spore: profile
id: stainless-2304
spore_version: '0.2'
family: stainless-duplex
name: Lean duplex stainless steel 2304
abbreviation: 2304 (UNS S32304, EN 1.4362)
role: structural alloy
category: metals
type: steels-and-stainless
summary: Lean duplex 2304 is an austenite-ferrite stainless steel with about 23 percent chromium, 4 percent nickel and very little molybdenum (UNS S32304, EN 1.4362). ATI gives a typical PREN of 26 and a minimum 0.2 percent yield strength of 400 MPa for plate, and says its corrosion resistance is comparable to 316L in most environments with much higher strength. Alleima says it resists chloride stress corrosion cracking up to about 125 C in dilute oxygen-bearing chloride, where 304 and 316 are limited to 60 C.
best_for: Chloride-bearing process piping and heat exchangers, pulp and paper equipment, and strength-limited structures where 304 or 316 would crack or be too weak (Alleima, ATI)
weakest_at: Exposure above about 315 C (600 F), where 475 C embrittlement can follow (ATI); prolonged exposure above 280 C (Alleima); weld metal without an overmatched filler (ATI)
identity:
  formula: Fe balance, 21.5 to 24.5 Cr, 3.0 to 5.5 Ni, 0.05 to 0.60 Mo, 0.05 to 0.60 Cu, 0.05 to 0.20 N, max 0.030 C, max 2.50 Mn, max 1.00 Si, max 0.040 P, max 0.030 S (wt%, ASTM A240 UNS S32304)
  source: icast-s32304
  where: Chemical Composition table (ASTM A240 UNS S32304)
  designations:
    - system: UNS
      code: S32304
      source: ati-tds
      where: Title block, ATI 2304 (UNS S32304)
    - system: EN
      code: '1.4362'
      source: alleima-saf2304
      where: Standards list, EN Number
    - system: EN name
      code: X2CrNiN23-4
      source: alleima-saf2304
      where: Standards list, EN Name
    - system: DIN
      code: X 2 CrNiN 23 4
      source: alleima-saf2304
      where: Standards list, DIN
    - system: SS
      code: '2327'
      source: alleima-saf2304
      where: Standards list, SS
    - system: AFNOR
      code: Z 2 CN 23.04AZ
      source: alleima-saf2304
      where: Standards list, AFNOR
    - system: ASTM
      code: A240
      note: plate, sheet and strip
      source: ati-tds
      where: Specifications paragraph
    - system: ASTM
      code: A276
      note: bar and shape
      source: ati-tds
      where: Specifications paragraph
    - system: ASTM
      code: A789
      note: seamless and welded tube and pipe
      source: alleima-saf2304
      where: Product standards, tube and pipe
    - system: ASTM
      code: A790
      note: seamless and welded tube and pipe
      source: alleima-saf2304
      where: Product standards, tube and pipe
    - system: ASTM
      code: A928
      note: steel and pipe
      source: icast-s32304
      where: Cross Reference Table, A928 S32304
    - system: EN
      code: 10216-5
      note: seamless tube and pipe
      source: alleima-saf2304
      where: Product standards, seamless tube and pipe
    - system: EN
      code: 10088-2
      note: strip and sheet
      source: alleima-saf2304
      where: Product standards, strip and sheet
    - system: EN
      code: 10088-3
      note: bar and forged billets
      source: alleima-saf2304
      where: Product standards, bar steel and forged billets
    - system: Trade name
      code: ATI 2304
      note: ATI
      source: ati-tds
      where: Title block, ATI 2304
    - system: Trade name
      code: SAF® 2304
      note: Alleima
      source: alleima-saf2304
      where: Datasheet title, SAF 2304
    - system: Trade name
      code: PW 400
      note: hydraulic tubing, Alleima
      source: alleima-saf2304
      where: Forms of supply, hydraulic tubing
tags:
  environments: []
  stresses: []
  applications:
    - structures
    - mechanisms
properties:
  - benchmark: density
    value: 7.8
    unit: g/cm3
    scope: material
    conditions:
      form: ATI 2304 plate (TDS typical data)
      heat_treatment: not printed
      temperature: not printed
    method: Physical Properties table, printed as 0.28 lb/in3 (7.8 g/cm3); ATI says the data are typical, not maximum or minimum values
    status: ground
    source: ati-tds
    where: Physical Properties, Density row
  - benchmark: elastic_modulus
    value: 200
    unit: GPa
    scope: material
    conditions:
      form: ATI 2304 plate (TDS typical data)
      heat_treatment: not printed
      temperature: not printed
    method: Physical Properties table, Elastic Modulus row, printed as 29 x 10^6 psi (200 GPa)
    status: ground
    source: ati-tds
    where: Physical Properties, Elastic Modulus row
    note: An asterisk follows the printed value; its meaning is not explained in the fetched text
  - benchmark: thermal_conductivity
    value: 13
    unit: W/m.K
    scope: material
    conditions:
      form: ATI 2304 plate (TDS typical data)
      heat_treatment: not printed
      temperature: 20 to 100 C (68 to 212 F)
    method: Thermal Conductivity table, metric column (W/m.K), 20 to 100 C row printed as 13
    status: ground
    source: ati-tds
    where: Thermal Conductivity table (metric, 20 to 100 C row)
  - benchmark: thermal_conductivity
    value: 14
    unit: W/m.K
    scope: material
    conditions:
      form: ATI 2304 plate (TDS typical data)
      heat_treatment: not printed
      temperature: 20 to 300 C (68 to 572 F)
    method: Thermal Conductivity table, metric column (W/m.K), 20 to 300 C row printed as 14
    status: ground
    source: ati-tds
    where: Thermal Conductivity table (metric, 20 to 300 C row)
  - benchmark: cte
    value: 13
    unit: 10-6/K
    scope: material
    conditions:
      form: ATI 2304 plate (TDS typical data)
      heat_treatment: not printed
      temperature: 20 to 100 C mean
      unit_in_source: 10^-6 cm/cm C (printed as cm/cm°C x 10^-6)
    method: Thermal Expansion table, mean coefficient over range, metric column, 68 to 212 F (20 to 100 C) row printed as 13
    status: ground
    source: ati-tds
    where: Thermal Expansion table (metric, 20 to 100 C row)
  - benchmark: cte
    value: 14
    unit: 10-6/K
    scope: material
    conditions:
      form: ATI 2304 plate (TDS typical data)
      heat_treatment: not printed
      temperature: 20 to 300 C mean
      unit_in_source: 10^-6 cm/cm C (printed as cm/cm°C x 10^-6)
    method: Thermal Expansion table, mean coefficient over range, metric column, 68 to 572 F (20 to 300 C) row printed as 14
    status: ground
    source: ati-tds
    where: Thermal Expansion table (metric, 20 to 300 C row)
  - benchmark: yield_strength
    value: 400
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: ATI 2304 plate, ASTM A240 minimum
      heat_treatment: annealed (ASTM A240 minimum)
      temperature: room temperature
    method: Minimum Room Temperature Mechanical Properties table for plate, 0.2 percent yield strength printed as 58 ksi and 400 MPa
    status: ground
    source: ati-tds
    where: Minimum Room Temperature Mechanical Properties for Plate (Yield Strength row, ATI 2304)
  - benchmark: ultimate_tensile_strength
    value: 600
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: ATI 2304 plate, ASTM A240 minimum
      heat_treatment: annealed (ASTM A240 minimum)
      temperature: room temperature
    method: Minimum Room Temperature Mechanical Properties table for plate, ultimate strength printed as 87 ksi and 600 MPa
    status: ground
    source: ati-tds
    where: Minimum Room Temperature Mechanical Properties for Plate (Ultimate Strength column, ATI 2304 row)
  - benchmark: elongation
    value: 25
    unit: '%'
    bound: lower
    scope: material
    conditions:
      form: ATI 2304 plate, ASTM A240 minimum
      heat_treatment: annealed (ASTM A240 minimum)
      temperature: room temperature
      gauge: 2 in or 50 mm
    method: Minimum Room Temperature Mechanical Properties table for plate, elongation in 2 in or 50 mm printed as 25 percent
    status: ground
    source: ati-tds
    where: Minimum Room Temperature Mechanical Properties for Plate (Elongation column, ATI 2304 row)
  - benchmark: hardness
    value: 290
    unit: BHN
    bound: upper
    scope: material
    conditions:
      form: ATI 2304 plate, ASTM A240 limit
      heat_treatment: annealed (ASTM A240 limit)
      temperature: room temperature
    method: Minimum Room Temperature Mechanical Properties table for plate, hardness maximum printed as 290 BHN
    status: ground
    source: ati-tds
    where: Minimum Room Temperature Mechanical Properties for Plate (Hardness Max BHN column, ATI 2304 row)
  - benchmark: hardness
    value: 32
    unit: Rc
    bound: upper
    scope: material
    conditions:
      form: ATI 2304 plate, ASTM A240 limit
      heat_treatment: annealed (ASTM A240 limit)
      temperature: room temperature
    method: Minimum Room Temperature Mechanical Properties table for plate, hardness maximum printed as 32 Rc
    status: ground
    source: ati-tds
    where: Minimum Room Temperature Mechanical Properties for Plate (Hardness Max Rc column, ATI 2304 row)
  - benchmark: pitting_resistance_equivalent
    value: 26
    unit: '-'
    scope: material
    conditions:
      form: ATI typical composition, PREN = %Cr + 3.3(%Mo) + 16(%N)
      heat_treatment: not printed
      temperature: not applicable
    method: Corrosion Resistance section, typical PREN table, ATI 2304 row printed as 26; Type 316L row printed as 24; ATI says the figures are typical, not minimum
    status: ground
    source: ati-tds
    where: Corrosion Resistance section, typical PREN table (ATI 2304 row)
    note: Typical ATI composition basis, not a minimum
  - benchmark: pitting_resistance_equivalent
    value: 25
    unit: '-'
    scope: material
    conditions:
      form: nominal composition, Cr 22.5, Mo 0.3, N 0.1 (Alleima)
      heat_treatment: not printed
      temperature: not applicable
    method: Pitting section, PRE table, SAF 2304 row printed as 25 (PRE = % Cr + 3.3 x % Mo + 16 x % N); ASTM 316L row printed as 24 and ASTM 304L row as 18
    status: ground
    source: alleima-saf2304
    where: Pitting section, PRE table (SAF 2304 row)
    note: Nominal composition basis, against 26 typical from ATI; both kept
  - benchmark: max_service_temp
    value: 315
    unit: °C
    bound: upper
    scope: material
    conditions:
      form: ATI 2304 plate, ASME Section VIII Division 1
      heat_treatment: not printed
      temperature: 600 F (315 C) upper limit
    method: Elevated Temperature Mechanical Properties text, printed as an upper temperature limit of 600°F (315°C) for use of ATI 2304 under the ASME Boiler and Pressure Vessel Code
    status: ground
    source: ati-tds
    where: Elevated Temperature Mechanical Properties section
  - benchmark: charpy_impact_energy
    value: 40
    unit: J
    bound: lower
    scope: material
    conditions:
      form: ATI 2304 plate
      heat_treatment: not printed
      temperature: '-40 C'
      test: Charpy, type not printed
    method: 'Low-Temperature Impact Properties text: ATI says 2304 retains toughness to exceed the commonly required Charpy impact energy of 40 J at -40 C; 40 J is the requirement the alloy exceeds, not a measured result'
    status: ground
    source: ati-tds
    where: Low-Temperature Impact Properties section
    note: Lower bound from the statement that the alloy exceeds 40 J; no measured number is printed
  - benchmark: density
    value: 7.8
    unit: g/cm3
    scope: material
    conditions:
      form: seamless tube and pipe (SAF 2304 datasheet)
      heat_treatment: not printed
      temperature: not printed
    method: Physical properties, printed as Density 7.8 g/cm3, 0.28 lb/in3
    status: ground
    source: alleima-saf2304
    where: Physical properties, Density line
  - benchmark: specific_heat
    value: 490
    unit: J/(kg °C)
    scope: material
    conditions:
      form: seamless tube and pipe (SAF 2304 datasheet)
      heat_treatment: not printed
      temperature: 20 C
    method: Specific heat capacity table, 20 C row printed as 490 J/(kg °C)
    status: ground
    source: alleima-saf2304
    where: Specific heat capacity table (20 C row)
  - benchmark: thermal_conductivity
    value: 16
    unit: W/(m °C)
    scope: material
    conditions:
      form: seamless tube and pipe (SAF 2304 datasheet)
      heat_treatment: not printed
      temperature: 20 C
    method: Thermal conductivity table, metric, SAF 2304 row, 20 C column printed as 16 W/(m °C); ASTM 316L row printed as 14 at 20 C
    status: ground
    source: alleima-saf2304
    where: Thermal conductivity table (metric, SAF 2304 row, 20 C column)
    note: Differs from ATI 13 W/m.K at 20 to 100 C; both kept, not averaged
  - benchmark: cte
    value: 13.5
    unit: 10-6/K
    scope: material
    conditions:
      form: seamless tube and pipe (SAF 2304 datasheet)
      heat_treatment: not printed
      temperature: 30 to 100 C mean
      unit_in_source: x10-6 per C (printed as Per °C)
    method: Thermal expansion, mean values in temperature ranges, metric, SAF 2304 row, 30-100 C column printed as 13.5; ASTM 304L/316L row printed as 16.5
    status: ground
    source: alleima-saf2304
    where: Thermal expansion table (metric, SAF 2304 row, 30-100 C column)
    note: Range and value differ from ATI 13 for 20 to 100 C; both kept
  - benchmark: elastic_modulus
    value: 180
    unit: GPa
    scope: material
    conditions:
      form: seamless tube and pipe (SAF 2304 datasheet)
      heat_treatment: not printed
      temperature: 300 C
      unit_in_source: x10^3 MPa (printed value 180)
    method: Modulus of elasticity table, 300 C row printed as 180 (x10^3 MPa), equal to 26.2 ksi at 600 F
    status: ground
    source: alleima-saf2304
    where: Modulus of elasticity table (300 C row)
  - benchmark: yield_strength
    value: 400
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: seamless tube and pipe, wall up to 20 mm
      heat_treatment: solution annealed
      temperature: 20 C
    method: Mechanical properties table at 20 C, Rp0.2 printed as 400 MPa minimum; footnote c says tubes up to 25.4 mm OD are guaranteed at 450 MPa (ASTM A789)
    status: ground
    source: alleima-saf2304
    where: Mechanical properties, 20 C table (Rp0.2 column)
    note: 'Footnote c: 450 MPa guaranteed for tube up to 25.4 mm OD'
  - benchmark: ultimate_tensile_strength
    value: 630
    value_high: 820
    unit: MPa
    bound: range
    scope: material
    conditions:
      form: seamless tube and pipe, wall up to 20 mm
      heat_treatment: solution annealed
      temperature: 20 C
    method: Mechanical properties table at 20 C, Rm printed as 630-820 MPa; footnote c says tubes up to 25.4 mm OD are guaranteed at 690 MPa minimum (ASTM A789)
    status: ground
    source: alleima-saf2304
    where: Mechanical properties, 20 C table (Rm column)
  - benchmark: yield_strength
    value: 270
    unit: MPa
    bound: lower
    scope: material
    conditions:
      form: seamless tube and pipe, wall above 4 mm
      heat_treatment: solution annealed
      temperature: 300 C
    method: High temperature proof strength table, Rp0.2 minimum, metric, Wt > 4 mm column, 300 C row printed as 270
    status: ground
    source: alleima-saf2304
    where: At high temperatures, proof strength table (300 C row, Wt > 4 mm)
  - benchmark: hardness
    value: 30
    unit: HRC
    bound: upper
    scope: material
    conditions:
      form: seamless tube and pipe, wall up to 20 mm
      heat_treatment: solution annealed
      temperature: 20 C
    method: Mechanical properties table at 20 C, HRC column printed as 30 maximum
    status: ground
    source: alleima-saf2304
    where: Mechanical properties, 20 C table (HRC column)
  - benchmark: max_service_temp
    value: 280
    unit: °C
    bound: upper
    scope: material
    conditions:
      form: pressure vessel applications (VdTÜV-Wb 496)
      heat_treatment: not printed
      temperature: 280 C (540 F) maximum for prolonged exposure
    method: 'At high temperatures section, printed: for pressure vessel applications 280 C (540 F) is required as a maximum according to VdTÜV-Wb 496'
    status: ground
    source: alleima-saf2304
    where: At high temperatures section
corrosion:
  - environment: Chloride stress corrosion cracking, dilute oxygen-bearing chloride
    headline: Resists SCC up to about 125 C; 304 and 316 limited to 60 C
    effect: Alleima says SAF 2304 can be used in dilute oxygen-bearing chloride solutions up to about 125 C (260 F) without any risk of SCC (Figure 9, about 8 ppm oxygen, 1000 hours). It says ASTM 304/304L and 316/316L should not be used above 60 C (140 F) in such environments. ATI says the duplex structure gives greater chloride SCC resistance than 304L and 316L.
    rating: low
    conditions:
      environment: oxygen-bearing neutral chloride, about 8 ppm oxygen
      temperature: up to 125 C (260 F) for SAF 2304; 60 C (140 F) limit for 304 and 316
      test: Figure 9, 1000 hours, load above yield strength at test temperature
    source: alleima-saf2304
    where: Stress corrosion and cracking section, Figure 9 text
  - environment: Chloride SCC in oxygen-bearing solution above 125 C
    headline: Above 125 C with more than about 10 ppm chloride, do not use SAF 2304
    effect: Alleima says at temperatures above 125 C, SAF 2304 should not be used in oxygen-bearing solutions with more than about 10 ppm Cl-, and it recommends SAF 2205, SAF 2507 or Sanicro 28 for such conditions. At low oxygen contents, considerably higher chloride and temperature are tolerated.
    rating: moderate
    conditions:
      environment: oxygen-bearing solution with more than about 10 ppm Cl-
      temperature: above 125 C (260 F)
    source: alleima-saf2304
    where: Stress corrosion and cracking section, Figure 9 text
  - environment: Chloride SCC in concentrated chloride (40 percent CaCl2)
    headline: Threshold stress much higher than 304 and 316
    effect: Alleima Figure 8 shows the threshold stress for SCC in 40 percent CaCl2 at 100 C is much higher for SAF 2304 than for ASTM 304/304L and 316/316L. The figure values are not printed in the text, so no number is recorded.
    rating: low
    conditions:
      environment: 40 percent CaCl2, pH 6.5, aerated
      temperature: 100 C (210 F)
    source: alleima-saf2304
    where: Stress corrosion and cracking section, Figure 8
  - environment: Chloride pitting and crevice corrosion
    headline: PRE 25 nominal, comparable to 316L; crevice better than 304
    effect: Alleima's PRE table gives 25 for SAF 2304 against 24 for ASTM 316L and 18 for ASTM 304L. Its critical pitting temperature is higher than 304L and comparable to 316L (Figure 7, potentiostatic test in neutral chloride; no number in the text). Crevice resistance is better than 304/304L and comparable to 316/316L. ATI gives a typical PREN of 26 and 24 for Type 316L.
    rating: low
    conditions:
      environment: neutral chloride solutions, pH 6 (Figure 7)
      temperature: critical pitting temperature from Figure 7, not printed as a number
    source: alleima-saf2304
    where: Pitting and Crevice corrosion sections, PRE table and Figure 7
  - environment: General corrosion in acids
    headline: Excellent in acids (Alleima); comparable to 316L in most environments (ATI)
    effect: Alleima says SAF 2304 has excellent corrosion resistance in acidic environments, with corrosion-rate tables for acetic, formic, hydrochloric, nitric, phosphoric and sulphuric acid mixtures and isocorrosion diagrams for sulphuric, formic and nitric acid (Figures 4 to 6). ATI says general corrosion resistance is comparable to Type 316L in most environments.
    rating: low
    conditions:
      environment: acetic, formic, hydrochloric, nitric, phosphoric and sulphuric acid mixtures
      temperature: varies by table; not summarised as one value
    source: alleima-saf2304
    where: General corrosion section, corrosion-rate tables and Figures 4 to 6
  - environment: Intergranular corrosion in welds and erosion corrosion
    headline: Welds pass the Strauss test; very good erosion resistance
    effect: Alleima says welded joints easily pass Strauss intergranular corrosion testing (SS-EN ISO 3651-2 Method A). It says 304/304L and 316/316L types can be attacked by erosion corrosion in abrasive flow, while SAF 2304 shows very good resistance.
    rating: low
    conditions:
      environment: welded joints (Strauss test); abrasive flowing media
      temperature: not printed
    source: alleima-saf2304
    where: Intergranular corrosion and Erosion corrosion sections
  - environment: Corrosion fatigue
    headline: Better fatigue strength under corrosive conditions than austenitic steels
    effect: Alleima says SAF 2304 has higher strength and better corrosion resistance than ordinary austenitic stainless steels, and so has considerably better fatigue strength under corrosive conditions. No fatigue number is printed in the text.
    rating: low
    conditions:
      environment: corrosive conditions (qualitative statement)
      temperature: not printed
    source: alleima-saf2304
    where: Corrosion fatigue section
risks:
  hazards:
    - text: PubChem GHS notifications for elemental nickel (CID 935) list H250, H317, H334, H341, H350, H351, H360, H360F, H370, H372, H411 and H412. These describe the element, not the 2304 alloy.
      ghs:
        - H250
        - H317
        - H334
        - H341
        - H350
        - H351
        - H360
        - H360F
        - H370
        - H372
        - H411
        - H412
      source: pubchem-nickel
      where: UN GHS Classification (PubChem record, CID 935)
    - text: PubChem GHS notifications for elemental chromium (CID 23976) list H317, H319, H320, H334, H335, H341, H371, H400 and H410. These describe the element, not the 2304 alloy.
      ghs:
        - H317
        - H319
        - H320
        - H334
        - H335
        - H341
        - H371
        - H400
        - H410
      source: pubchem-chromium
      where: UN GHS Classification (PubChem record, CID 23976)
    - text: PubChem GHS notifications for elemental molybdenum (CID 23932) list H225, H228, H315, H319, H335 and H361, with signal words Danger and Warning. These describe the element, not the 2304 alloy.
      ghs:
        - H225
        - H228
        - H315
        - H319
        - H335
        - H361
      source: pubchem-molybdenum
      where: UN GHS Classification (PubChem record, CID 23932)
  failure_risks:
    - mode: 885 F (475 C) embrittlement
      trigger: Exposure at temperatures above about 600 F (315 C)
      consequence: Embrittlement of the ferrite phase; ATI gives the ASME upper temperature limit of 600 F (315 C) for use of ATI 2304
      severity: high
      source: ati-tds
      where: Elevated Temperature Mechanical Properties section
    - mode: Lower impact strength after prolonged high-temperature exposure
      trigger: Prolonged exposure above 280 C (540 F)
      consequence: The microstructure changes and impact strength falls; 280 C is the maximum for pressure vessels (VdTÜV-Wb 496)
      severity: moderate
      source: alleima-saf2304
      where: At high temperatures section
    - mode: Chloride stress corrosion cracking
      trigger: Oxygen-bearing solution above 125 C (260 F) with more than about 10 ppm Cl-
      consequence: SCC risk rises; Alleima recommends SAF 2205, SAF 2507 or Sanicro 28 for these conditions
      severity: high
      source: alleima-saf2304
      where: Stress corrosion and cracking section, Figure 9 text
    - mode: Stress corrosion after moderate cold bending
      trigger: Moderate cold bending where the material reaches nearly 125 C (255 F) in a neutral oxygen-bearing environment with about 100 ppm Cl-
      consequence: Heat treatment is recommended after bending, because the SCC risk starts to increase
      severity: moderate
      source: alleima-saf2304
      where: Bending section
    - mode: Deleterious phase precipitation
      trigger: Heat treatment not followed by rapid cooling
      consequence: Deleterious phases precipitate (ATI)
      severity: moderate
      source: ati-tds
      where: Heat Treatment section
    - mode: Weld phase imbalance
      trigger: Welding without an overmatched (higher-nickel) filler metal, or with unsuitable parameters
      consequence: The weld and heat-affected zone can lose phase balance, and deleterious phases can form (ATI)
      severity: moderate
      source: ati-tds
      where: Welding section
    - mode: Higher ferrite content from high-temperature anneal
      trigger: Annealing above the 1800 F (980 C) minimum
      consequence: Ferrite content rises above the level from an anneal near 980 C (ATI)
      severity: low
      source: ati-tds
      where: Heat Treatment section
  side_effects: []
  handling:
    - text: Solution anneal at 930 to 1050 C (1710 to 1920 F) and cool rapidly in air or water (Alleima). ATI gives a minimum annealing temperature of 1800 F (980 C) under ASTM A480 and says rapid cooling prevents deleterious phases.
      source: alleima-saf2304
      where: Heat treatment, Solution annealing
    - text: Weld without preheating, at a heat input of 0.5 to 2.5 kJ/mm and an interpass temperature below 150 C (300 F) (Alleima).
      source: alleima-saf2304
      where: Welding section
    - text: 'Use overmatched filler metals: ISO 14343 S 23 7 N L (Exaton 23.7.L) for TIG or MIG, and ISO 14343 S 22 9 3 N L or AWS A5.9 ER2209 (Exaton 22.8.3.L) (Alleima). ATI suggests overmatched fillers with more nickel than the base metal.'
      source: alleima-saf2304
      where: Welding section, recommended filler metals
    - text: Cold bend to 25 percent deformation without subsequent heat treatment (Alleima). ATI suggests bend radii of at least two times the metal thickness.
      source: alleima-saf2304
      where: Bending section
    - text: Hot bend at 1100 to 950 C (2010 to 1740 F) and solution anneal afterwards (Alleima).
      source: alleima-saf2304
      where: Bending section
    - text: Expand tubes in one operation, because expansion needs higher initial force than austenitic steels (Alleima).
      source: alleima-saf2304
      where: Expanding section
    - text: Machine at about 25 percent lower cutting speed than 304L, with a tougher insert grade for semi-roughing (Alleima).
      source: alleima-saf2304
      where: Machining section
  mitigations:
    - text: Above 125 C in oxygen-bearing chloride with more than about 10 ppm Cl-, choose SAF 2205, SAF 2507 or Sanicro 28 (Alleima).
      source: alleima-saf2304
      where: Stress corrosion and cracking section
    - text: Use an overmatched filler metal so the weld keeps a phase balance close to the base metal (ATI).
      source: ati-tds
      where: Welding section
    - text: Rapid cooling after heat treatment prevents precipitation of deleterious phases (ATI).
      source: ati-tds
      where: Heat Treatment section
    - text: Heat treat after moderate cold bending where the SCC risk starts to increase (Alleima).
      source: alleima-saf2304
      where: Bending section
uses:
  - application: structures
    device: Process heat exchangers and piping where chlorides are present
    example: Alleima lists these as higher-SCC-resistance replacements for ASTM 304/304L and 316/316L, together with instrumentation tubing and steam tracing
    source: alleima-saf2304
    where: Applications table, process industry rows
  - application: structures
    device: Pulp and paper digester preheaters and evaporators
    example: Alleima lists digester preheaters and evaporators as a use where SAF 2304 gives higher resistance to SCC than 304 and 316
    source: alleima-saf2304
    where: Applications table, pulp and paper row
  - application: structures
    device: Oil and gas coolers, piping and flowlines on and offshore, and offshore rig tensioning systems
    example: Alleima lists these uses, citing optimal combination of strength, weldability, corrosion resistance and cost
    source: alleima-saf2304
    where: Applications table, oil and gas row
  - application: mechanisms
    device: Beams and torque-transmitting shafts
    example: Alleima lists high strength combined with excellent corrosion resistance, ease of fabrication and low cost for engineering use
    source: alleima-saf2304
    where: Applications table, engineering row
  - application: mechanisms
    device: Hydraulic tubing, also sold as PW 400
    example: Alleima lists excellent corrosion resistance and reduced installation cost, owing to easy cleaning, for hydraulic tubing
    source: alleima-saf2304
    where: Applications table, hydraulic system row; Forms of supply
supply:
  - subject: Nickel production by country (USGS 2026)
    abundance: World mine production 3,900,000 tons in 2025 (estimated). World reserves more than 140,000,000 tons, of which Indonesia holds 62,000,000 tons. Stainless and alloy steel and nickel-containing alloys typically account for more than 85% of domestic consumption. US net import reliance was 41% of apparent consumption in 2025 (estimated). Shares are computed from the printed 2025e tonnage divided by the printed world total of 3,900,000 tons.
    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: Nickel recovered from scrap accounted for approximately 60% of US apparent consumption in 2025 (USGS).
    substitutes:
      - Low-nickel, duplex, or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction (USGS 2026)
    source: usgs-nickel-2026
    where: World Mine Production and Reserves table; Salient Statistics; Recycling; Substitutes
  - subject: Chromium production by country (USGS 2026)
    abundance: World mine production 51,000 thousand metric tons in 2025 (estimated, gross weight). World resources greater than 12 billion tons of shipping-grade chromite, 95% in Kazakhstan and southern Africa. US net import reliance was 79% of apparent consumption in 2025 (estimated). Shares are computed from the printed 2025e gross-weight tonnage of 51,000 thousand metric tons. The grade contains chromium at 21.5 to 24.5 percent (ASTM A240).
    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: Recycled chromium contained in stainless-steel scrap receipts was 21% of US apparent consumption in 2025 (USGS).
    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; World Resources; Salient Statistics; Recycling; Substitutes
  - subject: Molybdenum production by country (USGS 2026)
    abundance: World mine production 260,000 tons of molybdenum content in 2025 (estimated). China, Chile, the United States, Peru and Mexico accounted for 90% of world production. The grade contains 0.05 to 0.60 percent molybdenum (ICAST, ATI), so molybdenum supply applies. US net import reliance is shown as E (net exporter, USGS footnote). Shares are computed from the printed 2025e tonnage divided by the printed world total of 260,000 tons.
    producers:
      - country: China
        share_percent: 37.3
        year: 2025
      - country: Chile
        share_percent: 16.2
        year: 2025
      - country: United States
        share_percent: 15.4
        year: 2025
      - country: Peru
        share_percent: 15
        year: 2025
      - country: Mexico
        share_percent: 6.5
        year: 2025
    critical_lists: []
    recycling: Molybdenum recycled as part of new and old steel and other scrap may be as much as 30% of the apparent supply of molybdenum (USGS 2026).
    substitutes:
      - Little substitution for molybdenum in steels and cast irons; potential substitutes include boron, chromium, niobium and vanadium in alloy steels (USGS 2026)
    source: usgs-molybdenum-2026
    where: World Mine Production and Reserves table; Recycling; Substitutes; Events, Trends, and Issues
media: []
documents:
  - title: 'ATI 2304 Technical Data Sheet, version 1 (2014): Stainless Steel Duplex (UNS S32304)'
    type: datasheet
    url: https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/duplex/ati_2304_tds_en_v1.pdf
    year: 2014
  - title: ATI 2304 Duplex Stainless Steel product page (UNS S32304)
    type: datasheet
    url: https://atimaterials.com/Products/ati-2304
  - title: Alleima SAF 2304 tube and pipe, seamless datasheet (updated 2026-02-11)
    type: datasheet
    url: https://www.alleima.com/en/technical-center/material-datasheets/tube-and-pipe-seamless/saf-2304?show=pdf
    year: 2026
  - title: 'ICAST Alloys: ASTM A240 UNS S32304 chemical composition and mechanical summary'
    type: datasheet
    url: https://www.icastllp.com/material_db_pdf/ASTM%20A240%20UNS%20S32304.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: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.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: Molybdenum (CID 23932), UN GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/JSON
gaps:
  - No melting range is printed in the fetched 2304 sources, so melting_point is not filled.
  - Electrical resistivity, Poisson ratio, sour-service (NACE) limits, a fatigue strength number and a CAS number are not printed in the fetched 2304 sources.
  - Alleima's impact (Figure 2), critical pitting temperature (Figure 7), SCC threshold (Figure 8) and acid corrosion-rate tables are graphs or tables that did not parse as numbers in the text, so only their stated conclusions are recorded.
  - The ATI TDS is version 1 dated 2014 with typical data, not limits; no newer ATI revision appeared in the search results.
  - Thermal conductivity, expansion and modulus differ between ATI (2014, plate) and Alleima (2026, seamless tube and pipe) at the same temperatures; both are kept and not averaged.
  - 'PREN basis differs: 26 typical from ATI against 25 on Alleima''s nominal composition (Cr 22.5, Mo 0.3, N 0.1, which is not a specification range). None was calculated for this file.'
  - ATI gives no measured Charpy value. The 40 J figure is the requirement the alloy exceeds and is recorded as a lower bound.
  - PREN, hardness and charpy_impact_energy are not in property-canon.yaml, so snake_case names are used. Critical pitting temperature has no printed number in the text.
  - The USGS 2026 nickel, chromium and molybdenum texts print no critical-minerals list membership, so critical_lists are empty; the nickel text names critical minerals only in the Executive Order 14285 context.
  - Hazards are PubChem records for the elements nickel, chromium and molybdenum. No safety data sheet for 2304 was read, so welding-fume hazards for this grade are not covered.
  - Cryogenic data (4 K and 20 K) for 2304 were not found in the fetched sources, and no space source naming 2304 in a spacecraft part was found, so the space link is open.
  - No Outokumpu, Aperam or Acerinox datasheet was fetched in this run. ASM Alloy Digest entries for ATI 2304 and Sandvik SAF 2304 are behind a login and were not read. Resellers and aggregators were not used for values.
sources:
  ati-tds:
    title: 'ATI 2304 Technical Data Sheet, version 1 (2014): Stainless Steel Duplex (UNS S32304)'
    id: ati_2304_tds_en_v1
    url: https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/duplex/ati_2304_tds_en_v1.pdf
    kind: datasheet
    year: 2014
    license: cited, not reproduced
  ati-product:
    title: 'ATI: 2304 Duplex Stainless Steel (UNS S32304), composition, density and mechanical table'
    id: ati-2304
    url: https://atimaterials.com/Products/ati-2304
    kind: datasheet
    license: cited, not reproduced
  alleima-saf2304:
    title: 'Alleima: SAF 2304 tube and pipe, seamless datasheet (updated 2026-02-11)'
    id: SAF 2304 seamless tube and pipe
    url: https://www.alleima.com/en/technical-center/material-datasheets/tube-and-pipe-seamless/saf-2304?show=pdf
    kind: datasheet
    year: 2026
    license: cited, not reproduced
  icast-s32304:
    title: 'ICAST Alloys: ASTM A240 UNS S32304 chemical composition and mechanical summary'
    id: ASTM A240 UNS S32304
    url: https://www.icastllp.com/material_db_pdf/ASTM%20A240%20UNS%20S32304.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
  usgs-molybdenum-2026:
    title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
    id: mcs2026-molybdenum
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.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-molybdenum:
    title: 'PubChem: Molybdenum (CID 23932), UN GHS classification'
    id: CID 23932
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/JSON
    kind: database
    license: PubChem terms (public)
license: CC-BY-4.0
updated: '2026-10-24'
review:
  status: draft
  method: assistant
  checked_values: 25
  unreachable: 0
  caveats: 7
  note: 'Read by an AI assistant on 2026-10-24 from pages fetched in this run: ATI 2304 TDS version 1 (2014), the ATI 2304 product page, the Alleima SAF 2304 seamless tube and pipe datasheet (updated 2026-02-11), the ICAST ASTM A240 UNS S32304 summary, USGS MCS 2026 nickel, chromium and molybdenum, and PubChem nickel, chromium and molybdenum GHS records. Composition ranges come from the ICAST and ATI product pages. ATI 2014 values are typical, not limits. Resellers and aggregators were not used for values.'
story:
  why: Lean duplex 2304 (UNS S32304, EN 1.4362) gives about twice the proof strength of austenitic stainless steels, with chloride stress corrosion resistance that ATI and Alleima both rate above the 304 and 316 grades. ATI says its general corrosion resistance is comparable to 316L in most environments, and its typical PREN is 26. Its limits are the 475 C embrittlement that ATI links to exposure above about 315 C (600 F), and Alleima's 280 C maximum for prolonged exposure in pressure vessels.
  recipe:
    line: Lean duplex 2304 is an austenite-ferrite steel with a nearly equal mixture of the two phases (ATI). Composition limits in weight percent under ASTM A240 for UNS S32304 are chromium 21.5 to 24.5, nickel 3.0 to 5.5, molybdenum 0.05 to 0.60, copper 0.05 to 0.60, nitrogen 0.05 to 0.20, carbon 0.030 max, manganese 2.50 max, silicon 1.00 max, phosphorus 0.040 max, sulphur 0.030 max, and iron as the balance (ICAST, ATI). Alleima's nominal composition is Cr 22.5, Ni 4.5, Mo 0.3, Cu 0.3 and N 0.1. Seamless tube is delivered solution annealed and white pickled or bright annealed (Alleima).
    parts:
      - name: Iron
        symbol: Fe
        share_note: balance (the rest)
        role: Matrix of the alloy, with the austenite and ferrite phases
        source: ati-product
        where: Composition table, Fe Balance row
      - name: Chromium
        symbol: Cr
        share_percent: 21.5
        share_high: 24.5
        role: Forms the passive film; with Mo and N it sets the PREN (ATI)
        source: ati-product
        where: Composition table, Minimum and Maximum weight percent (Cr row)
      - name: Nickel
        symbol: Ni
        share_percent: 3
        share_high: 5.5
        role: Austenite-forming element; overmatched fillers carry more nickel (ATI)
        source: ati-product
        where: Composition table, Minimum and Maximum weight percent (Ni row)
      - name: Molybdenum
        symbol: Mo
        share_percent: 0.05
        share_high: 0.6
        role: Adds to the PREN (Cr + 3.3 Mo + 16 N, ATI)
        source: ati-product
        where: Composition table, Minimum and Maximum weight percent (Mo row)
      - name: Nitrogen
        symbol: 'N'
        share_percent: 0.05
        share_high: 0.2
        role: Adds to the PREN (16 times the nitrogen weight percent, ATI)
        source: ati-product
        where: Composition table, Minimum and Maximum weight percent (N row)
      - name: Copper
        symbol: Cu
        share_percent: 0.05
        share_high: 0.6
        role: Alloying addition inside the ASTM A240 range; no role printed in the sources
        source: ati-product
        where: Composition table, Minimum and Maximum weight percent (Cu row)
      - name: Carbon
        symbol: C
        share_percent: 0
        share_high: 0.03
        role: Maximum limit (ASTM A240)
        source: ati-product
        where: Composition table (C 0.030 row)
      - name: Manganese
        symbol: Mn
        share_percent: 0
        share_high: 2.5
        role: Maximum limit (ASTM A240)
        source: ati-product
        where: Composition table (Mn 2.50 row)
      - name: Silicon
        symbol: Si
        share_percent: 0
        share_high: 1
        role: Maximum limit (ASTM A240)
        source: ati-product
        where: Composition table (Si 1.00 row)
      - name: Phosphorus
        symbol: P
        share_percent: 0
        share_high: 0.04
        role: Maximum limit (ASTM A240)
        source: ati-product
        where: Composition table (P 0.040 row)
      - name: Sulphur
        symbol: S
        share_percent: 0
        share_high: 0.03
        role: Maximum limit (ASTM A240)
        source: ati-product
        where: Composition table (S 0.030 row)
  risk_groups:
    - title: For people
      level: 0
      verdict: Element records, not alloy tests
      lead: PubChem lists hazards for elemental nickel, chromium and molybdenum. No 2304 safety data sheet was read.
      points:
        - label: Nickel
          line: PubChem lists H250, H317, H334, H341, H350, H351, H360, H360F, H370, H372, H411 and H412 for elemental nickel.
        - label: Chromium
          line: PubChem lists H317, H319, H320, H334, H335, H341, H371, H400 and H410 for elemental chromium.
        - label: Molybdenum
          line: PubChem lists H225, H228, H315, H319, H335 and H361 for elemental molybdenum.
    - title: In the environment
      level: 1
      verdict: Chloride and oxidising service are the watch points
      lead: The PREN of 25 to 26 holds off pitting, but chloride SCC rises above 125 C in oxygen-bearing solutions with more than about 10 ppm chloride.
      points:
        - label: Chloride
          line: 'Alleima: safe to about 125 C without SCC in dilute oxygen-bearing chloride; above 125 C avoid oxygen-bearing solutions with more than about 10 ppm Cl-.'
        - label: Pitting
          line: Critical pitting temperature is not printed as a number; Alleima says it is comparable to 316L.
    - title: Heat history
      level: 2
      verdict: Heat history sets the embrittlement risk
      lead: The 475 C embrittlement and the prolonged-exposure limit both come from heat history.
      points:
        - label: Band
          line: 'ATI: 885 F (475 C) embrittlement follows exposure above about 600 F (315 C).'
        - label: Prolonged
          line: 'Alleima: prolonged exposure above 280 C (540 F) reduces impact strength.'
        - label: Fix
          line: Solution anneal at 930 to 1050 C with rapid cooling (Alleima); rapid cooling also prevents deleterious phases (ATI).
  uses:
    - where: Process heat exchangers and piping where chlorides are present
      line: Alleima lists these as higher-SCC-resistance replacements for 304 and 316.
    - where: Pulp and paper digester preheaters and evaporators
      line: Alleima lists these uses against 304 and 316.
    - where: Oil and gas coolers, flowlines and offshore rig tensioning systems
      line: Alleima lists these uses, citing strength, weldability, corrosion resistance and cost.
  can_do:
    - label: Strength
      benchmark: yield_strength
      line: Minimum 0.2 percent proof strength is 400 MPa for plate (ATI) and for tube and pipe up to 20 mm wall (Alleima). Alleima says the proof strength is about twice that of austenitic steels.
    - label: Tensile
      benchmark: ultimate_tensile_strength
      line: Minimum tensile strength is 600 MPa for plate (ATI). Alleima tube and pipe reaches 630 to 820 MPa.
    - label: Chloride pitting
      benchmark: pitting_resistance_equivalent
      line: PREN is 26 typical (ATI) and 25 on Alleima's nominal composition, against 24 for 316L.
    - label: Chloride SCC
      line: Resists SCC in dilute oxygen-bearing chloride up to about 125 C (Alleima), where 304 and 316 are limited to 60 C.
    - label: Density
      benchmark: density
      line: Density is 7.8 g/cm3 (ATI, Alleima).
    - label: Stiffness
      benchmark: elastic_modulus
      line: Elastic modulus is 200 GPa (ATI) and 180 GPa at 300 C (Alleima).
    - label: Expansion
      benchmark: cte
      line: Mean expansion is 13 x 10-6 per C from 20 to 100 C (ATI) and 13.5 x 10-6 per C from 30 to 100 C (Alleima), against 16.5 for 304L and 316L (Alleima).
  compare: 'Against 316L and 304L, 2304 has the higher PREN: 25 on Alleima''s nominal composition against 24 for 316L and 18 for 304L, and ATI''s typical PREN of 26 against 24 for 316L. Its minimum strengths for plate (400 MPa yield and 600 MPa tensile, ATI) are well above the austenitic grades, and Alleima says its proof strength is about twice that of austenitic steels. Alleima says 304 and 316 should not be used above 60 C in dilute oxygen-bearing chloride, while 2304 is safe to about 125 C. The trade-off is the 475 C embrittlement band that ATI ties to exposure above about 315 C, and the 280 C limit for prolonged exposure in pressure vessels (Alleima).'
  compare_rows:
    - label: Pitting resistance (PREN)
      benchmark: pitting_resistance_equivalent
      scope: material
    - label: Yield strength (0.2 percent minimum)
      benchmark: yield_strength
      scope: material
    - label: Tensile strength (minimum)
      benchmark: ultimate_tensile_strength
      scope: material
  handling:
    - Solution anneal at 930 to 1050 C (1710 to 1920 F) and cool rapidly in air or water (Alleima); ATI gives a minimum of 980 C (1800 F).
    - Weld without preheating, at a heat input of 0.5 to 2.5 kJ/mm and an interpass temperature below 150 C (Alleima).
    - Use overmatched filler metal, such as ER2209 or the 23.7 types (Alleima, ATI).
    - Cold bend to 25 percent deformation without heat treatment; use a bend radius of at least two times the thickness (Alleima, ATI).
    - Expand tubes in one operation, since expansion needs higher initial force (Alleima).
  good_for:
    - Chloride-bearing process heat exchangers and piping where 304 and 316 would crack (Alleima).
    - Structures and tubing that need about twice the proof strength of austenitic steels (Alleima, ATI).
    - Pressure parts up to 315 C under the ASME Section VIII Division 1 limit for plate (ATI), with prolonged exposure held to 280 C or below (Alleima).
  watch_out:
    - Embrittlement after exposure above about 315 C (600 F), the 885 F (475 C) effect (ATI).
    - Above 125 C in oxygen-bearing chloride with more than about 10 ppm Cl-, do not use it; choose SAF 2205, SAF 2507 or Sanicro 28 (Alleima).
    - Welds need overmatched filler metal and controlled heat input, because the weld phase balance depends on them (ATI, Alleima).
  verdict: Lean duplex 2304 is a strong, chloride-resistant duplex option, with a typical PREN of 26 (ATI) and a plate minimum yield of 400 MPa (ATI). Keep it under the 315 C ASME limit for plate, hold prolonged pressure-part exposure to 280 C or below (Alleima), and do not use it in oxygen-bearing chloride above 125 C with more than about 10 ppm Cl- (Alleima). No source in this file ties it to a space part, so the space link is open.