spore: profile
id: inconel-625
spore_version: 0.2
family: nickel-alloys
name: Inconel 625
abbreviation: IN625 (UNS N06625)
role: corrosion-resistant solid-solution nickel superalloy
category: metals
type: nickel-superalloys
summary: |
  Inconel 625 (UNS N06625, W.Nr. 2.4856) is a nickel-chromium-molybdenum-niobium alloy. Its strength comes from solid solution, so it needs no precipitation-hardening treatment. Special Metals gives a melting range of 1290 to 1350 C and a yield strength of 60 to 95 ksi for the annealed (grade 1) condition, which is stronger than the solution-annealed (grade 2) condition. It is used for corrosion-resistant chemical plant and marine parts, and for aerospace ducting and rocket tubing.
best_for: Corrosion-resistant parts that also need strength and good weldability, such as chemical plant, marine hardware, aerospace ducting and rocket tubing
weakest_at: Long exposure near 1200 F hardens the annealed alloy and cuts its room-temperature elongation from 54 to 30 percent after 2000 hours
identity:
  formula: 'Nickel-chromium-molybdenum-niobium solid-solution alloy: 58.0 min Ni, 20.0 to 23.0 Cr, 8.0 to 10.0 Mo, 3.15 to 4.15 Nb plus Ta, 5.0 max Fe, 1.0 max Co (if determined), 0.50 max Mn, 0.50 max Si, 0.40 max Al, 0.40 max Ti, 0.10 max C, 0.015 max P, 0.015 max S (wt%)'
  source: sm625
  where: Table 1, Limiting Chemical Composition, % (Special Metals datasheet); UNS N06625 and W.Nr. 2.4856 from the introduction and the Available Products section
  designations:
    - system: UNS
      code: N06625
      source: sm625
      where: Introduction, and Available Products and Specifications (designated as UNS N06625)
    - system: EN
      code: '2.4856'
      source: sm625
      where: Available Products and Specifications; the Wikipedia infobox also gives EN 2.4856
    - system: ISO
      code: NW6625
      source: sm625
      where: Available Products and Specifications
    - system: ASTM
      code: B 443
      source: sm625
      where: Available Products and Specifications, plate, sheet and strip
    - system: ASTM
      code: B 444
      note: B 829; ASME SB 444, SB 829
      source: sm625
      where: Available Products and Specifications, pipe and tube
    - system: ASTM
      code: B 446
      source: sm625
      where: Available Products and Specifications, rod, bar, wire and forging stock
    - system: AMS
      code: '5599'
      source: ati-tds
      where: 'ATI TDS, Specifications: AMS 5599 with ASTM B 443 (sheet, strip, plate); AMS 5666 (bars, forgings, extrusions, rings); AMS 5837 (welding wire)'
    - system: AMS
      code: '5666'
      source: ati-tds
      where: 'ATI TDS, Specifications: AMS 5599 with ASTM B 443 (sheet, strip, plate); AMS 5666 (bars, forgings, extrusions, rings); AMS 5837 (welding wire)'
    - system: AMS
      code: '5837'
      source: ati-tds
      where: 'ATI TDS, Specifications: AMS 5599 with ASTM B 443 (sheet, strip, plate); AMS 5666 (bars, forgings, extrusions, rings); AMS 5837 (welding wire)'
    - system: MIL
      code: N-24687
      source: ati-tds
      where: 'ATI TDS, Specifications: bars, forgings, extrusions and rings'
    - system: MIL
      code: MIL-DTL-24799
      source: ati-tds
      where: 'ATI TDS, Specifications: bars, forgings, extrusions and rings'
    - system: EN
      code: '10095'
      source: sm625
      where: 'Available Products and Specifications: rod, bar and sections; plate, sheet and strip'
    - system: NACE
      code: MR-01-75
      source: sm625
      where: 'Available Products and Specifications: listed in NACE MR-01-75; the Wikipedia infobox gives NACE MR0175-3'
    - system: Trade name
      code: INCONEL alloy 625
      source: sm625
      where: Datasheet title (Special Metals trademark)
    - system: Trade name
      code: ATI 625
      source: ati-page
      where: ATI product page, ATI 625 Nickel-Based Alloy
    - system: Trade name
      code: Haynes 625
      source: wiki625
      where: Introduction, other well known names
    - system: Trade name
      code: Nickelvac 625
      source: wiki625
      where: Introduction, other well known names
    - system: Trade name
      code: Nicrofer 6020
      source: wiki625
      where: Introduction, other well known names
    - system: Trade name
      code: Altemp 625
      source: wiki625
      where: Introduction, other well known names
    - system: Trade name
      code: Chronin 625
      source: wiki625
      where: Introduction, other well known names
tags:
  environments:
    - launch
  stresses: []
  applications:
    - propulsion-and-tanks
    - structures
    - thermal-control
properties:
  - benchmark: density
    value: 8.44
    unit: g/cm3
    scope: material
    conditions:
      basis: datasheet physical constant, no test temperature printed
      unit_in_source: gram/cc (0.305 lb/cu in printed alongside)
    method: Table 2, Physical Constants, Density, printed as 0.305 lb/cu in and 8.44 gram/cc; the gram/cc value is kept
    status: ground
    source: sm625
    where: Table 2, Density, gram/cc row
  - benchmark: melting_point
    value: 1290
    value_high: 1350
    bound: range
    unit: °C
    scope: material
    conditions:
      basis: melting range as printed in Table 2 (2350 to 2460 F)
    method: Table 2, metric row printed as 1290-1350 C; the ATI TDS prints 1,288 to 1,343 C (2,350 to 2,450 F), and the Special Metals range is kept here
    status: ground
    source: sm625
    where: Table 2, Melting Range, C row
  - benchmark: specific_heat
    value: 410
    unit: J/(kg·K)
    scope: material
    conditions:
      basis: at 70 F (21 C); printed as 0.098 Btu/lb F
      unit_in_source: J/kg °C
    method: Table 2, metric value in parentheses; the datasheet marks the row as calculated (footnote a)
    status: calculated
    source: sm625
    where: Table 2, Specific Heat, 70 F (21 C) row
  - benchmark: curie_temperature
    value: -196
    bound: upper
    unit: °C
    scope: material
    conditions:
      basis: printed as less than -320 F; metric value -196 C
    method: Table 2, Curie Temperature, C row; the metric row has no less-than sign, so the value is recorded as an upper bound
    status: ground
    source: sm625
    where: Table 2, Curie Temperature, C row
  - benchmark: thermal_conductivity
    value: 9.8
    unit: W/m°C
    scope: material
    conditions:
      basis: at 21 C (70 F); material annealed 2100 F for 1 h (footnote c); measured at Battelle (footnote b)
    method: Table 3, Thermal Conductivity, metric column; the same row prints 68 Btu·in/ft²·h·°F at 70 F
    status: ground
    source: sm625
    where: Table 3, Thermal Conductivity, row 21 C (70 F)
  - benchmark: thermal_conductivity
    value: 25.2
    unit: W/m°C
    scope: material
    conditions:
      basis: at 982 C (1800 F); material annealed 2100 F for 1 h (footnote c)
    method: Table 3, Thermal Conductivity, metric column, row 982 C (1800 F)
    status: ground
    source: sm625
    where: Table 3, Thermal Conductivity, row 982 C (1800 F)
  - benchmark: electrical_resistivity
    value: 129
    unit: µΩ-cm
    scope: material
    conditions:
      basis: at 21 C (70 F); material annealed 2100 F for 1 h (footnote c)
    method: Table 3, Electrical Resistivity, metric column; the imperial column prints 776 ohm circ mil/ft at 70 F
    status: ground
    source: sm625
    where: Table 3, Electrical Resistivity, row 21 C (70 F)
  - benchmark: cte
    value: 12.8
    unit: ppm/°C
    scope: material
    conditions:
      basis: mean linear expansion from 21 C (70 F) to 93 C (200 F), footnote a
      material: not stated in the datasheet
      unit_in_source: µm/µm·°C
    method: Table 3, Mean Linear Expansion, metric column (µm/µm·°C is the same unit as ppm/°C); the imperial column prints 7.1 x 10^-6 in/in·°F at 200 F
    status: ground
    source: sm625
    where: Table 3, Mean Linear Expansion, row 93 C (200 F)
  - benchmark: cte
    value: 14.8
    unit: ppm/°C
    scope: material
    conditions:
      basis: mean linear expansion from 21 C (70 F) to 649 C (1200 F), footnote a
      material: not stated in the datasheet
      unit_in_source: µm/µm·°C
    method: Table 3, Mean Linear Expansion, metric column, row 649 C; the imperial column prints 8.2 x 10^-6 in/in·°F at 1200 F
    status: ground
    source: sm625
    where: Table 3, Mean Linear Expansion, row 649 C (1200 F)
  - benchmark: elastic_modulus
    value: 207.5
    unit: GPa
    scope: material
    conditions:
      condition: annealed (grade 1)
      temperature: 21 C (70 F)
      basis: tension modulus, measured dynamically on 3/4 in hot-rolled rod (footnote a)
    method: Table 4, Modulus of Elasticity, tension, GPa column; the imperial column prints 30.1 x 10^3 ksi for the same row
    status: ground
    source: sm625
    where: Table 4, Modulus of Elasticity, row 70 F (21 C), Annealed column
  - benchmark: elastic_modulus
    value: 204.8
    unit: GPa
    scope: material
    conditions:
      condition: solution-annealed (grade 2; Special Metals calls it solution-treated)
      temperature: 21 C (70 F)
      basis: tension modulus, measured dynamically on 3/4 in hot-rolled rod (footnote a)
    method: Table 4, Modulus of Elasticity, tension, GPa column; the imperial column prints 29.7 x 10^3 ksi for the same row
    status: ground
    source: sm625
    where: Table 4, Modulus of Elasticity, row 70 F (21 C), Solution-Treated column
  - benchmark: elastic_modulus
    value: 147.5
    unit: GPa
    scope: material
    conditions:
      condition: annealed (grade 1)
      temperature: 871 C (1600 F)
      basis: tension modulus, measured dynamically on 3/4 in hot-rolled rod (footnote a)
    method: Table 4, Modulus of Elasticity, tension, GPa column; the imperial column prints 21.4 x 10^3 ksi for the same row
    status: ground
    source: sm625
    where: Table 4, Modulus of Elasticity, row 1600 F (871 C), Annealed column
  - benchmark: elastic_modulus
    value: 148.2
    unit: GPa
    scope: material
    conditions:
      condition: solution-annealed (grade 2; Special Metals calls it solution-treated)
      temperature: 871 C (1600 F)
      basis: tension modulus, measured dynamically on 3/4 in hot-rolled rod (footnote a)
    method: Table 4, Modulus of Elasticity, tension, GPa column; the imperial column prints 21.5 x 10^3 ksi for the same row
    status: ground
    source: sm625
    where: Table 4, Modulus of Elasticity, row 1600 F (871 C), Solution-Treated column
  - benchmark: poissons_ratio
    value: 0.278
    unit: '-'
    scope: material
    conditions:
      condition: annealed (grade 1)
      temperature: 21 C (70 F)
    method: Table 4, Poisson ratio column, annealed, printed for the 70 F row
    status: ground
    source: sm625
    where: Table 4, Poisson ratio, row 70 F (21 C), Annealed column
  - benchmark: poissons_ratio
    value: 0.312
    unit: '-'
    scope: material
    conditions:
      condition: solution-annealed (grade 2; Special Metals calls it solution-treated)
      temperature: 21 C (70 F)
    method: Table 4, Poisson ratio column, solution-treated, printed for the 70 F row
    status: ground
    source: sm625
    where: Table 4, Poisson ratio, row 70 F (21 C), Solution-Treated column
  - benchmark: ultimate_tensile_strength
    value: 120
    value_high: 150
    bound: range
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: rod, bar and plate, composite for sizes up to 4 in
      temperature: room temperature
    method: Table 5, printed as 120-150 ksi (827-1034 MPa); the table footnote says these are composites and are not for specification
    status: ground
    source: sm625
    where: Table 5, Nominal Room-Temperature Mechanical Properties, ROD BAR PLATE, Annealed row, Tensile Strength
  - benchmark: yield_strength
    value: 60
    value_high: 95
    bound: range
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: rod, bar and plate, composite for sizes up to 4 in
      temperature: room temperature, 0.2 percent offset
    method: Table 5, printed as 60-95 ksi (414-655 MPa); composite values, not for specification
    status: ground
    source: sm625
    where: Table 5, ROD BAR PLATE, Annealed row, Yield Strength (0.2% Offset)
  - benchmark: elongation
    value: 30
    value_high: 60
    bound: range
    unit: '%'
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: rod, bar and plate, composite for sizes up to 4 in
      temperature: room temperature
    method: Table 5 prints 60-30 percent; recorded here low to high
    status: ground
    source: sm625
    where: Table 5, ROD BAR PLATE, Annealed row, Elongation
  - benchmark: ultimate_tensile_strength
    value: 105
    value_high: 130
    bound: range
    unit: ksi
    scope: material
    conditions:
      condition: solution-annealed (grade 2; Special Metals calls it solution-treated)
      product: rod, bar and plate, composite for sizes up to 4 in
      temperature: room temperature
    method: Table 5, printed as 105-130 ksi (724-896 MPa); composite values, not for specification
    status: ground
    source: sm625
    where: Table 5, ROD BAR PLATE, Solution-Treated row, Tensile Strength
  - benchmark: yield_strength
    value: 42
    value_high: 60
    bound: range
    unit: ksi
    scope: material
    conditions:
      condition: solution-annealed (grade 2; Special Metals calls it solution-treated)
      product: rod, bar and plate, composite for sizes up to 4 in
      temperature: room temperature, 0.2 percent offset
    method: Table 5, printed as 42-60 ksi (290-414 MPa); composite values, not for specification
    status: ground
    source: sm625
    where: Table 5, ROD BAR PLATE, Solution-Treated row, Yield Strength (0.2% Offset)
  - benchmark: elongation
    value: 40
    value_high: 65
    bound: range
    unit: '%'
    scope: material
    conditions:
      condition: solution-annealed (grade 2; Special Metals calls it solution-treated)
      product: rod, bar and plate, composite for sizes up to 4 in
      temperature: room temperature
    method: Table 5 prints 65-40 percent; recorded here low to high
    status: ground
    source: sm625
    where: Table 5, ROD BAR PLATE, Solution-Treated row, Elongation
  - benchmark: ultimate_tensile_strength
    value: 120
    value_high: 150
    bound: range
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: sheet and strip, composite for sizes up to 4 in
      temperature: room temperature
    method: Table 5, SHEET and STRIP, Annealed, printed as 120-150 ksi (827-1034 MPa); composite values, not for specification
    status: ground
    source: sm625
    where: Table 5, SHEET and STRIP, Annealed row, Tensile Strength
  - benchmark: yield_strength
    value: 60
    value_high: 90
    bound: range
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: sheet and strip, composite for sizes up to 4 in
      temperature: room temperature, 0.2 percent offset
    method: Table 5, SHEET and STRIP, Annealed, printed as 60-90 ksi (414-621 MPa); composite values, not for specification
    status: ground
    source: sm625
    where: Table 5, SHEET and STRIP, Annealed row, Yield Strength (0.2% Offset)
  - benchmark: ultimate_tensile_strength
    value: 143.5
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1); 1 h anneal at 1800 F (982 C), inside the 1700-1900 F annealing range
      product: hot-rolled rod
      temperature: room temperature
      basis: annealing study, one hour at each temperature
    method: Table 8, Effect of Annealing (1 Hour) on Room-Temperature Properties of Hot-Rolled Rod, 1800 F row
    status: ground
    source: sm625
    where: Table 8, row 1800 F (982 C), Tensile Strength column
  - benchmark: yield_strength
    value: 83.6
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1); 1 h anneal at 1800 F (982 C), inside the 1700-1900 F annealing range
      product: hot-rolled rod
      temperature: room temperature, 0.2 percent offset
      basis: annealing study, one hour at each temperature
    method: Table 8, same row, Yield Strength (0.2% offset) column
    status: ground
    source: sm625
    where: Table 8, row 1800 F (982 C), Yield Strength column
  - benchmark: ultimate_tensile_strength
    value: 116
    unit: ksi
    scope: material
    conditions:
      condition: solution-annealed (grade 2); 1 h anneal at 2100 F (1149 C), inside the 2000-2200 F solution treatment range
      product: hot-rolled rod
      temperature: room temperature
      basis: annealing study, one hour at each temperature
    method: Table 8, row 2100 F (1149 C), Tensile Strength column, printed as 116.0 ksi
    status: ground
    source: sm625
    where: Table 8, row 2100 F (1149 C), Tensile Strength column
  - benchmark: yield_strength
    value: 50
    unit: ksi
    scope: material
    conditions:
      condition: solution-annealed (grade 2); 1 h anneal at 2100 F (1149 C), inside the 2000-2200 F solution treatment range
      product: hot-rolled rod
      temperature: room temperature, 0.2 percent offset
      basis: annealing study, one hour at each temperature
    method: Table 8, row 2100 F (1149 C), Yield Strength (0.2% offset) column, printed as 50.0 ksi
    status: ground
    source: sm625
    where: Table 8, row 2100 F (1149 C), Yield Strength column
  - benchmark: ultimate_tensile_strength
    value: 146.5
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1), hot-rolled annealed bar
      exposure: 2000 hours at 1200 F (649 C) before test
      temperature: 1200 F (649 C), tested at the exposure temperature
    method: Table 6, Effect of Intermediate-Temperature Exposure (2000 hrs), properties at exposure temperature, tensile strength, 1200 F row (1010.1 MPa)
    status: ground
    source: sm625
    where: Table 6, row 1200 (649), Properties at Exposure Temperature, Tensile Strength
  - benchmark: yield_strength
    value: 106.5
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1), hot-rolled annealed bar
      exposure: 2000 hours at 1200 F (649 C) before test
      temperature: 1200 F (649 C), tested at the exposure temperature, 0.2 percent offset
    method: Table 6, same row, Properties at Exposure Temperature, Yield Strength (0.2% offset), printed as 106.5 ksi (734.3 MPa)
    status: ground
    source: sm625
    where: Table 6, row 1200 (649), Properties at Exposure Temperature, Yield Strength
  - benchmark: elongation
    value: 54
    unit: '%'
    scope: material
    conditions:
      condition: annealed (grade 1), hot-rolled annealed bar
      exposure: none (unexposed reference)
      temperature: room temperature
    method: Table 6, No Exposure row, Properties at Room Temperature, Elongation
    status: ground
    source: sm625
    where: Table 6, No Exposure row, Properties at Room Temperature, Elongation
  - benchmark: elongation
    value: 30
    unit: '%'
    scope: material
    conditions:
      condition: annealed (grade 1), hot-rolled annealed bar
      exposure: 2000 hours at 1200 F (649 C) before test
      temperature: room temperature, after exposure
    method: Table 6, row 1200 (649), Properties at Room Temperature, Elongation
    status: ground
    source: sm625
    where: Table 6, row 1200 (649), Properties at Room Temperature, Elongation
  - benchmark: fatigue_strength
    value: 90000
    unit: psi
    scope: material
    conditions:
      condition: annealed, cold-rolled annealed sheet (condition as printed)
      specimen: smooth
      test: endurance limit at 10^8 cycles, completely reversed bending, room temperature
    method: Fatigue Strength section, printed as 90,000 psi for smooth bar; the text names bar for a sheet test, and the value is kept as printed
    status: ground
    source: sm625
    where: Fatigue Strength section, first paragraph
  - benchmark: fatigue_strength
    value: 35000
    unit: psi
    scope: material
    conditions:
      condition: annealed, cold-rolled annealed sheet (condition as printed)
      specimen: notched, Kt+3.3
      test: endurance limit at 10^8 cycles, completely reversed bending, room temperature
    method: Fatigue Strength section, printed as 35,000 psi for the notched specimen (Kt+3.3)
    status: ground
    source: sm625
    where: Fatigue Strength section, first paragraph
  - benchmark: max_service_temp
    value: 982
    unit: °C
    scope: material
    conditions:
      basis: datasheet service range statement; the sentence says service from cryogenic to 1800 F (982 C) and is a range, not a specification limit
    method: Introduction, printed as 1800 F (982 C) and recorded here in C
    status: ground
    source: sm625
    where: Introduction, first paragraph
  - benchmark: ultimate_tensile_strength
    value: 120
    bound: lower
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: plate (ASTM B443, ASME SB-443, AMS 5599)
      basis: minimum as printed on the ATI product page
    method: ATI product page, plate table, printed as 120 min ksi (827 min MPa)
    status: ground
    source: ati-page
    where: ATI product page, Plate table, annealed (Grade 1) condition, Tensile Strength
  - benchmark: yield_strength
    value: 60
    bound: lower
    unit: ksi
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: plate (ASTM B443, ASME SB-443, AMS 5599)
      basis: minimum as printed on the ATI product page
    method: ATI product page, plate table, printed as 60 min ksi (414 min MPa)
    status: ground
    source: ati-page
    where: ATI product page, Plate table, annealed (Grade 1) condition, Yield Strength
  - benchmark: elongation
    value: 30
    bound: lower
    unit: '%'
    scope: material
    conditions:
      condition: annealed (grade 1)
      product: plate (ASTM B443, ASME SB-443, AMS 5599)
      basis: minimum as printed on the ATI product page
    method: ATI product page, plate table, printed as 30% min
    status: ground
    source: ati-page
    where: ATI product page, Plate table, annealed (Grade 1) condition, Elongation
corrosion:
  - environment: 'Mild aqueous media: atmosphere, fresh and sea water, neutral salts and alkaline media'
    headline: Almost no attack in mild environments (Special Metals).
    effect: Special Metals says that in the atmosphere, fresh and sea water, neutral salts and alkaline media there is almost no attack. The statement is qualitative, and no exposure time or corrosion rate is printed.
    rating: low
    conditions:
      basis: qualitative statement, no exposure time or corrosion rate printed
    source: sm625
    where: Corrosion Resistance, Aqueous Corrosion, first paragraph
  - environment: Oxidising and non-oxidising chemicals, including hydrochloric and nitric acid wastes
    headline: Resists oxidising and non-oxidising chemicals, and was recommended for a storage tank for chemical wastes that include hydrochloric and nitric acid.
    effect: Nickel and chromium give resistance to oxidising chemicals, and high nickel and molybdenum give resistance to non-oxidising environments. Special Metals notes that materials resisting one of these acids are normally severely attacked by the other.
    rating: low
    conditions:
      basis: qualitative statements, no concentration, temperature or exposure time printed
    source: sm625
    where: Corrosion Resistance, Aqueous Corrosion, first two paragraphs
  - environment: Chloride pitting and crevice attack
    headline: Very resistant to pitting and crevice corrosion because of its high molybdenum content (Special Metals; ATI).
    effect: Special Metals says the high molybdenum content makes the alloy very resistant to pitting and crevice corrosion, and the ATI sheet says the same. The sources give no critical pitting temperature or ASTM G48 result.
    rating: low
    conditions:
      basis: qualitative statements, no test method printed
    source: sm625
    where: Corrosion Resistance, Aqueous Corrosion, first paragraph
  - environment: Chloride-ion stress-corrosion cracking
    headline: Freedom from chloride-ion stress-corrosion cracking, credited to the high nickel content (Special Metals).
    effect: Special Metals says the high nickel content gives freedom from chloride-ion stress-corrosion cracking. The ATI sheet says the alloy shows good corrosion resistance to chloride ion stress corrosion cracking.
    rating: none
    conditions:
      basis: qualitative statements, no test stress or medium printed
    source: sm625
    where: Corrosion Resistance, Aqueous Corrosion, first paragraph
  - environment: Sour oil and gas service (NACE MR0175)
    headline: Listed in NACE MR-01-75 (Special Metals); no sour-service test result was read.
    effect: Special Metals says the alloy is listed in NACE MR-01-75, and the Wikipedia infobox gives NACE MR0175-3. No sour-service test data were read in this run.
    rating: unknown
    conditions:
      standard: NACE MR-01-75 (listed)
    source: sm625
    where: Available Products and Specifications
  - environment: Welding and heat-affected zones
    headline: Niobium stabilises the alloy against sensitisation, which prevents intergranular cracking after welding (Special Metals).
    effect: Special Metals says niobium acts to stabilise the alloy against sensitisation during welding, which prevents later intergranular cracking. The 625 welding products have a higher alloy content to offset segregation that can cause preferential weld corrosion.
    rating: low
    conditions:
      basis: qualitative statement, no weld test printed
    source: sm625
    where: Corrosion Resistance, Aqueous Corrosion, first paragraph; Welding section
  - environment: Air oxidation and scaling at high temperature
    headline: Excellent oxidation resistance up to 2,000 F (1,093 C) according to ATI; good scaling resistance in the Special Metals cyclic test at 1800 F.
    effect: ATI says the alloy shows excellent oxidation resistance up to 2,000 F (1,093 C). Special Metals says it has good resistance to oxidation and scaling at high temperature. Its cyclic scaling comparison at 1800 F is printed only as a graph, so no mass-loss number was read.
    rating: low
    conditions:
      temperature: up to 2000 F (1093 C), ATI; cyclic test at 1800 F, Special Metals
      test: cyclic weight-loss scaling test, shown as a graph (Figure 15 of the datasheet)
    source: ati-tds
    where: Oxidation Resistance, page 1 of the ATI TDS
  - environment: Long exposure at intermediate temperatures near 1200 F
    headline: Hardens on exposure near 1200 F and loses ductility; no embrittling sigma phase was found after 1000 to 1800 F exposure (Special Metals).
    effect: Annealed rod exposed for 2000 hours at 1200 F gained room-temperature strength and lost ductility (Table 6). Special Metals says the hardening is sluggish precipitation of a niobium-rich gamma prime phase, which transforms to orthorhombic Ni3Nb on long heating. Its stability tests from 1000 to 1800 F showed no embrittling intermetallic phases such as sigma.
    rating: moderate
    conditions:
      temperature: 1200 F (649 C) for 2000 hours; stability tests 1000 to 1800 F
      test: room-temperature tensile tests after exposure
    source: sm625
    where: Mechanical Properties, Table 6; Microstructure section
  - environment: Creep and rupture at high temperature under stress
    headline: The solution-annealed grade is recommended for the best creep and rupture resistance; the creep curves are graphs only.
    effect: Special Metals recommends the solution-treated condition for components that need optimum resistance to creep or rupture, and says annealed material is adequate for many creep uses. The creep and rupture curves (Figures 11 to 14) are graphs and were not read as numbers.
    rating: unknown
    conditions:
      basis: qualitative statement; graphical creep data not read
    source: sm625
    where: Creep and Rupture Strength section; Mechanical Properties section
risks:
  hazards:
    - text: 'PubChem aggregated GHS for nickel metal, from 4778 company reports and 86 ECHA C&L notifications: H317 in 99.9% of the reports that give a code, H351 in 72.9%, H372 in 99.7%, H350 in 22.5%, H360F in 18%, H341 in 13.5%, H334 in 10.3% and H412 in 47.2%. The record is for nickel, which is about 58 percent of this alloy, not for the alloy itself.'
      ghs:
        - H317
        - H351
        - H372
        - H350
        - H360F
        - H341
        - H334
        - H412
      source: pubchem-nickel
      where: Safety and Hazards, GHS Classification (PubChem PUG View JSON, aggregated ECHA C&L notifications)
    - text: 'Renishaw safety data sheet for Inconel 625 metal powder (document H-5800-3483-02-A_EN, SDS date 1/27/2023, version 1.0): classified Skin Sens. 1, Resp. Sens. 1, Carc. 1B, Repr. 1B and STOT RE 1, with signal word Danger. This applies to the powder for additive manufacture, not to solid stock.'
      ghs:
        - H317
        - H334
        - H350
        - H360F
        - H372
      source: renishaw-sds
      where: Sections 1 and 2 (identification, hazard classification and label elements)
    - text: The powder SDS says it may form an explosible dust-air mixture when dispersed, and that dust deposits should not be allowed to accumulate because they may form an explosive mixture.
      ghs: []
      source: renishaw-sds
      where: Section 2 (other hazards); Section 6 (accidental release measures)
  failure_risks:
    - mode: Ageing and loss of ductility near 1200 F
      trigger: Long exposure, tested after 2000 hours at 1200 F
      consequence: Room-temperature tensile strength rises from 140.0 ksi unexposed to 176.0 ksi after exposure, while elongation falls from 54 to 30 percent (Special Metals Table 6).
      severity: moderate
      source: sm625
      where: Mechanical Properties, Table 6
    - mode: Precipitation that weakens creep resistance
      trigger: Exposure in the range 923 to 1148 K; gamma double prime forms at 973 K and delta phase begins to form at 998 K (Wikipedia)
      consequence: Precipitates detrimental to creep properties form in that range. Wikipedia reports that rupture elongation is about half of the solution-treated value when they form, citing Mathew et al.
      severity: moderate
      source: wiki625
      where: Creep and microstructure sections (Wikipedia Inconel 625)
    - mode: Notch sensitivity in fatigue
      trigger: A notched specimen, Kt+3.3, cut from cold-rolled annealed sheet, tested in completely reversed bending at room temperature
      consequence: The endurance limit at 10^8 cycles falls from 90,000 psi for a smooth specimen to 35,000 psi for the notched specimen.
      severity: high
      source: sm625
      where: Fatigue Strength section
    - mode: Duplex grain structure in hot forming
      trigger: Non-uniform reductions during hot forming
      consequence: A duplex grain structure can form. The datasheet asks for uniform reductions and final minimum reductions of 15 to 20 percent for open-die work.
      severity: moderate
      source: sm625
      where: Hot and cold forming section
  side_effects: []
  handling:
    - text: Anneal hot- or cold-formed parts at 1700 to 1900 F for times set by thickness, and solution treat at 2000 to 2200 F (Special Metals). ATI gives 1600 to 1900 F for the anneal (ATI TDS).
      source: sm625
      where: Working Instructions, Heating
    - text: Remove sulphur-bearing lubricants before heat treating and pickling (ATI TDS).
      source: ati-tds
      where: Special Precautions
    - text: Use a fused-salt bath before pickling to remove the oxide that heating forms (Special Metals).
      source: sm625
      where: Pickling
    - text: Hot form in a furnace held at no more than 2150 F, with heavy forging from 2150 to 1850 F and lighter reductions down to 1700 F. Use uniform reductions to guard against duplex grain (Special Metals).
      source: sm625
      where: Hot and cold forming
    - text: Stress-relieve cold-drawn material at 1100 to 1400 F; stress relief is virtually complete at 1600 F (Special Metals).
      source: sm625
      where: Working Instructions, Heating (stress relief); Tables 8 and 9
    - text: For welds, use INCONEL Filler Metal 625 (gas-tungsten-arc) or Welding Electrode 112 (shielded-metal-arc). The datasheet says the weld metal needs no postweld heat treatment to keep its strength and ductility (Special Metals).
      source: sm625
      where: Welding section
  mitigations:
    - text: Above 1200 F, specify the solution-treated (solution-annealed, grade 2) condition where creep or rupture resistance is critical. At 1200 F and below, the datasheet recommends hot-finished, cold-finished or annealed conditions (Special Metals).
      source: sm625
      where: Mechanical Properties, service recommendations
    - text: Heating to 1148 K for 5 hours dissolves the gamma double prime and delta precipitates back into the matrix, which recovers creep properties (Wikipedia).
      source: wiki625
      where: Microstructure section (Wikipedia Inconel 625)
    - text: 'Control powder dust: do not breathe dust (P260), and wear respiratory protection where ventilation is inadequate (P284) (Renishaw SDS, powder).'
      source: renishaw-sds
      where: Section 2, precautionary statements
    - text: Use the matching over-alloyed filler metals for welds. The 625 welding products offset segregation that can cause preferential weld corrosion (Special Metals).
      source: sm625
      where: Welding section; All-Weld-Metal Properties
uses:
  - application: propulsion-and-tanks
    device: Thrust-chamber tubing for rocket engines, fuel and hydraulic line tubing, and engine exhaust systems
    example: Special Metals lists thrust-chamber tubing for rocket engines, fuel and hydraulic line tubing, engine exhaust systems and combustion-system transition liners among its aerospace uses.
    source: sm625
    where: Introduction, aerospace paragraph
  - application: structures
    device: Aircraft ducting systems, resistance-welded honeycomb structures housing engine controls, and turbine shroud rings
    example: Special Metals names these aerospace uses. The ATI TDS says the alloy is widely used in aerospace for airframe and jet engine applications.
    source: sm625
    where: Introduction, aerospace paragraph; ATI TDS, Introduction
  - application: thermal-control
    device: Heat-exchanger tubing in environmental control systems
    example: Special Metals lists heat-exchanger tubing in environmental control systems among its aerospace uses.
    source: sm625
    where: Introduction, aerospace paragraph
supply:
  - subject: Nickel
    abundance: Globally, nickel resources have been estimated to contain more than 350 million tons of nickel (USGS)
    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: In 2025, nickel recovered from scrap accounted for approximately 60% of apparent consumption (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-mcs2026-nickel
    where: World Mine Production and Reserves table, 2025e column, shares calculated by Space Mushroom against the printed world total of 3,900,000 t (not printed as shares); Recycling; Substitutes
  - subject: Chromium
    abundance: World resources are greater than 12 billion tons of shipping-grade chromite (USGS)
    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
    recycling: In 2025, recycled chromium in reported stainless-steel scrap receipts accounted for 21% of apparent consumption (USGS).
    substitutes:
      - Chromium has no substitute in stainless steel, the leading end use, or in superalloys, the major strategic end use (USGS).
    source: usgs-mcs2026-chromium
    where: World Mine Production and Reserves table, 2025e column, shares calculated by Space Mushroom against the printed world total of 51,000 thousand t; Recycling; Substitutes
  - subject: Molybdenum
    abundance: Identified resources in the United States are about 5.4 million tons and, in the rest of the world, about 20 million tons (USGS)
    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; the recycled amount may be as much as 30% of apparent supply (USGS).
    substitutes:
      - There is little substitution for molybdenum in steels and cast irons. Potential substitutes in alloy steels include boron, chromium, niobium and vanadium (USGS).
    source: usgs-mcs2026-molybdenum
    where: World Mine Production and Reserves table, 2025e column, shares calculated by Space Mushroom against the printed world total of 260,000 t; Recycling; Substitutes
  - subject: Niobium
    abundance: World resources of niobium are more than adequate to supply projected needs (USGS)
    producers:
      - country: Brazil
        share_percent: 92.9
        year: 2025
      - country: Canada
        share_percent: 5.4
        year: 2025
    recycling: Niobium scrap recovery was negligible; recycled niobium may have been as much as 20% of apparent consumption (USGS).
    substitutes:
      - Ceramic matrix composites, molybdenum, tantalum and tungsten can replace niobium in high-temperature superalloy applications, with a performance loss or higher cost (USGS).
    source: usgs-mcs2026-niobium
    where: World Mine Production and Reserves table, 2025e column (niobium content), shares calculated by Space Mushroom against the printed world total of 112,000 t; Recycling; Substitutes
media: []
documents:
  - title: Special Metals INCONEL alloy 625 datasheet (2013 Aug 13)
    type: datasheet
    url: https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-625.pdf
    year: 2013
  - title: ATI 625 Alloy Technical Data Sheet, version 1 (3/4/2012), Allvac version
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/nickel-cobalt/nickel-based/ati_625_allvac_version_tds_en_v1.pdf
    year: 2012
  - title: ATI 625 Nickel-Based Alloy product page (plate minimums, Grade 1 and Grade 2 condition statement)
    type: datasheet
    url: https://www.atimaterials.com/Products/ati-625
  - 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: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.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 (PUG View JSON)'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON?heading=GHS+Classification
  - title: Renishaw safety data sheet, Inconel 625 metal powder (document H-5800-3483-02-A_EN, SDS date 1/27/2023)
    type: sds
    url: https://www.renishaw.com/media/pdf/en/ec20c331517e4b0ba85c69455df4e8f3.pdf
    year: 2023
gaps:
  - Grade 2 (solution-annealed) ASTM B 443 and B 446 minimum strengths were not read on a fetched standard or manufacturer page. The solution-annealed values here are Special Metals ranges and the Table 8 anneal results.
  - The ASTM standard texts are paywalled and the ASTM B 443 page did not load, so the designations come from the datasheets and the Wikipedia infobox.
  - The EN steel name NiCr22Mo9Nb is not printed in any source read here, so only W.Nr. 2.4856 and EN 10095 are listed.
  - No numeric minimum service temperature is printed. The datasheet says service from cryogenic temperatures, so min_service_temp is left out.
  - Creep and rupture curves (datasheet Figures 11 to 14), elevated-temperature tensile curves (Figures 3 to 5) and the scaling chart (Figure 15) are graphs and were not read as numbers.
  - 'Charpy impact at -320 F (Table 7) and Brinell hardness (Table 5) are printed but not added: the impact results are triplicate values with no canonical name, and hardness has no canonical name.'
  - The USGS 2026 summaries for nickel, chromium, molybdenum and niobium print no critical-mineral list status (nickel is mentioned only in an executive order), so there are no critical_lists entries.
  - The Renishaw SDS covers the powder form only. No safety data sheet for solid Inconel 625 stock was read, so the hazards for solid alloy rely on the nickel record.
  - No quantitative corrosion test (critical pitting temperature, ASTM G48, corrosion rate or SCC threshold) was read in this run. The corrosion entries are qualitative, from the Special Metals and ATI datasheets.
  - The Special Metals datasheet is dated 2013 and the ATI sheet is dated 2012 (Allvac version). The USGS production figures are 2025 estimates, and the shares are calculated from printed tonnages.
  - Table 5 values are composites for product sizes up to 4 in and are not specification values. No size-specific data were read.
  - ATI notes that lower-carbon versions can be age hardened (aged up to 120 hours at 1050 to 1350 F). No property data for that version were read, so it is not covered.
  - The ATI bar (AMS 5666) minimums are not used because the bar rows do not state the condition.
sources:
  sm625:
    title: INCONEL alloy 625 datasheet, Special Metals Corporation
    id: Special Metals Corporation, copyright 2013 (Aug 13)
    url: https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-625.pdf
    year: 2013
    kind: datasheet
    license: Special Metals terms (cited, not reproduced)
  ati-tds:
    title: ATI 625 Alloy Technical Data Sheet (Allvac version)
    id: ATI Allegheny Technologies, version 1 (3/4/2012)
    url: https://www.atimaterials.com/Products/Documents/datasheets/nickel-cobalt/nickel-based/ati_625_allvac_version_tds_en_v1.pdf
    year: 2012
    kind: datasheet
    license: ATI terms (cited, not reproduced)
  ati-page:
    title: ATI 625 Nickel-Based Alloy product page
    id: ATI product page, read in this run (2026-10-24)
    url: https://www.atimaterials.com/Products/ati-625
    kind: web
    license: ATI terms (cited, not reproduced)
  usgs-mcs2026-nickel:
    title: 'Mineral Commodity Summaries 2026: Nickel'
    id: USGS, Mineral Commodity Summaries 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, Mineral Commodity Summaries 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: US Government work (public domain)
  usgs-mcs2026-molybdenum:
    title: 'Mineral Commodity Summaries 2026: Molybdenum'
    id: USGS, Mineral Commodity Summaries 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
    kind: report
    license: US Government work (public domain)
  usgs-mcs2026-niobium:
    title: 'Mineral Commodity Summaries 2026: Niobium (Columbium)'
    id: USGS, Mineral Commodity Summaries 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/rest/pug_view/data/compound/935/JSON?heading=GHS+Classification
    kind: database
    license: PubChem (NIH, public domain)
  renishaw-sds:
    title: Renishaw safety data sheet, Inconel 625 metal powder
    id: Renishaw plc, document H-5800-3483-02-A_EN, SDS date 1/27/2023, version 1.0
    url: https://www.renishaw.com/media/pdf/en/ec20c331517e4b0ba85c69455df4e8f3.pdf
    year: 2023
    kind: datasheet
    license: Renishaw terms (cited, not reproduced)
  wiki625:
    title: Inconel 625
    id: Wikipedia, English article (read in this run, 2026-10-24)
    url: https://en.wikipedia.org/wiki/Inconel_625
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-24'
review:
  status: draft
  method: assistant
  checked_values: 37
  unreachable: 0
  caveats: 15
  note: Written by an AI assistant on 2026-10-24 from the Special Metals 625 datasheet (2013), the ATI 625 TDS (2012) and product page, the Renishaw powder SDS, the USGS 2026 nickel, chromium, molybdenum and niobium summaries, the PubChem nickel GHS record and Wikipedia (designations, trade names and phase data only). Every number was read from a page fetched in this run; none came from search snippets. The file structure is copied from the Inconel 718 sibling (inconel-718), which the compare paragraph links to.
story:
  recipe:
    line: 'Inconel 625 is a solid-solution nickel-chromium-molybdenum-niobium alloy, made by vacuum induction melting followed by electroslag remelting (ATI TDS). Special Metals gives the limiting composition in weight percent: at least 58 percent nickel, 20 to 23 percent chromium, 8 to 10 percent molybdenum, 3.15 to 4.15 percent niobium plus tantalum, and up to 5 percent iron, with small maximum limits on the other elements.'
    parts:
      - name: Nickel
        symbol: Ni
        share_percent: 58
        share_note: minimum (the matrix)
        role: Matrix of the alloy, a face-centred-cubic solid solution
        source: sm625
        where: Table 1, Limiting Chemical Composition
      - name: Chromium
        symbol: Cr
        share_percent: 20
        share_high: 23
        role: Gives resistance to oxidising chemicals and to oxidation and scaling at high temperature
        source: sm625
        where: Table 1, Limiting Chemical Composition
      - name: Molybdenum
        symbol: Mo
        share_percent: 8
        share_high: 10
        role: Stiffens the matrix and makes the alloy very resistant to pitting and crevice corrosion
        source: sm625
        where: Table 1, Limiting Chemical Composition
      - name: Niobium plus tantalum
        symbol: Nb
        share_percent: 3.15
        share_high: 4.15
        role: Stiffens the matrix, which is the main strengthening effect, and stabilises the alloy against sensitisation during welding
        source: sm625
        where: Table 1, Limiting Chemical Composition
      - name: Iron
        symbol: Fe
        share_note: 5.0 maximum
        role: Residual element, limited to 5.0 percent
        source: sm625
        where: Table 1, Limiting Chemical Composition
      - name: Cobalt
        symbol: Co
        share_note: 1.0 maximum, if determined
        role: Residual element
        source: sm625
        where: Table 1, footnote a
      - name: Minor elements
        share_note: C 0.10, Mn 0.50, Si 0.50, Al 0.40, Ti 0.40, P 0.015 and S 0.015 maximum (wt%)
        role: Residual limits. The datasheet says precipitation-hardening treatments are not required.
        source: sm625
        where: Table 1; Introduction
  risk_groups:
    - title: For people
      level: 2
      verdict: Solid metal flagged by the nickel record; powder is Danger
      lead: No GHS classification was read for the solid alloy. The hazard flags come from the PubChem nickel record (nickel is about 58 percent of this alloy) and from the Renishaw safety data sheet for the metal powder.
      points:
        - label: Solid metal
          line: The PubChem aggregated nickel record lists skin sensitisation (H317, 99.9 percent of reports), suspected cancer (H351, 72.9 percent) and organ damage from prolonged exposure (H372, 99.7 percent).
        - label: Powder and dust
          line: The Renishaw safety data sheet for the metal powder carries the signal word Danger and the codes H317, H334, H350, H360F and H372, and says the powder may form an explosible dust-air mixture.
    - title: If a part is held in the wrong temperature range
      lead: These results come from the datasheets and the Wikipedia summary of phase behaviour, not from field incidents.
      points:
        - label: Long exposure near 1200 F
          line: After 2000 hours at 1200 F, room-temperature tensile strength rises from 140.0 to 176.0 ksi and elongation falls from 54 to 30 percent (Special Metals Table 6).
        - label: Precipitates from 923 to 1148 K
          line: Wikipedia says precipitates form in the range 923 to 1148 K that are detrimental to creep properties, and that delta phase begins to form at 998 K.
    - title: Handling and heat treatment
      points:
        - label: Forming
          line: Hot forming uses a furnace held at no more than 2150 F, with heavy forging from 2150 to 1850 F and lighter reductions down to 1700 F (Special Metals).
        - label: Scale removal
          line: Heating scale is tightly adherent, so a fused-salt bath before pickling is usually recommended (Special Metals).
  why: Inconel 625 was first developed as a steam-line piping material and has since spread to chemical processing, marine and nuclear equipment and aerospace ducting (Wikipedia; ATI). Its strength comes from molybdenum and niobium stiffening the nickel-chromium matrix, so it needs no precipitation-hardening step (Special Metals). That combination gives resistance to a wide range of corrosive media, including chloride stress-corrosion cracking, and good oxidation resistance (Special Metals; ATI).
  uses:
    - where: Rocket engines and fuel lines
      line: Special Metals lists thrust-chamber tubing for rocket engines, fuel and hydraulic line tubing, engine exhaust systems and combustion-system transition liners among its aerospace uses.
    - where: Aircraft structures and ducting
      line: Aircraft ducting systems, resistance-welded honeycomb structures housing engine controls, and turbine shroud rings are named in the datasheet. ATI says the alloy is widely used in aerospace for airframe and jet engine applications.
    - where: Heat exchangers in environmental control systems
      line: Special Metals lists heat-exchanger tubing in environmental control systems among its aerospace uses.
    - where: Chemical plant and marine service
      line: Special Metals names bubble caps, tubing, reaction vessels, distillation columns, heat exchangers and valves for chemical processing, and wire rope for mooring cables, propeller blades and sheathing for undersea cables for marine service.
  can_do:
    - label: Strength in the annealed grade
      line: Annealed (grade 1) rod, bar and plate give 60 to 95 ksi yield and 120 to 150 ksi tensile strength at room temperature (Special Metals Table 5, composite ranges).
    - label: Lower strength in the solution-annealed grade
      line: Solution-annealed (grade 2) rod, bar and plate give 42 to 60 ksi yield and 105 to 130 ksi tensile strength, so the two grades differ in strength (Table 5).
    - label: Stiffness
      line: Young modulus is 207.5 GPa for the annealed grade and 204.8 GPa for the solution-annealed grade at 21 C (Table 4).
    - label: Oxidation at high temperature
      line: The datasheet gives service up to 1800 F (982 C), and ATI rates oxidation resistance as excellent up to 2,000 F (1,093 C).
    - label: Corrosion in mild and severe media
      line: Almost no attack in the atmosphere, fresh and sea water, neutral salts and alkaline media, and freedom from chloride-ion stress-corrosion cracking (Special Metals).
  compare: Compare with [Inconel 718](/profiles/inconel-718/), the age-hardened sibling. Its strength comes from precipitates formed in heat treatment, while Inconel 625 is solid-solution strengthened and the Special Metals datasheet says no precipitation-hardening treatment is required. The 718 profile carries its own precipitation and heat-treatment data.
  compare_rows:
    - label: Density
      benchmark: density
      scope: material
    - label: Stiffness
      benchmark: elastic_modulus
      scope: material
    - label: Melting range
      benchmark: melting_point
      scope: material
  handling:
    - Anneal hot- or cold-formed parts at 1700 to 1900 F for times set by thickness (annealed, grade 1). Solution treat at 2000 to 2200 F where optimum creep-rupture strength is needed (solution-annealed, grade 2) (Special Metals). ATI gives 1600 to 1900 F for the anneal.
    - Remove sulphur-bearing lubricants before heat treating and pickling (ATI).
    - Remove heating scale with a fused-salt bath before pickling (Special Metals).
    - Hot form in a furnace held at no more than 2150 F, with heavy forging from 2150 to 1850 F and lighter reductions to 1700 F. Use uniform reductions to avoid duplex grain (Special Metals).
    - Stress-relieve cold-drawn material at 1100 to 1400 F. Stress relief is virtually complete at 1600 F (Special Metals).
    - For welds, use INCONEL Filler Metal 625 or Welding Electrode 112. The datasheet says the weld metal needs no postweld heat treatment to keep its strength and ductility (Special Metals).
  good_for:
    - Corrosion-resistant parts that must also carry strength, such as chemical plant equipment, marine hardware and sea-water service (Special Metals).
    - Hot ducting and exhaust parts up to 1800 F (982 C) where oxidation resistance matters (Special Metals; ATI).
    - Welded assemblies that need corrosion resistance matched to the base alloy (Special Metals).
  watch_out:
    - Long exposure near 1200 F hardens the annealed alloy and drops room-temperature elongation from 54 to 30 percent after 2000 hours (Special Metals Table 6).
    - The annealed (grade 1) and solution-annealed (grade 2) grades differ in strength, so the grade must be stated on any design basis (Special Metals; ATI).
    - Strength ranges are composites for product sizes up to 4 in and are not specification values (Special Metals).
    - Notched fatigue strength is far below smooth fatigue strength, 35,000 psi against 90,000 psi (Special Metals).
    - The corrosion entries are qualitative. No corrosion rate or critical pitting temperature was read in this run.
  verdict: Inconel 625 is a corrosion-resistant solid-solution alloy for strength up to 1800 F. Its annealed and solution-annealed grades differ in strength, so state the grade for each design, and keep long exposures near 1200 F in mind.