Aluminium alloy 6061 6061

spore: profile
id: aluminium-6061
spore_version: 0.2
family: aluminium-alloys
name: Aluminium alloy 6061
abbreviation: '6061'
role: structural alloy
category: metals
type: aluminium
summary: |
  6061 is a wrought aluminium alloy (one that is rolled, extruded or forged rather than cast) whose main additions are magnesium and silicon. In the T6 temper its typical yield strength is 276 MPa and its density is 2.7 g/cm3. A 1972 NASA handbook says aluminium alloys such as 6061 have been used in launch vehicles and spacecraft with excellent success and are relatively insensitive to the space environment, but that the alloy is attacked by strong alkalis and by hydrochloric and hydrofluoric acids.
best_for: A light, workable structural metal with good corrosion resistance (the NASA handbook ranks 6061 best of the heat-treatable aluminium alloys for corrosion)
weakest_at: Galvanic attack when coupled to more noble metals, especially in sea water (NASA handbook); typical strength values are marked not for design
identity:
  formula: 'Al-Mg-Si alloy; composition limits in wt%: Al 95.8 to 98.6 (remainder), Mg 0.8 to 1.2, Si 0.4 to 0.8, Cu 0.15 to 0.4, Cr 0.04 to 0.35, Fe max 0.7, Zn max 0.25, Mn max 0.15, Ti max 0.15'
  source: asm-6061
  where: Composition table of the ASM Material Data Sheet for 6061-T6 (aluminium content calculated as remainder; composition from the Aluminum Association, marked not for design)
  designations:
    - system: UNS
      code: A96061
      source: asm-6061
      where: Key Words line, UNS A96061
    - system: AA
      code: '6061'
      source: asm-6061
      where: Key Words line, AA6061-T6 (AA number; the temper is not a designation)
    - system: ISO
      code: AlMg1SiCu
      source: asm-6061
      where: Key Words line, ISO AlMg1SiCu
    - system: EN
      code: '3.3211'
      source: alloysintl-6061
      where: Designations and cross reference table, Werkstoff (W.Nr) 3.3211
    - system: EN name
      code: AW-6061
      source: alloysintl-6061
      where: Designations and cross reference table, EN designation EN AW-6061
    - system: AMS
      code: '4021'
      source: alloysintl-6061
      where: Commonly ordered specifications list, AMS 4021
    - system: AMS
      code: '4022'
      source: alloysintl-6061
      where: Commonly ordered specifications list, AMS 4022
    - system: AMS
      code: '4023'
      source: alloysintl-6061
      where: Commonly ordered specifications list, AMS 4023
    - system: AMS
      code: '4026'
      source: alloysintl-6061
      where: Commonly ordered specifications list, AMS 4026
    - system: AMS
      code: '4027'
      note: sheet and plate
      source: sae-ams4027
      where: Title line, AMS4027G (6061; -T6 Sheet, -T651 Plate)
    - system: AMS
      code: '4115'
      source: alloysintl-6061
      where: Commonly ordered specifications list, AMS 4115
    - system: AMS
      code: '4150'
      note: extrusions and rings
      source: sae-ams4150
      where: Title line, AMS4150M (6061-T6), extrusions and rings
tags:
  environments:
    - launch
    - low-earth-orbit
  stresses:
    - micrometeoroids-and-debris
    - galling-and-cold-welding
  applications:
    - structures
    - propulsion-and-tanks
properties:
  - benchmark: yield_strength
    label: Tensile yield strength, typical, T6 and T651
    value: 276
    unit: MPa
    scope: material
    conditions:
      temper: T6 and T651 (datasheet covers both)
      basis: Aluminum Association typical value, marked NOT FOR DESIGN
      temperature: room temperature (not stated)
      product_form: not stated
    method: Typical value listed in a datasheet (ASM Material Data Sheet, Aluminum Association data)
    status: ground
    source: asm-6061
    where: Mechanical Properties table, row Tensile Yield Strength
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, typical, T6 and T651
    value: 310
    unit: MPa
    scope: material
    conditions:
      temper: T6 and T651 (datasheet covers both)
      basis: Aluminum Association typical value, marked NOT FOR DESIGN
      temperature: room temperature (not stated)
      product_form: not stated
    method: Typical value listed in a datasheet (ASM Material Data Sheet, Aluminum Association data)
    status: ground
    source: asm-6061
    where: Mechanical Properties table, row Ultimate Tensile Strength
  - benchmark: elongation
    label: Elongation at break (round bar specimen)
    value: 17
    unit: '%'
    scope: material
    conditions:
      temper: T6 and T651
      specimen: 1/2 in. (12.7 mm) diameter
      basis: Aluminum Association typical value
      note: the same table lists 12 % for a 1/16 in. (1.6 mm) thick specimen, so elongation depends on specimen size
    method: Typical value listed in a datasheet
    status: ground
    source: asm-6061
    where: Mechanical Properties table, row Elongation at Break (second entry)
  - benchmark: elastic_modulus
    label: Modulus of elasticity
    value: 68.9
    unit: GPa
    scope: material
    conditions:
      temper: T6 and T651
      basis: average of tension and compression; compression modulus is about 2 % greater than tensile (datasheet comment)
      type: Aluminum Association typical value
    method: Typical value listed in a datasheet
    status: ground
    source: asm-6061
    where: Mechanical Properties table, row Modulus of Elasticity
  - benchmark: fatigue_strength
    label: Fatigue strength at 500,000,000 cycles
    value: 96.5
    unit: MPa
    scope: material
    conditions:
      temper: T6 and T651
      loading: completely reversed stress
      test: RR Moore machine and specimen
      cycles: 500,000,000
      basis: Aluminum Association typical value
    method: Typical value listed in a datasheet
    status: ground
    source: asm-6061
    where: Mechanical Properties table, row Fatigue Strength
  - benchmark: density
    value: 2.7
    unit: g/cm3
    scope: material
    conditions:
      basis: Aluminum Association typical value
      temper: T6 and T651
      temperature: room temperature (not stated)
    method: Typical value listed in a datasheet
    status: ground
    source: asm-6061
    where: Physical Properties table, row Density
  - benchmark: thermal_conductivity
    label: Thermal conductivity at room temperature
    value: 167
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 77 °F
      temper: T6 and T651
      basis: Aluminum Association typical value
    method: Typical value listed in a datasheet
    status: ground
    source: asm-6061
    where: Thermal Properties table, row Thermal Conductivity
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 77 K (curve-fit value)
    value: 83.5
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 77 K
      temper: T6
      fit_range: data 4 to 300 K, equation 1 to 300 K
      fit_error: 0.5 % relative to the underlying data
    method: Calculated by Space Mushroom by evaluating the NIST log10 polynomial fit (coefficients a to i as printed on the NIST page) at 77 K; the page tabulates no values and gives only the equation
    status: calculated
    note: The same fit gives about 154 W/(m·K) at 293 K, close to the room-temperature datasheet value, which supports the transcription of the coefficients.
    source: nist-6061
    where: Thermal Conductivity coefficient block (a = 0.07918, b = 1.0957, c = -0.07277, d = 0.08084, e = 0.02803, f = -0.09464, g = 0.04179, h = -0.00571, i = 0)
  - benchmark: cte
    label: Mean coefficient of thermal expansion, 68 to 212 °F
    value: 23.6
    unit: ppm/K
    scope: material
    conditions:
      temperature_range: 68 to 212 °F (20 to 100 °C)
      unit_in_source: µm/m-°C, equal to ppm/K
      temper: T6 and T651
      basis: Aluminum Association typical value
      note: an estimated 25.2 µm/m-°C for 20 to 300 °C is also listed
    method: Typical value listed in a datasheet
    status: ground
    source: asm-6061
    where: Thermal Properties table, row CTE, linear 68°F
  - benchmark: melting_range
    label: Melting range (solidus to liquidus)
    value: 582
    value_high: 652
    bound: range
    unit: °C
    scope: material
    conditions:
      basis: typical range for the typical composition of wrought products 1/4 inch thickness or greater
      note: eutectic melting can be eliminated by homogenization (datasheet comment)
    method: Typical range listed in a datasheet (solidus 582 °C, liquidus 652 °C)
    status: ground
    source: asm-6061
    where: Thermal Properties table, rows Melting Point, Solidus and Liquidus
  - benchmark: electrical_resistivity
    label: Electrical resistivity, T6
    value: 4
    unit: µΩ·cm
    scope: material
    conditions:
      temperature: 20 °C
      temper: T6
      unit_in_source: microhm-cm
      other_tempers: 3.7 for O temper and 4.3 for T4 in the same section
    method: Value printed in a NASA materials handbook (cites an earlier reference)
    status: ground
    source: nasa-cr123772
    where: Chapter 9, section 9.31 (p. 75)
  - benchmark: thermal_emittance
    label: Emissivity in air
    value: 0.035
    value_high: 0.07
    bound: range
    unit: dimensionless
    scope: material
    conditions:
      temperature: 77 °F (25 °C)
      atmosphere: in air
      surface_finish: not stated
      alloy_note: listed under physical properties of the 6061 handbook
    method: Range printed in a NASA materials handbook (cites an earlier reference); the surface condition is not stated
    status: ground
    source: nasa-cr123772
    where: Chapter 9, section 9.61 (p. 75)
corrosion:
  - environment: Rural, industrial and marine atmospheres
    headline: NASA ranks 6061 as the best-resisting heat-treatable aluminium alloy in air, whatever the temper.
    effect: The handbook says 6061 has high resistance to rural atmospheres and good resistance to weathering in industrial and marine atmospheres, and that its corrosion resistance is independent of temper. Aluminium resists corrosion because it forms a thin, hard, adherent oxide film (the handbook estimates 20 to 100 x 10^-7 mm thick in air) that protects the metal. The handbook says that under normal conditions in ordinary environments the alloy needs no surface protection.
    rating: low
    conditions:
      basis: general statements in a 1972 NASA handbook that cite earlier sources; no exposure times or corrosion rates given for 6061
      temper: independent of temper according to the handbook
    source: nasa-cr123772
    where: Chapter 10, sections 10.1, 10.3 and 10.41 (p. 80 to 81)
  - environment: Contact with other metals in a conductive liquid (galvanic coupling), especially sea water
    headline: Aluminium is anodic to most common metals, so it corrodes first when the two touch in salty water.
    effect: The handbook says aluminium is strongly anodic to most other common metals (it gives up electrons more readily, so it is the one that corrodes), and that galvanic coupling with them generally produces severe attack on the aluminium, especially in sea water. Table 10.1 lists the electrode potential of 6061-T6 as -0.83 volt against a 0.1 N calomel reference electrode.
    rating: severe
    conditions:
      basis: general statement for aluminium and its alloys; the potential in Table 10.1 was measured in an aqueous solution of 53 g NaCl and 3 g H2O2 per litre at 25 °C
      alloy: 6061-T6 potential -0.83 volt; 6061-T4 -0.80 volt; clad 6061 -0.96 volt
    source: nasa-cr123772
    where: Chapter 10, section 10.1 (p. 80); Table 10.1 (p. 82)
  - environment: Strong alkalis and acids
    headline: Strong alkalis and hydrochloric or hydrofluoric acid attack 6061.
    effect: The handbook lists aqua regia, hydrochloric acid, hydrofluoric acid, lithium hydroxide, perchloric acid, potassium cyanide, potassium and sodium hydroxide and various mercury compounds as severe environments that attack the alloy. Pitting occurs in waters containing chloride or other halogen ions, particularly at crevices or stagnant areas.
    rating: severe
    conditions:
      basis: list of attacking environments in a 1972 NASA handbook; no concentrations, temperatures or rates given
      note: the handbook adds that extensive information on the alloy's resistance to chemicals does not appear to be available
    source: nasa-cr123772
    where: Chapter 10, sections 10.1 and 10.3 (p. 80)
  - environment: Rocket propellants (hydrazine, nitrogen tetroxide, liquid oxygen)
    headline: In sealed storage tests 6061-T6 resisted hydrazine fuels and nitrogen tetroxide very well.
    effect: 6061-T6 stored with hydrazine and a hydrazine-hydrazine nitrate mixture in sealed capsules for 4 years showed excellent resistance to corrosion, and showed excellent resistance and compatibility with nitrogen tetroxide in similar tests. The handbook cautions that surfaces in contact with hydrazine fuels must be free of organic contamination or traces of catalytic metals or ions. In high-velocity impact tests on 6061-T3 tank walls, no interaction occurred with liquid oxygen.
    rating: low
    conditions:
      storage: sealed capsules at 110 °F (44 °C) for 4 years (hydrazine tests)
      temper: 6061-T6 in the storage tests; 6061-T3 sheet in the impact tests
      basis: ground tests summarised in a 1972 handbook
    source: nasa-cr123772
    where: Chapter 10, section 10.32 (p. 81)
risks:
  hazards:
    - text: PubChem's aggregated GHS reports for aluminium metal (4,079 company reports) give H261 in 90.8% of reports (in contact with water releases flammable gas), H228 in 60.6% (flammable solid) and H250 in 34.2% (catches fire spontaneously if exposed to air). 8.3% of reports say it does not meet GHS criteria. PubChem does not state the physical form the reports cover, so these are element-level statements, not a classification of the alloy as supplied.
      ghs:
        - H261
        - H228
        - H250
      source: pubchem-al
      where: Safety and Hazards, GHS Classification (CID 5359268)
    - text: PubChem's aggregated GHS reports for magnesium metal (2,205 company reports) give H228 in 44.9% of reports (flammable solid), H250 in 36.5% (catches fire spontaneously if exposed to air), and H260 in 36.7% (in contact with water releases flammable gases which may ignite spontaneously). 18.4% of reports say it does not meet GHS criteria. As with aluminium, these are element-level statements and do not classify the alloy.
      ghs:
        - H228
        - H250
        - H260
      source: pubchem-mg
      where: Safety and Hazards, GHS Classification (CID 5462224)
  failure_risks:
    - mode: Galvanic corrosion of the aluminium
      trigger: 6061 in electrical contact with a more noble metal while wet, especially with chloride (sea water)
      consequence: The handbook says the coupling generally produces severe attack on the aluminium.
      severity: high
      source: nasa-cr123772
      where: Chapter 10, section 10.1 (p. 80)
    - mode: Faster fatigue crack growth in moist air
      trigger: Cyclic loading of 6061-T6 in a humid atmosphere
      consequence: Water vapour is described as a principal corrosive agent that causes loss of fatigue properties and speeds up crack propagation, especially at low stress intensities. It does not change the crack initiation period; moist-air cycles before initiation did not change total fatigue life.
      severity: moderate
      source: nasa-cr123772
      where: Chapter 10, sections 10.1 and 10.31 and Figure 10.31 (p. 80, 83)
    - mode: Stress-corrosion cracking
      trigger: Sustained surface stress together with a corrosive environment
      consequence: The handbook lists paint topcoats as the most effective protection and says zinc-rich paints are the least effective coating against this cracking; it does not give a susceptibility rating for the alloy.
      severity: moderate
      source: nasa-cr123772
      where: Chapter 11, section 11.81
    - mode: Cold welding of bare surfaces in space
      trigger: Space radiation removing surface films in vacuum
      consequence: The handbook says indigenous space radiation tends to accelerate removal of surface films, which might cause loss of lubricity and an increased propensity to cold weld.
      severity: moderate
      source: nasa-cr123772
      where: Chapter 6, p. 32
  side_effects:
    - text: Surface erosion of aluminium alloys by corpuscular radiation is probably insignificant, of the order of 254 nanometers per year. Sputtering and micrometeoroids can change surface properties by desorption and erosion, which matters if optical properties, lubrication or certain electrical properties are critical.
      affects: Surface finish, optical and lubrication behaviour in space
      source: nasa-cr123772
      where: Chapter 6, section 6.1 (p. 31 to 32)
  handling:
    - text: Keep the alloy away from strong alkalis and from hydrochloric and hydrofluoric acid. In contact with hydrazine fuels, surfaces must be free of organic contamination and catalytic metals.
      source: nasa-cr123772
      where: Chapter 10, sections 10.3 and 10.32 (p. 80 to 81)
  mitigations:
    - text: Under normal conditions the handbook says 6061 needs no surface protection. For more severe environments, use clad material (commonly clad with alloy 7072), or a topcoat of epoxy-polyamide or polyurethane paint against stress-corrosion cracking.
      source: nasa-cr123772
      where: Chapter 10, section 10.41 (p. 81); Chapter 11, section 11.81
uses:
  - application: structures
    device: Launch vehicle and spacecraft structures (aluminium alloys, 6061 named as a structural alloy)
    example: The NASA handbook says aluminium alloys have been used in both structural and nonstructural applications in launch vehicles and spacecraft with excellent success.
    source: nasa-cr123772
    where: Chapter 6, section 6.1 (p. 31)
  - application: propulsion-and-tanks
    device: Simulated propellant tanks of 6061-T3 sheet (ground impact tests, not flown)
    example: High-velocity impact tests on tank walls 0.020 to 0.125 inch thick found no interaction between the 6061-T3 wall and liquid oxygen or hydrazine.
    source: nasa-cr123772
    where: Chapter 10, section 10.32 (p. 81)
  - application: mechanisms
    device: Fittings, couplings, hinge pins, valves and valve parts, and hydraulic and brake pistons
    example: The ASM datasheet lists these among typical applications, with aircraft fittings, camera lens mounts, electrical fittings and connectors, and marine hardware.
    source: asm-6061
    where: Applications paragraph
supply:
  - subject: Aluminium (primary smelter production)
    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
      - country: United Arab Emirates
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (listed as Aluminum)
        listed: true
      - list: EU critical raw materials list of 34 (as shown on the European Commission page, which says aluminium and bauxite have been merged)
        listed: true
    recycling: 'USGS: in 2025 aluminium recovered from purchased scrap in the United States was about 3.6 million tons, of which about 56% came from new scrap and 44% from old scrap; recovery from old scrap equalled about 28% of apparent consumption.'
    substitutes:
      - 'USGS: composites can substitute for aluminium in aircraft fuselages and wings; composites, magnesium, steel and titanium in ground transportation; copper can replace it in electrical and heat-exchange applications.'
    source: usgs-mcs2026-aluminum
    where: 'World Smelter Production table, 2025e (world total 74,000 thousand t; shares calculated by Space Mushroom); Recycling; Substitutes. Lists: USGS and European Commission pages (see sources).'
  - subject: Bauxite (aluminium ore)
    producers:
      - country: Guinea
        share_percent: 34.1
        year: 2025
      - country: Australia
        share_percent: 22
        year: 2025
      - country: China
        share_percent: 19.8
        year: 2025
      - country: Brazil
        share_percent: 7.5
        year: 2025
      - country: India
        share_percent: 5.7
        year: 2025
    critical_lists:
      - list: EU critical raw materials list of 34 (Bauxite listed)
        listed: true
    recycling: 'USGS bauxite and alumina chapter: ''None.'''
    substitutes:
      - 'USGS: bauxite is the only raw material used to produce alumina on a commercial scale in the United States; clay and other materials are technically feasible but not currently economically competitive.'
    source: usgs-mcs2026-bauxite
    where: World Alumina Refinery and Bauxite Mine Production table, bauxite 2025e (world total 440,000 thousand t; shares calculated by Space Mushroom); Recycling; Substitutes
documents:
  - title: 'ASM Material Data Sheet: Aluminum 6061-T6; 6061-T651 (printed copy hosted by Quickparts, May 2023)'
    type: datasheet
    url: https://quickparts.com/wp-content/uploads/2024/05/Aluminum-6061.pdf
    year: 2023
  - title: 'NASA CR-123772: Materials Data Handbook, Aluminum Alloy 6061, 2nd edition (Muraca and Whittick, 1972)'
    type: report
    url: https://ntrs.nasa.gov/citations/19720022808
    year: 1972
  - title: 'NIST Cryogenic Material Properties: 6061-T6 Aluminum (UNS A96061)'
    type: database
    url: https://trc.nist.gov/cryogenics/materials/6061%20Aluminum/6061_T6Aluminum_rev.htm
  - 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: Bauxite and Alumina'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bauxite-alumina.pdf
    year: 2026
  - title: 'Alloys International: 6061 grade page (UNS A96061, W.Nr 3.3211, EN AW-6061 and commonly ordered AMS specifications)'
    type: datasheet
    url: https://alloysintl.com/inventory/aluminum-alloys/aluminum-6061/
  - title: 'SAE AMS4027G: Aluminum Alloy Sheet and Plate, 6061 (-T6 Sheet, -T651 Plate), SAE page'
    type: standard
    url: https://saemobilus.sae.org/content/ams4027g
  - title: 'SAE AMS4150M: Aluminum Alloy, Extrusions and Rings, 6061-T6, SAE page'
    type: standard
    url: https://saemobilus.sae.org/standards/ams4150m-aluminum-alloy-extrusions-rings-10mg-060si-028cu-020cr-6061-t6-solution-precipitation-heat-treated
gaps:
  - No vacuum outgassing (TML and CVCM), atomic-oxygen erosion, thermal-vacuum or flight result for bare 6061-T6 was found in an openly readable source; the NASA outgassing database entry for it was not located.
  - Minimum guaranteed (design allowable) strengths were not found in an open source; the strengths here are Aluminum Association typical values that the datasheet marks NOT FOR DESIGN. MMPDS and MIL-HDBK-5 are not openly available.
  - Cryogenic strength, elongation and fracture toughness at 77 K and 4 K were not found as values (the NASA handbook gives them only as graphs, and a 2023 Springer paper was not readable); only a calculated thermal conductivity at 77 K is given.
  - 'Radiation: the NASA handbook has a table of neutron-irradiation effects on tensile properties, but its text says nuclear data were found only for 6063 while the table is headed 6061, so it was not used.'
  - No safety data sheet for the 6061 alloy was opened. PubChem GHS data for aluminium and magnesium metal is recorded as element-level hazards only; dust and fumes from cutting or welding are not recorded.
  - Stress-corrosion cracking susceptibility rating (NASA MSFC-STD-3029) was not opened; only coating advice from the 1972 handbook is recorded.
  - Galvanic corrosion rates for specific metal pairs were not extracted (NASA TP-2236, a scanned report on 6061-T6 coupled to graphite-epoxy, was found but not read).
  - Crustal abundance and supply of the alloying elements (magnesium, silicon, copper, chromium) were not looked up.
  - The original ASM MatWeb page (asm.matweb.com) could not be reached; the datasheet values come from a printed copy hosted by Quickparts.
  - 'Designations not found in a source read in this run: ASTM B209, B221, B211 and B210 for 6061 (no readable page printed them), DIN AlMg1SiCu, JIS A6061, AFNOR, GB and BS. Not listed as other grades or unconfirmed: AlMgSi1 (Alloys International prints it beside EN AW-6061, but the ASM datasheet gives AlMg1SiCu for this grade and EN 573 was not read) and AD-33 (Russia), a key word on the ASM datasheet that the source does not call the same grade. Not reached: Aluminum Association Teal Sheets, Constellium 6061 page, Aalco 6061 datasheet (404), TW Metals (bot check, 403) and McMaster-Carr (JavaScript only). The Kaiser sheet (Rev. 05/06, Protolabs copy) prints only ''Alloy 6061''. Product form of AMS 4021, 4022, 4023, 4026 and 4115 was not read.'
sources:
  asm-6061:
    title: 'ASM Material Data Sheet: Aluminum 6061-T6; 6061-T651 (printed copy, 12 May 2023)'
    id: ASM/MatWeb bassnum ma6061t6; data from Alcoa, Starmet and the Aluminum Association
    url: https://quickparts.com/wp-content/uploads/2024/05/Aluminum-6061.pdf
    year: 2023
    kind: datasheet
    license: MatWeb terms of use (cited, not reproduced)
  nasa-cr123772:
    title: 'Materials Data Handbook: Aluminum Alloy 6061 (2nd edition), NASA CR-123772, Western Applied Research and Development for NASA Marshall Space Flight Center'
    id: NTRS 19720022808; NAS8-26644; May 1972
    url: https://ntrs.nasa.gov/citations/19720022808
    year: 1972
    kind: report
    license: public domain (NASA)
  nist-6061:
    title: 'Material Properties: 6061-T6 Aluminum (UNS A96061), NIST Cryogenic Material Properties'
    id: NIST Cryogenics Technologies Group, curve fits for 4 to 300 K
    url: https://trc.nist.gov/cryogenics/materials/6061%20Aluminum/6061_T6Aluminum_rev.htm
    kind: database
    license: NIST public web page
  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-bauxite:
    title: Mineral Commodity Summaries 2026, Bauxite and Alumina
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bauxite-alumina.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  ec-crm:
    title: Critical raw materials (European Commission, list of 34 critical raw materials)
    id: European Commission critical raw materials page
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: European Commission web page
  pubchem-al:
    title: 'Aluminum, PubChem compound CID 5359268: Safety and Hazards, GHS Classification'
    id: PubChem CID 5359268 (PUG View JSON, read 2026-10-19); aggregated from ECHA C&L notifications
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5359268
    kind: database
    license: PubChem (NCBI) public data
  pubchem-mg:
    title: 'Magnesium, PubChem compound CID 5462224: Safety and Hazards, GHS Classification'
    id: PubChem CID 5462224 (PUG View JSON, read 2026-10-19); aggregated from ECHA C&L notifications
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5462224
    kind: database
    license: PubChem (NCBI) public data
  alloysintl-6061:
    title: 'Alloys International: 6061 grade page, with UNS, W.Nr and EN designations and a list of commonly ordered specifications'
    id: Alloys International (stockist), Ronkonkoma, NY; grade page for 6061 (UNS A96061)
    url: https://alloysintl.com/inventory/aluminum-alloys/aluminum-6061/
    kind: datasheet
    license: supplier web page (cited, not reproduced)
  sae-ams4027:
    title: 'SAE AMS4027G: Aluminum Alloy Sheet and Plate 1.0Mg - 0.60Si - 0.30Cu - 0.25Cr (6061; -T6 Sheet, -T651 Plate), SAE page'
    id: SAE International material specification; the page shows AMS4027G and lists the current revision AMS4027P (2022-04-29)
    url: https://saemobilus.sae.org/content/ams4027g
    kind: standard
    license: SAE International web page (cited, not reproduced)
  sae-ams4150:
    title: 'SAE AMS4150M: Aluminum Alloy, Extrusions and Rings 1.0Mg - 0.60Si - 0.28Cu - 0.20Cr - (6061-T6) Solution and Precipitation Heat Treated, SAE page'
    id: SAE International material specification; the page shows AMS4150M and lists the current revision AMS4150P (2024-03-27)
    url: https://saemobilus.sae.org/standards/ams4150m-aluminum-alloy-extrusions-rings-10mg-060si-028cu-020cr-6061-t6-solution-precipitation-heat-treated
    kind: standard
    license: SAE International web page (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-19'
review:
  status: draft
  method: assistant
  checked_values: 12
  unreachable: 1
  caveats: 3
  note: 'Deepen pass on 2026-10-19 (no property changed): added story recipe from the ASM composition table, hazards from PubChem GHS for aluminium and magnesium, and two PubChem sources. Re-read by an AI assistant on 2026-10-17: 12 of 12 property values match their cited source (datasheet values re-read from the printed copy''s extracted text; NASA values re-read from page images of the scanned handbook; the NIST value recomputed from the coefficients, which were fetched twice). 1 source page (asm.matweb.com) could not be reached. Caveats: strengths are typical values marked not for design; the 1972 handbook is old and its page text is scanned; the 77 K conductivity is a curve-fit value with a 0.5% stated fit error.'
story:
  recipe:
    line: 'Wrought Al-Mg-Si alloy. Composition limits from the Aluminum Association data sheet: magnesium 0.8 to 1.2 wt%, silicon 0.4 to 0.8 wt%, copper 0.15 to 0.4 wt% and chromium 0.04 to 0.35 wt%, with aluminium as the balance. Magnesium and silicon form Mg2Si, which the NASA handbook names as the main precipitation-hardening agent (heat treatment to T6 or T651).'
    parts:
      - name: Aluminium
        symbol: Al
        share_note: balance (the rest)
        role: The matrix of the alloy; its thin oxide film gives the corrosion resistance.
      - name: Magnesium
        symbol: Mg
        share_percent: 0.8
        share_high: 1.2
        role: With silicon forms Mg2Si, the main precipitation-hardening compound.
      - name: Silicon
        symbol: Si
        share_percent: 0.4
        share_high: 0.8
        role: With magnesium forms Mg2Si, the hardening compound.
      - name: Copper
        symbol: Cu
        share_percent: 0.15
        share_high: 0.4
        role: Minor addition inside the composition limits printed on the data sheet.
      - name: Chromium
        symbol: Cr
        share_percent: 0.04
        share_high: 0.35
        role: Minor addition inside the composition limits printed on the data sheet.
  risk_groups:
    - title: For people
      lead: No safety data sheet for the alloy was opened. Element-level GHS data for aluminium and magnesium from PubChem is in the hazards list, but the profile records no toxicity or dust data for the alloy.
      gap: Hazard classification for 6061 as supplied, and for dust or fumes from machining or welding, was not found in a source we could open.
      points:
        - label: What the sources cover
          line: The sources opened describe the metal's corrosion, fatigue and space-environment behaviour, not its effects on health. Before cutting, grinding or welding it, read the supplier's safety data sheet for the exact product.
    - title: If it fails
      lead: These are failure routes named in a 1972 NASA handbook. They are statements and test summaries, not field incident data.
      points:
        - label: Galvanic attack
          line: Aluminium is strongly anodic to most other common metals, so when it touches them in a conductive liquid it is the part that corrodes. The handbook says this generally produces severe attack on the aluminium, especially in sea water.
        - label: Fatigue in moist air
          line: Water vapour speeds up the growth of fatigue cracks, especially at low stress intensities, but does not change how long a crack takes to start.
        - label: Stress-corrosion cracking
          line: Cracking can occur when a sustained surface stress and a corrosive environment act together. The handbook names epoxy-polyamide or polyurethane paint topcoats as the most effective protection and zinc-rich paints as the least effective.
        - label: Cold welding in space
          line: Space radiation tends to strip away surface films, which might cause loss of lubricity and an increased tendency of bare surfaces to cold weld, that is, to fuse when pressed together.
    - title: Handling and storage
      points:
        - label: Chemicals to avoid
          line: Strong alkalis such as sodium and potassium hydroxide, and hydrochloric and hydrofluoric acid, attack the alloy. The handbook lists several other severe environments, including aqua regia and various mercury compounds.
        - label: Hydrazine fuels
          line: 6061-T6 resisted hydrazine fuels in 4 years of sealed storage at 110 °F (44 °C), but surfaces must be free of organic contamination or traces of catalytic metals or ions.
        - label: Protection
          line: Under normal conditions the alloy needs no surface protection. For severe environments, clad material (commonly clad with alloy 7072) or a paint topcoat can be used.
  why: 'Aluminium alloy 6061 is a wrought, heat-treatable aluminium alloy. Wrought means it is worked into plate, bar, tube or shapes by rolling, extruding or forging rather than cast to shape. Its main additions are magnesium (0.8 to 1.2 wt%) and silicon (0.4 to 0.8 wt%), with smaller amounts of copper and chromium. These form a magnesium silicide compound, Mg2Si, which the NASA handbook identifies as the primary precipitation-hardening agent: tiny particles precipitate inside the metal on heat treatment and make it harder for atomic planes to slip, which raises strength. A temper is a code for the heat treatment and working given to the metal, and this profile concerns the T6 and T651 tempers, which the datasheet lists together. Because the alloying content is low, the alloy keeps many properties of pure aluminium, including a protective oxide film and good corrosion resistance. That combination of moderate strength, low density and ready fabrication explains why it is a common structural alloy.'
  uses:
    - where: Launch vehicle and spacecraft structures
      line: The 1972 NASA handbook states that aluminium alloys have been used in both structural and nonstructural applications in launch vehicles and spacecraft with excellent success, because they are relatively insensitive to degradation in typical space environment conditions.
    - where: Tested on the ground as propellant tank walls
      line: NASA tested simulated propellant tanks made of 6061-T3 sheet, with walls 0.020 to 0.125 inch thick, by firing projectiles through them. No interaction occurred between the tank wall and liquid oxygen or hydrazine. This was a ground test, not a flight.
    - where: Fittings and mechanical parts
      line: The ASM datasheet lists aircraft fittings, couplings, hinge pins, valves, hydraulic and brake pistons, electrical fittings and marine hardware among typical applications.
  can_do:
    - label: Strength
      value: 276 MPa yield
      line: In the T6 and T651 tempers the typical tensile yield strength (the stress at which permanent deformation begins) is 276 MPa and the typical ultimate tensile strength (the highest stress before fracture) is 310 MPa. These are Aluminum Association typical values, which the datasheet marks not for design. Elongation at break is 17% for a 1/2 inch (12.7 mm) diameter specimen.
    - label: Weight and stiffness
      value: 2.7 g/cm3
      line: Density is 2.7 g/cm3 and the modulus of elasticity, a measure of stiffness, is 68.9 GPa (average of tension and compression). The fatigue strength is 96.5 MPa after 500,000,000 cycles of completely reversed stress in an RR Moore rotating-beam test.
    - label: Heat conduction
      value: 167 W/(m·K)
      line: Thermal conductivity at 77 °F is 167 W/(m·K), the rate at which heat flows through the metal per metre of thickness and per kelvin of temperature difference. Evaluating the NIST curve fit at 77 K gives 83.5 W/(m·K), so conduction is lower at very low temperature.
    - label: Thermal expansion
      value: 23.6 ppm/K
      line: Between 68 and 212 °F the mean coefficient of thermal expansion is 23.6 ppm/K, meaning a length changes by 23.6 millionths for each kelvin of temperature change. A part bolted to a material that expands less will be stressed when the temperature changes.
    - label: Heat radiation from the surface
      value: 0.035 to 0.07
      line: The NASA handbook gives an emissivity (the fraction of ideal black-body radiation a surface emits) of 0.035 to 0.07 in air at 77 °F. The surface condition is not stated, and coatings or oxide growth would change it.
  compare: The record supports only a limited comparison. The USGS lists composites as substitutes for aluminium in aircraft fuselages and wings, and composites, magnesium, steel and titanium in ground transportation. It says copper can replace aluminium in electrical and heat-exchange uses. This profile holds no strength-per-mass numbers for those alternatives, so it does not rank them.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - Keep it away from strong alkalis and from hydrochloric and hydrofluoric acid.
    - Avoid contact with more noble metals in wet or salty conditions, or isolate them from the aluminium.
    - Paint topcoats are the most effective protection against stress-corrosion cracking, according to the handbook.
    - Read the supplier's safety data sheet before cutting, grinding or welding.
  good_for:
    - Light structures that need moderate strength. Typical yield strength is 276 MPa at a density of 2.7 g/cm3.
    - Corrosion resistance in air. The NASA handbook calls 6061 the best of the heat-treatable aluminium alloys, and says its resistance does not depend on temper.
    - Heat spreading. Thermal conductivity is 167 W/(m·K) at 77 °F.
  watch_out:
    - Contact with more noble metals in wet or salty conditions. Galvanic coupling generally produces severe attack on the aluminium.
    - Strong alkalis and hydrochloric or hydrofluoric acid attack the alloy.
    - The strength values here are typical, not design allowables, and the datasheet marks them not for design.
    - The melting range is 582 to 652 °C, and no vacuum outgassing, atomic-oxygen, flight or cryogenic strength values were found for this profile.
  verdict: 6061-T6 is a light, workable structural alloy with a long record in launch vehicles and spacecraft and good corrosion resistance in air. Its weak points in the record are galvanic coupling, strong alkalis and acids, and the lack of design-grade or space-environment numbers here.