spore: profile
id: stainless-303
spore_version: 0.2
family: stainless-austenitic
name: Stainless steel 303
abbreviation: 303 (UNS S30300)
role: free-machining structural alloy
category: metals
type: steels-and-stainless
summary: |
  Type 303 (UNS S30300, EN 1.4305) is the free-machining modification of the basic 18 percent chromium, 8 percent nickel austenitic stainless steel (Rolled Alloys). Sulphur, at least 0.15 percent, is added so that it machines more readily than 304/304L and 316/316L (Rolled Alloys), and Aalco calls it the most readily machined of the austenitic grades. The same sulphur costs corrosion resistance below 304 and weldability (Aalco).
best_for: Heavily machined parts in mild service, such as screws, nuts, bolts, shafts and fittings (Aalco, UPMET)
weakest_at: Chloride and marine service, where Aalco says 303 is not suitable, and welded joints, where Aalco says weldability is poor
identity:
  formula: Fe balance, 17.0 to 19.0 Cr, 8.0 to 10.0 Ni, max 0.15 C, max 2.0 Mn, max 0.20 P, min 0.15 S, max 1.0 Si, max 0.6 Mo (optional), wt%
  source: rolled-303
  where: Chemical Composition table, MIN and MAX rows (UNS S30300)
  designations:
    - system: UNS
      code: S30300
      source: rolled-303
      where: 'Specifications line, UNS: S30300'
    - system: EN
      code: '1.4305'
      source: rolled-303
      where: 'Specifications line, W. Nr./EN: 1.4305'
    - system: ASTM
      code: A582
      note: bar products
      source: aalco-303
      where: 'Property data note: typical for bar products covered by ASTM A582'
    - system: ASTM
      code: A581
      note: listed on the wire data sheet
      source: ulbrich-303
      where: 'Header list: AMS 5640, ASTM A314, ASTM A581, ASTM A582, QQ-S-764'
    - system: ASTM
      code: A895
      note: plate, from the UPMET data sheet title
      source: upmet-303
      where: 'Data sheet title: Plate - UNS S30300 - ASTM-A-895'
    - system: AMS
      code: '5640'
      source: upmet-303
      where: 'Header line: AMS 5640 (Chem Only) / UNS S30300'
    - system: AISI
      code: '303'
      source: outokumpu-global
      where: Table 4, ASTM column, 4305 row
    - system: JIS
      code: SUS 303
      source: outokumpu-global
      where: Table 4, JIS column, 4305 row
    - system: ISO
      code: 4305-303-00-I
      source: outokumpu-global
      where: Table 5, ISO column, 4305 row
    - system: BS
      code: 303S31
      source: outokumpu-global
      where: Table 5, BS/UK column, 4305 row
    - system: AFNOR
      code: Z8 CNF 18-09
      source: outokumpu-global
      where: Table 5, NF/France column, 4305 row
    - system: SS
      code: '2346'
      source: outokumpu-global
      where: Table 5, SS/Sweden column, 4305 row
    - system: GB
      code: Y1Cr18Ni9
      source: outokumpu-global
      where: Table 5, GB/PR China column, 4305 row
    - system: GOST
      code: 12X18H10E
      source: outokumpu-global
      where: Table 5, GOST/Russia column, 4305 row
tags:
  environments: []
  stresses: []
  applications:
    - structures
    - mechanisms
properties:
  - benchmark: density
    value: 7.9
    unit: kg/dm3
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: room temperature (RT)
    method: Physical properties table (Table 13), density value at RT for the 1.4305 row
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, density RT column
  - benchmark: density
    value: 7.89
    unit: g/cm3
    scope: material
    conditions:
      form: plate (UPMET ASTM A895 data sheet)
      temper: not printed
      temperature: not printed
    method: Physical Properties table, density row, printed as 7.89 g/cm3 beside 0.289 lb/in3
    status: ground
    source: upmet-303
    where: Physical Properties table, Density g/cm3 row
  - benchmark: density
    value: 8
    unit: g/cm3
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: not printed
      temperature: not printed
    method: Physical properties line, printed as 0.283 lb/in3, 8.00 g/cm3
    status: ground
    source: ulbrich-303
    where: Physical Properties, Density line
  - benchmark: density
    value: 8.03
    unit: g/cm3
    scope: material
    conditions:
      form: 'bar (Aalco note: typical for ASTM A582 bar products)'
      temper: not printed
      temperature: not printed
    method: Typical Physical Properties table, density row, as printed
    status: ground
    source: aalco-303
    where: Typical Physical Properties table, Density row
  - benchmark: melting_point
    value: 1455
    unit: °C
    scope: material
    conditions:
      form: bar (Aalco typical data)
      temper: not printed
      temperature: one typical value, not a range
    method: Typical Physical Properties table, Melting Point row, printed in °C
    status: ground
    source: aalco-303
    where: Typical Physical Properties table, Melting Point row
  - benchmark: melting_point
    value: 1400
    value_high: 1420
    bound: range
    unit: °C
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: not printed
      temperature: melting range
    method: Physical properties line, Melting Range row, printed as 2550-2590 F (1400-1420 C)
    status: ground
    source: ulbrich-303
    where: Physical Properties, Melting Range row
  - benchmark: elastic_modulus
    value: 193
    unit: GPa
    scope: material
    conditions:
      form: bar (Aalco typical data)
      temper: not printed
      temperature: in tension, temperature not stated
    method: Typical Physical Properties table, Modulus of Elasticity row, printed as 193 GPa
    status: ground
    source: aalco-303
    where: Typical Physical Properties table, Modulus of Elasticity row
  - benchmark: elastic_modulus
    value: 200
    unit: GPa
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: room temperature (RT)
    method: Physical properties table (Table 13), modulus of elasticity E, RT column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, E RT column
  - benchmark: thermal_conductivity
    value: 15
    unit: W/m°C
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: room temperature (RT)
    method: Physical properties table (Table 13), thermal conductivity RT column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, thermal conductivity RT column
  - benchmark: thermal_conductivity
    value: 20
    unit: W/m°C
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: 400 C
    method: Physical properties table (Table 13), thermal conductivity 400 C column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, thermal conductivity 400 C column
  - benchmark: thermal_conductivity
    value: 16.2
    unit: W/m-°K
    scope: material
    conditions:
      form: plate (UPMET ASTM A895 data sheet)
      temper: not printed
      temperature: 100 C (212 F)
    method: Physical Properties table, thermal conductivity at 212 F (100 C), as printed
    status: ground
    source: upmet-303
    where: Physical Properties table, Thermal Conductivity row
  - benchmark: thermal_conductivity
    value: 16.3
    unit: W/m.K
    scope: material
    conditions:
      form: bar (Aalco typical data)
      temper: not printed
      temperature: 100 C
    method: Typical Physical Properties table, Thermal Conductivity row, printed as 16.3 W/m.K at 100 C
    status: ground
    source: aalco-303
    where: Typical Physical Properties table, Thermal Conductivity row
  - benchmark: specific_heat
    value: 500
    unit: J/kg°C
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: room temperature (RT)
    method: Physical properties table (Table 13), thermal capacity c RT column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, thermal capacity RT column
  - benchmark: specific_heat
    value: 0.5
    unit: J/g-°C
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: not printed
      temperature: 0 to 100 C (32 to 212 F)
    method: Specific Heat line, printed as 0.12 (0.5) BTU/lb-F and J/g-C for 32 to 212 F
    status: ground
    source: ulbrich-303
    where: Specific Heat line, 32-212 F (0-100 C)
  - benchmark: cte
    value: 16
    unit: 10-6/°C
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: 20 to 100 C (mean between 20 C and T)
    method: Physical properties table (Table 13), coefficient of thermal expansion at 100 C column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, CTE 100 C column
  - benchmark: cte
    value: 17.5
    unit: 10-6/°C
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: 20 to 400 C (mean between 20 C and T)
    method: Physical properties table (Table 13), coefficient of thermal expansion at 400 C column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, CTE 400 C column
  - benchmark: cte
    value: 16.7
    unit: µm/m-°C
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: not printed
      temperature: 20 to 200 C (mean, 68 to 392 F)
    method: Mean Coefficient of Thermal Expansion line, printed as 9.3 (16.7) in the 68-392 F (20-200 C) row
    status: ground
    source: ulbrich-303
    where: Mean Coefficient of Thermal Expansion line, 68-392 F (20-200 C)
  - benchmark: cte
    value: 17.3
    unit: 10-6/K
    scope: material
    conditions:
      form: bar (Aalco typical data)
      temper: not printed
      temperature: 100 C (averaging basis not stated)
    method: Typical Physical Properties table, Thermal Expansion row, printed as 17.3x10-6 /K at 100 C
    status: ground
    source: aalco-303
    where: Typical Physical Properties table, Thermal Expansion row
  - benchmark: electrical_resistivity
    value: 72
    unit: microhm-cm
    scope: material
    conditions:
      form: plate (UPMET ASTM A895 data sheet)
      temper: not printed
      temperature: 20 C
    method: Physical Properties table, Electrical Resistivity row, printed as 72.0 Microhm-cm at 20 C
    status: ground
    source: upmet-303
    where: Physical Properties table, Electrical Resistivity row
  - benchmark: electrical_resistivity
    value: 0.73
    unit: μΩm
    scope: material
    conditions:
      form: not stated
      temper: not stated
      temperature: room temperature (RT)
    method: Physical properties table (Table 13), electrical resistivity RT column
    status: ground
    source: outokumpu-global
    where: Table 13, 4305 row, electrical resistivity RT column
  - benchmark: yield_strength
    value: 172
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: annealed (Annealed Typical block)
      temperature: room temperature
      basis: minimum, printed as 25 KSI min (172 MPa min)
    method: Mechanical Properties at Room Temperature, Annealed Typical block, Yield Strength line
    status: ground
    source: ulbrich-303
    where: Mechanical Properties at Room Temperature, Yield Strength line
  - benchmark: yield_strength
    value: 205
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: 'hot rolled plate, transverse (Table 7 note: EN and ASTM min values are mainly for this product)'
      temper: not printed
      temperature: room temperature (RT)
      basis: minimum, ASTM
    method: Table 7, ASTM min values at RT, Rp0.2 column, S30300 row
    status: ground
    source: outokumpu-global
    where: Table 7, 4305 row, ASTM min Rp0.2 column (S30300)
  - benchmark: yield_strength
    value: 190
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: 'hot rolled plate, transverse (Table 7 note: EN and ASTM min values are mainly for this product)'
      temper: not printed
      temperature: room temperature (RT)
      basis: minimum, EN
    method: Table 7, EN min values at RT, Rp0.2 column, 1.4305 row
    status: ground
    source: outokumpu-global
    where: Table 7, 4305 row, EN min Rp0.2 column
  - benchmark: yield_strength
    value: 190
    unit: MPa
    scope: material
    conditions:
      form: 'bar (Aalco note: typical for ASTM A582 bar products)'
      temper: not printed
      temperature: not printed
      basis: typical, 0.2 percent proof stress
    method: Mechanical properties table, Proof Stress 0.2 percent row, printed as 190 MPa
    status: ground
    source: aalco-303
    where: Mechanical properties table, Proof Stress 0.2 percent (MPa) row
  - benchmark: yield_strength
    value: 30
    unit: ksi
    scope: material
    conditions:
      form: not stated
      temper: not printed in this row
      temperature: not stated
      basis: typical
    method: Typical Tensile Properties table, Yield Strength row, printed in ksi
    status: ground
    source: rolled-303
    where: Mechanical Properties, Typical Tensile Properties, Yield Strength row
  - benchmark: ultimate_tensile_strength
    value: 517
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: annealed (Annealed Typical block)
      temperature: room temperature
      basis: minimum, printed as 75 KSI min (517 MPa min)
    method: Mechanical Properties at Room Temperature, Annealed Typical block, Ultimate Tensile Strength line
    status: ground
    source: ulbrich-303
    where: Mechanical Properties at Room Temperature, Ultimate Tensile Strength line
  - benchmark: ultimate_tensile_strength
    value: 515
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: 'hot rolled plate, transverse (Table 7 note: EN and ASTM min values are mainly for this product)'
      temper: not printed
      temperature: room temperature (RT)
      basis: minimum, ASTM
    method: Table 7, ASTM min values at RT, Rm column, S30300 row
    status: ground
    source: outokumpu-global
    where: Table 7, 4305 row, ASTM min Rm column (S30300)
  - benchmark: ultimate_tensile_strength
    value: 500
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: 'hot rolled plate, transverse (Table 7 note: EN and ASTM min values are mainly for this product)'
      temper: not printed
      temperature: room temperature (RT)
      basis: minimum, EN
    method: Table 7, EN min values at RT, Rm column, 1.4305 row
    status: ground
    source: outokumpu-global
    where: Table 7, 4305 row, EN min Rm column
  - benchmark: ultimate_tensile_strength
    value: 500
    unit: MPa
    scope: material
    conditions:
      form: 'bar (Aalco note: typical for ASTM A582 bar products)'
      temper: not printed
      temperature: not printed
      basis: typical
    method: Mechanical properties table, Tensile Strength (MPa) row, printed as 500
    status: ground
    source: aalco-303
    where: Mechanical properties table, Tensile Strength (MPa) row
  - benchmark: ultimate_tensile_strength
    value: 75
    unit: ksi
    scope: material
    conditions:
      form: not stated
      temper: not printed in this row
      temperature: not stated
      basis: typical
    method: Typical Tensile Properties table, Tensile Strength row, printed in ksi
    status: ground
    source: rolled-303
    where: Mechanical Properties, Typical Tensile Properties, Tensile Strength row
  - benchmark: elongation
    value: 35
    unit: '%'
    bound: lower
    scope: material
    conditions:
      form: wire (Ulbrich wire data sheet)
      temper: annealed (Annealed Typical block)
      temperature: room temperature
      gauge: not printed
      basis: minimum, printed as 35 % min
    method: Mechanical Properties at Room Temperature, Annealed Typical block, Elongation line
    status: ground
    source: ulbrich-303
    where: Mechanical Properties at Room Temperature, Elongation line
  - benchmark: elongation
    value: 35
    unit: '%'
    scope: material
    conditions:
      form: not stated
      temper: not printed in this row
      temperature: not stated
      gauge: 2 inches (printed as % Elongation in 2 inches)
      basis: typical
    method: Typical Tensile Properties table, % Elongation in 2 inches row
    status: ground
    source: rolled-303
    where: Mechanical Properties, Typical Tensile Properties, % Elongation in 2 inches row
  - benchmark: elongation
    value: 35
    unit: '%'
    scope: material
    conditions:
      form: 'bar (Aalco note: typical for ASTM A582 bar products)'
      temper: not printed
      temperature: not printed
      gauge: A5 (printed as Elongation A5)
      basis: typical
    method: Mechanical properties table, Elongation A5 (%) row, printed as 35
    status: ground
    source: aalco-303
    where: Mechanical properties table, Elongation A5 (%) row
  - benchmark: hardness
    value: 202
    unit: HBN
    bound: upper
    scope: material
    conditions:
      form: plate (UPMET ASTM A895 data sheet)
      temper: not printed
      temperature: not printed
      basis: maximum, printed as Max 202 (HBN)
    method: Mechanical Properties table, Hardness row, Max 202 (HBN) as printed
    status: ground
    source: upmet-303
    where: Mechanical Properties table, Hardness row
corrosion:
  - environment: Mild environments
    headline: Corrosion resistance remains good in mild environments (Aalco).
    effect: Aalco says sulphur lowers corrosion resistance to less than that of 304, but corrosion resistance remains good in mild environments.
    rating: low
    conditions:
      environment: mild environments, as printed
      temperature: not stated
    source: aalco-303
    where: Corrosion Resistance section
  - environment: Compared with Type 304
    headline: Sulphur gives pitting initiation sites, so 303 resists less than 304.
    effect: Aalco says sulphur additions act as initiation sites for pitting corrosion, which decreases the corrosion resistance of 303 to less than that for 304.
    rating: moderate
    conditions:
      comparison: Type 304
      temperature: not stated
    source: aalco-303
    where: Corrosion Resistance section, first sentences
  - environment: Chloride-containing environments above 60 C
    headline: Pitting and crevice corrosion in chloride environments over 60 C.
    effect: Aalco says that in chloride containing environments over 60 C, 303 is subject to pitting and crevice corrosion.
    rating: moderate
    conditions:
      environment: chloride containing
      temperature: over 60 C
    source: aalco-303
    where: Corrosion Resistance section
  - environment: Marine environments
    headline: Not suitable for marine use (Aalco).
    effect: Aalco says grade 303 stainless steel is not suitable for use in marine environments.
    rating: severe
    conditions:
      environment: marine
      temperature: not stated
    source: aalco-303
    where: Corrosion Resistance section, last sentence
  - environment: Continuous use at 425 to 860 C
    headline: Sensitive to carbide precipitation in continuous service at 425 to 860 C.
    effect: Aalco says continuous service at 870 C is not recommended because 303 is sensitive to carbide precipitation with continuous use at 425 to 860 C.
    rating: moderate
    conditions:
      temperature: 425 to 860 C continuous use
    source: aalco-303
    where: Heat Resistance section
  - environment: Oxidation in air at high temperature
    headline: Good oxidation resistance, intermittent to 760 C and continuous to 870 C.
    effect: Aalco says 303 has good resistance to oxidation when intermittently exposed to temperatures up to 760 C, and good oxidation resistance in continuous service to 870 C.
    rating: low
    conditions:
      temperature: intermittent up to 760 C; continuous to 870 C
    source: aalco-303
    where: Heat Resistance section
risks:
  hazards:
    - text: PubChem aggregated GHS notifications for elemental nickel include H317 (may cause an allergic skin reaction), H351 (suspected of causing cancer), H372 (causes damage to organs through prolonged or repeated exposure), H334 (may cause allergy or asthma symptoms or breathing difficulties if inhaled) and H412 (harmful to aquatic life with long lasting effects). These cover the element, not the 303 alloy.
      ghs:
        - H317
        - H351
        - H372
        - H334
        - H412
      source: pubchem-nickel
      where: GHS Classification, aggregated notifications (CID 935)
    - text: PubChem notifications for elemental chromium include H317 (may cause an allergic skin reaction), H319 (causes serious eye irritation), H334 (may cause allergy or asthma symptoms or breathing difficulties if inhaled) and H341 (suspected of causing genetic defects). These cover the element, not the alloy.
      ghs:
        - H317
        - H319
        - H334
        - H341
      source: pubchem-chromium
      where: GHS Classification, notifications (CID 23976)
    - text: PubChem notifications for elemental manganese include H372 (causes damage to organs through prolonged or repeated exposure), H360 (may damage fertility or the unborn child), H370 (causes damage to organs), H228 (flammable solid, 11.6 percent share in the notifications) and H411 (toxic to aquatic life with long lasting effects).
      ghs:
        - H372
        - H360
        - H370
        - H228
        - H411
      source: pubchem-manganese
      where: GHS Classification, notifications (CID 23930)
  failure_risks:
    - mode: Pitting and crevice corrosion at the sulphur additions
      trigger: Chloride-containing environment above 60 C, or marine service
      consequence: Aalco says 303 is subject to pitting and crevice corrosion in chloride above 60 C and is not suitable for marine environments
      severity: high
      source: aalco-303
      where: Corrosion Resistance section
    - mode: Poor weldability from the sulphur addition
      trigger: Fusion welding of 303 parts
      consequence: Aalco says the sulphur addition results in poor weldability, and recommends 308L or 309 filler and annealed welds
      severity: moderate
      source: aalco-303
      where: Welding section
    - mode: Carbide precipitation (sensitisation)
      trigger: Continuous use at 425 to 860 C
      consequence: Aalco says 303 is sensitive to carbide precipitation, and continuous service at 870 C is not recommended
      severity: moderate
      source: aalco-303
      where: Heat Resistance section
    - mode: Slightly lower toughness
      trigger: The sulphur addition
      consequence: Aalco says sulphur causes a slight lowering of the toughness
      severity: low
      source: aalco-303
      where: Opening paragraph
    - mode: Poor cold formability
      trigger: Sharp bending or cold working
      consequence: Aalco says type 303 is not readily cold workable and sharp bending should not be attempted
      severity: moderate
      source: aalco-303
      where: Cold Working section
  side_effects: []
  handling:
    - text: Keep cutting edges sharp, make cuts light but deep enough to avoid work hardening, use chip breakers, and use coolants and lubricants in large quantities (Aalco).
      source: aalco-303
      where: Machining section
    - text: Rolled Alloys gives starting speeds of 65 to 75 sfpm for twist drills in annealed type 303 with high speed tooling, at feeds of 0.0045 to 0.0055 inch per revolution.
      source: rolled-303
      where: Feeds and Speeds table, Twisting Drill rows
    - text: Use tooling and work surfaces dedicated to stainless steel, and clean them before use, to avoid contamination (Aalco).
      source: aalco-303
      where: Fabrication section
    - text: Not hardenable by heat treatment; solution treatment or annealing by rapid cooling after heating to 1010 to 1120 C (Aalco).
      source: aalco-303
      where: Heat Treatment section
    - text: Hot working after uniform heating to 1149 to 1260 C, then rapid cooling of the fabricated components for maximum corrosion resistance (Aalco).
      source: aalco-303
      where: Hot Working section
    - text: Type 303 is not readily cold workable, and sharp bending should not be attempted (Aalco).
      source: aalco-303
      where: Cold Working section
  mitigations:
    - text: If 303 must be welded, use 308L or 309 stainless steel filler rods or electrodes (Aalco).
      source: aalco-303
      where: Welding section
    - text: Anneal the welds for maximum corrosion resistance (Aalco).
      source: aalco-303
      where: Welding section
uses:
  - application: structures
    device: Nuts, bolts and screws
    example: Aalco lists nuts and bolts and screws among the applications that need parts heavily machined.
    source: aalco-303
    where: Applications list
  - application: structures
    device: Aircraft fittings
    example: UPMET lists aircraft applications including fittings, shafts and spindles; Aalco lists aircraft fittings.
    source: upmet-303
    where: Industry Applications list
  - application: mechanisms
    device: Shafts, gears and bushings
    example: Aalco lists gears, bushings and shafts; UPMET lists shafts and spindles.
    source: aalco-303
    where: Applications list
  - application: mechanisms
    device: Automatic screw machine parts
    example: UPMET lists automatic screw machine applications; Rolled Alloys also lists automatic screw machines.
    source: upmet-303
    where: Industry Applications list
supply:
  - subject: Chromium production by country
    abundance: World mine production was 51,000 thousand metric tons (gross weight) in 2025e, against 49,600 in 2024. World resources are greater than 12 billion tons of shipping-grade chromite, 95 percent in Kazakhstan and southern Africa. Shares are for the six largest producers, computed from the printed 2025e tonnage over the 51,000 world total.
    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
      - country: Brazil
        share_percent: 3.9
        year: 2025
      - country: Zimbabwe
        share_percent: 3.9
        year: 2025
    critical_lists: []
    recycling: In 2025, recycled chromium in reported stainless-steel scrap receipts accounted for 21 percent of apparent consumption.
    substitutes:
      - Chromium has no substitute in stainless steel, the leading end use (USGS 2026).
    source: usgs-chromium-2026
    where: World Mine Production and Reserves table (2025e column); World Resources; Substitutes; Recycling
  - subject: Chromium import reliance
    abundance: US net import reliance was 79 percent of apparent consumption in 2025e (76 percent in 2021). Chromite ore imports for 2021 to 2024 came from South Africa (96 percent), Turkey (3 percent) and other sources (1 percent).
    producers: []
    critical_lists: []
    substitutes: []
    source: usgs-chromium-2026
    where: Salient Statistics, net import reliance row (2025e); Import Sources (2021-24)
  - subject: Nickel production by country
    abundance: World nickel mine production was an estimated 3.9 million tons in 2025, up 5 percent from 2024. World reserves are printed as more than 140,000,000, of which Indonesia holds 62,000,000. Shares are for the six largest producers, computed from the printed 2025e tonnage over the 3.9 million world total.
    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
      - country: China
        share_percent: 3.1
        year: 2025
    critical_lists: []
    recycling: In 2025, nickel recovered from scrap accounted for approximately 60 percent of apparent consumption.
    substitutes:
      - Low-nickel, duplex, or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction.
      - Titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments.
    source: usgs-nickel-2026
    where: World Mine Production and Reserves table (2025e column); Recycling; Substitutes
  - subject: Nickel use and US import reliance
    abundance: Stainless and alloy steel and nickel-containing alloys typically account for more than 85 percent of domestic consumption. US net import reliance was 41 percent of apparent consumption in 2025e (38 percent in 2021).
    producers: []
    critical_lists: []
    substitutes: []
    source: usgs-nickel-2026
    where: Salient Statistics, net import reliance row (2025e); Domestic Production and Use
media: []
documents:
  - title: 'Outokumpu: Steel Grades, Properties and Global Standards (Tables 4, 5, 7 and 13)'
    type: datasheet
    url: https://www.outokumpu.com/-/media/from-sharepoint/documents/product/outokumpu-steel-grades-properties-global-standards.pdf
  - title: 'Rolled Alloys: 303 Stainless Steel Data Sheet (Bulletin No. 1355)'
    type: datasheet
    url: https://www.rolledalloys.com/wp-content/uploads/303_stainless-steel-data-sheet-rolled-alloys.pdf
  - title: 'United Performance Metals: Datasheet for 303 Stainless Steel Plate (UNS S30300, ASTM-A-895)'
    type: datasheet
    url: https://www.upmet.com/sites/default/files/datasheets/303-.pdf
    year: 2026
  - title: 'Ulbrich: 303 Stainless Steel, UNS S30300 wire data sheet'
    type: datasheet
    url: https://www.ulbrich.com/uploads/data-sheets/303-Stainless-Steel-Wire-UNS-S30300-wire.pdf
    year: 2015
  - title: 'Aalco: Stainless Steel Grade 303 / 1.4305 data sheet (PDF hosted by Farnell)'
    type: datasheet
    url: https://www.farnell.com/datasheets/26031.pdf
  - 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), UN GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON
  - title: 'PubChem: Chromium (CID 23976), UN GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
  - title: 'PubChem: Manganese (CID 23930), UN GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23930/JSON
gaps:
  - 'Weldability comes from one source only (Aalco): the sulphur addition gives poor weldability, with 308L or 309 filler. No weld-metal, weld toughness or weld cracking test was read.'
  - 'Composition conflicts: carbon maximum is 0.15 in Rolled Alloys and Aalco but 0.12 in Ulbrich, which also gives sulphur 0.150 minimum. UPMET prints sulphur 0.15 to 0.35, and its carbon and manganese maxima sit in a column the PDF text does not label, so they are taken from Rolled Alloys and Aalco. Rolled Alloys and Aalco print no sulphur maximum.'
  - 'Density: UPMET prints 7.89 g/cm3 beside 0.289 lb/in3, which does not agree with Ulbrich (8.00 g/cm3) or Aalco (8.03 g/cm3). All four values are kept with their own form.'
  - 'Melting point: Aalco prints one value (1455 C) and Ulbrich prints a range (1400 to 1420 C). UPMET prints 2552 F only, and it is not converted here.'
  - Hardness is not in the canonical property list, so the short name hardness is used. Only UPMET prints a value (202 HBN maximum, plate). Aalco prints 262max against the label Hardness Rockwell (HB), which is ambiguous, so it is not used.
  - EN name X8CrNiS18-9 was not printed on any page read in this run, so the EN entry is the number 1.4305 only.
  - SAE 30303 was not printed on any page read in this run, so it is not listed.
  - The selenium-bearing variant (303Se) was not read and is not listed as an alias.
  - Machinability is given as Rolled Alloys starting speeds and as qualitative statements (Aalco, Rolled Alloys, Ulbrich). No machinability rating index was printed on any page read.
  - Outokumpu typical values apply to hot rolled plate; EN and ASTM minimums are mainly for hot rolled plate in the transverse direction (Table 7 note). Rolled Alloys and Aalco print typical values with no temper. Ulbrich gives annealed values for wire.
  - Elevated-temperature and cryogenic strength values for 303 were not read. Poisson's ratio, shear modulus and bulk modulus were not printed on the pages read.
  - Corrosion ratings are judgements on printed text, not test results. No pitting resistance number (PREN) was printed on the pages read.
  - No safety data sheet for 303 was read. The hazards are PubChem GHS notifications for elemental nickel, chromium and manganese, not a supplier classification.
  - Supply shares are computed from printed 2025e tonnage; refinery and smelter shares were not read. No EU or BGS critical-mineral list was read, so critical_lists is empty.
  - No NASA or ESA source naming 303 in a spacecraft part was read, so the space link is not sourced.
  - The web search budget for this turn ran out, so no ATI, Carpenter, AK Steel or Cleveland-Cliffs, AZoM or other 303 product page was reached.
sources:
  outokumpu-global:
    title: 'Outokumpu: Steel Grades, Properties and Global Standards (Tables 4, 5, 7 and 13)'
    id: outokumpu-steel-grades-properties-global-standards.pdf
    url: https://www.outokumpu.com/-/media/from-sharepoint/documents/product/outokumpu-steel-grades-properties-global-standards.pdf
    kind: handbook
    license: cited, not reproduced
  rolled-303:
    title: 'Rolled Alloys: 303 Stainless Steel Data Sheet (Bulletin No. 1355)'
    id: 303_stainless-steel-data-sheet-rolled-alloys.pdf
    url: https://www.rolledalloys.com/wp-content/uploads/303_stainless-steel-data-sheet-rolled-alloys.pdf
    kind: datasheet
    license: cited, not reproduced
  upmet-303:
    title: 'United Performance Metals: Datasheet for 303 Stainless Steel Plate (UNS S30300, ASTM-A-895)'
    id: 303-.pdf
    url: https://www.upmet.com/sites/default/files/datasheets/303-.pdf
    kind: datasheet
    year: 2026
    license: cited, not reproduced
  ulbrich-303:
    title: 'Ulbrich: 303 Stainless Steel, UNS S30300 wire data sheet'
    id: 303-Stainless-Steel-Wire-UNS-S30300-wire.pdf
    url: https://www.ulbrich.com/uploads/data-sheets/303-Stainless-Steel-Wire-UNS-S30300-wire.pdf
    kind: datasheet
    year: 2015
    license: cited, not reproduced
  aalco-303:
    title: 'Aalco: Stainless Steel Grade 303 / 1.4305 data sheet (PDF hosted by Farnell)'
    id: 26031.pdf
    url: https://www.farnell.com/datasheets/26031.pdf
    kind: datasheet
    license: cited, not reproduced
  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), UN GHS classification'
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON
    kind: database
    license: PubChem terms (public)
  pubchem-chromium:
    title: 'PubChem: Chromium (CID 23976), UN GHS classification'
    id: CID 23976
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
    kind: database
    license: PubChem terms (public)
  pubchem-manganese:
    title: 'PubChem: Manganese (CID 23930), UN GHS classification'
    id: CID 23930
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23930/JSON
    kind: database
    license: PubChem terms (public)
license: CC-BY-4.0
updated: '2026-10-24'
review:
  status: draft
  method: assistant
  checked_values: 34
  unreachable: 0
  caveats: 5
  note: 'Read by an AI assistant on 2026-10-24 from pages fetched in this run: Outokumpu global standards PDF (Tables 4, 5, 7 and 13), Rolled Alloys 303 data sheet, UPMET 303 data sheet, Ulbrich 303 wire data sheet, Aalco 1.4305 data sheet (PDF hosted by Farnell), USGS Mineral Commodity Summaries 2026 (nickel and chromium), and PubChem records for nickel, chromium and manganese. The web search budget for this turn was used up, so no other 303 page was read.'
story:
  recipe:
    line: Type 303 is an iron-based austenitic stainless steel with 17.0 to 19.0 percent chromium and 8.0 to 10.0 percent nickel. Sulphur, at least 0.15 percent, is the free-machining addition (Rolled Alloys, Ulbrich, Aalco). The figures are datasheet limits in weight percent, not one heat's analysis.
    parts:
      - name: Iron
        symbol: Fe
        share_note: balance
        role: The matrix of the alloy; Rolled Alloys calls 303 a non-magnetic austenitic stainless steel.
      - name: Chromium
        symbol: Cr
        share_percent: 17
        share_high: 19
        source: rolled-303
        where: Chemical Composition table, MIN and MAX rows
        role: Chromium content of the basic 18 percent chromium, 8 percent nickel grade (Rolled Alloys).
      - name: Nickel
        symbol: Ni
        share_percent: 8
        share_high: 10
        source: rolled-303
        where: Chemical Composition table, MIN and MAX rows
        role: Nickel content of the basic 18 percent chromium, 8 percent nickel grade (Rolled Alloys).
      - name: Carbon
        symbol: C
        share_percent: 0
        share_high: 0.15
        source: rolled-303
        where: Chemical Composition table, MAX row
        role: Maximum limit only (Rolled Alloys and Aalco); Ulbrich prints 0.12.
      - name: Manganese
        symbol: Mn
        share_percent: 0
        share_high: 2
        source: rolled-303
        where: Chemical Composition table, MAX row
        role: Maximum limit only; the datasheets print no role for it.
      - name: Silicon
        symbol: Si
        share_percent: 0
        share_high: 1
        source: rolled-303
        where: Chemical Composition table, MAX row
        role: Maximum limit only; the datasheets print no role for it.
      - name: Phosphorus
        symbol: P
        share_percent: 0
        share_high: 0.2
        source: rolled-303
        where: Chemical Composition table, MAX row
        role: Maximum limit only; the datasheets print no role for it.
      - name: Sulphur
        symbol: S
        share_percent: 0.15
        share_note: minimum; UPMET prints a maximum of 0.35
        source: rolled-303
        where: Chemical Composition table, MIN row
        role: Free-machining addition. It gives the machinability and costs corrosion resistance (Aalco).
      - name: Molybdenum
        symbol: Mo
        share_percent: 0
        share_high: 0.6
        source: rolled-303
        where: Chemical Composition table, MAX row (optional)
        role: Optional element, maximum 0.6 (Rolled Alloys).
  risk_groups:
    - title: For people
      level: 1
      verdict: No SDS read; element notifications only
      lead: The PubChem records are for elemental nickel, chromium and manganese, not for the 303 alloy. No safety data sheet for 303 was read.
      points:
        - label: Nickel
          line: PubChem lists elemental nickel with H317, H351, H372, H334 and H412 in its aggregated notifications.
        - label: Chromium
          line: PubChem lists elemental chromium with H317, H319, H334 and H341 in its notifications.
        - label: Manganese
          line: PubChem lists elemental manganese with H372, H360, H370, H228 and H411 in its notifications.
    - title: In the environment
      level: 3
      verdict: Chloride and marine service are the watch points
      lead: Pitting at the sulphur additions is the main failure route. Aalco says 303 is not suitable for marine environments.
      points:
        - label: Chloride
          line: Aalco says chloride-containing environments over 60 C cause pitting and crevice corrosion.
        - label: Marine
          line: Aalco says grade 303 stainless steel is not suitable for use in marine environments.
    - title: Welding and heat
      level: 2
      verdict: Sulphur and heat history set the risk
      lead: Aalco calls the weldability poor because of the sulphur addition, and says continuous use at 425 to 860 C causes carbide precipitation.
      points:
        - label: Welding
          line: The sulphur addition results in poor weldability. Use 308L or 309 filler, and anneal the welds for maximum corrosion resistance.
        - label: Heat
          line: Sensitive to carbide precipitation with continuous use at 425 to 860 C. Continuous service at 870 C is not recommended.
  why: Type 303 is the free-machining version of the basic 18 percent chromium, 8 percent nickel stainless steel. Sulphur makes it the most readily machined of the austenitic grades (Aalco), and the price is lower corrosion resistance than 304 and poor weldability (Aalco). Aalco says the toughness is still excellent, though sulphur lowers it slightly. Rolled Alloys says the grade is non-magnetic and not hardenable by heat treatment.
  uses:
    - where: Nuts, bolts and screws
      line: Aalco lists them among the applications that need parts heavily machined.
    - where: Aircraft fittings, shafts and spindles
      line: UPMET lists aircraft applications including fittings, shafts and spindles; Aalco lists aircraft fittings.
    - where: Gears and bushings
      line: Aalco lists gears and bushings among its typical applications.
    - where: Automatic screw machine parts
      line: UPMET lists automatic screw machine applications, and Rolled Alloys lists automatic screw machines.
  can_do:
    - label: Strength
      benchmark: ultimate_tensile_strength
      line: Ulbrich gives a 517 MPa minimum for annealed wire. Aalco gives a typical 500 MPa for bar.
    - label: Yield
      benchmark: yield_strength
      line: Ulbrich gives a 172 MPa minimum for annealed wire. Outokumpu gives minimums of 190 MPa (EN) and 205 MPa (ASTM) for hot rolled plate.
    - label: Stiffness
      benchmark: elastic_modulus
      line: Elastic modulus is 193 GPa (Aalco) and 200 GPa at room temperature (Outokumpu).
    - label: Density
      benchmark: density
      line: Density is 7.89 g/cm3 (UPMET) to 8.03 g/cm3 (Aalco) across the datasheets; Ulbrich gives 8.00 g/cm3.
    - label: Machining
      line: Rolled Alloys gives starting speeds of 65 to 75 sfpm for twist drills in annealed type 303, at feeds of 0.0045 to 0.0055 inch per revolution.
  compare: Against 304, type 303 machines more readily, which Aalco ties to its sulphur, and it resists corrosion less, because sulphur gives pitting initiation sites (Aalco). Aalco also calls its weldability poor. Rolled Alloys says 303 has improved machinability over 304/304L and 316/316L. No 304 or 316 composition or property values were read in this run, so none are compared as numbers.
  compare_rows:
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
  handling:
    - Keep cutting edges sharp and use light but deep cuts with chip breakers; use coolants and lubricants in large quantities (Aalco).
    - Rolled Alloys gives starting speeds of 65 to 75 sfpm for twist drills on annealed type 303, at feeds of 0.0045 to 0.0055 inch per revolution.
    - Use tooling dedicated to stainless steel (Aalco).
    - Not hardenable by heat treatment; anneal by rapid cooling from 1010 to 1120 C (Aalco).
    - If it must be welded, use 308L or 309 filler and anneal the welds (Aalco).
  good_for:
    - Heavily machined parts such as nuts, bolts, screws, shafts, bushings and gears (Aalco, UPMET).
    - Automatic screw machine work and aircraft fittings (UPMET).
    - Mild-environment parts, where Aalco says corrosion resistance remains good.
  watch_out:
    - 'Chloride above 60 C and marine service: pitting and crevice corrosion, and Aalco says 303 is not suitable for marine environments.'
    - 'Welding: Aalco says the sulphur addition gives poor weldability.'
    - 'Continuous use at 425 to 860 C: sensitive to carbide precipitation (Aalco).'
    - 'Cold bending: not readily cold workable, and sharp bending should not be attempted (Aalco).'
  verdict: Aalco calls 303 the most readily machined of the austenitic grades. Its sulphur costs corrosion resistance below 304 and weldability, so use it for machined parts in mild service and not for marine use.