spore: profile
id: incoloy-825
spore_version: 0.2
family: nickel-alloys
name: Incoloy 825
abbreviation: Alloy 825 (UNS N08825)
role: corrosion-resistant austenitic nickel-iron-chromium alloy
category: metals
type: nickel-superalloys
summary: |
  Incoloy 825 (UNS N08825, W.Nr. 2.4858) is an austenitic nickel-iron-chromium alloy with molybdenum and copper additions, stabilised with titanium against intergranular attack. Special Metals gives a melting range of 1370 to 1400 C and a density of 8.14 g/cm3. Annealed plate has a typical yield strength of 338 MPa, a tensile strength of 662 MPa and 45 percent elongation. The alloy is sold for chemical plant, pickling equipment, sour-gas and oil-well piping, and nuclear fuel reprocessing, where it resists sulfuric and phosphoric acids and chloride stress cracking. None of the sources read ties it to a spacecraft, rocket or satellite part.
best_for: Corrosion service in sulfuric and phosphoric acid, sour gas and seawater, in sheet, plate, bar, tube and pipe that must be welded and formed
weakest_at: 'Strength against chloride pitting: Jacquet judges it only an improvement over Type 316 for pitting, and rates Alloy 625 and AL-6XN higher'
identity:
  formula: 'Nickel-iron-chromium-molybdenum-copper austenitic alloy, limiting composition (wt %): Ni 38.0 to 46.0, Fe 22.0 min, Cr 19.5 to 23.5, Mo 2.5 to 3.5, Cu 1.5 to 3.0, Ti 0.6 to 1.2, C 0.05 max, Mn 1.0 max, S 0.03 max, Si 0.5 max, Al 0.2 max'
  source: sm825
  where: Table 1, Limiting Chemical Composition, % of INCOLOY alloy 825 (Special Metals bulletin SMC-030)
  designations:
    - system: UNS
      code: N08825
      source: sm825
      where: Introduction paragraph (UNS N08825/W.Nr. 2.4858) and Available Products and Specifications
    - system: EN
      code: '2.4858'
      source: sm825
      where: Introduction paragraph, Werkstoff Number 2.4858; also EN 2.4858 in the VDM Table 1a
    - system: EN name
      code: NiCr21Mo
      source: vdm825
      where: Table 1a, Designations and standards, row EN (2.4858 - NiCr21Mo)
    - system: ISO
      code: NiFe30Cr21Mo3
      source: vdm825
      where: Table 1a, Designations and standards, row ISO
    - system: AFNOR
      code: NC21FeDU
      source: vdm825
      where: Table 1a, Designations and standards, row AFNOR
    - system: AMS
      code: '5542'
      source: ulbrich825
      where: Document header, specification list (AMS 5542, ASTM B424, ASTM B425, ASTM B564)
    - system: ASTM
      code: B 425
      note: rod and bar
      source: sm825
      where: Rod, Bar, Wire and Forging Stock list
    - system: ASTM
      code: B 424
      note: plate, sheet and strip
      source: sm825
      where: Plate, Sheet and Strip list
    - system: ASTM
      code: B 423
      note: pipe and tube
      source: sm825
      where: Pipe and Tube list
    - system: DIN
      code: '17750'
      note: plate, sheet and strip
      source: sm825
      where: Plate, Sheet and Strip list (DIN 17750)
    - system: DIN
      code: '17752'
      note: rod, bar, wire and forging stock
      source: sm825
      where: Rod, Bar, Wire and Forging Stock list (DIN 17752)
    - system: BS
      code: 3076NA16
      note: rod and bar
      source: sm825
      where: Rod, Bar, Wire and Forging Stock list (BS 3076NA16)
    - system: Trade name
      code: INCOLOY alloy 825
      source: sm825
      where: Title and first paragraph, INCOLOY alloy 825
    - system: Trade name
      code: Nicrofer 4221
      source: vdm825
      where: Title block, VDM Alloy 825 Nicrofer 4221
tags:
  environments: []
  stresses: []
  applications:
    - structures
properties:
  - benchmark: density
    label: Density, Incoloy 825
    value: 8.14
    unit: g/cm3
    scope: material
    conditions:
      unit_in_source: 0.294 lbs/in3
      temperature: not stated in the datasheet
    method: Value printed in a manufacturer datasheet
    status: ground
    source: ulbrich825
    where: Physical Properties section, Density line
  - benchmark: melting_point
    label: Melting range, Incoloy 825
    value: 1370
    value_high: 1400
    bound: range
    unit: °C
    scope: material
    conditions:
      unit_in_source: 2500-2550 °F
    method: Melting range printed in a manufacturer bulletin
    status: ground
    source: sm825
    where: Table 2, Physical Constants, row Melting Range (°C 1370-1400)
  - benchmark: specific_heat
    label: Specific heat capacity, 0 to 100 °C
    value: 440
    unit: J/(kg·K)
    scope: material
    conditions:
      temperature: 0 to 100 °C
      unit_in_source: 0.105 Btu/lb °F
    method: Value printed in a manufacturer datasheet in both units
    status: ground
    source: ulbrich825
    where: Physical Properties section, Specific Heat (0-100°C), J/kg °C row
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 21 °C
    value: 11.1
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 21 °C (70 °F)
      unit_in_source: 6.4 Btu/h-ft-°F
    method: Value printed in a manufacturer datasheet
    status: ground
    source: ulbrich825
    where: Thermal Conductivity table, row At 70°F (21°C)
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 100 °C
    value: 12.4
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 100 °C (212 °F)
      unit_in_source: 86 Btu·in/(sq. ft·h·°F)
      basis: typical
    method: Typical value printed in a manufacturer datasheet table
    status: ground
    source: vdm825
    where: Table 3, Typical physical properties, row 100 °C, column Thermal conductivity W/m·K
  - benchmark: cte
    label: Mean coefficient of thermal expansion, 20 to 100 °C
    value: 13.9
    unit: ppm/K
    scope: material
    conditions:
      temperature: mean, 20 to 100 °C (70 to 212 °F)
      unit_in_source: 7.7 x 10-6 in/in/°F
    method: Mean value printed in a manufacturer datasheet, metric value in parentheses
    status: ground
    source: ulbrich825
    where: Mean Coefficient of Thermal Expansion, row 70-212°F (20-100°C), value in parentheses
  - benchmark: elastic_modulus
    label: Modulus of elasticity at 20 °C, hot rolled and annealed plate
    value: 196
    unit: GPa
    scope: material
    conditions:
      temperature: 20 °C
      product_form: hot rolled and annealed plate
      load: Young's modulus
    method: Value printed in a manufacturer bulletin, table of Young's modulus against temperature
    status: ground
    source: sm825
    where: Table 4, Modulus of Elasticity (Hot Rolled and Annealed Plate), row 20 °C, GPa column
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C
    value: 112
    unit: µΩ·cm
    scope: material
    conditions:
      temperature: 20 °C (68 °F)
      unit_in_source: µΩ · cm
    method: Typical value printed in a manufacturer datasheet table
    status: ground
    source: vdm825
    where: Table 3, Typical physical properties, row 20 °C, column Electrical resistivity
  - benchmark: curie_temperature
    label: Curie temperature
    value: -196
    bound: upper
    unit: °C
    scope: material
    conditions:
      unit_in_source: <-320 °F
      meaning: the alloy is non-magnetic above this temperature
    method: Value printed in a manufacturer bulletin as less than the given temperature
    status: ground
    source: sm825
    where: Table 2, Physical Constants, row Curie Temperature (°C <-196)
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, annealed plate, typical
    value: 338
    unit: MPa
    scope: material
    conditions:
      product_form: plate, annealed
      temperature: room temperature
      basis: typical
      unit_in_source: 49 ksi
    method: Typical room-temperature value printed in a manufacturer bulletin
    status: ground
    source: sm825
    where: Table 5, Typical Room-Temperature Tensile Properties, row Plate, Annealed, column Yield Strength (0.2% offset) MPa
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, annealed plate, typical
    value: 662
    unit: MPa
    scope: material
    conditions:
      product_form: plate, annealed
      temperature: room temperature
      basis: typical
      unit_in_source: 96 ksi
    method: Typical room-temperature value printed in a manufacturer bulletin
    status: ground
    source: sm825
    where: Table 5, Typical Room-Temperature Tensile Properties, row Plate, Annealed, column Tensile Strength MPa
  - benchmark: elongation
    label: Elongation, annealed plate, typical
    value: 45
    unit: '%'
    scope: material
    conditions:
      product_form: plate, annealed
      temperature: room temperature
      basis: typical
    method: Typical room-temperature value printed in a manufacturer bulletin
    status: ground
    source: sm825
    where: Table 5, Typical Room-Temperature Tensile Properties, row Plate, Annealed, column Elongation %
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, cold drawn tubing, typical
    value: 889
    unit: MPa
    scope: material
    conditions:
      product_form: tubing, cold drawn
      temperature: room temperature
      basis: typical
      unit_in_source: 129 ksi
    method: Typical room-temperature value printed in a manufacturer bulletin
    status: ground
    note: The same table gives 1000 MPa tensile strength and 15 percent elongation for this cold-drawn tubing, against 324 MPa yield for annealed bar, so cold work changes strength strongly.
    source: sm825
    where: Table 5, Typical Room-Temperature Tensile Properties, row Tubing, Cold Drawn, column Yield Strength MPa
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, cold drawn tubing, typical
    value: 1000
    unit: MPa
    scope: material
    conditions:
      product_form: tubing, cold drawn
      temperature: room temperature
      basis: typical
      unit_in_source: 145 ksi
    method: Typical room-temperature value printed in a manufacturer bulletin
    status: ground
    source: sm825
    where: Table 5, Typical Room-Temperature Tensile Properties, row Tubing, Cold Drawn, column Tensile Strength MPa
  - benchmark: yield_strength
    label: Minimum yield strength 0.2 % offset, annealed sheet and plate 5 to 100 mm
    value: 240
    bound: lower
    unit: MPa
    scope: material
    conditions:
      product_form: sheet and plate, 5 to 100 mm, annealed
      temperature: room temperature
      standard: VdTÜV data sheet 432 minimum
    method: Minimum room-temperature value printed in a manufacturer datasheet
    status: ground
    source: vdm825
    where: Table 5, Mechanical properties at room temperature according to VdTÜV data sheet 432, row Sheet, plate 5-100, column Rp 0.2
  - benchmark: ultimate_tensile_strength
    label: Minimum tensile strength, annealed sheet and plate 5 to 100 mm
    value: 585
    bound: lower
    unit: MPa
    scope: material
    conditions:
      product_form: sheet and plate, 5 to 100 mm, annealed
      temperature: room temperature
      standard: VdTÜV data sheet 432 minimum
    method: Minimum room-temperature value printed in a manufacturer datasheet
    status: ground
    source: vdm825
    where: Table 5, Mechanical properties at room temperature according to VdTÜV data sheet 432, row Sheet, plate 5-100, column Rm
  - benchmark: elongation
    label: Minimum elongation, annealed sheet and plate 5 to 100 mm
    value: 30
    bound: lower
    unit: '%'
    scope: material
    conditions:
      product_form: sheet and plate, 5 to 100 mm, annealed
      temperature: room temperature
      standard: VdTÜV data sheet 432 minimum
    method: Minimum room-temperature value printed in a manufacturer datasheet
    status: ground
    source: vdm825
    where: Table 5, Mechanical properties at room temperature according to VdTÜV data sheet 432, row Sheet, plate 5-100, column A %
  - benchmark: corrosion_rate_intergranular
    label: Intergranular corrosion rate, boiling 50 % sulfuric acid with ferric sulfate
    value: 0.03
    unit: mm/a
    scope: material
    conditions:
      environment: boiling 50 % sulfuric acid with ferric sulfate, standard ASTM test named in the table header
      unit_in_source: 1 mils/year
    method: Rate printed in a manufacturer datasheet table
    status: ground
    note: Benchmark name is not in the canonical list, so it is a snake_case name (see gaps). The table gives 36 (0.91) for Type 316 and 26 (0.66) for Type 316L in the same test.
    source: jacquet825
    where: Resistance to Intergranular Corrosion table, row Alloy 825, column Boiling 50% Sulfuric Acid-Ferric
corrosion:
  - environment: Sulfuric and phosphoric acids, and oxidising and reducing acids
    headline: The nickel, molybdenum and copper together resist reducing acids better than standard stainless steels, and chromium resists oxidising acids.
    effect: Special Metals names sulfuric acid and phosphoric acid among the environments where the alloy is particularly useful, and says the nickel with molybdenum and copper gives outstanding resistance to reducing environments. VDM lists good resistance in sulfuric, phosphoric, nitric and organic acids. No quantitative general corrosion rate in these acids was taken from a page with a stated test condition.
    rating: low
    conditions:
      basis: qualitative statements in datasheets
      environments: sulfuric, phosphoric, nitric and organic acids, alkalis, sea water
    source: sm825
    where: Corrosion Resistance section, first paragraph (VDM Alloy 825 datasheet, Corrosion resistance section, gives the same list)
  - environment: Boiling 50 % sulfuric acid with ferric sulfate (ASTM intergranular test)
    headline: Alloy 825 shows an intergranular corrosion rate of 0.03 mm/a in the ASTM boiling sulfuric-ferric test, against 0.91 mm/a for Type 316.
    effect: Jacquet's intergranular table gives 1 (0.03) mils/year (mm/a) for Alloy 825 in boiling 50 % sulfuric acid with ferric sulfate, against 36 (0.91) for Type 316, 26 (0.66) for Type 316L and 19 (0.48) for AL-6XN. In boiling 65 % nitric acid the same table gives 12 (0.30) for Alloy 825 against 34 (0.85) for Type 316.
    rating: low
    conditions:
      environment: boiling 50 % sulfuric acid with ferric sulfate, ASTM standard test named in the table header
      unit_in_source: mils/year (mm/a)
    source: jacquet825
    where: Resistance to Intergranular Corrosion table
  - environment: Chloride pitting and crevice corrosion, including sea water
    headline: Alloy 825 resists chloride pitting only moderately and is judged an improvement, not a dramatic one, over Type 316.
    effect: Jacquet says the chromium and molybdenum content gives the alloy a level of chloride pitting resistance that falls short of AL-6XN and Alloy 625, and that the alloy is used in high-chloride environments such as sea water where some pitting can be tolerated. Special Metals lists sea water among the environments where the alloy is particularly useful. The G 48 Practice B crevice-onset temperature in the Jacquet table has no printed unit, so it is not entered.
    rating: moderate
    conditions:
      test: ASTM G 48 Practice B, 10 % ferric chloride, for the crevice-onset table
      basis: vendor comparison and service experience statement
    source: jacquet825
    where: Resistance to Chloride Pitting and Crevice Corrosion section; Special Metals Corrosion Resistance paragraph for sea water
  - environment: Chloride stress corrosion cracking, boiling magnesium chloride
    headline: Chloride stress cracking is resisted in most tests, but Alloy 825 cracks in some samples in boiling magnesium chloride over long times.
    effect: In U-bend tests, Jacquet gives Alloy 825 as Mixed in boiling 42 % magnesium chloride (Type 316 Fail), and as Resist in boiling 33 % lithium chloride and boiling 26 % sodium chloride. Jacquet says the alloy will crack in long-time tests in a percentage of samples in the severe boiling magnesium chloride test. VDM describes the high nickel content as giving virtual immunity to stress corrosion cracking.
    rating: moderate
    conditions:
      test: U-bend samples, boiling 42 % magnesium chloride, boiling 33 % lithium chloride, boiling 26 % sodium chloride
    source: jacquet825
    where: Resistance to Chloride Stress Corrosion Cracking table and the text beneath it
risks:
  hazards:
    - text: Solid Incoloy 825 as supplied is not classified as a hazardous substance (article). When it is cut, welded, melted or ground, the dust and fume carry the codes for the alloy's elements, in particular H350 may cause cancer, H317 may cause an allergic skin reaction, H334 may cause allergy or asthma symptoms, and H332 and H302 for harmful by inhalation and by mouth. The SDS is for a family of nickel alloys, not for 825 alone.
      ghs:
        - H350
        - H317
        - H334
        - H332
        - H302
        - H315
      source: vdm-sds
      where: Section 2.1 Classification, and the note that the dust and fume rules apply when the material is fabricated or physically altered
    - text: The nickel element is classified in the SDS as skin sensitiser (H317), carcinogen category 2 (H351), specific target organ toxicant (H372) and aquatic toxicant (H400, H412). The nominal 825 analysis row in the SDS gives nickel as the balance with 31.22 percent iron and 21.5 percent chromium.
      ghs:
        - H317
        - H351
        - H372
        - H400
        - H412
      source: vdm-sds
      where: Section 3.1 Substances, nickel row; Section 3.2 Mixtures, row 825
    - text: Inhalation of dusts and fumes from these alloys can cause metal fume fever, with a metallic or sweet taste, sweating, shivering, headache, throat irritation and fever. Fine particulates dispersed in air may present an explosion hazard, and processed dust may be a combustible dust hazard.
      ghs: []
      source: vdm-sds
      where: Section 2.3 Other Hazards, and the paragraph after the first page break on metal fume fever
  failure_risks:
    - mode: Chloride stress cracking in boiling magnesium chloride
      trigger: Long exposure to boiling 42 % magnesium chloride, as in the severe U-bend test
      consequence: Jacquet says the alloy cracks in long-time tests in a percentage of samples. The alloy is rated Mixed in that test, against Fail for Type 316.
      severity: moderate
      source: jacquet825
      where: Resistance to Chloride Stress Corrosion Cracking table and the text beneath it
    - mode: Intergranular attack after heating in the sensitising range
      trigger: Heavy sections cooled slowly from hot working, or semi-finished products used between 600 and 650 C and then reused in that range after repair welding, without a stabilising anneal
      consequence: Special Metals says heavy sections may become sensitised during cooling from hot-working temperature and be subject to intergranular corrosion in certain media. VDM recommends stabilising anneal on semi-finished products used between 600 and 650 C before reuse in that range.
      severity: moderate
      source: sm825
      where: Fabrication and Hot and Cold Forming sections (Special Metals); Post-weld treatment section (VDM)
    - mode: Chloride pitting and crevice attack
      trigger: Chloride service, including sea water, where minor pitting cannot be tolerated
      consequence: Jacquet judges the alloy only an improvement over Type 316 for pitting and says it is not suitable where even minor pitting cannot be tolerated; AL-6XN and Alloy 625 are used there instead.
      severity: moderate
      source: jacquet825
      where: Resistance to Chloride Pitting and Crevice Corrosion section
    - mode: Phase formation and loss of ductility after long exposure above 540 C
      trigger: Exposure to temperatures above about 1000 F (540 C), where creep-rupture is a design factor
      consequence: Special Metals says microstructural changes (phase formation) can significantly lower ductility and impact strength, so the alloy is not normally used where creep-rupture properties are design factors.
      severity: moderate
      source: sm825
      where: Mechanical Properties section, first paragraph
  side_effects:
    - text: Density is 8.14 g/cm3, so part mass is high for a given volume. The datasheet gives this value without a mass comparison against other alloys.
      affects: Mass of hardware
      source: ulbrich825
      where: Physical Properties section, Density line
  handling:
    - text: Anneal after fabrication at 1700 to 1800 F (930 to 980 C) and air cool or water quench rapidly, so that the stabilising titanium keeps its corrosion resistance. VDM gives a soft annealing range of 920 to 980 C, preferably 940 plus or minus 10 C, with rapid water quench.
      source: sm825
      where: Fabrication section (Special Metals); Heat treatment section (VDM)
    - text: The two sources differ on work hardening. VDM says the rate is higher than for austenitic stainless steels, while Special Metals says it is somewhat less but still relatively high, and both say forming equipment must be well powered. Cold work should be done on annealed material, with soft annealing after more than 15 percent deformation (VDM).
      source: sm825
      where: Hot and Cold Forming section (Special Metals); Cold working section (VDM)
    - text: Use a separate workplace and clean tools, and keep carbon-steel tools away from nickel alloy work, so that ferrous particles do not contaminate the surface and cause corrosion. Welding interpass temperature should not exceed 150 C (VDM).
      source: vdm825
      where: Welding section, Workplace and Tools and machines; Welding parameters section
    - text: Use only outdoors or in a well-ventilated area, avoid generating dust and sparks, and wear respiratory protection where ventilation is inadequate. The SDS gives these as precautions for cutting, welding and grinding of the alloy.
      source: vdm-sds
      where: Precautionary Statements P271 and P284; Section 2.3 Other Hazards
  mitigations: []
uses:
  - application: structures
    device: Process pressure vessels and heat exchangers in chemical plant
    example: VdTÜV approves VDM Alloy 825 for pressure vessels with wall temperatures up to 450 C, and ASME Section VIII Division 1 approves it up to 538 C (1,000 F). VDM lists heat exchangers, evaporators, washers and immersion pipes in phosphoric acid production.
    source: vdm825
    where: Introduction, approval bullet; Applications section, second bullet
  - application: structures
    device: Sour gas and oil well piping, offshore piping, and immersion pipes in sea-water-cooled heat exchangers
    example: Special Metals lists sour gas and oil wells and sea water among the environments where the alloy is particularly useful. VDM lists pipes, tubes and fittings for oil and gas extraction, and immersion pipes in sea-water-cooled heat exchangers.
    source: vdm825
    where: Applications section, first bullet; Special Metals Corrosion Resistance paragraph (sm825)
  - application: structures
    device: 'Steel pickling equipment: heating coils, vessels, baskets and chains in sulfuric acid pickling plants'
    example: VDM lists components in sulfuric acid pickling plants, including heating coils, vessels, boilers, baskets and chains, among the typical application fields for VDM Alloy 825.
    source: vdm825
    where: Applications section, second bullet
  - application: structures
    device: Nuclear fuel reprocessing equipment, fuel element dissolvers and radioactive waste handling
    example: Special Metals lists nuclear fuel reprocessing, fuel element dissolvers and handling of radioactive wastes among the applications for the alloy. VDM uses a nuclear fuel element dissolver as an example of one set of equipment handling sulfuric and nitric acids and sodium hydroxide.
    source: sm825
    where: Introduction paragraph (applications list); VDM Corrosion resistance section for the dissolver example
supply:
  - subject: Nickel
    abundance: World resources are more than 350 million tons of nickel (USGS 2026)
    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
      - country: New Caledonia
        share_percent: 3.6
        year: 2025
    recycling: In 2025, nickel recovered from scrap accounted for approximately 60 percent of apparent consumption, and most secondary nickel was stainless-steel scrap (USGS).
    substitutes:
      - Low-nickel, duplex, or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction. Titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments (USGS).
    source: usgs-nickel-2026
    where: World Mine Production and Reserves table, 2025e column, world total 3,900,000 t; shares calculated by Space Mushroom from the printed tonnages (Indonesia 2,600,000; Philippines 270,000; Russia 200,000; Canada 140,000; New Caledonia 140,000); Recycling; Substitutes; World Resources
  - subject: Molybdenum
    abundance: Identified resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world (USGS 2026)
    producers:
      - country: China
        share_percent: 37.3
        year: 2025
      - country: Chile
        share_percent: 16.2
        year: 2025
      - country: United States
        share_percent: 15.4
        year: 2025
      - country: Peru
        share_percent: 15
        year: 2025
      - country: Mexico
        share_percent: 6.5
        year: 2025
    recycling: Molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap, and the amount recycled may be as much as 30 percent of apparent supply (USGS).
    source: usgs-molybdenum-2026
    where: World Mine Production and Reserves table, 2025e column, world total 260,000 t of molybdenum content; shares calculated by Space Mushroom from the printed tonnages; Recycling; Domestic Production and Use (used principally as an alloying agent in superalloys)
documents:
  - title: Special Metals INCOLOY alloy 825 bulletin SMC-030 (copyright 2004, Sept 04)
    type: datasheet
    url: https://www.specialmetals.com/documents/technical-bulletins/incoloy/incoloy-alloy-825.pdf
    year: 2004
  - title: Incoloy 825 (Alloy 825) UNS N08825 datasheet, Ulbrich Stainless Steels and Special Metals (January 2014, revision 2015)
    type: datasheet
    url: https://d2ykdomew87jzd.cloudfront.net/data-sheets/Incoloy%C2%AE-825-Alloy-825-UNS-N08825.pdf
    year: 2014
  - title: VDM Alloy 825 (Nicrofer 4221) data sheet No. 4101, revision 01 (November 2020)
    type: datasheet
    url: https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Data_Sheets/Data_Sheet_VDM_Alloy_825.pdf
    year: 2020
  - title: Jacquet Alloy 825 (UNS N08825) data sheet, nickel-base alloy
    type: datasheet
    url: https://montreal.myjacquet.com/files/JCQusa-alloy-825.pdf
  - title: VDM Metals USA nickel alloys safety data sheet (revision dated 2026-09-18, Federal Register 89 FR 98)
    type: sds
    url: https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Safety_Information_Sheets/Nickel_Alloys_VDM_Metals_USA_EN.pdf
    year: 2026
  - 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: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
  - title: 'Wikipedia: Incoloy (trade name and family)'
    type: database
    url: https://en.wikipedia.org/wiki/Incoloy
    year: 2026
gaps:
  - No spacecraft, rocket or satellite use of Incoloy 825 was found. Searches of NASA NTRS and the general web returned only Incoloy 903, MA956 and other Incoloy grades, none of them 825. The uses list therefore has no space entry.
  - No AISI, SAE or JIS designation for Incoloy 825 is printed in any source read, so none is listed in designations.
  - The ASTM G 48 Practice B crevice-onset temperature in the Jacquet table (32 with 0.0 in brackets) is not entered because the table prints no unit.
  - The Jacquet boiling laboratory sulfuric acid table (20 (0.5), 11 (0.28), 20 (0.5) for Alloy 825) is not entered because the column has no printed unit and the concentrations are not clearly aligned.
  - The intergranular corrosion property uses the snake_case name corrosion_rate_intergranular because no canonical corrosion-rate name exists in property-canon.yaml.
  - The Charpy keyhole impact results (Special Metals Table 6; plate, room temperature 79.0 ft-lb and 107 J longitudinal) are not entered because impact energy has no canonical benchmark name.
  - Only the annealed plate and cold drawn tubing tensile rows of Special Metals Table 5 are entered. Annealed bar, sheet and tubing rows, and the Jacquet typical room-temperature values, were not added to keep one value per form.
  - The Ulbrich datasheet prints titanium as 0.06 to 1.2, which is probably a typing error for 0.6 to 1.2 (Special Metals and VDM give 0.6 to 1.2). The composition uses the Special Metals limits.
  - 'Iron: Special Metals gives 22.0 percent minimum, while the VDM Table 2 minimum column reads 20. The composition uses the Special Metals figure.'
  - The VDM datasheet gives a relative magnetic permeability of 1.005 maximum at 20 C, and Special Metals gives 1.005 at 200 oersted. Neither is entered because no canonical name fits.
  - No minimum or typical service temperature is printed as a rated limit. VDM's 538 C and 450 C figures are vessel code approval temperatures, not service limits, so max_service_temp is left out.
  - The Special Metals Resistance to Aqueous Corrosion bulletin is referenced but was not opened, so no general corrosion rate table from it is recorded.
  - The Outokumpu Ultra Alloy 825 datasheet was not reachable (host did not resolve), so its isocorrosion diagram in sulfuric acid is not used.
  - Thermal conductivity at 77 K, electrical resistivity at cryogenic temperatures, outgassing, atomic oxygen erosion and radiation effects were not found for this alloy and are not recorded.
  - The USGS 2026 nickel and molybdenum summaries print no critical-mineral list status in the text read, so critical_lists is empty for both.
  - No safety data sheet for solid Incoloy 825 plate or bar was read. The hazards come from VDM's multi-alloy nickel-alloy SDS, which classifies the solid as an article and covers the dust and fume.
  - The ATI 825 datasheet was not found in search results, so no ATI values are used.
sources:
  sm825:
    title: INCOLOY alloy 825 (UNS N08825/W.Nr. 2.4858), Special Metals bulletin SMC-030
    id: UNS N08825, W.Nr. 2.4858; publication SMC-030
    url: https://www.specialmetals.com/documents/technical-bulletins/incoloy/incoloy-alloy-825.pdf
    year: 2004
    kind: datasheet
    license: Manufacturer bulletin, informational data (cited, not reproduced)
  ulbrich825:
    title: Incoloy 825 (Alloy 825) UNS N08825, Ulbrich Stainless Steels and Special Metals datasheet
    id: AMS 5542, ASTM B424, B425, B564, B906
    url: https://d2ykdomew87jzd.cloudfront.net/data-sheets/Incoloy%C2%AE-825-Alloy-825-UNS-N08825.pdf
    year: 2014
    kind: datasheet
    license: Manufacturer datasheet, typical values only (cited, not reproduced)
  vdm825:
    title: VDM Alloy 825 Nicrofer 4221, VDM Metals data sheet No. 4101 rev 01
    id: EN 2.4858, UNS N08825, DIN 17744, 17750, 17752, VdTÜV 432
    url: https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Data_Sheets/Data_Sheet_VDM_Alloy_825.pdf
    year: 2020
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  jacquet825:
    title: Alloy 825 (UNS N08825), nickel-base alloy data sheet, Jacquet (montreal.myjacquet.com copy)
    url: https://montreal.myjacquet.com/files/JCQusa-alloy-825.pdf
    kind: datasheet
    license: Distributor datasheet, for internal use (cited, not reproduced)
  vdm-sds:
    title: Nickel Alloys Safety Data Sheet, VDM Metals USA (multi-alloy, revised 2026-09-18)
    url: https://www.vdm-metals.com/fileadmin/user_upload/Downloads/Safety_Information_Sheets/Nickel_Alloys_VDM_Metals_USA_EN.pdf
    year: 2026
    kind: datasheet
    license: Manufacturer safety data sheet (cited, not reproduced)
  usgs-nickel-2026:
    title: Mineral Commodity Summaries 2026, Nickel (USGS)
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-molybdenum-2026:
    title: Mineral Commodity Summaries 2026, Molybdenum (USGS)
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wikipedia-incoloy:
    title: Incoloy (Wikipedia), trade name and alloy family
    url: https://en.wikipedia.org/wiki/Incoloy
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 18
  unreachable: 1
  caveats: 6
  note: 'Values were read by an AI assistant on 2026-10-26 from the PDFs and pages named in each entry (Special Metals bulletin, Ulbrich datasheet, VDM datasheet and SDS, Jacquet datasheet, USGS 2026 summaries). Unreachable: the Outokumpu Ultra 825 datasheet (host did not resolve). Caveats: the strengths are typical values of one bulletin and one distributor sheet, the minimums come from VdTÜV 432 as printed by VDM, the intergranular rate uses a non-canonical name, the hazard SDS covers a family of nickel alloys, and no space use was found.'
story:
  risk_groups:
    - title: For people
      lead: The hazard for people depends on the dust and fume, not on the solid alloy. The SDS for the nickel-alloy family classifies the solid as an article and the dust or fume as carcinogenic and a skin sensitiser.
      level: 2
      verdict: Solid is an article, dust and fume are not
      points:
        - label: Solid metal
          line: The VDM SDS says the solid alloy as supplied is not classified. Its nickel content carries skin sensitisation (H317), carcinogenicity category 2 (H351) and target organ toxicity (H372).
        - label: Cutting, welding, grinding
          line: The SDS says these operations produce dust and fume with the element codes, including H350 may cause cancer and H334 may cause allergy or asthma symptoms. The SDS advises use only outdoors or in a well-ventilated area, and respiratory protection where ventilation is inadequate.
    - title: If it fails
      lead: These failure routes are in the sources read. The chloride ones are measured in vendor tests, and the heat-related one is a metallurgy warning.
      points:
        - label: Boiling magnesium chloride
          line: Jacquet says the alloy cracks in long-time tests in a percentage of samples in boiling magnesium chloride, where it is rated Mixed against Fail for Type 316.
        - label: Chloride pitting
          line: The alloy is judged only an improvement over Type 316 for chloride pitting. AL-6XN and Alloy 625 are used where minor pitting cannot be tolerated.
        - label: Heat exposure
          line: Above about 540 C phase formation can lower ductility and impact strength, so creep-rupture service is not normal for the alloy.
    - title: Handling and storage
      points:
        - label: Anneal after forming
          line: Anneal at 930 to 980 C and quench, so the titanium keeps the alloy resistant to intergranular corrosion after heating.
        - label: Keep iron out
          line: Use clean, dedicated tools and keep carbon steel contact off the surface, because ferrous particles pressed into the surface cause corrosion.
  why: Incoloy 825 is a nickel-rich austenitic alloy built for acid and chloride corrosion rather than for strength. Its nickel, molybdenum and copper together resist sulfuric and phosphoric acids, and the titanium stops intergranular attack after heating. Special Metals and VDM both point to chemical processing, pickling equipment, oil and gas piping and nuclear fuel reprocessing. The Special Metals bulletin says the alloy resists chloride stress cracking, but a Jacquet U-bend test shows cracking in boiling magnesium chloride over long times. Its density is 8.14 g/cm3, and it melts between 1370 and 1400 C. No spacecraft, rocket or satellite use was found in the sources read.
  uses:
    - where: Pressure vessels and heat exchangers
      line: VdTÜV approves VDM Alloy 825 for pressure vessels with walls up to 450 C, and ASME Section VIII Division 1 approves it up to 538 C (1,000 F).
    - where: Oil, gas and sour service
      line: Special Metals names sour gas, oil wells and sea water as useful environments, and VDM lists oil and gas extraction piping and offshore piping.
    - where: Pickling and nuclear
      line: VDM lists sulfuric acid pickling plant parts, and Special Metals lists fuel element dissolvers and radioactive waste handling.
  can_do:
    - label: Resist acids
      value: Sulfuric and phosphoric acid resistance
      line: Special Metals and VDM both name sulfuric and phosphoric acid among the environments the alloy is particularly useful in.
    - label: Carry strength when annealed
      value: 338 MPa yield (plate)
      benchmark: yield_strength
      line: Annealed plate has a typical yield strength of 338 MPa and a tensile strength of 662 MPa, stretching 45 percent before breaking (Special Metals).
    - label: Gain strength by cold work
      value: 889 MPa yield (cold drawn tubing)
      benchmark: yield_strength
      line: Cold drawn tubing has a typical yield strength of 889 MPa and tensile strength of 1000 MPa, with 15 percent elongation.
    - label: Weight
      value: 8.14 g/cm3
      benchmark: density
      line: Density is 8.14 g/cm3 in the Ulbrich datasheet.
    - label: Melt
      value: 1370 to 1400 C
      benchmark: melting_point
      line: Special Metals gives the melting range as 1370 to 1400 C (2500 to 2550 F).
  compare: Compare with Inconel 625 on this site (inconel-625), a nickel-chromium-molybdenum-niobium alloy. Incoloy 825 instead adds copper and titanium. Jacquet ranks Alloy 625 above Alloy 825 for chloride pitting resistance, and the Alloy 825 datasheets name sulfuric and phosphoric acid as its key service. The rows below use this profile's own values only, so read them as examples, not as a ranking against 625.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Yield strength
      benchmark: yield_strength
  handling:
    - Anneal after forming and welding, at 930 to 980 C with a rapid quench, to keep the titanium stabilisation.
    - Use local exhaust and dust control for cutting, welding and grinding, since dust and fume carry the element codes.
    - Specify the form and temper, because the typical yield strength goes from 338 MPa in annealed plate to 889 MPa in cold drawn tubing.
  good_for:
    - 'Acid service: sulfuric and phosphoric acid, with resistance to reducing and oxidising environments.'
    - 'Chloride stress cracking in most tests: the nickel content resists it, except in boiling magnesium chloride over long times.'
    - 'Welded and formed parts: the titanium stabilisation resists intergranular attack after welding.'
  watch_out:
    - Chloride pitting is only moderate. Use Alloy 625 or AL-6XN where minor pitting cannot be tolerated.
    - Boiling magnesium chloride cracks some samples over long times.
    - Annealed strength is modest, at 338 MPa yield for plate.
    - Dust and fume from cutting or welding carry cancer and sensitiser codes.
    - No spacecraft, rocket or satellite use was found in the sources read.
  verdict: Incoloy 825 is an acid- and chloride-resistant nickel-iron-chromium alloy, stabilised with titanium so that welded parts resist intergranular attack. Its annealed plate yields at a typical 338 MPa, and it melts at 1370 to 1400 C. Pitting resistance is only moderate, and boiling magnesium chloride cracks some samples over long times. Its dust and fume carry hazard codes. No space application was found.
  recipe:
    line: Incoloy 825 is an austenitic nickel-iron-chromium alloy with molybdenum, copper and titanium additions. Special Metals gives its limiting composition in weight percent (Table 1). The titanium addition stabilises the alloy against sensitisation to intergranular corrosion, and the alloy is supplied as bar, rod, wire, sheet, strip, plate, tube and pipe (Special Metals; VDM). Special Metals gives a hot-working range in its Hot and Cold Forming section and recommends that final hot working be done in the lower part of that range for best corrosion resistance.
    parts:
      - name: Nickel
        symbol: Ni
        share_percent: 38
        share_high: 46
        role: Gives resistance to chloride stress corrosion cracking, and with molybdenum and copper gives outstanding resistance to reducing environments (Special Metals)
        source: sm825
        where: Table 1, Limiting Chemical Composition
      - name: Iron
        symbol: Fe
        share_percent: 22
        share_note: minimum (matrix)
        role: Forms the austenitic matrix with nickel
        source: sm825
        where: Table 1, Limiting Chemical Composition
      - name: Chromium
        symbol: Cr
        share_percent: 19.5
        share_high: 23.5
        role: Confers resistance to oxidising substances such as nitric acid, nitrates and oxidising salt (Special Metals)
        source: sm825
        where: Table 1, Limiting Chemical Composition
      - name: Molybdenum
        symbol: Mo
        share_percent: 2.5
        share_high: 3.5
        role: Aids resistance to pitting and crevice corrosion, and with nickel and copper, to reducing acids (Special Metals)
        source: sm825
        where: Table 1, Limiting Chemical Composition
      - name: Copper
        symbol: Cu
        share_percent: 1.5
        share_high: 3
        role: With nickel and molybdenum, gives resistance to sulfuric and phosphoric acids (Special Metals)
        source: sm825
        where: Table 1, Limiting Chemical Composition
      - name: Titanium
        symbol: Ti
        share_percent: 0.6
        share_high: 1.2
        role: Stabilises the alloy against intergranular corrosion after heating in the sensitising range (Special Metals; VDM)
        source: sm825
        where: Table 1, Limiting Chemical Composition
      - name: Minor elements
        share_note: C 0.05 max, Mn 1.0 max, S 0.03 max, Si 0.5 max, Al 0.2 max (wt %)
        role: Residual limits
        source: sm825
        where: Table 1, Limiting Chemical Composition