spore: profile
id: stainless-409
spore_version: 0.2
family: stainless-ferritic
name: Stainless steel 409
abbreviation: 409 (UNS S40900, EN 1.4512)
role: exhaust and muffler stainless steel
category: metals
type: steels-and-stainless
summary: Grade 409 (EN 1.4512) is a titanium-stabilised ferritic chromium steel with about 10.5 to 11.75 percent chromium. Aalco calls it muffler grade stainless steel because most of its bulk use is in automotive exhaust systems. Combined Metals also lists heat exchangers as a use, where corrosion protection is needed beyond carbon steel.
best_for: Automotive exhaust systems and heat exchangers, where corrosion protection is needed beyond carbon steel (Combined Metals)
weakest_at: 'Pitting and intergranular corrosion: Outokumpu prints a critical pitting temperature below 10 °C and N/N for intergranular corrosion, and Aalco limits welded sheet to about 2.5 mm thick'
identity:
  formula: 'Fe balance; Cr 10.500 to 11.750, C max 0.080, Mn max 1.000, Si max 1.000, P max 0.045, S max 0.030, Mo max 0.350, Ni max 0.500, Cu max 0.350, Ti max 0.750 (wt%, ASTM A240 listing for UNS S40900, ICAST); Combined Metals sheet for UNS S40910, S40920 and S40930: C max 0.030, Cr 10.50 to 11.70, Mn max 1.0, Si max 1.00, P max 0.040, S max 0.020, Ni max 0.50, N max 0.030; EN 10088-2 limits (Aalco): Cr 10.50 to 12.50, Ti 0.0 to 0.65'
  source: icast-as409
  where: Chemical Composition table (Cr 10.500 to 11.750) and Cross Reference Table (A240 UNS S40900); Combined Metals Nominal Composition table; Aalco Chemical Composition table
  designations:
    - system: UNS
      code: S40900
      source: icast-as409
      where: Cross Reference Table, A240 UNS S40900 row
    - system: UNS
      code: S40910
      note: one of three UNS numbers on the 409 sheet
      source: combmet-409
      where: Header, UNS S40910/S40920/S40930
    - system: UNS
      code: S40920
      note: one of three UNS numbers on the 409 sheet
      source: combmet-409
      where: Header, UNS S40910/S40920/S40930
    - system: UNS
      code: S40930
      note: one of three UNS numbers on the 409 sheet
      source: combmet-409
      where: Header, UNS S40910/S40920/S40930
    - system: EN
      code: '1.4512'
      source: outokumpu-xref
      where: Table 2, 4512 row, EN column
    - system: EN name
      code: X2CrTi12
      source: aperam-409a
      where: Norms, alphanumerical designation
    - system: ASTM
      code: A240
      note: plate, sheet and strip
      source: icast-as409
      where: Cross Reference Table, A240 UNS S40900 row; specification title
    - system: ASME
      code: SA-240
      note: UNS S40900
      source: icast-as409
      where: Cross Reference Table, SA-240 UNS S40900 row
    - system: AISI
      code: '409'
      source: aperam-409a
      where: Norms, AISI 409
    - system: JIS
      code: SUS409
      source: outokumpu-xref
      where: Table 2, JIS column, 4512 row
    - system: JIS
      code: SUH409
      source: icast-as409
      where: Cross Reference Table, JIS row (SUH 409)
    - system: BS
      code: 409S19
      source: outokumpu-xref
      where: Table 3, BS/UK column, 4512 row (409S 19)
    - system: AFNOR
      code: Z3 CT12
      source: outokumpu-xref
      where: Table 3, NF/France column, 4512 row
    - system: Trade name
      code: muffler grade stainless steel
      source: aalco-1-4512
      where: Introduction paragraph
tags:
  environments: []
  stresses: []
  applications:
    - structures
    - thermal-control
properties:
  - benchmark: density
    value: 7.75
    unit: g/cm3
    scope: material
    conditions:
      form: 409 sheet (Combined Metals data sheet, ASTM A240 basis)
      temperature: 20 C (At 20C column)
    method: Physical Properties table, At 20C column, printed as 7.75 g/cm3 (0.280 lb/in3 at 70 F)
    status: ground
    source: combmet-409
    where: Physical Properties table (Density row, At 20C column)
    label: Density at 20 C (Combined Metals)
  - benchmark: elastic_modulus
    value: 208.22
    unit: GPa
    scope: material
    conditions:
      form: 409 sheet (Combined Metals data sheet)
      temperature: 20 C (At 20C column)
      unit_in_source: 208.22 x 10^3 MPa, printed as 208.22 x 103 MPa
    method: Physical Properties table, Modulus of Elasticity row, At 20C column; 208.22 x 10^3 MPa is the same number as 208.22 GPa
    status: ground
    source: combmet-409
    where: Physical Properties table (Modulus of Elasticity row, At 20C column)
    label: Modulus of elasticity at 20 C (Combined Metals)
  - benchmark: electrical_resistivity
    value: 60
    unit: micro-ohm-cm
    scope: material
    conditions:
      form: 409 sheet (Combined Metals data sheet)
      temperature: 20 C (At 20C column)
    method: Physical Properties table, Electrical Resistivity row, At 20C column, printed as 60 μ ohm.cm
    status: ground
    source: combmet-409
    where: Physical Properties table (Electrical Resistivity row, At 20C column)
    label: Electrical resistivity at 20 C (Combined Metals)
  - benchmark: yield_strength
    value: 170
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: 409 sheet, ASTM A240 basis (Combined Metals data sheet)
      temper: annealed (Min)
      temperature: room temperature (typical room temperature table)
      basis: 0.2 percent offset, minimum
    method: Typical Room Temperature Mechanical Properties table, Annealed (Min) row, 0.2% YS Min column, printed as 25 ksi (170 MPa)
    status: ground
    source: combmet-409
    where: Typical Room Temperature Mechanical Properties table (Annealed (Min) row, 0.2% YS Min column)
    label: Annealed minimum 0.2% yield strength (Combined Metals)
  - benchmark: ultimate_tensile_strength
    value: 380
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: 409 sheet, ASTM A240 basis (Combined Metals data sheet)
      temper: annealed (Min)
      temperature: room temperature (typical room temperature table)
    method: Typical Room Temperature Mechanical Properties table, Annealed (Min) row, Tensile Strength Min column, printed as 55 ksi (380 MPa)
    status: ground
    source: combmet-409
    where: Typical Room Temperature Mechanical Properties table (Annealed (Min) row, Tensile Strength Min column)
    label: Annealed minimum tensile strength (Combined Metals)
  - benchmark: elongation
    value: 20
    unit: '%'
    bound: lower
    scope: material
    conditions:
      form: 409 sheet, ASTM A240 basis (Combined Metals data sheet)
      temper: annealed (Min)
      temperature: room temperature (typical room temperature table)
      gauge: 2 in (50.8 mm)
    method: Typical Room Temperature Mechanical Properties table, Annealed (Min) row, Elongation Min column, printed as 20% in 2 in (50.8 mm)
    status: ground
    source: combmet-409
    where: Typical Room Temperature Mechanical Properties table (Annealed (Min) row, Elongation column)
    label: Annealed minimum elongation in 2 in (Combined Metals)
  - benchmark: hardness
    value: 88
    unit: HRB
    bound: upper
    scope: material
    conditions:
      form: 409 sheet, ASTM A240 basis (Combined Metals data sheet)
      temper: annealed (row labelled Annealed (Min); hardness printed as a maximum)
      temperature: room temperature (typical room temperature table)
      scale: Rockwell B (HRBW printed)
    method: Typical Room Temperature Mechanical Properties table, Hardness Rockwell column, Annealed (Min) row, printed as 88 HRBW (Max)
    status: ground
    source: combmet-409
    where: Typical Room Temperature Mechanical Properties table (Hardness Rockwell column, Annealed (Min) row)
    label: Annealed maximum hardness, Rockwell B (Combined Metals)
  - benchmark: density
    value: 7.6
    unit: g/cm3
    scope: material
    conditions:
      form: 409 / 1.4512 sheet (Aalco datasheet, EN 10088-2:2005 basis, indicative)
      temperature: not printed
    method: Physical Property table, Density row, printed as 7.6 g/cm³
    status: ground
    source: aalco-1-4512
    where: Physical Property table (Density row)
    label: Density (Aalco)
  - benchmark: elastic_modulus
    value: 208
    unit: GPa
    scope: material
    conditions:
      form: 409 / 1.4512 sheet (Aalco datasheet, EN 10088-2:2005 basis, indicative)
      temperature: not printed
    method: Physical Property table, Modulus of Elasticity row, printed as 208 GPa
    status: ground
    source: aalco-1-4512
    where: Physical Property table (Modulus of Elasticity row)
    label: Modulus of elasticity (Aalco)
  - benchmark: thermal_conductivity
    value: 25.8
    unit: W/m.K
    scope: material
    conditions:
      form: 409 / 1.4512 sheet (Aalco datasheet, EN 10088-2:2005 basis, indicative)
      temperature: not printed
    method: Physical Property table, Thermal Conductivity row, printed as 25.8 W/m.K
    status: ground
    source: aalco-1-4512
    where: Physical Property table (Thermal Conductivity row)
    label: Thermal conductivity (Aalco)
  - benchmark: yield_strength
    value: 210
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: sheet up to 8 mm thick (EN 10088-2:2005)
      temperature: not printed
      basis: proof stress, minimum
    method: Mechanical Property table, sheet up to 8 mm, Proof Stress row, printed as 210 Min MPa
    status: ground
    source: aalco-1-4512
    where: Mechanical Property table, sheet up to 8 mm (Proof Stress row)
    label: Proof stress minimum, sheet up to 8 mm (Aalco)
  - benchmark: ultimate_tensile_strength
    value: 380
    value_high: 560
    bound: range
    unit: MPa
    scope: material
    conditions:
      form: sheet up to 8 mm thick (EN 10088-2:2005)
      temperature: not printed
    method: Mechanical Property table, sheet up to 8 mm, Tensile Strength row, printed as 380 - 560 MPa
    status: ground
    source: aalco-1-4512
    where: Mechanical Property table, sheet up to 8 mm (Tensile Strength row)
    label: Tensile strength range, sheet up to 8 mm (Aalco)
  - benchmark: elongation
    value: 25
    unit: '%'
    bound: lower
    scope: material
    conditions:
      form: sheet up to 8 mm thick (EN 10088-2:2005)
      temperature: not printed
      gauge: A50 mm
    method: Mechanical Property table, sheet up to 8 mm, Elongation A50 mm row, printed as 25 Min %
    status: ground
    source: aalco-1-4512
    where: Mechanical Property table, sheet up to 8 mm (Elongation A50 mm row)
    label: Elongation A50 minimum, sheet up to 8 mm (Aalco)
  - benchmark: density
    value: 7.7
    unit: g/cm3
    scope: material
    conditions:
      temperature: room temperature (RT)
      unit_in_source: kg/dm3 (1 kg/dm3 = 1 g/cm3, so the number is unchanged)
    method: Table 12 (Physical properties), 4512 row, density RT column, printed as 7.7 kg/dm3
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, density RT column
    label: Density at room temperature (Outokumpu)
  - benchmark: elastic_modulus
    value: 220
    unit: GPa
    scope: material
    conditions:
      temperature: room temperature (RT)
    method: Table 12, 4512 row, modulus of elasticity RT column, printed as 220 GPa
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, modulus of elasticity RT column
    label: Modulus of elasticity at room temperature (Outokumpu)
  - benchmark: thermal_conductivity
    value: 25
    unit: W/m°C
    scope: material
    conditions:
      temperature: room temperature (RT)
    method: Table 12, 4512 row, thermal conductivity RT column, printed as 25 W/m°C
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, thermal conductivity RT column
    label: Thermal conductivity at room temperature (Outokumpu)
  - benchmark: specific_heat
    value: 460
    unit: J/kg°C
    scope: material
    conditions:
      temperature: room temperature (RT)
    method: Table 12, 4512 row, thermal capacity RT column, printed as 460 J/kg°C
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, thermal capacity RT column
    label: Specific heat at room temperature (Outokumpu)
  - benchmark: cte
    value: 10.5
    unit: 10-6/°C
    scope: material
    conditions:
      temperature: 20 C to 100 C (CTE between 20 C and T, 100 C column)
    method: Table 12, 4512 row, CTE between 20 C and 100 C column, printed as 10.5 (10-6 per C)
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, CTE 100 C column
    label: Coefficient of thermal expansion, 20 to 100 C (Outokumpu)
  - benchmark: cte
    value: 12
    unit: 10-6/°C
    scope: material
    conditions:
      temperature: 20 C to 400 C (CTE between 20 C and T, 400 C column)
    method: Table 12, 4512 row, CTE between 20 C and 400 C column, printed as 12.0 (10-6 per C)
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, CTE 400 C column
    label: Coefficient of thermal expansion, 20 to 400 C (Outokumpu)
  - benchmark: electrical_resistivity
    value: 0.6
    unit: μΩm
    scope: material
    conditions:
      temperature: room temperature (RT)
    method: Table 12, 4512 row, electrical resistivity RT column, printed as 0.60 μΩm
    status: ground
    source: outokumpu-xref
    where: Table 12, 4512 row, electrical resistivity RT column
    label: Electrical resistivity at room temperature (Outokumpu)
  - benchmark: yield_strength
    value: 255
    unit: MPa
    scope: material
    conditions:
      form: cold rolled coil and sheet (Outokumpu product code C)
      temperature: room temperature (RT)
      basis: Outokumpu typical value, Rp0.2
    method: Table 6 (Mechanical properties, room temperature), 4512 row, product C, typical Rp0.2 column, printed as 255 MPa
    status: ground
    source: outokumpu-xref
    where: Table 6, 4512 row, typical Rp0.2 column
    label: Typical 0.2% proof stress, cold rolled sheet (Outokumpu)
  - benchmark: ultimate_tensile_strength
    value: 425
    unit: MPa
    scope: material
    conditions:
      form: cold rolled coil and sheet (Outokumpu product code C)
      temperature: room temperature (RT)
      basis: Outokumpu typical value
    method: Table 6, 4512 row, product C, typical Rm column, printed as 425 MPa
    status: ground
    source: outokumpu-xref
    where: Table 6, 4512 row, typical Rm column
    label: Typical tensile strength, cold rolled sheet (Outokumpu)
  - benchmark: elongation
    value: 33
    unit: '%'
    scope: material
    conditions:
      form: cold rolled coil and sheet (Outokumpu product code C)
      temperature: room temperature (RT)
      gauge: A5
      basis: Outokumpu typical value
    method: Table 6, 4512 row, product C, typical A5 column, printed as 33 %
    status: ground
    source: outokumpu-xref
    where: Table 6, 4512 row, typical A5 column
    label: Typical elongation A5, cold rolled sheet (Outokumpu)
  - benchmark: yield_strength
    value: 220
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: EN 10088 minimum values, mainly hot rolled plate in the transverse direction (Table 6 note)
      temperature: room temperature (RT)
      basis: EN minimum Rp0.2
    method: Table 6, 4512 row, EN min Rp0.2 column, printed as 220 MPa
    status: ground
    source: outokumpu-xref
    where: Table 6, 4512 row, EN min Rp0.2 column
    label: EN minimum 0.2% proof stress at room temperature (Outokumpu)
  - benchmark: yield_strength
    value: 200
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: EN minimum values, mainly hot rolled plate (Table 8 note)
      temperature: 100 C
      basis: EN minimum Rp0.2
    method: Table 8 (Mechanical properties, elevated temperatures), 4512 row, EN min Rp0.2 MPa, 100 C column, printed as 200
    status: ground
    source: outokumpu-xref
    where: Table 8, 4512 row, 100 C column
    label: EN minimum 0.2% proof stress at 100 C (Outokumpu)
  - benchmark: yield_strength
    value: 190
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: EN minimum values, mainly hot rolled plate (Table 8 note)
      temperature: 200 C
      basis: EN minimum Rp0.2
    method: Table 8 (Mechanical properties, elevated temperatures), 4512 row, EN min Rp0.2 MPa, 200 C column, printed as 190
    status: ground
    source: outokumpu-xref
    where: Table 8, 4512 row, 200 C column
    label: EN minimum 0.2% proof stress at 200 C (Outokumpu)
  - benchmark: critical_pitting_temperature
    value: 10
    unit: °C
    bound: upper
    scope: material
    conditions:
      test: potentiostatic at +700 mV SCE with the Avesta cell, footnote 7
      electrolyte: 1 M NaCl
      surface: ground to P 320 (ASTM G 150)
      printed: < 10
    method: Table 14 (Fabrication and use characteristics), 4512 row, CPT column, printed as < 10 °C; footnote 7 gives the test
    status: ground
    source: outokumpu-xref
    where: Table 14, 4512 row, CPT column (footnote 7)
    label: Critical pitting temperature, Avesta cell test (Outokumpu)
  - benchmark: yield_strength
    value: 205
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: plate, sheet and strip, ASTM A240 listing for UNS S40900 (AS 409 data sheet)
      temperature: not printed
      basis: minimum; heat treatment printed as annealing or hardening plus tempering, not tied to one condition
    method: Mechanical Properties table (AS 409 data sheet), Yield Strength in Mpa row, printed as 205 min.
    status: ground
    source: icast-as409
    where: Mechanical Properties table (Yield Strength row)
    label: Minimum yield strength, ASTM A240 listing for S40900 (ICAST)
  - benchmark: ultimate_tensile_strength
    value: 380
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: plate, sheet and strip, ASTM A240 listing for UNS S40900 (AS 409 data sheet)
      temperature: not printed
      basis: minimum; heat treatment printed as annealing or hardening plus tempering, not tied to one condition
    method: Mechanical Properties table (AS 409 data sheet), Tensile Strength in Mpa row, printed as 380 min.
    status: ground
    source: icast-as409
    where: Mechanical Properties table (Tensile Strength row)
    label: Minimum tensile strength, ASTM A240 listing for S40900 (ICAST)
  - benchmark: elongation
    value: 20
    unit: '%'
    bound: lower
    scope: material
    conditions:
      form: plate, sheet and strip, ASTM A240 listing for UNS S40900 (AS 409 data sheet)
      temperature: not printed
      basis: minimum; heat treatment printed as annealing or hardening plus tempering, not tied to one condition
    method: Mechanical Properties table (AS 409 data sheet), Elongation in % row, printed as 20 min.
    status: ground
    source: icast-as409
    where: Mechanical Properties table (Elongation row)
    label: Minimum elongation, ASTM A240 listing for S40900 (ICAST)
  - benchmark: hardness
    value: 80
    unit: HB
    bound: lower
    scope: material
    conditions:
      form: plate, sheet and strip, ASTM A240 listing for UNS S40900 (AS 409 data sheet)
      temperature: not printed
      scale: Brinell (HB printed)
      basis: minimum; heat treatment printed as annealing or hardening plus tempering
    method: Mechanical Properties table (AS 409 data sheet), Hardness in HB row, printed as 80 min.
    status: ground
    source: icast-as409
    where: Mechanical Properties table (Hardness row)
    label: Minimum hardness, ASTM A240 listing for S40900 (ICAST)
corrosion:
  - environment: General use against carbon steel (no test data given)
    headline: Combined Metals says 409 is used where corrosion protection is needed beyond carbon steel.
    effect: Combined Metals says 409 stainless steel is used when corrosion protection is needed beyond a carbon steel capacity, and lists automotive exhaust systems and heat exchangers as its applications. The sheet gives no corrosion test data.
    rating: unknown
    source: combmet-409
    where: Introduction text (Applications include)
  - environment: Chloride pitting (critical pitting temperature test)
    headline: Outokumpu's test gives a critical pitting temperature below 10 °C for 409, the same mark it prints for 430 and 304.
    effect: 'Outokumpu''s Table 14 prints the critical pitting temperature (CPT) of 4512 as < 10 °C. Footnote 7 gives the method: potentiostatic testing at +700 mV SCE with the Avesta cell in 1 M NaCl, on surfaces ground to P 320 (ASTM G 150); other methods give other values. The same table prints < 10 for 430 (4016) and for 304 (4301). Table 2 gives typical chromium of 11.5 percent for 409, 16.2 for 430 and 18.1 for 304, and typical nickel of 0.2 for 409 and 8.1 for 304.'
    rating: moderate
    conditions:
      test: potentiostatic, +700 mV SCE, Avesta cell
      electrolyte: 1 M NaCl
      surface: ground to P 320 (ASTM G 150)
    source: outokumpu-xref
    where: Table 14, 4512 row, CPT column (footnote 7); Table 2 typical composition
  - environment: Intergranular corrosion, delivery and welded condition (EN ISO 3651-2)
    headline: Outokumpu prints N/N for 409 for intergranular corrosion, which its legend reads as no in both delivery and welded condition.
    effect: Outokumpu's Table 14 prints N/N for 4512 in the intergranular corrosion column. Footnote 6 says the test follows EN 10088-2 and EN ISO 3651-2, and that Y means yes and N means no for the delivery and welded conditions. For 430 (4016) the same column prints Y/N, and for 304 (4301) Y/N*, where the Table 15 note says the asterisk means it may be multi-certified as Y/Y. The source does not explain the 409 marks, so they are reported as printed.
    rating: moderate
    conditions:
      standard: EN 10088-2, tested to EN ISO 3651-2
      condition: delivery and welded
    source: outokumpu-xref
    where: Table 14, 4512 row, intergranular corrosion column (footnote 6); Table 15 note (asterisk)
risks:
  hazards:
    - text: PubChem's aggregated GHS notifications for elemental chromium (CID 23976) give H317 (20.7%), H319 (19.1%) and H334 (20.3%, signal word Danger), and also list H320, H335, H341, H371, H400 and H410. The record is for chromium, not for the 409 alloy.
      ghs:
        - H317
        - H319
        - H320
        - H334
        - H335
        - H341
        - H371
        - H400
        - H410
      source: pubchem-chromium
      where: Safety and Hazards, GHS Classification (CID 23976)
    - text: PubChem says the chemical does not meet GHS hazard criteria for 50% (1202 of 2404) of the company reports.
      ghs: []
      source: pubchem-chromium
      where: Safety and Hazards, GHS Classification (CID 23976)
  failure_risks:
    - mode: Pitting in chloride solution
      trigger: Chloride exposure, tested at +700 mV SCE in 1 M NaCl
      consequence: Critical pitting temperature printed as below 10 °C for 409, and the same mark for 430 and 304 in the same table, so the test does not separate the grades.
      severity: moderate
      source: outokumpu-xref
      where: Table 14, CPT column (footnote 7)
    - mode: Intergranular corrosion in delivery or welded condition
      trigger: Delivery, or welding of 409
      consequence: Outokumpu prints N (no) for both the delivery and welded condition in its intergranular corrosion column for 4512.
      severity: moderate
      source: outokumpu-xref
      where: Table 14, intergranular corrosion column (footnote 6)
    - mode: Weld thickness limit
      trigger: Welding material thicker than about 2.5 mm
      consequence: Aalco says weldability is good up to about 2.5 mm thick and advises grade 1.4003 where thicker welded material is needed.
      severity: moderate
      source: aalco-1-4512
      where: Weldability section
  side_effects: []
  handling:
    - text: Anneal at 800 ± 30 °C; A in the source means annealing (Outokumpu Table 14, heat treatment temperature column).
      source: outokumpu-xref
      where: Table 14, 4512 row, heat treatment temperature column (footnote 1)
    - text: Outokumpu lists 13 or 19 9L as welding consumables for 4512 (covered electrodes to ISO 3581 or ISO 14172).
      source: outokumpu-xref
      where: Table 14, welding consumables column (footnote 2)
    - text: Aalco says welding is good up to about 2.5 mm thick and advises grade 1.4003 for thicker material.
      source: aalco-1-4512
      where: Weldability section
  mitigations:
    - text: For thicker welded parts, use grade 1.4003, which Aalco says is available in thicker sheets and plates.
      source: aalco-1-4512
      where: Weldability section and supplied forms
    - text: Choose the welding consumable from the 13 or 19 9L group that Outokumpu lists for 4512.
      source: outokumpu-xref
      where: Table 14, welding consumables column
uses:
  - application: structures
    device: Automotive exhaust systems, mufflers and pipes
    example: Aalco calls 409 'muffler grade stainless steel' because the major bulk usage of the material is for automotive exhaust systems.
    source: aalco-1-4512
    where: Introduction paragraph
  - application: structures
    device: Exhaust manifolds, down-pipes, converter casings and mufflers
    example: 'Aperam''s 409A (extra low carbon) product page lists automotive exhaust systems: manifolds, down-pipes, converter casings and mufflers. The list is cited for its 409A product.'
    source: aperam-409a
    where: Applications section
  - application: thermal-control
    device: Heat exchangers
    example: Combined Metals lists automotive exhaust systems and heat exchangers as applications for its 409 sheet.
    source: combmet-409
    where: Introduction text (Applications include)
supply:
  - subject: Chromium
    abundance: World mine production 51,000 thousand t gross weight in 2025 (estimated, world total rounded); world resources greater than 12 billion tons of shipping-grade chromite, 95 percent in Kazakhstan and southern Africa. US net import reliance 79 percent of apparent consumption in 2025 (estimated).
    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
      - country: Finland
        share_percent: 3.7
        year: 2025
    critical_lists: []
    recycling: Recycled chromium in reported stainless-steel scrap receipts was 21 percent of US apparent consumption in 2025.
    substitutes:
      - Chromium has no substitute in stainless steel, the leading end use (USGS 2026).
    source: usgs-cr-2026
    where: World Mine Production and Reserves table (2025e, gross weight; shares calculated from the printed tonnage over the 51,000 world total); Salient Statistics (net import reliance); Recycling; Substitutes
media: []
documents:
  - title: 'Combined Metals: Alloy 409 Stainless Steel data sheet (rev. 2024 01 11)'
    type: datasheet
    url: https://www.combmet.com/wp-content/uploads/2024/01/409-Stainless-Steel-Alloy-Data-Sheet-2024-01-11.pdf
    year: 2024
  - title: 'Aalco: Stainless Steel - Ferritic - 1.4512 Sheet (datasheet page)'
    type: datasheet
    url: https://www.aalco.co.uk/datasheets/Stainless-Steel-14512-Sheet_313.ashx
  - title: 'Outokumpu: Steel Grades, Properties and Global Standards (Tables 2, 3, 6, 8, 12, 14 and 15)'
    type: datasheet
    url: https://www.outokumpu.com/-/media/from-sharepoint/documents/product/outokumpu-steel-grades-properties-global-standards.pdf
  - title: 'Aperam: 409A - 1.4512 product page (extra low carbon, norms and applications)'
    type: datasheet
    url: https://www.aperam.com/product/409a-1-4512/
  - title: 'ICAST Alloys: AS 409 material data sheet (ASTM A240 listing, cross-reference table)'
    type: datasheet
    url: https://www.icastllp.com/material_db_pdf/AS%20409.pdf
  - title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
  - title: 'PubChem: Chromium (CID 23976), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
    year: 2026
gaps:
  - No safety data sheet for 409 was read in this run. The hazard entries rest on the PubChem record for elemental chromium, which is not the alloy. Welding fume and hexavalent-chromium hazards for 409 are not sourced.
  - UNS numbers differ by source. Combined Metals prints S40910, S40920 and S40930 for its 409 sheet, Outokumpu prints a dash for UNS in its 4512 row, and ICAST prints S40900 for A240. The S40900 entry is taken from ICAST and Aperam's 409A norm list, and all UNS numbers are kept as printed.
  - Carbon limit differs. ICAST prints 0.080 maximum for A240 UNS S40900, Combined Metals prints 0.030 maximum for its S40910/S40920/S40930 sheet, and Aalco prints 0.0 to 0.30, which is read as a probable typo and not used. Both maxima appear in identity.formula.
  - Minimum yield strength differs. ICAST prints 205 MPa for the S40900 listing and Combined Metals prints 170 MPa for the annealed condition on the ASTM A240 basis. Both are recorded with their own conditions.
  - 'Titanium: the sources give a titanium limit (ICAST maximum 0.750; Aalco EN 10088-2 0.0 to 0.65), but none explains its metallurgical role. No titanium supply entry is given, because no page read links titanium supply to this grade.'
  - Niobium stabilisation is not sourced for 409. No page read names niobium for this grade.
  - Oxidation and maximum service temperature for 409 are not sourced. The Atlas Steels 409 data sheets (2008 and 2021) returned a bot-verification page and were not opened, and Outokumpu's Table 14 gives no maximum service temperature for 4512.
  - Aperam's 409A page describes an extra-low-carbon product. Its typical composition and its oxidation statements are not used as 409 values. Only its norm list (AISI 409, EN 1.4512, X2CrTi12) and its exhaust application list are used.
  - Outokumpu's typical values for 4512 are for cold rolled coil and sheet (product code C). Its EN minimum values are mainly for hot rolled plate in the transverse direction. Each value carries its own product condition.
  - The intergranular corrosion marks (N/N for 409, Y/N for 430, Y/N* for 304) are reported as printed. The source does not explain the 409 marks.
  - Critical-mineral status of chromium is not established. The USGS 2025 critical minerals page returned a stub, and the EU critical raw materials page read in this run does not name chromium, so critical_lists is empty.
  - Low-temperature (impact) data for 409 are not in the sources read. Outokumpu's low-temperature table has no 4512 row.
  - Fatigue strength, Poisson's ratio, shear and bulk modulus, creep strength and crystal structure are not printed by any source read for 409, so they are not in the file.
  - Exhaust-condensate, road-salt and sea-water corrosion data for 409 were not found in the sources read.
  - Hardness and critical_pitting_temperature are not in spores/property-canon.yaml. Hardness is written on the scale each source prints (HRB or HB), and critical_pitting_temperature is a snake_case name.
  - The exhaust and heat-exchanger uses are not space applications. The closest listed slugs (structures, thermal-control) are used for them, so tags.applications does not describe a space use.
  - 'Media: no photograph or micrograph of 409 was added, because no licensed image was fetched in this run.'
  - 'Sources that could not be used: Suppliers Online (503 error), Atlas Steels (bot check), Continental Steel and ULProspector (stub pages), a guessed Deutsche Edelstahlwerke 1.4512 datasheet URL (returned a general product page with no 1.4512 data), and the USGS 2025 critical minerals page (stub).'
  - Corrosion ratings are the assistant's reading of the printed marks. The sources give no rating scale for these marks.
  - Aalco states that its data are indicative only and not to be relied on in place of the full specification. Its values are used with that caveat.
  - Wikipedia is used only for the 10.5 percent chromium threshold for stainless steel, for the statement that Type 409 has the lower chromium content, and for the statement that it is mainly used in automotive exhaust systems.
sources:
  combmet-409:
    title: 'Combined Metals Company: Alloy 409 Stainless Steel data sheet (rev. 2024 01 11)'
    id: 409-Stainless-Steel-Alloy-Data-Sheet-2024-01-11.pdf
    url: https://www.combmet.com/wp-content/uploads/2024/01/409-Stainless-Steel-Alloy-Data-Sheet-2024-01-11.pdf
    kind: datasheet
    year: 2024
    license: cited, not reproduced
  aalco-1-4512:
    title: 'Aalco: Stainless Steel - Ferritic - 1.4512 Sheet'
    id: Stainless-Steel-14512-Sheet_313
    url: https://www.aalco.co.uk/datasheets/Stainless-Steel-14512-Sheet_313.ashx
    kind: datasheet
    license: distributor data sheet, cited (states its data are indicative only)
  outokumpu-xref:
    title: 'Outokumpu: Steel Grades, Properties and Global Standards'
    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: datasheet
    license: cited, not reproduced
  aperam-409a:
    title: 'Aperam: 409A - 1.4512 product page (extra low carbon, norms and applications)'
    id: 409a-1-4512
    url: https://www.aperam.com/product/409a-1-4512/
    kind: datasheet
    license: cited, not reproduced
  icast-as409:
    title: 'ICAST Alloys: AS 409 material data sheet (ASTM A240 listing, cross-reference table)'
    id: AS 409
    url: https://www.icastllp.com/material_db_pdf/AS%20409.pdf
    kind: datasheet
    license: cited, not reproduced
  usgs-cr-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 (USGS)
  pubchem-chromium:
    title: 'PubChem: Chromium (CID 23976), GHS classification'
    id: CID 23976
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
    kind: database
    year: 2026
    license: PubChem terms (public)
  wiki-ferritic:
    title: 'Wikipedia: Ferritic stainless steel (used for composition and the grade summary only)'
    id: Ferritic_stainless_steel
    url: https://en.wikipedia.org/wiki/Ferritic_stainless_steel
    kind: web
    license: CC BY-SA (Wikipedia), cited
license: CC-BY-4.0
updated: '2026-10-24'
review:
  status: draft
  method: assistant
  checked_values: 31
  unreachable: 0
  caveats: 8
  note: 'Read by an AI assistant on 2026-10-24 from pages fetched in this run: Combined Metals 409 data sheet (rev. 2024 01 11), Aalco 1.4512 sheet page, Outokumpu Steel Grades, Properties and Global Standards (Tables 2, 3, 6, 8, 12, 14 and 15), Aperam 409A product page, ICAST AS 409 data sheet, USGS Mineral Commodity Summaries 2026 chromium, PubChem chromium record and Wikipedia ferritic stainless steel. Caveats: the Aalco values are indicative; the modulus and density rows are unit notation or conversions (kg/dm3 and 10^3 MPa); the Outokumpu typical values are for product C and the EN minimums are for hot rolled plate; the ICAST minima carry no single heat-treatment condition; the Aperam page is an extra-low-carbon product used only for designations and uses.'
story:
  recipe:
    line: Grade 409 is an iron-chromium steel with 10.5 to 11.75 percent chromium and a titanium addition (ICAST). Aalco and Outokumpu describe it as titanium-stabilised. Carbon, manganese, silicon, phosphorus and sulfur are held low, and nickel is 0.5 percent at most (ICAST).
    parts:
      - name: Iron
        symbol: Fe
        share_note: balance (the rest)
        role: The matrix of the alloy. Outokumpu marks the grade as magnetisable.
      - name: Chromium
        symbol: Cr
        share_percent: 10.5
        share_high: 11.75
        source: icast-as409
        where: Chemical Composition table, Cr row (10.500 to 11.750)
        role: The main alloying element. Wikipedia says a Fe-base alloy must contain at least 10.5 percent Cr to qualify as stainless steel.
      - name: Titanium
        symbol: Ti
        share_percent: 0
        share_high: 0.75
        source: icast-as409
        where: Chemical Composition table, Ti row (max 0.750)
        role: The stabilising addition. Aalco's EN 10088-2 limit is 0.0 to 0.65 percent.
      - name: Carbon
        symbol: C
        share_percent: 0
        share_high: 0.08
        source: icast-as409
        where: Chemical Composition table, C row (max 0.080)
        role: Held low. The Combined Metals sheet for UNS S40910, S40920 and S40930 gives 0.030 maximum.
      - name: Nitrogen
        symbol: 'N'
        share_percent: 0
        share_high: 0.03
        source: combmet-409
        where: Nominal Composition table, N row (max 0.030)
        role: Held low. Combined Metals gives 0.030 maximum.
      - name: Manganese
        symbol: Mn
        share_percent: 0
        share_high: 1
        source: icast-as409
        where: Chemical Composition table, Mn row (max 1.000)
        role: Melt addition, held at 1.000 percent maximum.
      - name: Silicon
        symbol: Si
        share_percent: 0
        share_high: 1
        source: icast-as409
        where: Chemical Composition table, Si row (max 1.000)
        role: Melt addition, held at 1.000 percent maximum.
      - name: Nickel
        symbol: Ni
        share_percent: 0
        share_high: 0.5
        source: icast-as409
        where: Chemical Composition table, Ni row (max 0.500)
        role: Held low. Outokumpu prints 0.2 as typical.
      - name: Molybdenum
        symbol: Mo
        share_percent: 0
        share_high: 0.35
        source: icast-as409
        where: Chemical Composition table, Mo row (max 0.350)
        role: Present in a small amount, 0.350 percent maximum.
      - name: Copper
        symbol: Cu
        share_percent: 0
        share_high: 0.35
        source: icast-as409
        where: Chemical Composition table, Cu row (max 0.350)
        role: Present in a small amount, 0.350 percent maximum.
      - name: Phosphorus
        symbol: P
        share_percent: 0
        share_high: 0.045
        source: icast-as409
        where: Chemical Composition table, P row (max 0.045)
        role: Impurity held low.
      - name: Sulfur
        symbol: S
        share_percent: 0
        share_high: 0.03
        source: icast-as409
        where: Chemical Composition table, S row (max 0.030)
        role: Impurity held low.
  risk_groups:
    - title: For people
      level: 1
      verdict: Chromium record, not the alloy
      lead: No safety data sheet for 409 was read in this run. The PubChem record for elemental chromium is the only hazard source, and it is not a rating for the alloy.
      points:
        - label: Chromium record
          line: PubChem lists sensitisation codes H317 and H334 and eye codes H319 and H320 for elemental chromium in its aggregated notifications. Half of the 2404 company reports (1202) say it does not meet GHS criteria.
    - title: In the environment
      level: 2
      verdict: Pitting is the watch point
      lead: Outokumpu's pitting test marks 409 below 10 °C, the same mark it prints for 430 and 304.
      points:
        - label: Pitting
          line: Critical pitting temperature below 10 °C in the Avesta cell test in 1 M NaCl (Outokumpu).
        - label: Intergranular
          line: Outokumpu prints N/N for 409 for intergranular corrosion in the delivery and welded conditions, where 430 is Y/N.
    - title: Welding
      level: 2
      verdict: Keep welded sheet below 2.5 mm
      lead: Aalco says weldability is good up to about 2.5 mm thick and recommends grade 1.4003 for thicker welded material.
      points:
        - label: Thickness
          line: Usually available up to a maximum of 2.5 mm thick, and weldable to about that thickness (Aalco).
        - label: Filler
          line: Outokumpu lists 13 or 19 9L covered electrodes for welding 409 (ISO 3581 or ISO 14172).
    - title: Heat
      level: 1
      verdict: Anneal at 800 ± 30 °C
      lead: Outokumpu gives the annealing temperature as 800 ± 30 °C. The sources read give no service temperature limit for 409.
      points:
        - label: Annealing
          line: A 800 ± 30 °C anneal, with A meaning annealing (Outokumpu Table 14).
  why: Grade 409 is a titanium-stabilised ferritic chromium steel. Aalco calls it muffler grade stainless steel because most of its bulk use is in automotive exhaust systems. Wikipedia's ferritic summary calls Type 409 the lower-chromium grade, mainly used in automotive exhaust systems. Combined Metals says it is used where corrosion protection is needed beyond carbon steel.
  uses:
    - where: Automotive exhaust systems
      line: Aalco calls 409 muffler grade stainless steel because most of its bulk use is in automotive exhaust systems. Aperam's 409A page lists manifolds, down-pipes, converter casings and mufflers.
    - where: Heat exchangers
      line: Combined Metals lists automotive exhaust systems and heat exchangers as applications of its 409 sheet.
  can_do:
    - label: Strength
      benchmark: ultimate_tensile_strength
      line: Annealed sheet has a minimum tensile strength of 380 MPa under ASTM A240 (Combined Metals). The EN 10088-2 range for sheet up to 8 mm is 380 to 560 MPa (Aalco).
    - label: Yield
      benchmark: yield_strength
      line: The minimum 0.2 percent proof stress is 170 MPa for annealed sheet in the Combined Metals table and 210 MPa for EN sheet up to 8 mm (Aalco). The typical room-temperature value for cold rolled sheet is 255 MPa (Outokumpu).
    - label: Stiffness
      benchmark: elastic_modulus
      line: Elastic modulus is 208 GPa (Aalco), 208.22 GPa at 20 °C (Combined Metals) and 220 GPa at room temperature in Outokumpu's table.
    - label: Density
      benchmark: density
      line: Density is 7.6 g/cm3 (Aalco), 7.7 kg/dm3 (Outokumpu) and 7.75 g/cm3 at 20 °C (Combined Metals).
    - label: Heat
      benchmark: yield_strength
      value: 200 MPa at 100 °C, 190 MPa at 200 °C
      line: The EN minimum 0.2 percent proof stress falls from 220 MPa at room temperature to 200 MPa at 100 °C and 190 MPa at 200 °C (Outokumpu Table 8).
  compare: Against Type 430, Outokumpu's table gives 11.5 percent chromium for 409 against 16.2 percent for 430, and Wikipedia calls 409 the lower-chromium grade. Both grades print a critical pitting temperature below 10 °C in the same test, but 409's intergranular corrosion mark is N/N where 430's is Y/N. Against Type 304 (18.1 percent chromium, 8.1 percent nickel), 409 has 0.2 percent nickel and the same below-10 °C pitting mark, and 304's intergranular mark is Y/N*. Outokumpu's table shows no test result for 409 that is better than 430 or 304 on pitting or intergranular corrosion, and the sources read do not compare exhaust-condensate or salt-spray performance.
  compare_rows:
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Anneal at 800 ± 30 °C (Outokumpu Table 14).
    - Weld only sheet up to about 2.5 mm thick, or use grade 1.4003 for thicker welded parts (Aalco).
    - Choose welding consumables from the 13 or 19 9L group that Outokumpu lists for 4512.
  good_for:
    - Automotive exhaust systems, mufflers and converter casings, which Aalco gives as the bulk use (Aalco; Aperam 409A page).
    - Heat exchangers, where corrosion protection beyond carbon steel is needed (Combined Metals).
  watch_out:
    - Pitting. The critical pitting temperature is below 10 °C in Outokumpu's test, the same as for 430 and 304.
    - Intergranular corrosion. Outokumpu prints N/N for 409 in the delivery and welded conditions.
    - Welded thickness. Aalco limits weldability to about 2.5 mm thick.
  verdict: Grade 409 is the titanium-stabilised exhaust grade. It is magnetisable and anneals at 800 ± 30 °C. Outokumpu's table marks its intergranular corrosion weaker than 430 and 304, and its pitting mark is no better than theirs in the same test.