spore: profile
id: stainless-309
spore_version: 0.2
family: stainless-austenitic
name: AISI 309 stainless steel
abbreviation: '309'
role: Chromium-nickel austenitic stainless steel for hot oxidising and sulphur-bearing furnace service
category: metals
type: steels-and-stainless
summary: |
  AISI 309 (UNS S30900) is an austenitic stainless steel with 22.00 to 24.00 % chromium and 12.00 to 15.00 % nickel, built for heat. Its carbon limit is 0.20 % maximum, which is higher than the low-carbon 309S variant (0.08 % maximum). The Jacquet technical sheet prints a density of 8.03 g/cm3 and a modulus of 200 GPa, and a typical tensile strength of 621 MPa at room temperature that falls to 379 MPa at 1200 °F. The Rolled Alloys and NKS sheets print oxidation resistance to 1900 to 2000 °F. No space-environment data were found for this grade.
best_for: Hot furnace and heat-treatment parts that must resist oxidation to about 1900 to 2000 °F and keep a useful share of their room-temperature strength (Rolled Alloys, NKS, Jacquet)
weakest_at: 'Carburising atmospheres and hot strength: moderate resistance to carbon absorption (Rolled Alloys), and typical tensile strength falls from 90.0 ksi at 77 °F to 55.0 ksi at 1200 °F (Jacquet)'
identity:
  formula: 'Fe-based austenitic alloy: Fe balance, Cr 22.00 to 24.00 %, Ni 12.00 to 15.00 %, C 0.20 % maximum, Mn 2.00 % maximum, Si 0.75 % maximum, P 0.045 % maximum, S 0.030 % maximum (ASTM A167 and A240 limits)'
  source: jacquet309
  where: Chemical Composition table, column 309 (UNS S30900); the sheet states that its limits are from ASTM A167 and A240. The same limits are printed in the NKS datasheet, Chemical Composition table, Type 309 column.
  designations:
    - system: UNS
      code: S30900
      source: jacquet309
      where: Chemical Composition table, column 309 (UNS S30900); Relevant Standards table, row 309
    - system: AISI
      code: '309'
      source: jacquet309
      where: Relevant Standards table, row 309, AISI 309
    - system: SAE
      code: '30309'
      source: jacquet309
      where: Relevant Standards table, row 309, SAE 30309
    - system: ASTM
      code: A167
      note: sheet and strip, Type 309
      source: nks309
      where: Specifications line, ASTM A167 (309)
    - system: Trade name
      code: Type 309
      source: nks309
      where: Title line and description paragraph, Types 309 Stainless Steel
tags:
  environments: []
  stresses: []
  applications:
    - thermal-control
    - structures
properties:
  - benchmark: density
    label: Density, 309
    value: 8.03
    unit: g/cm3
    scope: material
    conditions:
      temperature: 68 °F (20 °C)
      unit_in_source: 0.29 lbm/in3
      basis: representative for average composition in the annealed condition
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, row Density, column 309
  - benchmark: melting_point
    label: Melting range, NKS datasheet
    value: 2550
    value_high: 2650
    bound: range
    unit: °F
    scope: material
    conditions:
      grade: 309 and 309S (one range printed for both)
      unit_in_source: 2550 - 2650 °F
    method: Melting range printed in a manufacturer datasheet
    status: ground
    note: The Rolled Alloys sheet prints a different range (2500 to 2590 °F); both are kept.
    source: nks309
    where: Physical Properties section, Melting Point Range (oF)
  - benchmark: melting_point
    label: Melting range, Rolled Alloys sheet
    value: 2500
    value_high: 2590
    bound: range
    unit: °F
    scope: material
    conditions:
      grade: 309
      unit_in_source: 2500 - 2590 °F
    method: Melting range printed in a manufacturer datasheet
    status: ground
    note: The NKS datasheet prints a different range (2550 to 2650 °F); both are kept.
    source: rolled309
    where: 'Physical Properties block, Melting Range: 2500 - 2590°F'
  - benchmark: elastic_modulus
    label: Modulus of elasticity in tension, annealed
    value: 200
    unit: GPa
    scope: material
    conditions:
      state: annealed
      temperature: not stated
      note: The source prints one value that it says is common to both 309 and 310
      unit_in_source: 29 x 10^6 psi
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, row Modulus of Elasticity (annealed), in tension (E), GPa
  - benchmark: thermal_conductivity
    label: Thermal conductivity, 20 to 100 °C
    value: 15.6
    unit: W/m·K
    scope: material
    conditions:
      temperature_range: 68 to 212 °F (20 to 100 °C)
      unit_in_source: 9.0 Btu/hr·ft·°F
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Thermal Conductivity, row 68 to 212 °F, column 309, W/m·K
  - benchmark: thermal_conductivity
    label: Thermal conductivity, 20 to 500 °C
    value: 18.7
    unit: W/m·K
    scope: material
    conditions:
      temperature_range: 68 to 932 °F (20 to 500 °C)
      unit_in_source: 10.8 Btu/hr·ft·°F
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Thermal Conductivity, row 68 to 932 °F, column 309, W/m·K
  - benchmark: specific_heat
    label: Specific heat capacity, 0 to 100 °C
    value: 502
    unit: J/kg·K
    scope: material
    conditions:
      temperature_range: 32 to 212 °F (0 to 100 °C)
      unit_in_source: 0.12 Btu/lbm·°F
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Specific Heat, row 32 to 212 °F, column 309, J/kg·K
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C
    value: 78
    unit: µΩ·cm
    scope: material
    conditions:
      temperature: 68 °F (20 °C)
      unit_in_source: 30.7 µΩ·in
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Electrical Resistivity, row 68 °F (20 °C), column 309, µΩ·cm
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 648 °C
    value: 114.8
    unit: µΩ·cm
    scope: material
    conditions:
      temperature: 1200 °F (648 °C)
      unit_in_source: 45.1 µΩ·in
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Electrical Resistivity, row 1200 °F (648 °C), column 309, µΩ·cm
  - benchmark: cte
    label: Mean coefficient of linear thermal expansion, 20 to 100 °C
    value: 15.6
    unit: µm/(m·K)
    scope: material
    conditions:
      temperature_range: 68 to 212 °F (20 to 100 °C)
      unit_in_source: 8.7 µin/(in·°F)
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Coefficient of Thermal Expansion, row 68 to 212 °F (20 to 100 °C), column 309, (µm/m)·K
  - benchmark: cte
    label: Mean coefficient of linear thermal expansion, 20 to 500 °C
    value: 17.6
    unit: µm/(m·K)
    scope: material
    conditions:
      temperature_range: 68 to 932 °F (20 to 500 °C)
      unit_in_source: 9.8 µin/(in·°F)
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Coefficient of Thermal Expansion, row 68 to 932 °F (20 to 500 °C), column 309, (µm/m)·K
  - benchmark: cte
    label: Mean coefficient of linear thermal expansion, 20 to 1000 °C
    value: 19.4
    unit: µm/(m·K)
    scope: material
    conditions:
      temperature_range: 68 to 1832 °F (20 to 1000 °C)
      unit_in_source: 10.8 µin/(in·°F)
    method: Value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Physical Properties table, Coefficient of Thermal Expansion, row 68 to 1832 °F (20 to 1000 °C), column 309, (µm/m)·K
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, typical, 25 °C
    value: 290
    unit: MPa
    scope: material
    conditions:
      temperature: 77 °F (25 °C)
      basis: typical short-term values, ASTM E8, average of two to ten samples
      unit_in_source: 42.0 ksi
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 77 (25), column Yield Strength MPa
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, typical, 427 °C
    value: 207
    unit: MPa
    scope: material
    conditions:
      temperature: 800 °F (427 °C)
      basis: typical short-term values, ASTM E8, average of two to ten samples
      unit_in_source: 30.0 ksi
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 800 (427), column Yield Strength MPa
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, typical, 649 °C
    value: 152
    unit: MPa
    scope: material
    conditions:
      temperature: 1200 °F (649 °C)
      basis: typical short-term values, ASTM E8, average of two to ten samples
      unit_in_source: 22.0 ksi
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 1200 (649), column Yield Strength MPa
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, typical, 25 °C
    value: 621
    unit: MPa
    scope: material
    conditions:
      temperature: 77 °F (25 °C)
      basis: typical short-term values, ASTM E8, average of two to ten samples
      unit_in_source: 90.0 ksi
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 77 (25), column Tensile Strength MPa
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, typical, 427 °C
    value: 497
    unit: MPa
    scope: material
    conditions:
      temperature: 800 °F (427 °C)
      basis: typical short-term values, ASTM E8, average of two to ten samples
      unit_in_source: 72.0 ksi
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 800 (427), column Tensile Strength MPa
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, typical, 649 °C
    value: 379
    unit: MPa
    scope: material
    conditions:
      temperature: 1200 °F (649 °C)
      basis: typical short-term values, ASTM E8, average of two to ten samples
      unit_in_source: 55.0 ksi
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 1200 (649), column Tensile Strength MPa
  - benchmark: elongation
    label: Elongation, typical, 25 °C
    value: 49
    unit: '%'
    scope: material
    conditions:
      temperature: 77 °F (25 °C)
      gauge_length: 2 in (50.8 mm)
      basis: typical short-term values, ASTM E8
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 77 (25), column Elongation %
  - benchmark: elongation
    label: Elongation, typical, 427 °C
    value: 40
    unit: '%'
    scope: material
    conditions:
      temperature: 800 °F (427 °C)
      gauge_length: 2 in (50.8 mm)
      basis: typical short-term values, ASTM E8
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 800 (427), column Elongation %
  - benchmark: elongation
    label: Elongation, typical, 649 °C
    value: 35
    unit: '%'
    scope: material
    conditions:
      temperature: 1200 °F (649 °C)
      gauge_length: 2 in (50.8 mm)
      basis: typical short-term values, ASTM E8
    method: Typical value printed in a manufacturer technical sheet
    status: ground
    source: jacquet309
    where: Typical Short-Term Mechanical Properties table, grade 309, row 1200 (649), column Elongation %
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, minimum, ASTM A167
    value: 30
    bound: lower
    unit: ksi
    scope: material
    conditions:
      spec: ASTM A167 (309)
      form: sheet and strip
      measure: 0.2 % offset, minimum
    method: Minimum value printed in a manufacturer datasheet
    status: ground
    source: nks309
    where: Mechanical Properties table, row 309, column Yield Strength 0.2% offset (KSI), value 30 min.
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, minimum, ASTM A167
    value: 75
    bound: lower
    unit: ksi
    scope: material
    conditions:
      spec: ASTM A167 (309)
      form: sheet and strip
    method: Minimum value printed in a manufacturer datasheet
    status: ground
    source: nks309
    where: Mechanical Properties table, row 309, column Tensile Strength (KSI), value 75 min.
  - benchmark: elongation
    label: Elongation, minimum, ASTM A167
    value: 40
    bound: lower
    unit: '%'
    scope: material
    conditions:
      spec: ASTM A167 (309)
      form: sheet and strip
      gauge_length: 2 in
    method: Minimum value printed in a manufacturer datasheet
    status: ground
    source: nks309
    where: Mechanical Properties table, row 309, column % Elongation (2 in Gauge Length), value 40.0 min.
  - benchmark: max_service_temp
    label: Oxidation resistance, continuous service
    value: 2000
    unit: °F
    scope: material
    conditions:
      environment: air
      basis: oxidation rating for continuous service, not a mechanical limit
    method: Value printed in a manufacturer datasheet
    status: ground
    source: nks309
    where: Physical Properties section, Oxidation Resistance - Continuous Service (oF)
  - benchmark: max_service_temp
    label: Oxidation resistance, intermittent service
    value: 1800
    unit: °F
    scope: material
    conditions:
      environment: air
      basis: oxidation rating for intermittent service, not a mechanical limit
    method: Value printed in a manufacturer datasheet
    status: ground
    source: nks309
    where: Physical Properties section, Oxidation Resistance - Intermittent Service (oF)
  - benchmark: max_service_temp
    label: Oxidation resistance, constant temperature
    value: 1900
    unit: °F
    scope: material
    conditions:
      environment: air
      basis: oxidation rating under constant temperature; about 1850 °F with frequent thermal cycling (same sheet)
    method: Value printed in a manufacturer datasheet
    status: ground
    source: rolled309
    where: Opening paragraph, 309 is an austenitic heat resistant alloy with oxidation resistance to 1900°F under constant temperature conditions
corrosion:
  - environment: Aqueous and nitric-acid service at room temperature
    headline: Both NKS and Jacquet describe excellent general corrosion resistance; the grade is more resistant to marine air than 304.
    effect: NKS says 309 provides excellent general corrosion resistance, is more resistant to marine atmospheres than Type 304, and is useful for handling nitric acid, nitric-sulfuric mixtures, and acetic, citric and lactic acids. Jacquet says the grade is resistant to aqueous corrosion because of its high chromium and nickel contents. Neither sheet prints a corrosion rate for 309.
    rating: low
    conditions:
      basis: datasheet statements; no corrosion rate or test duration printed for 309
    source: nks309
    where: Corrosion section of the NKS datasheet; Jacquet, Aqueous Corrosion Resistance, opening paragraph
  - environment: High-temperature air oxidation
    headline: Chromium-rich scale protects the grade in air up to about 1900 to 2000 °F.
    effect: Rolled Alloys and NKS print oxidation ratings of 1900 °F (constant) and 2000 °F (continuous) in air. Jacquet says scale volatilisation becomes a significant problem above about 2000 °F and is worse in rapidly flowing gases, and that oxide scale spallation is the most common oxidation problem in stainless steels.
    rating: low
    conditions:
      basis: datasheet ratings and general oxidation discussion; no weight-gain or spalling data for 309 printed
    source: rolled309
    where: Opening paragraph of the Rolled Alloys sheet; Jacquet, Elevated Temperature Oxidation Resistance
  - environment: Sulphur-bearing hot gases
    headline: Good resistance to high-temperature sulphur atmospheres, with nickel content below the level that favours sulphidation.
    effect: Rolled Alloys says the high chromium and relatively low nickel content of 309 give good resistance to high-temperature sulphur-bearing atmospheres. Jacquet says sulphidation is enhanced in alloys with about 25 % or more nickel, which is above the 309 range of 12 to 15 %.
    rating: low
    conditions:
      basis: datasheet statements; no sulphidation rate printed for 309
    source: rolled309
    where: Opening paragraph of the Rolled Alloys sheet; Jacquet, Elevated Temperature Oxidation Resistance, sulfidation paragraph
  - environment: Carburising and metal-dusting atmospheres
    headline: Moderate resistance to carbon absorption; not recommended for highly carburising atmospheres.
    effect: Rolled Alloys says 309 has only moderate resistance to carbon absorption and is not suggested for highly carburising atmospheres. Jacquet says carburisation generally occurs above 800 °C (1470 °F) and metal dusting at 350 to 900 °C (660 to 1650 °F), and that higher nickel and silicon are somewhat effective in reducing carburisation susceptibility.
    rating: moderate
    conditions:
      basis: datasheet statements; no carburisation depth or weight-gain test printed for 309
    source: rolled309
    where: Opening paragraph of the Rolled Alloys sheet; Jacquet, Carburization paragraphs
risks:
  hazards:
    - text: 'Uddeholm safety information sheet for steel articles, nickel entry: H317 May cause an allergic skin reaction. H351 Suspected of causing cancer by inhalation. H372 Causes damage to organs through prolonged or repeated exposure by inhalation. Signal word DANGER. The sheet says massive steel needs no label, but dust and fumes from grinding, polishing, welding or cutting carry the risk.'
      ghs:
        - H317
        - H351
        - H372
      source: uddeholm-sis
      where: Classification of the major hazard substances, Nickel entry (the sheet is for Uddeholm alloys, not a 309 sheet)
    - text: 'The same sheet quotes the CLP rule for steels: more than 10 % nickel should be classed STOT RE1, 1 to 10 % nickel STOT RE 2, and more than 1 % nickel Carcinogen Category 2. The 309 range of 12.00 to 15.00 % nickel is above the 10 % line and above the 1 % line, so the rule would apply to the grade; the sheet gives it as a general rule, not as a classification for 309.'
      ghs: []
      source: uddeholm-sis
      where: Note under the Nickel entry
    - text: The sheet says alloys containing nickel or chromium may cause health hazards by inhalation of dusts and fumes produced by mechanical and thermal treatment such as grinding, polishing, welding or cutting, and that prolonged or repeated skin contact may cause dermatitis in nickel-sensitised persons.
      ghs: []
      source: uddeholm-sis
      where: Description of Hazards
  failure_risks:
    - mode: Sigma phase embrittlement
      trigger: Prolonged exposure in the 1100 to 1600 °F range
      consequence: Rolled Alloys says sigma forms and lowers room-temperature ductility and impact resistance, so heavy impact at room temperature should be avoided after such exposure.
      severity: moderate
      source: rolled309
      where: Opening paragraph of the Rolled Alloys sheet
    - mode: Carburisation and metal dusting
      trigger: Service above about 800 °C (1470 °F) in carbon-bearing atmospheres; metal dusting at 350 to 900 °C
      consequence: Internal carbides form, changing mechanical and physical properties; metal dusting can cause deep craters through the metal (Jacquet). Rolled Alloys says 309 is not suggested for highly carburising atmospheres.
      severity: moderate
      source: jacquet309
      where: Carburization paragraphs of the Jacquet sheet; Rolled Alloys opening paragraph
    - mode: Loss of strength when hot
      trigger: Service at 1200 °F
      consequence: Typical tensile strength falls from 90.0 ksi at 77 °F to 55.0 ksi at 1200 °F, and typical 0.2 % yield strength from 42.0 ksi to 22.0 ksi (Jacquet).
      severity: low
      source: jacquet309
      where: Typical Short-Term Mechanical Properties table, grade 309, rows 77 and 1200
    - mode: Hot cracking in welds
      trigger: Restrained or wide joints welded with a low-ferrite filler metal
      consequence: Jacquet says the high thermal expansion, low thermal conductivity and low ferrite in the weld metal can lead to hot cracking; a filler with lower alloy content, such as ER308, raises ferrite and reduces the risk, but dilutes the weld corrosion and heat resistance.
      severity: moderate
      source: jacquet309
      where: Welding paragraph of the Jacquet sheet
  side_effects: []
  handling:
    - text: Anneal and water quench or rapidly air cool. NKS prints an anneal at 1900 to 2050 °F (1038 to 1121 °C); Jacquet prints a hold at 2050 to 2150 °F (1120 to 1175 °C) for about 30 minutes per inch of section. The two ranges differ, so follow the producer's heat-treatment instruction.
      source: nks309
      where: Processing section of the NKS datasheet; Jacquet, Heat Treatment / Annealing paragraph
    - text: Rolled Alloys recommends welding with AWS E309-16 covered electrodes or ER309 bare wire. Jacquet says the S grades are low in carbon, that ER309L can be used where low carbon is needed, and that heat tint must be removed to restore corrosion resistance near the weld.
      source: rolled309
      where: Opening paragraph and Welding paragraph of the Rolled Alloys sheet; Jacquet, Welding paragraphs
    - text: NKS says 309 is not hardenable by heat treatment, is essentially nonmagnetic as annealed, becomes lightly magnetic when cold worked, and forms readily; in-process annealing is usually needed to reduce hardness and restore ductility.
      source: nks309
      where: Description, Processing and Forming sections of the NKS datasheet
  mitigations:
    - text: Jacquet says oxygen normally prevents carbon ingress by forming a protective external scale, so carburisation is most likely where the gas is oxygen-poor.
      source: jacquet309
      where: Carburization paragraph of the Jacquet sheet
uses:
  - application: thermal-control
    device: Furnace parts, heating elements and heat exchangers
    example: NKS lists furnace parts, heating elements, aircraft and jet engine parts, heat exchangers, kiln liners and boiler baffles among the typical applications of 309 and 309S. The NKS page covers both grades.
    source: nks309
    where: Typical Applications section
  - application: thermal-control
    device: Heat-treatment furnace parts, retorts and radiant tubes
    example: Jacquet lists conveyor belts, rollers, burner parts, refractory supports, retorts, oven linings, fans and tube hangers for heat-treatment furnaces, and baskets and trays for small parts.
    source: jacquet309
    where: Applications paragraph of the Jacquet sheet
  - application: structures
    device: Power boiler tube hangers and anchor bolts
    example: Rolled Alloys lists power boiler tube hangers, anchor bolts, thermowells and glass forming equipment among its 309 applications.
    source: rolled309
    where: Applications list of the Rolled Alloys sheet
supply:
  - subject: Nickel (world mine production, nickel content, 2025 estimate)
    producers:
      - country: Indonesia
        share_percent: 66.7
        year: 2025
      - country: Philippines
        share_percent: 6.9
        year: 2025
      - country: Russia
        share_percent: 5.1
        year: 2025
      - country: New Caledonia
        share_percent: 3.6
        year: 2025
      - country: Canada
        share_percent: 3.6
        year: 2025
    critical_lists: []
    recycling: 'USGS: nickel recovered from scrap accounted for approximately 60 % of apparent consumption in 2025; most recycled nickel went into new alloys and stainless steel.'
    substitutes:
      - 'USGS: low-nickel, duplex or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction; titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments.'
    source: usgs-nickel-2026
    where: World Mine Production and Reserves table, 2025e world total 3,900,000 t; shares calculated by Space Mushroom from the country values 2,600,000; 270,000; 200,000; 140,000; 140,000. Recycling; Substitutes.
  - subject: Chromium (world mine production, chromium content, 2025 estimate)
    producers:
      - country: South Africa
        share_percent: 45.1
        year: 2025
      - country: Turkey
        share_percent: 17.6
        year: 2025
      - country: Kazakhstan
        share_percent: 13.7
        year: 2025
      - country: India
        share_percent: 5.9
        year: 2025
    critical_lists: []
    recycling: 'USGS: recycled chromium, contained in stainless-steel scrap receipts, accounted for 21 % of apparent consumption in 2025.'
    substitutes:
      - 'USGS: chromium has no substitute in stainless steel, the leading end use, or in superalloys.'
    source: usgs-chromium-2026
    where: World Mine Production and Reserves table, 2025e world total 51,000 thousand t; shares calculated by Space Mushroom from the country values 23,000; 9,000; 7,000; 3,000. Recycling paragraph; Substitutes paragraph.
documents:
  - title: 'Technical Sheet 309/309S, 310/310S Stainless Steel: Austenitic (Jacquet)'
    type: datasheet
    url: https://usa.myjacquet.com/wp-content/uploads/sites/55/2025/08/Technical_Sheet_309_310.pdf
    year: 2025
  - title: 309 & 309S Stainless Steel data sheet (NKS, 800-722-5029)
    type: datasheet
    url: https://nks.com/wp-content/uploads/309-309S-Stainless-Steel.pdf
  - title: Bulletin No. 109, 309 Stainless Steel data sheet (Rolled Alloys, rev 07/12)
    type: datasheet
    url: https://www.rolledalloys.com/wp-content/uploads/309_stainless-steel-data-sheet-rolled-alloys.pdf
    year: 2012
  - title: UNS S30900 Stainless steels (TotalMateria)
    type: database
    url: https://www.totalmateria.com/en-us/material/1241521
  - title: Alloys delivered from Uddeholms AB, material safety information sheet (release 2010-01-04, review 2018-09-10)
    type: sds
    url: https://www.uddeholm.com/app/uploads/sites/235/2024/05/Alloys-delivered-from-Uddeholms-AB.pdf
    year: 2018
  - 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
gaps:
  - No hardness value for AISI 309 was read in a fetched source; the sheets give only 309S or unlabelled values, so no hardness property is entered.
  - No EN, JIS or AMS designation was printed for AISI 309 by a source read in this run. EN 1.4833 and JIS SUS 309 belong to the 309S row of the Outokumpu table, and EN 1.4828 is the silicon-enriched 309Si grade, so they are left out.
  - No vacuum, radiation, outgassing, atomic-oxygen, cryogenic or flight data were found for 309 in this run.
  - The two sheets give different melting ranges (NKS 2550 to 2650 °F; Rolled Alloys 2500 to 2590 °F) and different annealing ranges (NKS 1900 to 2050 °F; Jacquet 2050 to 2150 °F). Both are kept as printed; no value was chosen.
  - The modulus of 200 GPa is one value the Jacquet sheet says is common to both 309 and 310; it is not a grade-specific measurement.
  - Nickel for UNS S30900 was not visible on the TotalMateria page (behind a free registration); the nickel range comes from the Jacquet and NKS sheets, which agree.
  - No process route (melting, refining) for 309 was read from a primary source, so the recipe gives no process description.
  - Atomic weights were not read from a fetched page and are left out of the recipe parts.
  - Official critical-mineral list status for nickel and chromium was not read, so critical_lists is left empty.
  - The Uddeholm sheet is for Uddeholm alloys (release 2010, review 2018) and states the CLP steel rule in general terms; it is cited for the rule, not as a 309 classification. No safety data sheet for a 309 base alloy was opened, and PubChem was not read for nickel.
  - Aperam and ICAST sheets that describe 309S were found but not used, because 309S is a separate grade and their values are for 309S.
  - Seven sources were reached, below the eight the lithium standard asks for. A search for Smiths Metal Centres, Combined Metals and Aalco 309 datasheets found no such page.
sources:
  jacquet309:
    title: 'Technical Sheet 309/309S, 310/310S Stainless Steel: Austenitic (Jacquet)'
    id: UNS S30900, S30908, S31000, S31008
    url: https://usa.myjacquet.com/wp-content/uploads/sites/55/2025/08/Technical_Sheet_309_310.pdf
    year: 2025
    kind: datasheet
    license: Manufacturer technical sheet (cited, not reproduced)
  nks309:
    title: 309 & 309S Stainless Steel (NKS datasheet)
    id: ASTM A167 (309), ASTM A240 (309S)
    url: https://nks.com/wp-content/uploads/309-309S-Stainless-Steel.pdf
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  rolled309:
    title: Bulletin No. 109, 309 Stainless Steel data sheet (Rolled Alloys)
    id: UNS S30908, S30909; W. Nr. 1.4833; AMS 5523
    url: https://www.rolledalloys.com/wp-content/uploads/309_stainless-steel-data-sheet-rolled-alloys.pdf
    year: 2012
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  totalmateria309:
    title: UNS S30900 Stainless steels (TotalMateria)
    id: UNS S30900
    url: https://www.totalmateria.com/en-us/material/1241521
    kind: database
    license: Database page, reference only (cited, not reproduced)
  uddeholm-sis:
    title: Alloys delivered from Uddeholms AB, material safety information sheet (release 2010-01-04, review 2018-09-10)
    url: https://www.uddeholm.com/app/uploads/sites/235/2024/05/Alloys-delivered-from-Uddeholms-AB.pdf
    year: 2018
    kind: datasheet
    license: Manufacturer safety information sheet (cited, not reproduced)
  usgs-nickel-2026:
    title: Mineral Commodity Summaries 2026, Nickel
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-chromium-2026:
    title: Mineral Commodity Summaries 2026, Chromium
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 1
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: Rolled Alloys HTML data-sheet pages (HTTP 404), Outokumpu grade page (HTTP 404), and the Aalco or Smiths 309 pages (not found by search). Caveats: the Jacquet modulus is common to 309 and 310; the NKS and Rolled Alloys melting and annealing ranges differ; the hazard classes come from a general steel-article sheet for Uddeholm alloys; the nickel composition is from two sheets, not from a 309-specific SDS.'
story:
  risk_groups:
    - title: For people
      lead: Dust and fumes from working the steel carry the hazards, because the sources classify nickel, not the massive metal.
      level: 1
      verdict: Nickel classes apply to dust and fumes
      points:
        - label: Nickel in the alloy
          line: Uddeholm's safety information sheet for steel articles classes nickel with H317, H351 and H372 (DANGER). It says massive steel needs no label, but dust and fumes from grinding, polishing, welding or cutting carry the risk.
        - label: Nickel limit rule
          line: The same sheet puts steels above 10 % nickel in STOT RE1 and steels above 1 % nickel in Carcinogen Category 2. The 309 range of 12 to 15 % nickel sits above both lines, so the rule would apply to the grade.
    - title: If it fails
      lead: These are failure routes printed in the sources. None is a measured space result.
      points:
        - label: Sigma phase
          line: Rolled Alloys says prolonged exposure at 1100 to 1600 °F forms sigma, which lowers room-temperature ductility and impact resistance.
        - label: Carburisation
          line: Rolled Alloys says the grade has only moderate resistance to carbon absorption. Jacquet says carburisation occurs above 800 °C and metal dusting at 350 to 900 °C.
        - label: Hot strength
          line: Jacquet gives a typical tensile strength of 90.0 ksi at 77 °F and 55.0 ksi at 1200 °F.
    - title: Handling and storage
      points:
        - label: Annealing
          line: NKS prints an anneal at 1900 to 2050 °F and a water quench or rapid air cool. Jacquet prints a hold at 2050 to 2150 °F for about 30 minutes per inch. The two ranges differ.
        - label: Welding
          line: Rolled Alloys recommends AWS E309-16 electrodes or ER309 wire. Jacquet warns that the joint can hot-crack when it is restrained or wide.
        - label: Magnetism
          line: NKS says the grade is essentially nonmagnetic when annealed and becomes lightly magnetic when cold worked.
  why: AISI 309 is a chromium-nickel austenitic stainless steel built for heat. It carries 22 to 24 % chromium and 12 to 15 % nickel, which gives it oxidation resistance to about 1900 to 2000 °F in air and a good share of its strength at elevated temperature. Its carbon limit of 0.20 % is higher than the 309S variant, which is why 309S is the more common weldable choice. The Jacquet sheet prints a density of 8.03 g/cm3 and a modulus of 200 GPa for the family.
  uses:
    - where: Furnace parts and heating elements
      line: NKS lists furnace parts, heating elements, aircraft and jet engine parts, heat exchangers and kiln liners. Jacquet lists conveyor belts, rollers, burner parts, retorts and radiant parts for heat-treatment furnaces.
    - where: Boiler and furnace supports
      line: Rolled Alloys lists power boiler tube hangers, anchor bolts, thermowells and glass forming equipment among its 309 applications.
  can_do:
    - label: Carry heat in air
      value: 2000 °F
      benchmark: max_service_temp
      line: NKS prints an oxidation rating of 2000 °F for continuous service and 1800 °F for intermittent service. Rolled Alloys prints 1900 °F for constant temperature.
    - label: Strength when hot
      value: 55 ksi at 1200 °F
      benchmark: ultimate_tensile_strength
      line: Jacquet gives a typical tensile strength of 55.0 ksi at 1200 °F (379 MPa), down from 90.0 ksi at 77 °F.
    - label: Stiffness
      value: 200 GPa
      benchmark: elastic_modulus
      line: The Jacquet sheet prints a modulus of elasticity of 200 GPa for annealed material, a value it says is common to 309 and 310.
    - label: Strength at room temperature
      value: 290 MPa yield
      benchmark: yield_strength
      line: Jacquet gives a typical 0.2 % yield strength of 290 MPa (42.0 ksi) at 77 °F. The NKS minimum for ASTM A167 is 30 ksi.
  compare: 309 sits in the same chromium-nickel family as 310, which carries more chromium and nickel than 309 (Jacquet). The sibling 310 profile is in this site as stainless-310. Jacquet says 310 has higher oxidation resistance and retains more room-temperature strength than the common austenitic alloys such as Type 304. Rolled Alloys says 309 is oxidation resistant to 1900 °F and has moderate strength at high temperature.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting range
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Specify the grade (309 or 309S) and the product form, because the carbon limit and the minimum values differ between them.
    - Anneal to restore ductility after heavy forming, and pick the annealing range that the producer prints for the heat.
    - Weld with an AWS E309-16 electrode or ER309 wire (Rolled Alloys); remove heat tint after welding (Jacquet).
    - Control dust and fumes when grinding, polishing, welding or cutting, since the Uddeholm sheet names inhalation of nickel and chromium dust and fumes as the hazard.
  good_for:
    - Hot furnace and heat-treatment parts in air, rated to about 1900 to 2000 °F (Rolled Alloys, NKS).
    - Sulphur-bearing hot gases, where the chromium-rich, low-nickel composition gives good resistance (Rolled Alloys).
    - Heating elements, furnace fans and radiant tubes (NKS, Jacquet).
  watch_out:
    - 'Carburising atmospheres: moderate resistance to carbon absorption, and not suggested for highly carburising service (Rolled Alloys).'
    - Prolonged exposure at 1100 to 1600 °F forms sigma, which lowers room-temperature ductility and impact resistance (Rolled Alloys).
    - 'Strength falls when hot: 90.0 ksi at 77 °F against 55.0 ksi at 1200 °F (Jacquet).'
    - Nickel content of 12 to 15 % puts the hazard class above the 10 % CLP line, so check the heat certificate and treat dust as a hazard (Uddeholm sheet).
    - No space-environment data (vacuum, radiation, atomic oxygen) were found for this profile.
  verdict: AISI 309 is an austenitic heat-resistant stainless steel rated to about 1900 to 2000 °F in air, with a modulus of 200 GPa and typical strength of 621 MPa at room temperature. Its strength falls steeply at high temperature, carburising atmospheres are a weak point, and the grade has no space-environment data in this profile.
  recipe:
    line: AISI 309 is an iron-based austenitic alloy. Composition in weight percent is the ASTM A167 and A240 limits printed in the Jacquet sheet and the NKS datasheet; the TotalMateria UNS S30900 page prints the same carbon, manganese and chromium limits. The process route (melting and refining) was not read from a primary source.
    parts:
      - name: Iron
        symbol: Fe
        share: balance
        role: The matrix of the alloy; the other elements are dissolved in it.
      - name: Chromium
        symbol: Cr
        share: 22.00 to 24.00 wt %
        role: Gives the stainless steel its oxidation and corrosion resistance; the high chromium content is the main reason for the oxidation rating (Jacquet, Rolled Alloys).
      - name: Nickel
        symbol: Ni
        share: 12.00 to 15.00 wt %
        role: Keeps the structure austenitic and non-magnetic when annealed (NKS); the 12 to 15 % range is also the source of the hazard class above the 10 % line (Uddeholm).
      - name: Carbon
        symbol: C
        share: 0.20 wt % maximum
        role: Kept at a low level; the 309S variant limits it to 0.08 % maximum to reduce carbide precipitation (NKS).
      - name: Manganese
        symbol: Mn
        share: 2.00 wt % maximum
        role: Printed in the ASTM A167 and A240 limits; the sheets give no function for it.
      - name: Silicon
        symbol: Si
        share: 0.75 wt % maximum
        role: Printed in the ASTM A167 and A240 limits; the sheets give no function for it.
      - name: Phosphorus
        symbol: P
        share: 0.045 wt % maximum
        role: An impurity limit in the ASTM A167 and A240 composition.
      - name: Sulphur
        symbol: S
        share: 0.030 wt % maximum
        role: An impurity limit in the ASTM A167 and A240 composition.