals-x750
    where: Rods, Bars and Forgings section, equalized plus precipitation-treated table, row Under 4.0 in, column Elongation in 4D
  - benchmark: hardness_brinell
    label: Hardness, rod and forgings, equalized plus precipitation-treated
    value: 302
    value_high: 363
    bound: range
    unit: BHN
    scope: material
    conditions:
      form: rod, bar and forgings
      temper: equalized plus precipitation-treated (AMS 5667)
      temperature: room temperature
    method: Range printed in a manufacturer datasheet, as the AMS 5667 hardness range
    status: ground
    source: special-metals-x750
    where: Rods, Bars and Forgings section, sentence Hardness will lie in the range of 302-363 BHN
  - benchmark: yield_strength
    label: Yield strength, sheet and strip, minimum after precipitation treatment
    value: 115
    bound: lower
    unit: ksi
    scope: material
    conditions:
      form: sheet, strip and plate, 0.010 to 0.250 in
      temper: furnace-cool precipitation-treated, 1350°F/8 hr, F.C. to 1150°F, hold at 1150°F for 18 hr total, A.C. (AMS 5598)
      temperature: room temperature
      measure: 0.2 % offset
    method: Minimum value printed in a manufacturer datasheet for the AMS 5598 condition
    status: ground
    source: special-metals-x750
    where: Sheet, Strip and Plate section, After Precipitation Treating, row Sheet 0.010 to 0.250 incl., column Yield Strength (0.2% offset)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, sheet and strip, minimum after precipitation treatment
    value: 170
    bound: lower
    unit: ksi
    scope: material
    conditions:
      form: sheet, strip and plate, 0.010 to 0.250 in
      temper: furnace-cool precipitation-treated, 1350°F/8 hr, F.C. to 1150°F, hold at 1150°F for 18 hr total, A.C. (AMS 5598)
      temperature: room temperature
    method: Minimum value printed in a manufacturer datasheet for the AMS 5598 condition
    status: ground
    source: special-metals-x750
    where: Sheet, Strip and Plate section, After Precipitation Treating, row Sheet 0.010 to 0.250 incl., column Tensile Strength
  - benchmark: elongation
    label: Elongation, sheet and strip, minimum after precipitation treatment
    value: 18
    bound: lower
    unit: '%'
    scope: material
    conditions:
      form: sheet, strip and plate, 0.010 to 0.250 in
      temper: furnace-cool precipitation-treated (AMS 5598)
      temperature: room temperature
      basis: in 2 in.
    method: Minimum value printed in a manufacturer datasheet for the AMS 5598 condition
    status: ground
    source: special-metals-x750
    where: Sheet, Strip and Plate section, After Precipitation Treating, row Sheet 0.010 to 0.250 incl., column Elongation in 2 in.
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at 1000 °F, cold-rolled sheet, precipitation-treated
    value: 155
    unit: ksi
    scope: material
    conditions:
      form: cold-rolled annealed 0.050 in sheet
      temper: precipitation-treated 1350°F/8 hr, F.C. to 1150°F, hold at 1150°F for 18 hr total, A.C.
      temperature: 1000 °F
    method: Typical value printed in a manufacturer datasheet, high-temperature tensile table
    status: ground
    source: special-metals-x750
    where: Table 27 High-Temperature Tensile Properties of Cold-Rolled Annealed 0.050-in Sheet, row 1000, column Tensile Strength
  - benchmark: yield_strength
    label: Yield strength at 1000 °F, cold-rolled sheet, precipitation-treated
    value: 116
    unit: ksi
    scope: material
    conditions:
      form: cold-rolled annealed 0.050 in sheet
      temper: precipitation-treated 1350°F/8 hr, F.C. to 1150°F, hold at 1150°F for 18 hr total, A.C.
      temperature: 1000 °F
      measure: 0.2 % offset
    method: Typical value printed in a manufacturer datasheet, high-temperature tensile table
    status: ground
    source: special-metals-x750
    where: Table 27 High-Temperature Tensile Properties of Cold-Rolled Annealed 0.050-in Sheet, row 1000, column Yield Strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, spring-temper wire, minimum
    value: 220
    bound: lower
    unit: ksi
    scope: material
    conditions:
      product: spring-temper wire, AMS 5699
      temper: spring temper, 1200°F/4 hr, A.C. (constant-temperature precipitation treatment)
      size: 0.012 to 0.250 in
      service: up to 700 °F
    method: Minimum value printed in a manufacturer datasheet, spring wire table
    status: ground
    source: special-metals-x750
    where: Table 31 Specifications for Spring Wire, row Spring 1200/4, column Min. Tensile Strength, size 0.012 to 0.250
  - benchmark: max_service_temp
    label: Upper service limit for springs and fasteners
    value: 1200
    unit: °F
    scope: material
    conditions:
      application: springs and fasteners
      lower_limit: sub-zero
    method: Service range stated in the introduction of a manufacturer datasheet
    status: ground
    source: special-metals-x750
    where: Introduction, sentence For springs and fasteners, INCONEL alloy X-750 is used from sub-zero to 1200°F
  - benchmark: yield_strength
    label: Yield strength, 0 % cold work (fully annealed baseline), typical
    value: 393
    unit: MPa
    scope: material
    conditions:
      cold_work_percent: 0
      temperature: not stated
      unit_in_source: MPa [57 ksi]
      gauge_length: 25.4 cm [10 in]
      note: typical values, may not represent all diameters
    method: Typical value printed on a manufacturer web page, cold-work table
    status: ground
    source: fortwayne-x750
    where: Mechanical properties table, row 0 (cold worked %), column Yield strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, 0 % cold work (fully annealed baseline), typical
    value: 855
    unit: MPa
    scope: material
    conditions:
      cold_work_percent: 0
      temperature: not stated
      unit_in_source: MPa [124 ksi]
      gauge_length: 25.4 cm [10 in]
    method: Typical value printed on a manufacturer web page, cold-work table
    status: ground
    source: fortwayne-x750
    where: Mechanical properties table, row 0 (cold worked %), column Ultimate tensile strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, 75 % cold worked, typical
    value: 1586
    unit: MPa
    scope: material
    conditions:
      cold_work_percent: 75
      temperature: not stated
      unit_in_source: MPa [230 ksi]
      gauge_length: 25.4 cm [10 in]
    method: Typical value printed on a manufacturer web page, cold-work table
    status: ground
    source: fortwayne-x750
    where: Mechanical properties table, row 75 (cold worked %), column Ultimate tensile strength
corrosion:
  - environment: Oxidising air at high temperature
    headline: Resists oxidation up to 1800 F in all heat-treated conditions.
    effect: The datasheet says that in all conditions X-750 is resistant to oxidation up to 1800 F. It also says it resists a wide variety of industrial corrosives under both oxidising and reducing conditions, and that information on specific media is in the INCONEL alloy 600 publication.
    rating: low
    conditions:
      basis: datasheet statement; no exposure time given for the oxidation claim
    source: special-metals-x750
    where: Mechanical Properties introduction (page 2) and Corrosion Resistance section
  - environment: Hot salt mixture (90 % Na2SO4 + 10 % NaCl) in air
    headline: About 5 % weight loss after 100 hours in a hot-corrosion test for automotive parts.
    effect: Weight loss after exposure for 100 hours in 90 % Na2SO4 + 10 % NaCl mixture in air was about 5 %, in a hot-corrosion test for automotive applications.
    rating: moderate
    conditions:
      exposure: 100 hours
      medium: 90 % Na2SO4 + 10 % NaCl mixture in air
    source: special-metals-x750
    where: Corrosion Resistance section, hot corrosion test paragraph
  - environment: Sodium chloride precoat in air containing 1 % SO2 at 1700 F
    headline: About 0.007 in of penetration after 100 hours at 1700 F with sulphur dioxide and sodium chloride.
    effect: Samples precoated with sodium chloride, exposed for 100 hours at 1700 F to a moving gas stream of air containing 1 % SO2, showed corrosion penetration of approximately 0.007 in.
    rating: moderate
    conditions:
      exposure: 100 hours at 1700 F
      medium: air with 1 % SO2 and sodium chloride precoat
    source: special-metals-x750
    where: Corrosion Resistance section, hot corrosion paragraph
  - environment: Boiling 42 % magnesium chloride
    headline: No chloride stress-corrosion cracking after 30 days in boiling 42 % magnesium chloride, even at 33 Rc.
    effect: Standard U-bend specimens of precipitation-hardened material (hardness 33 Rc) showed no signs of cracking when exposed to boiling 42 % magnesium chloride for 30 days.
    rating: low
    conditions:
      exposure: 30 days, boiling
      hardness: 33 Rc
      medium: 42 % magnesium chloride
    source: special-metals-x750
    where: Corrosion Resistance section, chloride-ion stress-corrosion paragraph
  - environment: Nitric-hydrofluoric acid pickling bath
    headline: Intergranular attack in nitric-hydrofluoric pickling, worst when precipitation-hardened; bath should not exceed 125 F.
    effect: X-750 is subject to intergranular attack in nitric-hydrofluoric acid pickling, particularly in the precipitation-hardened condition. Time in the bath should be kept to a minimum, and the bath temperature should not exceed 125 F. The fumes are toxic.
    rating: moderate
    conditions:
      bath: nitric-hydrofluoric acid
      max_temperature: 125 F
    source: special-metals-x750
    where: Heating and Pickling section
risks:
  hazards:
    - text: 'Nickel-based alloy family sheet (VDM Metals, not specific to X-750): as supplied in massive form the product is not classified under GHS-US. Welding, cutting or processing may release dust or fumes that are hazardous, and inhalation of dusts and fumes can cause metal fume fever. The sheet''s X-750 row is the nominal composition used in the identity block.'
      ghs: []
      source: vdm-nickel-sds
      where: Section 2.1 Classification (article, not classified) and Section 4.2 Most Important Symptoms and Effects
    - text: Nickel is the hazard driver in the alloy. A nickel sputtering target safety data sheet (pure nickel, CAS 7440-02-0) carries H351 suspected of causing cancer, H372 causes damage to organs through prolonged or repeated exposure, and H317 may cause an allergic skin reaction. The sheet is for pure nickel, not for X-750.
      ghs:
        - H351
        - H372
        - H317
      source: ufl-nickel-sds
      where: GHS hazard statements listed near the start of the sheet (GHS08 and GHS07 pictograms)
    - text: 'Nickel exposure limits from the same pure-nickel sheet: PEL 1 mg/m3 and REL 0.015 mg/m3, both as nickel (REL as Ni, see NIOSH Pocket Guide).'
      ghs: []
      source: ufl-nickel-sds
      where: Control parameters, Nickel (100.0 %) limit values
  failure_risks:
    - mode: Spring relaxation in the wrong temper
      trigger: Spring-temper or No. 1 temper spring held under load at about 800 F for hundreds of hours
      consequence: Spring-temper wire precipitation-treated 1350 F/16 hr relaxed 12 % in the test, against 3 % for a No. 1 temper spring with the same heat treatment (loaded at 70 ksi for 500 hr at 800 F).
      severity: moderate
      source: special-metals-x750
      where: Wire for Springs section, text on relaxation at 800 F and Table 33 comparison
    - mode: Parent-metal cracking after precipitation hardening and welding
      trigger: Welding a part that is already precipitation-hardened, or re-exposing a weld to the precipitation range
      consequence: The datasheet warns that the weld or heat-affected zone should not be precipitation-treated or exposed to service temperatures within the precipitation-hardening range, because of the danger of parent-metal cracking. Weldments should be solution-treated before precipitation treating.
      severity: high
      source: special-metals-x750
      where: Joining (welding) section
    - mode: Loss of rupture properties after cold work
      trigger: Cold work applied after solution treatment at 2100 F
      consequence: Cold work after solution treatment generates new dislocations and impairs rupture properties, so the solution-treated material should not be cold-worked.
      severity: moderate
      source: special-metals-x750
      where: Metallography discussion, text on solution treatment at 2100 F
    - mode: Rupture in forming with too few anneals
      trigger: Successive cold reductions in forming without intermediate anneals
      consequence: The datasheet says a forming operation of successive reductions needs enough intermediate anneals to guard against rupturing. Strain-hardening is relatively rapid.
      severity: moderate
      source: special-metals-x750
      where: Cold Forming paragraph
  side_effects:
    - text: Density of 8.28 g/cm3 is the mass cost of the alloy. The USGS notes that titanium alloys can substitute for nickel-base alloys in corrosive environments, but no mass comparison for X-750 was found in a source.
      affects: Mass of springs, fasteners and structural parts
      source: special-metals-x750
      where: Table 2, density row; USGS substitutes in usgs-mcs2026-nickel
  handling:
    - text: Hot work at 1800 to 2200 F, with heavy hot work above 1900 F. Below 1800 F the metal is stiff and hard to move, and forging can be finished with light reduction in the 1800 to 1900 F range.
      source: special-metals-x750
      where: Hot Forming section
    - text: Springs keep their thin oxide coating after heat treatment; removing the oxide by mechanical means lowers relaxation resistance. If cleaning is needed, the datasheet recommends a reducing bath (sodium hydride) followed by quenching and rinsing.
      source: special-metals-x750
      where: Wire for Springs section, text on oxide and cleaning
    - text: Pickling and welding fumes and dusts are hazardous. Pickling tanks must be ventilated, and the nitric-hydrofluoric bath should stay below 125 F.
      source: special-metals-x750
      where: Heating and Pickling section
  mitigations: []
uses:
  - application: mechanisms
    device: Helical and flat springs and fasteners
    example: Spring-temper wire heat treated at 1200 F/4 hr is for service up to 700 F. Triple heat treatment (2100 F, 1550 F and 1300 F) is for springs needing maximum relaxation resistance from about 850 F to 1200 F. The datasheet says X-750 is used for springs and fasteners from sub-zero to 1200 F.
    source: special-metals-x750
    where: Table 6 Applicable Heat Treatments (wire rows, AMS 5699), Wire for Springs section, and Introduction
  - application: propulsion-and-tanks
    device: Rocket-engine thrust chambers
    example: The datasheet says the alloy is used extensively in rocket-engine thrust chambers. Wikipedia records that Rocketdyne used Inconel X-750 for the thrust chamber of the F-1 engine on the Saturn V first stage.
    source: special-metals-x750
    where: Introduction, first page (applications paragraph); the F-1 example is from wikipedia-inconel, Inconel article
documents:
  - title: INCONEL alloy X-750 technical bulletin SMC-067, Special Metals Corporation, 2004
    type: datasheet
    url: https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-x-750.pdf
    year: 2004
  - title: X-750 Data Sheet, Rolled Alloys
    type: datasheet
    url: https://rolledalloys.com/wp-content/uploads/X-750_DS_USA.pdf
  - title: INCONEL alloy X-750 properties, Fort Wayne Metals
    type: datasheet
    url: https://www.fwmetals.com/what-we-do/materials/high-performance-alloys/inconel-alloy-x-750
  - title: Nickel Based Alloys, Safety Data Sheet, VDM Metals USA (Federal Register 2024 format, with X-750 nominal analysis)
    type: sds
    url: https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Safety_Information_Sheets/Nickel_Alloys_VDM_Metals_USA_EN.pdf
    year: 2024
  - title: Nickel sputtering target safety data sheet, stock 40876, University of Florida (pure nickel, CAS 7440-02-0)
    type: sds
    url: https://nrf.aux.eng.ufl.edu/_files/msds/2/Nickel.pdf
    year: 2012
  - title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: Inconel, Wikipedia (history of the alloy family, composition ranges, F-1 thrust chamber)
    type: report
    url: https://en.wikipedia.org/wiki/Inconel
    year: 2026
gaps:
  - Critical-mineral status of nickel (USGS 2025 or 2026 list, EU list) was not found in the USGS nickel text that was read, so no critical-list entry is recorded in supply.
  - 'Use in spacecraft or satellites was not found in a source: rocket-engine thrust chambers (datasheet) and the F-1 engine (Wikipedia) are rocket uses only. No NASA or ESA document naming X-750 on a spacecraft was found.'
  - Hardness is recorded as hardness_brinell because the canonical file has no hardness name; the site may need a canonical name for it.
  - Emissivity of oxidised surface (0.895 at 600 F, 0.925 at 2000 F, Table 2) is printed in the datasheet but not entered, because the canonical file has no emissivity name.
  - Low-temperature tensile, Charpy and cryogenic properties (Tables 15 and 16 of the datasheet) were not entered; only room-temperature and 1000 F values are recorded.
  - Stress-relaxation curves, fatigue data, stress-rupture tables and spring design-stress tables were not entered because they are figures or multi-column tables not transcribed here.
  - The datasheet text on the sheet furnace-cool treatment says 1300 F/8 hr, while Table 6 and Table 27 print 1350 F/8 hr. The profile uses the 1350 F/8 hr value from the tables and the 1350 F label on the sheet conditions.
  - No atmospheric corrosion rate, total-mass-loss outgassing test, atomic-oxygen erosion yield or radiation data for X-750 was found.
  - The VDM hazard classification is for a nickel-based alloy family sheet, not an X-750-specific SDS. The pure-nickel SDS carries the nickel hazard codes. No supplier SDS for X-750 itself was found.
  - Nickel supply shares are calculated by Space Mushroom from the 2025 estimated mine production country values over the 2025 estimated world total, rounded to one decimal.
  - The Alloys International page gives the W. Nr. 2.4669 and UNS N07750 entries in a family table; no separate X-750 page with physical properties was read there.
sources:
  special-metals-x750:
    title: INCONEL alloy X-750 technical bulletin, publication SMC-067
    id: Special Metals Corporation, copyright 2004 (Sept 04)
    url: https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-x-750.pdf
    year: 2004
    kind: datasheet
    license: Special Metals terms (cited, not reproduced)
  rolled-alloys-x750:
    title: X-750 data sheet, Rolled Alloys
    url: https://rolledalloys.com/wp-content/uploads/X-750_DS_USA.pdf
    kind: datasheet
    license: Rolled Alloys (cited, not reproduced)
  fortwayne-x750:
    title: INCONEL alloy X-750, Fort Wayne Metals
    url: https://www.fwmetals.com/what-we-do/materials/high-performance-alloys/inconel-alloy-x-750
    kind: web
    license: Fort Wayne Metals (cited, not reproduced)
  alloysintl-nickel-list:
    title: 'Nickel and cobalt alloys, Alloys International: Inconel X-750 entry'
    url: https://alloysintl.com/inventory/nickel-cobalt-alloys/inconel_x-750/
    kind: web
    license: Alloys International (cited, not reproduced)
  vdm-nickel-sds:
    title: Nickel Based Alloys, Safety Data Sheet, VDM Metals USA
    url: https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Safety_Information_Sheets/Nickel_Alloys_VDM_Metals_USA_EN.pdf
    year: 2024
    kind: datasheet
    license: VDM Metals (cited, not reproduced)
  ufl-nickel-sds:
    title: Material Safety Data Sheet, nickel sputtering target, stock 40876, University of Florida
    url: https://nrf.aux.eng.ufl.edu/_files/msds/2/Nickel.pdf
    year: 2012
    kind: datasheet
    license: University of Florida (cited, not reproduced)
  usgs-mcs2026-nickel:
    title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: Public domain (USGS)
  wikipedia-inconel:
    title: Inconel, Wikipedia
    url: https://en.wikipedia.org/wiki/Inconel
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
supply:
  - subject: Nickel (mine production)
    abundance: More than 350 million tons of nickel in global resources (USGS, Nickel, World Resources)
    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: New Caledonia
        share_percent: 3.6
        year: 2025
      - country: Canada
        share_percent: 3.6
        year: 2025
    critical_lists: []
    recycling: 'USGS: nickel recovered from scrap accounted for approximately 60 % of apparent consumption in 2025, and most secondary nickel was stainless-steel scrap. Stainless and alloy steel and nickel-containing alloys typically account for more than 85 % of domestic consumption.'
    substitutes:
      - 'USGS: titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments; low-nickel, duplex or ultrahigh-chromium stainless steels replace austenitic grades in construction.'
    source: usgs-mcs2026-nickel
    where: World Mine Production and Reserves table, mine production 2025e (world total 3,900,000 t, country values Indonesia 2,600,000, Philippines 270,000, Russia 200,000, New Caledonia 140,000, Canada 140,000; shares calculated by Space Mushroom); Recycling; Substitutes; Domestic Production and Use
review:
  status: draft
  method: assistant
  checked_values: 24
  unreachable: 0
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-10-26 from the datasheet PDF text (Special Metals SMC-067), the Rolled Alloys and Fort Wayne Metals pages, the VDM and UF safety sheets, the USGS nickel summary and the Alloys International family table. Caveats: the VDM hazard sheet is a family sheet, the UF sheet is pure nickel, the Fort Wayne values are typical and use cold work rather than temper, and the Wikipedia F-1 statement is history only.'
license: CC-BY-4.0
updated: '2026-10-26'
story:
  recipe:
    line: X-750 is a nickel-chromium alloy with about 70 % nickel or more by specification. Titanium and aluminium combine with nickel to form gamma-prime, Ni3(Al,Ti), which precipitates during the ageing treatment and makes the alloy strong (Special Metals datasheet; Wikipedia). Niobium adds strength in the same way, and iron and chromium keep it stable.
    parts:
      - name: Nickel
        symbol: Ni
        share_percent: 73
        basis: nominal wt %, VDM; minimum 70.00 wt % in the specification
        role: The matrix of the alloy. Nickel gives the face-centred austenitic structure that the gamma-prime precipitates sit in.
      - name: Chromium
        symbol: Cr
        share_percent: 15
        basis: nominal wt %, VDM; 14.0 to 17.0 wt % in the specification
        role: Gives oxidation and corrosion resistance, as the datasheet describes.
      - name: Iron
        symbol: Fe
        share_percent: 7
        basis: nominal wt %, VDM; 5.0 to 9.0 wt % in the specification
        role: Lowers the cost of the alloy against a pure nickel-chromium grade.
      - name: Titanium
        symbol: Ti
        share_percent: 2.5
        basis: nominal wt %, VDM; 2.25 to 2.75 wt % in the specification
        role: Gamma-prime former. Titanium combines with nickel and aluminium during ageing.
      - name: Aluminium
        symbol: Al
        share_percent: 0.9
        basis: nominal wt %, VDM; 0.40 to 1.00 wt % in the specification
        role: Gamma-prime former, with titanium.
      - name: Niobium
        symbol: Nb
        share_percent: 0.9
        basis: nominal wt %, VDM; niobium plus tantalum 0.70 to 1.20 wt % in the specification
        role: Adds to the age-hardening and strengthens the grain structure.
  risk_groups:
    - title: For people
      lead: The alloy is inert in solid form, but dusts and fumes from machining, welding or pickling carry nickel-related hazards. The nickel hazard codes come from a pure-nickel sheet.
      level: 1
      verdict: Dust and fume hazard
      points:
        - label: Solid alloy
          line: The VDM family sheet classes the massive alloy as not classified under GHS-US, and says it may release hazardous dust or fumes when processed.
        - label: Nickel itself
          line: A pure-nickel sheet carries H351, H372 and H317 and sets a REL of 0.015 mg/m3 as Ni. The alloy is at least 70 % nickel, so the same classes are a reasonable guide, but the X-750 sheet is not in this record.
    - title: If it fails
      lead: The failure routes come from the datasheet text. Welding a precipitation-hardened part and the wrong temper for a spring are the two most important.
      points:
        - label: Spring temper
          line: A No. 1 temper spring relaxed 3 % in 500 hours at 800 F, while spring-temper wire of the same heat treatment relaxed 12 %.
        - label: Welding
          line: Welding a precipitation-hardened part can crack the parent metal, so the weld must be solution-treated before precipitation treatment.
        - label: Oxidation
          line: The alloy resists oxidation up to 1800 F in all heat-treated conditions, so oxidation is a service limit only well above the 1200 F spring limit.
    - title: Handling and storage
      points:
        - label: Keep the oxide on springs
          line: The datasheet says removing the oxide by mechanical means lowers relaxation resistance, so springs should be used with the oxide on.
        - label: Pickling
          line: Nitric-hydrofluoric pickling causes intergranular attack, worst in the precipitation-hardened state, and the bath must stay at or below 125 F.
  why: Inconel X-750 is a nickel-chromium alloy that gets its strength from heat treatment rather than from cold work alone. The datasheet gives a density of 8.28 g/cm3 and a melting range of 1393 to 1427 C. After the right heat treatment, aged rod meets a minimum of 165 ksi tensile and 105 ksi yield, and spring-temper wire meets a minimum of 220 ksi. It keeps useful strength up to 1800 F, and the datasheet says it is used for springs and fasteners from sub-zero temperatures to 1200 F. Rocket-engine thrust chambers are the space-related use the datasheet names.
  uses:
    - where: Springs and fasteners
      line: The datasheet recommends spring-temper wire heat treated at 1200 F for 4 hours for service up to 700 F. For maximum relaxation resistance from about 850 F to 1200 F, it recommends the triple heat treatment.
    - where: Rocket-engine thrust chambers
      line: The datasheet says the alloy is used extensively in rocket-engine thrust chambers. Wikipedia records the Rocketdyne F-1 thrust chamber on the Saturn V first stage. No spacecraft use was found in a source.
  can_do:
    - label: Strength after heat treatment
      value: 165 ksi tensile
      benchmark: ultimate_tensile_strength
      line: Aged rod, under 4.0 in, has a minimum tensile strength of 165 ksi and a minimum yield strength of 105 ksi (AMS 5667).
    - label: Spring wire
      value: 220 ksi tensile
      benchmark: ultimate_tensile_strength
      line: Spring-temper wire heat treated at 1200 F for 4 hours has a minimum tensile strength of 220 ksi for sizes from 0.012 to 0.250 in.
    - label: Heat
      value: 1800 F oxidation resistance
      line: Oxidation resistance up to 1800 F in all heat-treated conditions. Above about 1300 F the precipitation effect is lost, but the heat-treated material keeps useful strength to 1800 F.
    - label: Expansion
      value: 7.0 x 10-6 in./in./F mean expansion
      benchmark: cte
      line: The mean linear expansion from 70 to 200 F is 7.0 x 10-6 in./in./F, and 6.7 in the distributor sheet for 68 to 212 F.
    - label: Weight
      value: 8.28 g/cm3
      benchmark: density
      line: Density is 8.28 g/cm3, printed as 0.299 lb/in3, so mass is a real cost in parts where weight matters.
  compare: X-750 is chosen for strength and high-temperature load rather than for conduction. Its thermal conductivity is 83 Btu/in./hr/sq ft/F at 70 F, and its strength comes from heat treatment, so the temper decides the number. The table rows compare the printed values for X-750 only, and they are not a ranking against other profiles.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Specify the temper and heat treatment, because the yield and tensile strength change strongly with cold work and ageing.
    - Solution-treat a weldment before precipitation treatment, and never weld a precipitation-hardened part without a plan for its heat treatment.
    - Keep the oxide on springs, and use a reducing bath if they must be cleaned.
    - Ventilate pickling tanks and keep the bath at or below 125 F.
  good_for:
    - Springs that must keep their load from sub-zero to 1200 F, using the spring-temper wire with the right heat treatment.
    - Rocket-engine thrust chambers and high-temperature structural parts, as the datasheet names.
    - Oxidation resistance up to 1800 F in all heat-treated conditions.
  watch_out:
    - 'Weight: 8.28 g/cm3, so mass is a real cost in parts where weight matters.'
    - Welding a precipitation-hardened part can crack the parent metal.
    - 'Spring relaxation depends on the temper: spring-temper wire relaxed 12 % in the test against 3 % for No. 1 temper.'
    - Nitric-hydrofluoric pickling causes intergranular attack, worst in the precipitation-hardened state.
    - No spacecraft use or cryogenic property data beyond the datasheet was found.
  verdict: X-750 is a heat-treatable nickel-chromium spring and fastener alloy. It gives 165 ksi tensile and 105 ksi yield in aged rod, and 220 ksi in spring-temper wire, with useful strength to 1800 F. It is heavy at 8.28 g/cm3, its welds are the weak point, and its relaxation depends on the temper and heat treatment.