Stainless steel 304 304 (UNS S30400)

spore: profile
id: stainless-steel-304
spore_version: 0.2
family: stainless-austenitic
name: Stainless steel 304
abbreviation: 304 (UNS S30400)
role: structural alloy
category: metals
type: steels-and-stainless
summary: |
  Type 304 is the most common austenitic stainless steel. It is an iron alloy with about 18 percent chromium and 8 to 11 percent nickel, and it resists rust in ordinary air and water. It is used for device housings, fasteners and spacecraft hardware such as propellant tanks. Its tensile strength and yield-type limits are modest next to high-strength steels, but it keeps its toughness at very low temperatures.
best_for: Corrosion-resistant housings, fasteners and tanks where ordinary steel would rust
weakest_at: Chloride pitting in acidic solutions, and low strength compared with precipitation-hardened steels
identity:
  formula: Fe balance, 17.5 to 20 Cr, 8 to 11 Ni, under 0.08 C (wt%)
  source: azom-304
  where: Composition section (AZoM, Stainless Steel Grade 304 page)
  designations:
    - system: UNS
      code: S30400
    - system: EN
      code: '1.4301'
    - system: JIS
      code: SUS 304
    - system: AISI
      code: '304'
    - system: ASTM
      code: A240
    - system: ASTM
      code: A276
    - system: ASTM
      code: A182
    - system: ASTM
      code: A249
    - system: ASTM
      code: A269
    - system: ASTM
      code: A312
    - system: ASTM
      code: A314
    - system: ASTM
      code: A403
    - system: ASTM
      code: A409
    - system: ASTM
      code: A473
    - system: ASTM
      code: A478
    - system: ASTM
      code: A479
    - system: ASTM
      code: A554
    - system: ASME
      code: SA-240
    - system: ASME
      code: SA-182
    - system: ASME
      code: SA-249
    - system: ASME
      code: SA-312
    - system: ASME
      code: SA-403
    - system: ASME
      code: SA-409
    - system: ASME
      code: SA-479
    - system: BS
      code: 304S31
    - system: NF
      code: Z7 CN 18-09
    - system: SS
      code: '2333'
    - system: GB
      code: 0Cr18Ni9
    - system: KS
      code: STS 304
    - system: GOST
      code: 08X18H10
    - system: ISO
      code: 4301-304-00-I
    - system: Common name
      code: 18-8
tags:
  environments: []
  stresses: []
  applications:
    - propulsion-and-tanks
    - mechanisms
    - structures
properties:
  - benchmark: density
    value: 7.85
    value_high: 8.06
    unit: Mg/m3
    scope: material
    conditions:
      basis: no temperature stated in the table
    method: Physical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Physical Properties table (S.I. units as printed)
  - benchmark: density
    value: 7900
    unit: kg/m3
    scope: material
    conditions:
      basis: infobox value, no temperature stated
    method: Infobox value in Wikipedia article, cross-check of the AZoM range
    status: ground
    source: wiki-304
    where: Infobox (density)
  - benchmark: youngs_modulus
    value: 190
    value_high: 203
    unit: GPa
    scope: material
    conditions:
      basis: mechanical properties table, no temperature stated
    method: Mechanical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Mechanical properties table (Young's Modulus row)
  - benchmark: youngs_modulus
    value: 183
    value_high: 200
    unit: GPa
    scope: material
    conditions:
      basis: mechanical properties section, no temperature stated
    method: Mechanical properties section of the Wikipedia article
    status: ground
    source: wiki-304
    where: Mechanical properties section
  - benchmark: tensile_strength
    value: 510
    value_high: 620
    unit: MPa
    scope: material
    conditions:
      basis: mechanical properties table, no heat-treatment condition stated
    method: Mechanical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Mechanical properties table (Tensile Strength row)
  - benchmark: tensile_strength
    value: 210
    value_high: 1050
    unit: MPa
    scope: material
    conditions:
      basis: range across tempers, from weakest annealed to strongest full-hard
    method: Mechanical properties section; the range spans tempers, not one condition
    status: ground
    source: wiki-304
    where: Mechanical properties section (tensile strength 210 to 1,050 MPa)
  - benchmark: elastic_limit
    value: 205
    value_high: 310
    unit: MPa
    scope: material
    conditions:
      basis: AZoM labels this Elastic Limit and does not call it yield strength
    method: Mechanical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Mechanical properties table (Elastic Limit row)
  - benchmark: elongation_at_break
    value: 70
    unit: '%'
    scope: material
    conditions:
      basis: infobox value, condition not stated
    method: Infobox value in Wikipedia article
    status: ground
    source: wiki-304
    where: Infobox (elongation at break)
  - benchmark: poissons_ratio
    value: 0.27
    unit: dimensionless
    scope: material
    conditions:
      basis: infobox value, no temperature stated
    method: Infobox value in Wikipedia article
    status: ground
    source: wiki-304
    where: Infobox (Poisson's ratio)
  - benchmark: melting_point
    value: 1673
    value_high: 1723
    unit: K
    scope: material
    conditions:
      basis: physical properties table, melting range
    method: Physical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Physical Properties table (Melting Point row)
  - benchmark: melting_point
    value: 1400
    value_high: 1450
    unit: °C
    scope: material
    conditions:
      basis: infobox melting temperature range
    method: Infobox value in Wikipedia article
    status: ground
    source: wiki-304
    where: Infobox (melting temperature)
  - benchmark: specific_heat
    value: 490
    value_high: 530
    unit: J/kg.K
    scope: material
    conditions:
      basis: physical properties table, no temperature stated
    method: Physical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Physical Properties table (Specific Heat row)
  - benchmark: thermal_conductivity
    value: 14
    value_high: 17
    unit: W/m.K
    scope: material
    conditions:
      basis: single range given, no temperature stated
    method: Physical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Physical Properties table (Thermal Conductivity row)
  - benchmark: thermal_expansion
    value: 16
    value_high: 18
    unit: 10-6/K
    scope: material
    conditions:
      basis: physical properties table, no temperature range stated
    method: Physical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Physical Properties table (Thermal Expansion row)
  - benchmark: electrical_resistivity
    value: 65
    value_high: 77
    unit: 10-8 ohm.m
    scope: material
    conditions:
      basis: physical properties table, no temperature stated
    method: Physical properties table, minimum and maximum as printed
    status: ground
    source: azom-304
    where: Physical Properties table (Resistivity row)
  - benchmark: yield_strength
    label: Yield strength (0.2% offset), ASTM A240 minimum
    value: 205
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: 304 (UNS S30400)
      temper: annealed (A240 product condition)
      form: plate, sheet and strip (ASTM A240); the table note says mainly hot rolled plate, transverse direction
    method: Minimum as printed in the ASTM min values column of Table 7 (row 4301, S30400)
    status: ground
    source: outokumpu-grades
    where: Table 7, mechanical properties at room temperature, row 4301, ASTM Rp0.2 column
  - benchmark: yield_strength
    label: Yield strength (0.2% offset), EN minimum for 1.4301
    value: 210
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: 304 (EN 1.4301)
      temper: annealed (product standard condition, not restated in the table)
      form: hot rolled plate (product P), transverse direction; cold rolled strip minimums are 10 to 20 MPa higher
    method: Minimum as printed in the EN min values column of Table 7 (row 4301, product P)
    status: ground
    source: outokumpu-grades
    where: Table 7, mechanical properties at room temperature, row 4301, EN Rp0.2 column
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, ASTM A240 minimum
    value: 515
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: 304 (UNS S30400)
      temper: annealed (A240 product condition)
      form: plate, sheet and strip (ASTM A240); the table note says mainly hot rolled plate, transverse direction
    method: Minimum as printed in the ASTM min values column of Table 7 (row 4301, S30400)
    status: ground
    source: outokumpu-grades
    where: Table 7, mechanical properties at room temperature, row 4301, ASTM Rm column
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, EN minimum for 1.4301
    value: 520
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: 304 (EN 1.4301)
      temper: annealed (product standard condition, not restated in the table)
      form: hot rolled plate (product P), transverse direction
    method: Minimum as printed in the EN min values column of Table 7 (row 4301, product P)
    status: ground
    source: outokumpu-grades
    where: Table 7, mechanical properties at room temperature, row 4301, EN Rm column
  - benchmark: elongation
    label: Elongation over 2 in (51 mm), ASTM A240 minimum
    value: 40
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: 304 (UNS S30400)
      temper: annealed (A240 product condition)
      form: plate, sheet and strip (ASTM A240)
      gauge: 2 in (51 mm), A2
    method: Minimum as printed in the ASTM min values column of Table 7 (row 4301, A2 column)
    status: ground
    source: outokumpu-grades
    where: Table 7, mechanical properties at room temperature, row 4301, ASTM A2 column
  - benchmark: elongation
    label: Elongation (A5), EN minimum for 1.4301
    value: 45
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: 304 (EN 1.4301)
      temper: annealed (product standard condition, not restated in the table)
      form: hot rolled plate (product P), transverse direction
      gauge: A5
    method: Minimum as printed in the EN min values column of Table 7 (row 4301, A5 column)
    status: ground
    source: outokumpu-grades
    where: Table 7, mechanical properties at room temperature, row 4301, EN A5 column
  - benchmark: brinell_hardness
    label: Brinell hardness, ASTM A240 maximum
    value: 201
    bound: upper
    unit: HB
    scope: material
    conditions:
      grade: 304 (UNS S30400)
      temper: annealed (A240 product condition)
      form: plate, sheet and strip (ASTM A240)
    method: Maximum as printed in the ASTM A 240 minimum mechanical properties table, 304 column
    status: ground
    source: jacquet-304
    where: Minimum Mechanical Properties Required by ASTM A 240 and ASME SA-240 table, Hardness Max Brinell row, 304 column
  - benchmark: rockwell_b_hardness
    label: Rockwell B hardness, ASTM maximum
    value: 92
    bound: upper
    unit: HRB
    scope: material
    conditions:
      grade: 304 (UNS S30400)
      temper: annealed (A240 product condition)
      form: ASTM product forms (the table gives no form; typical values are for 0.375 inch plate)
    method: Maximum in the ASTM column of Table 1, Mechanical Properties (typical 82 HRB not used)
    status: ground
    source: outokumpu-304-us
    where: Table 1, Mechanical Properties, Hardness Rockwell B row, ASTM 304 column (92 max)
  - benchmark: elastic_modulus
    label: Elastic modulus, room temperature
    value: 200
    unit: GPa
    scope: material
    conditions:
      grade: 304 (EN 1.4301)
      temperature: room temperature (RT)
    method: Value printed in the RT column of Table 13, physical properties (400 C value of 172 GPa not used here)
    status: ground
    source: outokumpu-grades
    where: Table 13, physical properties, row 4301, modulus of elasticity E, RT column
corrosion:
  - environment: Acidic chloride solution (1 M chloride, pH 1.2)
    headline: Local pitting corrosion was studied in acidic chloride solution; the abstract gives no potential values.
    effect: The 2019 study tested pitting of as-received 304 with immersion (ASTM G48) and cyclic potentiodynamic (ASTM G61) methods. Only the test setup and pH were read from the abstract, so no quantified attack is reported here.
    rating: unknown
    conditions:
      solution: 1 M chloride
      pH: 1.2
    source: zatkalikova-2019
    where: Abstract
  - environment: Warm chloride environments
    headline: Pitting and crevice corrosion in warm chloride; pitting resistance is limited to about 400 mg/L chloride at ambient temperature and about 150 mg/L at 60 C.
    effect: Per Wikipedia, 304 is subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion cracking above about 60 C. It is considered resistant to pitting in water with up to about 400 mg/L chlorides at ambient temperatures, reducing to about 150 mg/L at 60 C. 304 and 302 are subject to chloride stress fracture in tropical salt-water conditions such as oil and gas rigs; 316 is the preferred alloy there.
    rating: moderate
    conditions:
      chloride: 400 mg/L at ambient, 150 mg/L at 60 C
      temperature: ambient and 60 C
    source: wiki-304
    where: Corrosion resistance section
  - environment: Heating or welding in the 450 to 900 C range
    headline: 'Sensitization: chromium carbide precipitates at grain boundaries and leaves the boundary open to intergranular attack.'
    effect: Thermal Processing reports that austenitic stainless steels heated in the range 450 to 900 C become sensitized; chromium carbide (Cr23C6) precipitates at grain boundaries, most often in the weld heat-affected zone when the weld cools slowly through that range (weld decay). Deliberate sensitization is often done by holding at 650 C for one to two hours. Testing follows ASTM A262. Wikipedia gives the range as 900 to 1500 F  for the same effect.
    rating: low
    conditions:
      temperature: 450 to 900 C (Thermal Processing); 900 to 1500 F (Wikipedia)
      test: ASTM A262, deliberate hold at 650 C for 1 to 2 h
    source: thermal-processing
    where: Sensitization of Austenitic Stainless Steels; Testing for Sensitization
  - environment: Welded tanks and pipes with corrosive solutions
    headline: 304L (maximum 0.035 percent C) is the welded variant and is preferred over 304 (maximum 0.08 percent C).
    effect: 'Per Wikipedia, 304, 304H and 304L have the same nominal chromium and nickel content and the same corrosion resistance and weldability. The carbon difference prevents sensitization: 304L limits carbon to 0.035 percent to prevent sensitization during welding, while 304 (0.08 percent maximum) is not useful where welding is needed in corrosive service. Titanium, niobium and tantalum are strong carbide formers used to prevent chromium carbide (Thermal Processing).'
    rating: unknown
    conditions:
      carbon: 304 max 0.08 wt%; 304L max 0.035 wt%; 304H 0.04 to 0.10 wt%
    source: wiki-304
    where: Carbon content section
risks:
  hazards:
    - text: 'PubChem aggregated GHS for elemental nickel (Danger): H317 May cause an allergic skin reaction; H351 Suspected of causing cancer; H372 Causes damage to organs through prolonged or repeated exposure. H412 (harmful to aquatic life) appears in some company reports. The data cover the element, not solid 304 alloy.'
      ghs:
        - H317
        - H351
        - H372
        - H412
      source: pubchem-nickel
      where: Safety and Hazards, GHS Classification
    - text: 'PubChem aggregated GHS for elemental chromium (Danger, from notifications): H317 (20.7 percent of reports with codes) May cause an allergic skin reaction; H319 (19.1 percent) Causes serious eye irritation; H334 (20.3 percent) May cause allergy or asthma symptoms if inhaled. About 50 percent of 2,404 reports say it does not meet GHS criteria.'
      ghs:
        - H317
        - H319
        - H334
      source: pubchem-chromium
      where: Safety and Hazards, GHS Classification
  failure_risks:
    - mode: Local (pitting) corrosion in chloride solution
      trigger: Chloride exposure in an acidic solution, the test condition in the source
      consequence: The abstract reports pitting tests but no depth or rate
      source: zatkalikova-2019
      where: Abstract
    - mode: Intergranular corrosion after welding or slow cooling
      trigger: Slow cooling through 450 to 900 C, as in a weld heat-affected zone, or exposure in the 500 to 800 C range in fabrication or service
      consequence: Chromium carbide at grain boundaries lowers local corrosion resistance, so the part corrodes where 304 would normally resist
      severity: high
      source: thermal-processing
      where: Sensitization; weld decay; Fabrication note
    - mode: Chloride stress corrosion cracking
      trigger: Chloride exposure above about 60 C, or tropical salt-water service
      consequence: Stress corrosion cracking and chloride stress fracture; 316 is the usual replacement
      severity: moderate
      source: wiki-304
      where: Corrosion resistance section
  side_effects: []
  handling:
    - text: Cannot be hardened by heat treatment; it is strengthened by cold working and is weakest when annealed.
      source: wiki-304
    - text: Specify 304L (maximum 0.035 percent C) for welded tanks and pipes that carry corrosive solutions. Plain 304 is not useful where welding is needed.
      source: wiki-304
      where: Carbon content section
    - text: Avoid holding or slow-cooling 304 between 500 and 800 C during fabrication or service.
      source: thermal-processing
      where: Sensitization
  mitigations:
    - text: Use a low-carbon grade (304L) or a stabilised grade with titanium, niobium or tantalum to suppress chromium carbide. A solution anneal near 1,050 C dissolves carbides and sigma phase.
      source: thermal-processing
      where: Mill processing; carbide formers
    - text: Replace 304 with 316 where chloride pitting or crevice corrosion is a concern.
      source: wiki-304
      where: Corrosion resistance section
uses:
  - application: propulsion-and-tanks
    device: Spacecraft propellant tank
    example: SAE 304L was adopted for the SN7 test tank and Starship SN8 in 2020.
    source: wiki-304
    where: Applications section (spacecraft)
  - application: mechanisms
    device: Fasteners and screws
    example: A2 is the designation for stainless fasteners outside the US, per ISO 3506.
    source: wiki-304
    where: Introduction and Applications sections
  - application: structures
    device: Architectural cladding
    example: 304 was used to clad the Gateway Arch in St. Louis.
    source: wiki-304
    where: Applications section (architecture)
supply:
  - subject: Nickel
    abundance: About 65% of the nickel consumed in the Western World is used to make austenitic stainless steel (USGS).
    producers: []
    critical_lists: []
    recycling: Not sourced.
    substitutes: []
    source: usgs-nickel
    where: Nickel Insights and Data (introductory text)
  - subject: Nickel production by country
    abundance: World mine production 3.9 million t in 2025 (estimated); world reserves more than 140 million t, of which Indonesia holds 62 million t (USGS 2026).
    producers:
      - country: Indonesia
        share_percent: 66.7
        year: 2025
        basis: 2.6 million t of 3.9 million t mine production (estimated), computed from printed tonnage
      - country: Philippines
        share_percent: 6.9
        year: 2025
        basis: 270,000 t of 3.9 million t, computed
      - country: Russia
        share_percent: 5.1
        year: 2025
        basis: 200,000 t of 3.9 million t, computed
      - country: New Caledonia
        share_percent: 3.6
        year: 2025
        basis: 140,000 t of 3.9 million t, computed
      - country: Canada
        share_percent: 3.6
        year: 2025
        basis: 140,000 t of 3.9 million t, computed
      - country: China
        share_percent: 3.1
        year: 2025
        basis: 120,000 t of 3.9 million t, computed
    critical_lists: []
    recycling: Nickel recovered from scrap accounted for about 60% of US apparent consumption in 2025; most secondary nickel is stainless-steel scrap (USGS 2026).
    substitutes:
      - Low-nickel, duplex or ultrahigh-chromium stainless steels replace austenitic grades in construction
      - Titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments (USGS 2026)
    source: usgs-nickel-2026
    where: Domestic Production and Use; Recycling; World Mine Production and Reserves; Substitutes
  - subject: Nickel use and US import reliance
    abundance: 'US consumption: stainless and alloy steel plus nickel-containing alloys typically above 85% of domestic use (USGS 2026). US net import reliance 41% in 2025 (estimated).'
    producers: []
    critical_lists: []
    recycling: Recycled share 60% of US apparent consumption in 2025.
    substitutes: []
    source: usgs-nickel-2026
    where: Domestic Production and Use; Salient Statistics (net import reliance)
  - subject: Chromium production by country
    abundance: World resources greater than 12 billion t of shipping-grade chromite; 95% of world chromium resources are in Kazakhstan and southern Africa (USGS 2026).
    producers:
      - country: South Africa
        share_percent: 45.1
        year: 2025
        basis: 23 of 51 million t gross weight mine production (estimated), computed from the USGS table in thousand metric tons (23,000 of 51,000)
      - country: Turkey
        share_percent: 17.6
        year: 2025
        basis: 9 of 51 million t, computed from the USGS table in thousand metric tons (9,000 of 51,000)
      - country: Kazakhstan
        share_percent: 13.7
        year: 2025
        basis: 7 of 51 million t, computed from the USGS table in thousand metric tons (7,000 of 51,000)
      - country: India
        share_percent: 5.9
        year: 2025
        basis: 3 of 51 million t, computed from the USGS table in thousand metric tons (3,000 of 51,000)
      - country: Brazil
        share_percent: 3.9
        year: 2025
        basis: 2 of 51 million t, computed from the USGS table in thousand metric tons (2,000 of 51,000)
      - country: Zimbabwe
        share_percent: 3.9
        year: 2025
        basis: 2 of 51 million t, computed from the USGS table in thousand metric tons (2,000 of 51,000)
    critical_lists: []
    recycling: Recycled chromium in stainless-steel scrap receipts was 21% of US apparent consumption in 2025.
    substitutes:
      - No substitute for chromium in stainless steel, the leading end use (USGS 2026)
    source: usgs-chromium-2026
    where: World Mine Production and Reserves; World Resources; Substitutes; Recycling
  - subject: Chromium import reliance
    abundance: 'US net import reliance 79% of apparent consumption in 2025 (estimated). Chromite imports 2021 to 2024: South Africa 96%, Turkey 3% (USGS 2026).'
    producers: []
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-chromium-2026
    where: Salient Statistics; Import Sources (2021-24)
  - subject: Critical-mineral policy
    abundance: USGS 2026 notes Executive Order 14285 (April 2025), which calls for seabed mineral development to help secure supplies of critical minerals such as nickel. The text does not reproduce a critical-minerals list.
    producers: []
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-nickel-2026
    where: Mine projects and seabed text (Executive Order 14285)
media: []
documents:
  - title: 'AZoM: Properties of Stainless Steel Grade 304 (UNS S30400)'
    type: datasheet
    url: https://www.azom.com/properties.aspx?ArticleID=965
    year: 2026
  - title: 'Zatkalikova et al. 2019: Local Corrosion of AISI 304 Stainless Steel in Acidic Chloride Solution'
    type: paper
    url: https://reference-global.com/article/10.2478/cqpi-2019-0036
    year: 2019
  - 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: 'PubChem: Nickel (CID 935) GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    year: 2026
  - title: 'PubChem: Chromium (CID 23976) GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23976
    year: 2026
  - title: 'Outokumpu: Steel Grades, Properties and Global Standards'
    type: datasheet
    url: https://www.outokumpu.com/-/media/from-sharepoint/documents/product/outokumpu-steel-grades-properties-global-standards.pdf
    year: 2026
  - title: 'Outokumpu: Type 304, Type 304L datasheet, North American version'
    type: datasheet
    url: https://docs.kmsheetmetal.com/web/image/734633-bb2a6f42/datasheet-304-304l-hpsa-imperial-outokumpu-en-americas.pdf
    year: 2026
  - title: 'Jacquet: 304/304L Stainless Steel technical sheet'
    type: datasheet
    url: https://usa.myjacquet.com/wp-content/uploads/sites/55/2025/08/Technical_Sheet_304_304L.pdf
    year: 2026
gaps:
  - Composition is taken from the Wikipedia table (ASTM A276 limits), not from ASTM A240 or a mill datasheet. Rolled Alloys, Smith Metal and Outokumpu 304 datasheets are image-only or were not read.
  - Cryogenic 304 tensile values were not read. The MDPI 2023 304L paper is blocked to the fetch tool, and a NASA NTRS search found no 304 report.
  - No 304 safety data sheet was read; the hazards are PubChem element records for nickel and chromium, not the finished alloy.
  - The EU critical raw materials list and the USGS critical minerals list were not read, so critical_lists are empty.
  - Chromium and nickel shares are mine production only; refinery and smelting shares were not read.
  - The full Zatkalikova 2019 paper was not reachable; only the abstract (1 M chloride, pH 1.2) is used, with no pitting potentials.
  - Sensitization sources give 450 to 900 C (Thermal Processing) and 900 to 1500 F (Wikipedia); a 425 to 870 C range was not found.
  - Thermal conductivity and density are given only as ranges without temperature. The room-temperature modulus of 200 GPa is now taken from Outokumpu Table 13.
  - Recycling and substitutes for 304 itself were not sourced beyond the nickel and chromium scrap data.
  - The earlier "about 65 percent of nickel in the Western World" line was not re-checked.
  - Hardness values are ASTM A240 maxima, Brinell 201 HB from the Jacquet sheet and Rockwell B 92 HRB from the Outokumpu North American datasheet. No EN 10088 hardness maximum was read. The names brinell_hardness and rockwell_b_hardness are short names because property-canon.yaml has no hardness entries.
  - Typical values, which are not minimums, were not added. Outokumpu hot rolled plate typical values are 270 MPa yield, 600 MPa tensile and 55 percent A5 elongation. The North American 0.375 inch plate typical values are 42 ksi yield, 87 ksi tensile, 58 percent elongation and 82 HRB.
  - Designations not printed by any source read are DIN X5CrNi18-10 and the grade code F304 for A182. The sources print A182 only for 304 and 304L flanges and fittings. AISI 304 is printed as Type 304 in the Outokumpu North American datasheet. National 304L codes printed in Outokumpu Table 5 (BS 304S11, NF Z3 CN 18-10, SS 2352, GB 00Cr19Ni10, KS STS 304L, GOST 03X18H11, ISO 4307-304-03-I) were not listed.
  - The nickel range in the recipe (8.0 to 11.0, from the Wikipedia ASTM A276 table) differs from 8.0 to 10.5 printed for 304 in the Outokumpu North American datasheet and the Jacquet ASTM A240 table. The existing value is unchanged and needs review.
  - The Outokumpu North American datasheet was read from a third-party copy on docs.kmsheetmetal.com, because the official Outokumpu copy could not be located by search.
  - EN minimum values are the figures printed in Outokumpu Table 7, and EN 10088 itself was not read. The 400 C modulus of 172 GPa in Outokumpu Table 13 was not added.
sources:
  azom-304:
    title: 'AZoM: Properties: Stainless Steel - Grade 304 (UNS S30400)'
    id: ArticleID=965
    url: https://www.azom.com/properties.aspx?ArticleID=965
    kind: web
    license: AZoM terms (cited, not reproduced)
  wiki-304:
    title: 'Wikipedia: SAE 304 stainless steel'
    id: SAE 304 stainless steel
    url: https://en.wikipedia.org/wiki/SAE_304_stainless_steel
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  usgs-nickel:
    title: 'USGS: Nickel statistics and information'
    id: USGS National Minerals Information Center
    url: https://www.usgs.gov/centers/national-minerals-information-center/nickel-statistics-and-information
    kind: web
    license: public domain
  zatkalikova-2019:
    title: Local Corrosion of AISI 304 Stainless Steel in Acidic Chloride Solution
    id: 10.2478/cqpi-2019-0036
    url: https://reference-global.com/article/10.2478/cqpi-2019-0036
    year: 2019
    kind: paper
    license: open access (cited)
  usgs-nickel-2026:
    title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    id: mcs2026-nickel
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    kind: report
    year: 2026
    license: public domain
  usgs-chromium-2026:
    title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    id: mcs2026-chromium
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    kind: report
    year: 2026
    license: public domain
  pubchem-nickel:
    title: 'PubChem: Nickel (CID 935), Safety and Hazards, GHS Classification'
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    kind: database
    license: PubChem terms (public)
  pubchem-chromium:
    title: 'PubChem: Chromium (CID 23976), Safety and Hazards, GHS Classification'
    id: CID 23976
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23976
    kind: database
    license: PubChem terms (public)
  thermal-processing:
    title: 'Thermal Processing: Intergranular Corrosion of Austenitic Stainless Steels'
    id: thermalprocessing.com
    url: https://thermalprocessing.com/intergranular-corrosion-of-austenitic-stainless-steels/
    kind: web
    license: web page (cited, not reproduced)
  outokumpu-grades:
    title: 'Outokumpu: Steel Grades, Properties and Global Standards (Tables 4, 5, 7 and 13)'
    id: outokumpu-steel-grades-properties-global-standards
    url: https://www.outokumpu.com/-/media/from-sharepoint/documents/product/outokumpu-steel-grades-properties-global-standards.pdf
    kind: handbook
    year: 2026
    license: cited, not reproduced
  outokumpu-304-us:
    title: 'Outokumpu: Type 304, Type 304L datasheet, North American version (copy on docs.kmsheetmetal.com)'
    id: Type 304/304L, UNS S30400, UNS S30403
    url: https://docs.kmsheetmetal.com/web/image/734633-bb2a6f42/datasheet-304-304l-hpsa-imperial-outokumpu-en-americas.pdf
    kind: datasheet
    year: 2026
    license: cited, not reproduced
  jacquet-304:
    title: 'Jacquet: 304/304L Stainless Steel technical sheet'
    id: Technical_Sheet_304_304L.pdf
    url: https://usa.myjacquet.com/wp-content/uploads/sites/55/2025/08/Technical_Sheet_304_304L.pdf
    kind: datasheet
    year: 2026
    license: cited, not reproduced
license: CC-BY-4.0
updated: '2026-10-24'
review:
  status: draft
  method: assistant
  checked_values: 29
  unreachable: 3
  caveats: 1
  note: 'Read by an AI assistant on 2026-10-19. Deepen pass: added composition (ASTM A276 table, Wikipedia), USGS 2026 nickel and chromium supply, PubChem GHS for nickel and chromium, sensitization and chloride corrosion (Wikipedia, Thermal Processing), and story sections. Properties unchanged. ASTM A276 limits as printed in the Wikipedia table: C 0.08 max, Si 1.00 max, Mn 2.00 max, P 0.045 max, S 0.030 max, Cr 18.0 to 20.0, Ni 8.0 to 11.0. Mill-form and Starship history per Wikipedia: earlier austenitic grade for the test tanks, then 304L for the SN7 tank. Second pass (2026-10-24): added yield, tensile, elongation, Brinell and Rockwell B limits and room-temperature elastic modulus, with 304L rows, from Outokumpu Tables 4, 5, 7 and 13, an Outokumpu North American datasheet and a Jacquet sheet; added designations from the same sources; corrected the USGS 2026 chromium world total from 51,000 t to 51 million t, since the table is in thousand metric tons (shares unchanged).'
story:
  recipe:
    line: 'Type 304 is an iron-based austenitic stainless steel with a nominal composition set by ASTM A276 (UNS S30400): 18.0 to 20.0 wt% chromium, 8.0 to 11.0 wt% nickel, and carbon, manganese, silicon, phosphorus and sulfur held to maximum limits, with iron as the balance. The alloy is made as solution-annealed sheet or bar, around 1,050 C, which dissolves carbides and any sigma phase (Thermal Processing).'
    parts:
      - name: Iron
        symbol: Fe
        share_note: balance (the rest)
        role: The matrix of the alloy, holding the austenite structure.
      - name: Chromium
        symbol: Cr
        share_percent: 18
        share_high: 20
        role: Forms the passive oxide film that gives the steel its corrosion resistance.
      - name: Nickel
        symbol: Ni
        share_percent: 8
        share_high: 11
        role: Stabilises the austenite structure, which keeps the steel non-magnetic and tough at low temperature.
      - name: Carbon
        symbol: C
        share_percent: 0
        share_high: 0.08
        limit: maximum
        role: Kept low so that chromium carbide does not form at grain boundaries when welded or slowly cooled.
      - name: Manganese
        symbol: Mn
        share_percent: 0
        share_high: 2
        limit: maximum
        role: Deoxidiser and austenite former in the melt.
      - name: Silicon
        symbol: Si
        share_percent: 0
        share_high: 1
        limit: maximum
        role: Deoxidiser in the melt.
      - name: Phosphorus
        symbol: P
        share_percent: 0
        share_high: 0.045
        limit: maximum
        role: Impurity held low.
      - name: Sulfur
        symbol: S
        share_percent: 0
        share_high: 0.03
        limit: maximum
        role: Impurity held low.
  risk_groups:
    - title: For people
      level: 0
      verdict: Alloy not checked against an SDS
      lead: The PubChem records below are for elemental nickel and chromium. No 304 safety data sheet has been checked.
      points:
        - label: Nickel
          line: 'PubChem lists elemental nickel as Danger: H317 (skin sensitiser), H351 (suspected carcinogen) and H372 (organ damage on repeated exposure).'
        - label: Chromium
          line: PubChem lists elemental chromium with H317, H319 and H334 in notifications that carry hazard codes; half of the reports say it does not meet GHS criteria.
        - label: Workshop
          line: Cutting, grinding and welding 304 can release metal fume and dust. Check the supplier safety data sheet before work.
    - title: In the environment
      level: 1
      verdict: Chloride is the watch point
      lead: Pitting and crevice corrosion are the main failure routes in service.
      points:
        - label: Chloride
          line: Pitting resistance is limited to about 400 mg/L chloride at ambient and about 150 mg/L at 60 C (Wikipedia).
        - label: Acidic chloride
          line: A 2019 study tested local pitting of as-received 304 in 1 M chloride at pH 1.2 (abstract only).
    - title: Welding and heat
      level: 1
      verdict: Use 304L for welded corrosive service
      lead: Sensitization is a fabrication risk, not a property of the grade as delivered.
      points:
        - label: Range
          line: Holding or slow cooling between 450 and 900 C precipitates chromium carbide at grain boundaries (Thermal Processing).
        - label: Fix
          line: Use 304L (maximum 0.035 percent C), or a stabilised grade, for welded parts in corrosive service (Wikipedia).
  why: Type 304 is the default austenitic stainless steel. Its 18 to 20 percent chromium forms a passive film, its 8 to 11 percent nickel keeps the structure austenitic, and it resists rust in ordinary air and water. Its weak point is chloride and heat history, which is why the same alloy is sold as a low-carbon 304L for welded parts.
  uses:
    - where: Spacecraft propellant tanks
      line: Early Starship test vehicles used an earlier austenitic grade, then moved to 304L for the SN7 test tank, per Wikipedia. The low-carbon 304L variant is preferred for welded tanks and pipes carrying corrosive solutions.
    - where: Fasteners and screws
      line: Screws are one of the listed household and industrial uses. The A2 designation for stainless fasteners outside the US is per ISO 3506, as cited in the Wikipedia article.
    - where: Architecture
      line: The Gateway Arch in St. Louis was clad in 304 stainless steel, per Wikipedia, and the alloy is used for exterior accents such as water and fire features.
    - where: Machinery and exhaust parts
      line: Food handling and processing equipment, machinery parts, utensils and exhaust manifolds are listed among its household and industrial applications.
  can_do:
    - label: Strength
      benchmark: tensile_strength
      line: Tensile strength runs from 510 to 620 MPa in the AZoM table. Wikipedia gives a wider range of 210 to 1,050 MPa across tempers, from annealed to full-hard.
    - label: Stiffness
      benchmark: youngs_modulus
      line: Young's modulus is 190 to 203 GPa in the AZoM table, and 183 to 200 GPa in Wikipedia.
    - label: Density
      benchmark: density
      line: Density is 7.85 to 8.06 Mg/m3 (AZoM), or 7900 kg/m3 (Wikipedia).
    - label: Work hardening
      line: It cannot be hardened by heat treatment. It is strengthened by cold working, and it is weakest when annealed (Wikipedia).
  compare: Type 304 is a corrosion-resistant austenitic steel with moderate strength and good ease of forming. Ordinary carbon steel rusts where 304 does not, while precipitation-hardened stainless grades give more strength for less forming ease. Its carbon variants (304, 304L, 304H) share the same chromium and nickel and differ mainly in how they behave in welds and at high temperature.
  compare_rows:
    - scope: material
      label: Stiffness
      benchmark: youngs_modulus
    - scope: material
      label: Density
      benchmark: density
    - scope: material
      label: Melting range
      benchmark: melting_point
  handling:
    - Do not expect hardening by heat treatment; strengthen by cold working (Wikipedia).
    - Use 304L for welded parts in corrosive service; plain 304 is not useful where welding is needed (Wikipedia).
    - Avoid holding or slow-cooling 304 between 450 and 900 C during fabrication, and check the safety data sheet before cutting or welding.
  good_for:
    - Corrosion resistance in ordinary air and water, where plain steel would rust.
    - Formed parts, housings, fasteners and tanks in the uses cited above.
  watch_out:
    - 'Warm chloride: pitting above about 400 mg/L at ambient and 150 mg/L at 60 C, and chloride stress cracking above about 60 C.'
    - Welded or slow-cooled parts can sensitize in the 450 to 900 C range, so specify 304L for corrosive welded service.
    - Strength is modest next to precipitation-hardened stainless grades, and it cannot be heat-treated for more.
  verdict: Type 304 is the everyday stainless choice. It trades strength for corrosion resistance and easy forming. Its limits are chloride and welding heat history; for welded corrosive service specify 304L, and for chloride-rich service consider 316.