spore: profile
id: aluminium-2219
spore_version: 0.2
family: aluminium-alloys
name: Aluminium alloy 2219
abbreviation: '2219'
role: launch-vehicle tank and high-temperature structural alloy
category: metals
type: aluminium
summary: |
  2219 is a wrought aluminium-copper alloy (AA 2219, UNS A92219, EN AW-2219) with about 6.3 wt% copper and small additions of manganese, zirconium, vanadium and titanium. The Aubert and Duval datasheet gives solution treatment at 535 °C, water quench and ageing at 165 to 195 °C. Alloys International gives a T87 minimum tensile strength of 62 ksi and minimum yield strength of 50 ksi, published for reference only. A NASA 2021 record found 5-inch 2219-T87 plate with ductility below 1 % in the short-transverse direction at half thickness.
best_for: 'Launch-vehicle and cryogenic tankage where weldability and fracture toughness matter (Smith datasheet: readily weldable, good fracture toughness; Alloys International: launch vehicle and cryogenic tanks)'
weakest_at: Ductility in thick plate, where 5-inch T87 plate showed below 1 % in the short-transverse direction (NASA 2021), and general corrosion resistance, which Wikipedia describes as lower than other aluminium alloys
identity:
  formula: 'Al-Cu-Mn-Zr-V-Ti alloy (AA 2219, UNS A92219, EN AW-2219); composition in wt%: Cu 6.30, Mn 0.30, Zr 0.18, V 0.10, Ti 0.06, Al balance'
  source: aubert-2219
  where: 'Composition list of the Aubert and Duval 2219 datasheet (no unit printed on that list; the Smith datasheet heads its composition table weight %). Heat treatment on the same datasheet: solution treatment 535 °C, water quench, ageing 165 to 195 °C, most common conditions T851, T852 and T854 (NF EN 515).'
  designations:
    - system: UNS
      code: A92219
      source: aubert-2219
      where: Header block, UNS line
    - system: EN name
      code: AW-2219
      source: aubert-2219
      where: 'Specifications box, European Standards line: EN AW-2219 (Al Cu6Mn)'
    - system: EN name
      code: AlCu6Mn
      source: aubert-2219
      where: 'Specifications box, European Standards line: EN AW-2219 (Al Cu6Mn)'
    - system: AFNOR
      code: AU6MT
      source: aubert-2219
      where: Specifications box, previous AFNOR designation
    - system: ASTM
      code: B211
      source: smith-2219
      where: Related Material Specifications box
    - system: ASTM
      code: B221
      source: smith-2219
      where: Related Material Specifications box
    - system: AMS
      code: '4162'
      source: smith-2219
      where: Related Material Specifications box (AMS 4162)
    - system: AMS
      code: '4163'
      source: smith-2219
      where: Related Material Specifications box (AMS 4163)
    - system: AMS
      code: '4094'
      source: alloysintl-2219
      where: Specifications section (AMS 4094)
    - system: ISO
      code: '6361'
      source: wiki-2219
      where: Lead section, standards list (ISO 6361)
tags:
  environments:
    - launch
  stresses: []
  applications:
    - propulsion-and-tanks
    - structures
    - cryogenic-fuel
properties:
  - benchmark: density
    label: Density (infobox value, no temper or test condition on the page)
    value: 2.84
    unit: g/cm3
    scope: material
    conditions:
      basis: infobox value; the page gives no temper or test temperature
    method: Value printed in the infobox of the Wikipedia article
    status: ground
    source: wiki-2219
    where: Infobox, Density (ρ)
  - benchmark: melting_point
    label: Melting temperature (infobox value)
    value: 543
    unit: °C
    scope: material
    conditions:
      basis: infobox value; the page gives no test condition
    method: Value printed in the infobox of the Wikipedia article (the page also gives 1,009 °F)
    status: ground
    source: wiki-2219
    where: Infobox, Melting temperature (Tm)
  - benchmark: elastic_modulus
    label: Modulus of elasticity at 20 °C
    value: 73.8
    unit: x10^3 N/mm2
    scope: material
    conditions:
      temperature: 20 °C
      form: not stated on the datasheet
    method: Typical value on the Aubert and Duval datasheet, which says it gives typical or average values rather than guaranteed minimums
    status: ground
    source: aubert-2219
    where: Physical properties, modulus of elasticity, at 20 °C
  - benchmark: poissons_ratio
    label: Poisson's ratio (infobox value)
    value: 0.33
    unit: '-'
    scope: material
    conditions:
      basis: infobox value; the page gives no test condition
    method: Value printed in the infobox of the Wikipedia article
    status: ground
    source: wiki-2219
    where: Infobox, Poisson's ratio (ν)
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C
    value: 130
    unit: W.m/m2.°C
    scope: material
    conditions:
      temperature: 20 °C
      temper: T62, T81 and T87
    method: Typical value on the Aubert and Duval datasheet, unit as printed
    status: ground
    source: aubert-2219
    where: Physical properties, thermal conductivity, at 20 °C (T62, T81 and T87 conditions)
  - benchmark: cte
    label: Mean coefficient of expansion, 20 to 100 °C
    value: 22.5
    unit: x10^-6 m/m.°C
    scope: material
    conditions:
      interval: 20 to 100 °C
      basis: mean coefficient as printed
    method: Typical value on the Aubert and Duval datasheet
    status: ground
    source: aubert-2219
    where: Physical properties, mean coefficient of expansion, between 20 and 100 °C
  - benchmark: specific_heat
    label: Mean specific heat at 200 °C
    value: 0.86
    unit: J/g.°C
    scope: material
    conditions:
      temperature: 200 °C
      basis: mean specific heat as printed
    method: Typical value on the Aubert and Duval datasheet
    status: ground
    source: aubert-2219
    where: Physical properties, mean specific heat, at 200 °C
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C
    value: 5.7
    unit: μΩ.cm2/cm
    scope: material
    conditions:
      temperature: 20 °C
      temper: T62, T81 and T87
    method: Typical value on the Aubert and Duval datasheet, unit as printed
    status: ground
    source: aubert-2219
    where: Physical properties, electrical resistivity, at 20 °C (T62, T81 and T87 conditions)
  - benchmark: electrical_conductivity
    label: Electrical conductivity at 20 °C
    value: 17.4
    unit: x10^6 S/m
    scope: material
    conditions:
      temperature: 20 °C
      temper: T62, T81 and T87
    method: Typical value on the Aubert and Duval datasheet, unit as printed
    status: ground
    source: aubert-2219
    where: Physical properties, electrical conductivity, at 20 °C (T62, T81 and T87 conditions)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, T87 minimum (typical published value)
    value: 62
    bound: lower
    unit: ksi
    scope: material
    conditions:
      temper: T87
      form: not stated in the table
      basis: minimum, shown as 'typical published values for reference only, not for design'
    method: Typical minimum value printed in the Alloys International table
    status: ground
    source: alloysintl-2219
    where: Typical mechanical properties table, T87 row, tensile strength
  - benchmark: yield_strength
    label: Yield strength, T87 minimum (typical published value)
    value: 50
    bound: lower
    unit: ksi
    scope: material
    conditions:
      temper: T87
      form: not stated in the table
      basis: minimum, shown as 'typical published values for reference only, not for design'
    method: Typical minimum value printed in the Alloys International table
    status: ground
    source: alloysintl-2219
    where: Typical mechanical properties table, T87 row, yield strength
  - benchmark: elongation
    label: Elongation, T87 minimum (typical published value)
    value: 6
    bound: lower
    unit: '%'
    scope: material
    conditions:
      temper: T87
      form: not stated in the table
      basis: minimum
    method: Typical minimum value printed in the Alloys International table
    status: ground
    source: alloysintl-2219
    where: Typical mechanical properties table, T87 row, elongation
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, bar, T8511, longitudinal
    value: 58
    unit: ksi
    scope: material
    conditions:
      form: bar and extrusions
      temper: T8511
      direction: L (longitudinal)
      specification: AMS 4162
    method: Value printed in the bar and extrusions table of the Smith datasheet (approximate testing, per its disclaimer)
    status: ground
    source: smith-2219
    where: Mechanical Properties, Bar and Extrusions table, row 2219 (AMS 4162) T8511 L
  - benchmark: yield_strength
    label: Yield strength, bar, T8511, longitudinal
    value: 42
    unit: ksi
    scope: material
    conditions:
      form: bar and extrusions
      temper: T8511
      direction: L (longitudinal)
      specification: AMS 4162
    method: Value printed in the bar and extrusions table of the Smith datasheet (approximate testing, per its disclaimer)
    status: ground
    source: smith-2219
    where: Mechanical Properties, Bar and Extrusions table, row 2219 (AMS 4162) T8511 L
  - benchmark: elongation
    label: Elongation in 2 in, bar, T8511, longitudinal
    value: 6
    unit: '%'
    scope: material
    conditions:
      form: bar and extrusions
      temper: T8511
      direction: L (longitudinal)
      gauge: 2 in
    method: Value printed in the bar and extrusions table of the Smith datasheet
    status: ground
    source: smith-2219
    where: Mechanical Properties, Bar and Extrusions table, row 2219 (AMS 4162) T8511 L, elongation in 2 in
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, forging, longitudinal, 100 to 200 mm thickness
    value: 395
    bound: lower
    unit: N/mm2
    scope: material
    conditions:
      form: open or closed-die forging
      thickness: 100 to 200 mm
      temper: T851, T852 or T854
      direction: longitudinal
      temperature: ambient
    method: Value printed on the Aubert and Duval datasheet as '>395 N/mm2' for the 100 to 200 mm forging
    status: ground
    source: aubert-2219
    where: Typical mechanical properties, second block (100/200 mm thickness), UTS
  - benchmark: yield_strength
    label: Yield strength (0.2 % offset), forging, longitudinal, 100 to 200 mm thickness
    value: 300
    bound: lower
    unit: N/mm2
    scope: material
    conditions:
      form: open or closed-die forging
      thickness: 100 to 200 mm
      temper: T851, T852 or T854
      direction: longitudinal
      temperature: ambient
    method: Value printed on the Aubert and Duval datasheet as '>300 N/mm2' for the 100 to 200 mm forging
    status: ground
    source: aubert-2219
    where: Typical mechanical properties, second block (100/200 mm thickness), 0.2 % yield strength
  - benchmark: elongation
    label: Elongation (5d), forging, longitudinal, 100 to 200 mm thickness
    value: 6
    bound: lower
    unit: '%'
    scope: material
    conditions:
      form: open or closed-die forging
      thickness: 100 to 200 mm
      temper: T851, T852 or T854
      direction: longitudinal
      gauge: 5d
    method: Value printed on the Aubert and Duval datasheet as '>6 %'
    status: ground
    source: aubert-2219
    where: Typical mechanical properties, second block (100/200 mm thickness), elongation (5d)
  - benchmark: elongation
    label: Elongation, 5-inch T87 plate, short-transverse direction at half thickness
    value: 1
    bound: upper
    unit: '%'
    scope: material
    conditions:
      form: 5-inch thick plate, LOX tank baffle support on Artemis-I
      temper: 2219-T87
      direction: short transverse
      location: half-thickness
    method: Upper bound ('below 1 %') quoted in the abstract of a NASA 2021 investigation of broken tensile samples
    status: ground
    source: nasa-artemis-2021
    where: Abstract, sentence beginning 'Recent material data indicated'
corrosion:
  - environment: Stress corrosion cracking, T8 temper
    headline: In the T8 temper the datasheet rates the alloy's stress-corrosion resistance as excellent.
    effect: The Aubert and Duval datasheet says that in the T8 condition (cold worked and aged) the alloy has excellent stress-corrosion resistance. The Smith datasheet says the T8 temper is resistant to stress corrosion cracking. Neither gives a test condition.
    rating: low
    conditions:
      basis: statements on two datasheets; no test data or exposure time given
      temper: T8 (cold worked and aged)
    source: aubert-2219
    where: 'Characteristics list, bullet on T8 condition (Smith datasheet: Key features and Product Description)'
  - environment: General corrosion of the unclad alloy
    headline: Wikipedia says the alloy is generally less corrosion resistant than other aluminium alloys, and that it can be clad to make up for this.
    effect: The article says that aluminium-copper alloys are generally less corrosion resistant and harder to weld than other aluminium alloys, and that 2219 can be clad to compensate for the lower corrosion resistance.
    rating: moderate
    conditions:
      basis: general statement; no environment or test condition given
    source: wiki-2219
    where: Lead and corrosion sentences of the article
risks:
  hazards:
    - text: A generic aluminium-alloy safety data sheet (supplier 'Aluminum Products', covering alloys with copper up to 6.8 % and beryllium up to 0.07 %) says that fumes from welding can vary in degree and that proper protection should be used when welding. It is a product-family sheet, not a 2219 sheet; the Aubert and Duval composition for 2219 has no beryllium.
      ghs: []
      source: sds-aluminum-products
      where: Hazard summary (first page, referring to Section 8) and Section 8, exposure control; composition table
  failure_risks:
    - mode: Low ductility in thick 2219-T87 plate
      trigger: Short-transverse loading at the half-thickness of a 5-inch plate (the Artemis-I LOX tank baffle support)
      consequence: The 2219-T87 material in the Artemis-I part showed unusually low fracture elongation. Recent data put the ductility of 5-inch T87 plate in the short-transverse direction at half thickness below 1 %.
      severity: high
      source: nasa-artemis-2021
      where: Abstract and title
  side_effects: []
  handling:
    - text: The Smith datasheet calls the alloy readily weldable, machinable and tough, with good fracture toughness.
      source: smith-2219
      where: Key features and Weldability box
    - text: The generic SDS advises ventilation and protection against welding fume and dust.
      source: sds-aluminum-products
      where: Section 8, exposure control
  mitigations:
    - text: Check short-transverse ductility on thick T87 plate before design use, since the NASA 2021 record found it below 1 %.
      source: nasa-artemis-2021
      where: Abstract
uses:
  - application: propulsion-and-tanks
    device: Space Shuttle Standard Weight Tank
    example: Wikipedia says the Space Shuttle Standard Weight Tank was also fabricated from the 2219 alloy.
    source: wiki-2219
    where: Article text, Space Shuttle paragraph
  - application: propulsion-and-tanks
    device: Space boosters and fuel tanks
    example: The Smith datasheet lists space boosters and fuel tanks as applications for 2219, along with high-temperature structural applications in the aerospace sector.
    source: smith-2219
    where: Applications box
  - application: cryogenic-fuel
    device: Launch-vehicle and cryogenic tankage
    example: Alloys International lists launch vehicle and cryogenic tanks, cryogenic pressure vessels and welded pressure vessels among typical applications for 2219.
    source: alloysintl-2219
    where: Typical applications section
  - application: structures
    device: Columbus module and Cupola module of the International Space Station
    example: Wikipedia says the Columbus module on the ISS also used 2219 aluminium alloy, and that the dome and skirt of the Cupola Module also use it.
    source: wiki-2219
    where: Article text, International Space Station paragraph
supply:
  - subject: Aluminium
    producers:
      - country: China
        share_percent: 60.8
        year: 2025
      - country: India
        share_percent: 5.7
        year: 2025
      - country: Russia
        share_percent: 5.3
        year: 2025
      - country: Canada
        share_percent: 4.5
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (lists 'Aluminum, used in almost all sectors of the economy')
        listed: true
    recycling: 'USGS aluminum summary: secondary production from new and old scrap decreased slightly in the US in 2025.'
    substitutes:
      - 'USGS: composites can substitute for aluminum in aircraft fuselages and wings.'
    source: usgs-mcs2026-aluminum
    where: World Smelter Production and Capacity table, 2025e (world total 74,000 thousand t; shares calculated by Space Mushroom from the printed figures); Substitutes; Domestic Production and Use
  - subject: Copper
    producers:
      - country: Chile
        share_percent: 23
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 13.9
        year: 2025
      - country: Peru
        share_percent: 11.7
        year: 2025
      - country: China
        share_percent: 7.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (lists 'Copper, used widely in wiring and cables')
        listed: true
    recycling: 'USGS copper summary: old scrap converted to refined metal, alloys and other forms provided an estimated 160,000 tons of copper in 2025.'
    substitutes:
      - 'USGS: aluminum substitutes for copper in automobile radiators, cooling and refrigeration tube, electrical equipment, and power cable.'
    source: usgs-mcs2026-copper
    where: World Mine and Refinery Production table, mine production 2025e (world total 23,000 thousand t; shares calculated by Space Mushroom from the printed figures); Recycling; Substitutes
documents:
  - title: 'Aubert and Duval datasheet: Aluminium alloy 2219 (Al Cu6Mn)'
    type: datasheet
    url: https://aubertduval.com/wp-content/uploads/2024/12/2219_GB.pdf
    year: 2024
  - title: 'Smiths Metal Centres technical datasheet: 2219 Aluminium'
    type: datasheet
    url: https://www.smithmetal.com/pdf/aluminium/2xxx/2219.pdf
    year: 2023
  - title: 'Alloys International: Aluminum 2219 (typical mechanical properties table)'
    type: datasheet
    url: https://alloysintl.com/inventory/aluminum-alloys/aluminum-2219
    year: 2026
  - title: 'NASA NTRS 20210025431: 5 Inch Thick 2219-T87 Plate Low Ductility Investigation'
    type: report
    url: https://ntrs.nasa.gov/citations/20210025431
    year: 2021
  - title: 'Safety data sheet: Aluminum Products (generic aluminium-alloy product family)'
    type: sds
    url: https://cdn.shopify.com/s/files/1/0036/2243/6937/files/SDSAL.pdf
    year: 2020
  - title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Copper'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
gaps:
  - No space-environment result (vacuum, radiation, thermal cycling or flight) for 2219 was found in a page we could read.
  - The ASM Handbook chapter on 2219 is paywalled, and the NASA weld reports (1972 TM X-64659, 1984 Jemian paper, 1986 VPPA brief) are image-only PDFs. No weld efficiency or weld strength value is included.
  - No T87 datasheet giving product form, thickness and test direction was read. The T87 minimums come from a supplier table marked for reference only, not for design.
  - MakeItFrom (2219-T87 and A92219 pages) and MatMatch returned errors, so their values are not used.
  - The Aubert and Duval density figure has no unit printed on the page, so density is taken from the Wikipedia infobox (2.84 g/cm3, printed unit).
  - No fracture toughness, fatigue, or cryogenic property with a stated temperature was read from a fetched page.
  - No alloy-specific SDS for 2219 was read. Hazard data rest on a generic aluminium-alloy product SDS and on the copper and aluminium entries in the USGS summaries.
  - Crustal abundance of aluminium and copper was not read, and the EU critical raw materials list was not checked in this run.
sources:
  aubert-2219:
    title: 'Aluminium alloy 2219 (Al Cu6Mn): datasheet'
    id: Aubert and Duval, EN AW-2219, UNS A92219
    url: https://aubertduval.com/wp-content/uploads/2024/12/2219_GB.pdf
    year: 2024
    kind: datasheet
    license: supplier datasheet, linked not reproduced
  smith-2219:
    title: '2219 Aluminium: Technical Datasheet (Smiths Metal Centres)'
    id: Smiths Metal Centres, © 2023
    url: https://www.smithmetal.com/pdf/aluminium/2xxx/2219.pdf
    year: 2023
    kind: datasheet
    license: supplier datasheet, linked not reproduced
  wiki-2219:
    title: 2219 aluminium alloy (Wikipedia)
    id: en.wikipedia.org article, accessed 2026-10-26
    url: https://en.wikipedia.org/wiki/2219_aluminium_alloy
    year: 2026
    kind: web
    license: CC BY-SA 4.0
  alloysintl-2219:
    title: 'Aluminum 2219 (Alloys International product page: nominal chemistry, typical mechanical properties, applications)'
    id: alloysintl.com, accessed 2026-10-26
    url: https://alloysintl.com/inventory/aluminum-alloys/aluminum-2219
    year: 2026
    kind: web
    license: supplier page, linked not reproduced
  nasa-artemis-2021:
    title: '5 Inch Thick 2219-T87 Plate Low Ductility Investigation: Material Analysis on Broken 2219 Tensile Samples'
    id: NASA NTRS 20210025431
    url: https://ntrs.nasa.gov/citations/20210025431
    year: 2021
    kind: report
    license: public domain (NASA)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS)
    id: Final 2025 List of Critical Minerals
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  usgs-mcs2026-aluminum:
    title: Mineral Commodity Summaries 2026, Aluminum
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-copper:
    title: Mineral Commodity Summaries 2026, Copper
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  sds-aluminum-products:
    title: 'Safety data sheet: Aluminum Products (generic aluminium-alloy family, not specific to 2219)'
    id: SDSAL, HQA-style composition table; revision date not read
    url: https://cdn.shopify.com/s/files/1/0036/2243/6937/files/SDSAL.pdf
    year: 2020
    kind: datasheet
    license: supplier document, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 19
  unreachable: 1
  caveats: 2
  note: Written by an AI assistant on 2026-10-26 from pages read in this run. The NASA weld reports and the ASM chapter could not be read (image-only or paywalled). The density unit is taken from the Wikipedia infobox because the Aubert and Duval page prints none.
story:
  recipe:
    line: 'AA 2219 is an aluminium alloy with about 6.3 wt% copper, the largest addition, plus small amounts of manganese, zirconium, vanadium and titanium. The Aubert and Duval datasheet gives the composition and the heat treatment: solution treatment at 535 °C, a water quench, then ageing at 165 to 195 °C to reach the required properties.'
    parts:
      - name: Aluminium
        symbol: Al
        share: balance
        role: The matrix of the alloy.
      - name: Copper
        symbol: Cu
        share: '6.30'
        role: The largest addition by weight. The datasheet lists 6.30 against the composition list.
      - name: Manganese
        symbol: Mn
        share: '0.30'
        role: Small addition listed on the datasheet.
      - name: Zirconium
        symbol: Zr
        share: '0.18'
        role: Small addition listed on the datasheet.
      - name: Vanadium
        symbol: V
        share: '0.10'
        role: Small addition listed on the datasheet.
      - name: Titanium
        symbol: Ti
        share: '0.06'
        role: Small addition listed on the datasheet.
  risk_groups:
    - title: For people
      level: 0
      verdict: Not hazardous as a wrought product, but welding fume needs…
      lead: The alloy is supplied as solid metal. The hazard comes from welding, cutting or grinding, which create fume and dust.
      points:
        - label: The metal
          line: The product-family safety data sheet does not give a 2219-specific hazard classification. It advises protection against welding fume and dust.
        - label: Welding
          line: Fume from welding can vary in degree. The safety data sheet advises ventilation and a respirator to limit exposure.
    - title: If a tank or structure fails
      lead: These results come from a ground investigation and from the material's own datasheet, not from a flight failure.
      points:
        - label: Thick plate
          line: NASA's 2021 investigation of 5-inch 2219-T87 plate found very low ductility, below 1 %, in the short-transverse direction at half thickness.
        - label: Corrosion
          line: Wikipedia notes that aluminium-copper alloys are generally less corrosion resistant than other aluminium alloys. Clad sheet is used to make up for this.
    - title: Handling and processing
      points:
        - label: Weldability
          line: The Smith datasheet calls 2219 readily weldable, with good fracture toughness and good machinability.
        - label: Heat treatment
          line: Solution treatment is 535 °C, then a water quench and ageing at 165 to 195 °C. The common conditions are T851, T852 and T854.
  why: 2219 is an aluminium-copper alloy chosen for high-strength structures that must still weld and keep their toughness. The datasheets name space boosters, fuel tanks, launch-vehicle tanks and cryogenic tanks as typical uses. The copper content gives the strength, and the alloy is heat-treated to the temper the job requires.
  uses:
    - where: Launch-vehicle and cryogenic tanks
      line: Alloys International lists launch vehicle and cryogenic tanks, and welded pressure vessels, among its typical applications for 2219. The Smith datasheet lists space boosters and fuel tanks.
    - where: Space Shuttle external tank
      line: Wikipedia says the Space Shuttle Standard Weight Tank was also fabricated from the 2219 alloy.
    - where: International Space Station
      line: Wikipedia says the Columbus module of the International Space Station also used 2219 aluminium alloy, and that the dome and skirt of the Cupola Module also use it.
  can_do:
    - label: Strength in the T87 temper
      benchmark: ultimate_tensile_strength
      value: 62 ksi minimum
      line: The Alloys International table gives a T87 minimum tensile strength of 62 ksi and a minimum yield strength of 50 ksi. The table is marked as typical values for reference only, not for design.
    - label: Stiffness
      benchmark: elastic_modulus
      value: 73.8 x10^3 N/mm2
      line: The modulus of elasticity is 73.8 x 10^3 N/mm2 at 20 °C on the Aubert and Duval datasheet.
    - label: Electrical conductivity
      benchmark: electrical_conductivity
      value: 17.4 x10^6 S/m
      line: Electrical conductivity is 17.4 x 10^6 S/m at 20 °C, in the T62, T81 and T87 conditions.
  compare: 2219 is a copper-bearing aluminium alloy with high strength for an aluminium alloy, and it is used where welding, toughness and cryogenic service matter. Its density of 2.84 g/cm3 is typical of aluminium alloys. The comparison rows show the density, stiffness and tensile strength against the other entries in the collection.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Stiffness
      benchmark: elastic_modulus
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
  handling:
    - Use the supplier's certificate for the product form and temper before design; the T87 minimums here are reference values.
    - Ventilate or use a respirator when welding, cutting or grinding, because the fume can vary in degree.
    - Check ductility in thick plate in the short-transverse direction, since 5-inch T87 plate has shown below 1 %.
  good_for:
    - Launch-vehicle and cryogenic tankage. The Alloys International table lists these applications for 2219.
    - Welded structures. The Smith datasheet calls the alloy readily weldable, with good fracture toughness.
  watch_out:
    - Thick plate. NASA's 2021 record found 5-inch T87 plate with ductility below 1 % in the short-transverse direction.
    - Corrosion resistance. Wikipedia describes the alloy as less corrosion resistant than other aluminium alloys; cladding is used to compensate.
    - Property sources differ by form and temper. Compare only values with the same temper, form and direction.
  verdict: 2219 is the heritage tank alloy of the Shuttle era. It gives high strength and good weldability for launch-vehicle tankage. Its thick-plate ductility needs checking for each product, and its values must come from the form and temper the design uses.