spore: profile
id: stainless-431
spore_version: 0.2
family: stainless-martensitic
name: Stainless steel 431
abbreviation: 431 (UNS S43100, EN 1.4057)
role: high-strength shaft and valve-stem stainless
category: metals
type: steels-and-stainless
summary: Type 431 (UNS S43100, EN 1.4057, X17CrNi16-2) is a martensitic chromium-nickel stainless steel with 15 to 17 percent chromium and 1.5 to 2.5 percent nickel (EN 10088-3 limits, Smiths High Performance and Team Edelstahl). Heat treated, it reaches 800 to 1000 MPa tensile strength with 12 percent elongation and good toughness. Smith Metal and Team Edelstahl list pump and propeller shafts, valve stems and pump parts as typical uses. Smiths High Performance calls it the most corrosion resistant of the martensitic grades, but it cracks in welds unless it is preheated.
best_for: High tensile and torsional strength in shafts, valve stems and pump parts that also need reasonable corrosion resistance (Smith Metal, Smiths High Performance)
weakest_at: 'Welding and cold forming: welds crack unless preheated, and the grade is not recommended for cold heading or bending (Smiths High Performance, Voestalpine)'
identity:
  formula: Fe balance with 15.0 to 17.0 Cr, 1.5 to 2.5 Ni, 0.12 to 0.22 C, up to 1.5 Mn, 1.0 Si, 0.04 P and 0.03 S (wt%, EN 10088-3 limits for 1.4057, as printed by Smiths High Performance and Team Edelstahl)
  source: team-1-4057
  where: Chemische Zusammensetzung table, min and max rows (C, Mn, Si, P, S, Cr, Ni), cross-checked with the Smiths High Performance chemical composition table
  designations:
    - system: UNS
      code: S43100
      source: aircraftmaterials-431
      where: Designations block of the Aircraft Materials page, UNS S43100
    - system: EN
      code: '1.4057'
      source: team-1-4057
      where: Normen und Bezeichnungen table, row EN
    - system: EN name
      code: X17CrNi16-2
      source: team-1-4057
      where: Normen und Bezeichnungen table, row DIN
    - system: AISI
      code: '431'
      source: abrams-1-4057
      where: Header block, field AISI/SAE, and the composition table heading AISI/SAE 431
    - system: BS
      code: 431S29
      source: aircraftmaterials-431
      where: Designations block of the Aircraft Materials page, line BS 970; 431S29
    - system: ASTM
      code: A276
      note: bar
      source: aircraftmaterials-431
      where: Designations block of the Aircraft Materials page, line ASTM A276 / ASME SA276
    - system: AMS
      code: '5628'
      note: bars, wire and forgings, heat treated
      source: aircraftmaterials-431
      where: Typical Mechanical Properties table, heat treated row, and the designations block line AMS 5628 Bars / wire / forgings
    - system: JIS
      code: SUS 431
      source: swiss-dew-2018
      where: Material description line on the bar page 11, Acidur 4057, 1.4057, Type 431, SUS 431
    - system: Trade name
      code: Acidur 4057
      source: swiss-dew-2018
      where: Material description line on the bar page 11
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
    - structures
properties:
  - benchmark: density
    label: Density, Smiths High Performance datasheet
    value: 7800
    unit: kg/m3
    scope: material
    conditions:
      grade: 1.4057, properties as per BS EN 10088-3
      temperature: not stated
    method: Value printed in a stockholder datasheet
    status: ground
    source: smiths-431
    where: Physical Properties table, row Density
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C
    value: 25
    unit: W/(m·K)
    scope: material
    conditions:
      grade: 1.4057 (X17CrNi16-2)
      temperature: 20 °C
      unit_in_source: W/(m • K)
    method: Value printed in a steel-grade datasheet
    status: ground
    source: abrams-1-4057
    where: Physical properties block, Thermal conductivity row, 20°C value
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 100 °C
    value: 20.2
    unit: W/(m·K)
    scope: material
    conditions:
      grade: '1.4057'
      temperature: 100 °C
    method: Value printed in a stockholder datasheet
    status: ground
    source: smiths-431
    where: Physical Properties table, row Thermal Conductivity at 100°C
  - benchmark: specific_heat
    label: Specific heat capacity at 20 °C
    value: 460
    unit: J/(kg·K)
    scope: material
    conditions:
      grade: '1.4057'
      temperature: 20 °C
      unit_in_source: J/kg K
    method: Value printed in a steel-grade datasheet
    status: ground
    source: team-1-4057
    where: Physikalische Eigenschaften table, column Spezifische Wärmekapazität, row bei 20°C
  - benchmark: elastic_modulus
    label: Modulus of elasticity at 20 °C
    value: 215
    unit: kN/mm2
    scope: material
    conditions:
      grade: '1.4057'
      temperature: 20 °C
      unit_in_source: kN / mm²
    method: Value printed in a steel-grade datasheet
    status: ground
    source: team-1-4057
    where: Mechanische Eigenschaften table, column Elastizitätsmodul, row bei 20°C
  - benchmark: elastic_modulus
    label: Modulus of elasticity, temperature not stated
    value: 200
    unit: GPa
    scope: material
    conditions:
      grade: 1.4057, properties as per BS EN 10088-3
      temperature: not stated
    method: Value printed in a stockholder datasheet
    status: ground
    source: smiths-431
    where: Physical Properties table, row Modulus of Elasticity
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C
    value: 0.7
    unit: ohm mm2/m
    scope: material
    conditions:
      grade: '1.4057'
      temperature: 20 °C
      unit_in_source: (ohm) mm²/m
    method: Value printed in a steel-grade datasheet
    status: ground
    source: team-1-4057
    where: Physikalische Eigenschaften table, column Elektrischer Widerstand, row bei 20°C
  - benchmark: cte
    label: Mean coefficient of thermal expansion, 20 to 100 °C
    value: 10
    unit: ppm/K
    scope: material
    conditions:
      grade: AISI/SAE 431 (1.4057)
      temperature: 20 to 100 °C
      unit_in_source: 10-6 m/(m·K)
    method: Value printed in a steel-grade datasheet, table of thermal expansion coefficients
    status: ground
    source: abrams-1-4057
    where: Thermal expansion coefficient table, column 20-100°C
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, annealed
    value: 862
    unit: MPa
    scope: material
    conditions:
      condition: annealed
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Annealed, column Tensile Strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, heat treated to AMS 5628
    value: 1379
    unit: MPa
    scope: material
    conditions:
      condition: heat treated to AMS 5628
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Heat Treated AMS 5628, column Tensile Strength
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, heat treated
    value: 850
    value_high: 1000
    bound: range
    unit: MPa
    scope: material
    conditions:
      condition: heat treated (recommended heat treatment, quench and tempered supply condition)
      product: not stated
    method: Range printed in a steel-grade datasheet
    status: ground
    source: voest-431
    where: MECHANICAL PROPERTIES (HEAT TREATED) table, column Tensile Mpa (Rm)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, QT800 at 60 to 160 mm
    value: 800
    value_high: 950
    bound: range
    unit: MPa
    scope: material
    conditions:
      condition: QT800 quench and tempered
      thickness: 60 to 160 mm
      basis: BS EN 10088-3, 1.4057
    method: Range printed in a stockholder datasheet
    status: ground
    source: smiths-431
    where: Mechanical Properties table, row Ultimate Tensile Strength, footnote QT800 60-160mm
  - benchmark: yield_strength
    label: Yield strength, heat treated
    value: 600
    unit: MPa
    scope: material
    conditions:
      condition: heat treated (recommended heat treatment)
      product: not stated
    method: Value printed in a steel-grade datasheet, shown as a single value
    status: ground
    source: voest-431
    where: MECHANICAL PROPERTIES (HEAT TREATED) table, column Yield Strength (MPa)
  - benchmark: yield_strength
    label: Proof stress 0.2 percent, annealed
    value: 655
    unit: MPa
    scope: material
    conditions:
      condition: annealed
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Annealed, column Proof Stress 0.2%
  - benchmark: yield_strength
    label: Proof stress 0.2 percent, heat treated to AMS 5628
    value: 1034
    unit: MPa
    scope: material
    conditions:
      condition: heat treated to AMS 5628
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Heat Treated AMS 5628, column Proof Stress 0.2%
  - benchmark: yield_strength
    label: Proof stress, T condition, minimum
    value: 665
    bound: lower
    unit: MPa
    scope: material
    conditions:
      condition: T condition, as printed
      product: not stated
    method: Minimum value printed in a stockholder datasheet
    status: ground
    source: smith-metal-431
    where: Mechanical Properties (T condition) table, row Proof Stress
  - benchmark: yield_strength
    label: Rp0.2, QT800 at 20 to 160 mm, minimum
    value: 620
    bound: lower
    unit: MPa
    scope: material
    conditions:
      condition: QT800
      thickness: 20 to 160 mm, longitudinal
      basis: BS EN 10088-3 table
    method: Minimum value printed in a supplier datasheet
    status: ground
    source: swiss-dew-2018
    where: Mechanical properties table, row Rp0,2 in MPa, column 20-160 mm longitudinal
  - benchmark: elongation
    label: Elongation, annealed
    value: 20
    unit: '%'
    scope: material
    conditions:
      condition: annealed
      gauge_length: 2 in
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Annealed, column Elongation 2 in
  - benchmark: elongation
    label: Elongation, heat treated to AMS 5628
    value: 10
    unit: '%'
    scope: material
    conditions:
      condition: heat treated to AMS 5628
      gauge_length: 2 in
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Heat Treated AMS 5628, column Elongation 2 in
  - benchmark: elongation
    label: Elongation, heat treated
    value: 12
    unit: '%'
    scope: material
    conditions:
      condition: heat treated (recommended heat treatment)
      product: not stated
    method: Value printed in a steel-grade datasheet
    status: ground
    source: voest-431
    where: MECHANICAL PROPERTIES (HEAT TREATED) table, column Elongation (%)
  - benchmark: hardness_brinell
    label: Hardness, annealed
    value: 260
    unit: HB
    scope: material
    conditions:
      condition: annealed
      product: not stated
    method: Typical value printed on the page
    status: ground
    source: aircraftmaterials-431
    where: Typical Mechanical Properties table, row Alloy 431 Annealed, column Brinell Hardness
  - benchmark: hardness_brinell
    label: Hardness, delivery condition, maximum
    value: 331
    bound: upper
    unit: HB
    scope: material
    conditions:
      condition: delivery condition, tempered
      product: not stated
    method: Maximum value printed in a steel-grade datasheet
    status: ground
    source: abrams-1-4057
    where: Physical properties block, row Hardness (delivery condition)
  - benchmark: hardness_brinell
    label: Hardness, QT800 maximum
    value: 321
    bound: upper
    unit: HBW
    scope: material
    conditions:
      condition: QT800
      thickness: 20 to 160 mm
    method: Maximum value printed in a supplier datasheet
    status: ground
    source: swiss-dew-2018
    where: Mechanical properties table, row Hardness in HBW, column 20-160 mm
  - benchmark: impact_energy
    label: Impact toughness, heat treated
    value: 25
    unit: J
    scope: material
    conditions:
      condition: heat treated
      test_temperature: not stated
    method: Value printed in a steel-grade datasheet, shown as a single value
    status: ground
    source: voest-431
    where: MECHANICAL PROPERTIES (HEAT TREATED) table, column Impact Toughness (J)
  - benchmark: impact_energy
    label: Impact energy ISO-V, QT800 minimum
    value: 27
    bound: lower
    unit: J
    scope: material
    conditions:
      condition: QT800
      thickness: 20 to 160 mm, longitudinal
      test_temperature: not stated
    method: Minimum value printed in a supplier datasheet
    status: ground
    source: swiss-dew-2018
    where: Mechanical properties table, row Av ISO-V in J, column 20-160 mm longitudinal
  - benchmark: max_service_temp
    label: Usable temperature, upper limit
    value: 400
    unit: °C
    scope: material
    conditions:
      basis: usable range stated in the datasheet
    method: Range printed in a steel-grade datasheet
    status: ground
    source: team-1-4057
    where: Besondere Eigenschaften row, text Von -40 bis 400 °C verwendbar
  - benchmark: min_service_temp
    label: Usable temperature, lower limit
    value: -40
    unit: °C
    scope: material
    conditions:
      basis: usable range stated in the datasheet
    method: Range printed in a steel-grade datasheet
    status: ground
    source: team-1-4057
    where: Besondere Eigenschaften row, text Von -40 bis 400 °C verwendbar
corrosion:
  - environment: Salt water and marine atmosphere
    headline: Considerable resistance to salt water, described as similar to Type 304.
    effect: Smith Metal says the alloy offers considerable resistance to saltwater and is used widely in marine equipment, and rates its corrosion resistance as similar to Type 304. No salt-spray test result or corrosion rate is printed.
    rating: moderate
    conditions:
      basis: manufacturer statement, no test conditions printed
    source: smith-metal-431
    where: Corrosion resistance section
  - environment: Nitrided surface
    headline: Nitriding raises hardness and fatigue resistance but lowers corrosion resistance.
    effect: Smiths High Performance says 431 has the highest corrosion resistance of all martensitic stainless steels, although resistance reduces once the material is nitrided. Nitriding increases hardness and fatigue resistance.
    rating: moderate
    conditions:
      basis: manufacturer statement, no test conditions printed
    source: smiths-431
    where: Opening text and Product Benefits list
  - environment: Carbide-sensitised zones after heat treatment or welding
    headline: Chromium carbides can make the alloy prone to intergranular corrosion.
    effect: Team Edelstahl says the grade is susceptible to intergranular corrosion because chromium carbides form and deplete chromium in some areas. It gives PREN 17.5 to 21.2, and says the maximum corrosion resistance is reached with a bare metallic surface.
    rating: moderate
    conditions:
      basis: manufacturer statement, PREN as printed
    source: team-1-4057
    where: Korrosionsbeständigkeit row
risks:
  hazards:
    - text: 'PubChem aggregated GHS notifications for elemental chromium (CID 23976), not for the 431 alloy: H317 (20.7 percent of notifications), H319 (19.1 percent) and H334 (20.3 percent), signal word Danger, pictograms GHS07 and GHS08. Of 2,404 company reports, 1,202 said chromium does not meet GHS criteria.'
      ghs:
        - H317
        - H319
        - H334
      source: pubchem-chromium
      where: GHS Classification section, ECHA C&L Inventory aggregate
  failure_risks:
    - mode: Intergranular corrosion from chromium carbides
      trigger: Heat treatment or welding that lets chromium carbides form along grain boundaries and deplete chromium next to them
      consequence: Team Edelstahl says the grade is susceptible to intergranular corrosion, so corrosion resistance falls in the affected zones.
      severity: moderate
      source: team-1-4057
      where: Korrosionsbeständigkeit row
    - mode: Cracking in welds
      trigger: Welding without preheat
      consequence: Smiths High Performance says welding is more complicated and susceptible to cracking unless pre-heated. Smith Metal says welding is difficult and recommends preheating.
      severity: moderate
      source: smiths-431
      where: Opening text, paragraph on machining and welding
    - mode: Lower corrosion resistance after nitriding
      trigger: Nitriding the surface for hardness or fatigue resistance
      consequence: Smiths High Performance says corrosion resistance reduces once the material is nitrided.
      severity: low
      source: smiths-431
      where: Opening text, paragraph on corrosion resistance
    - mode: Property loss from hydrogen or nitrogen gas during welding
      trigger: Welding under gases that contain hydrogen or nitrogen
      consequence: Team Edelstahl says such gases have a negative effect on the mechanical properties of the weld.
      severity: moderate
      source: team-1-4057
      where: Schweißeignung row
  side_effects: []
  handling:
    - text: Voestalpine says the grade cannot be readily cold worked and is not recommended for cold heading and bending.
      source: voest-431
      where: Description paragraph
    - text: Team Edelstahl says it can be welded only with precautions, and recommends heating to 100 to 300 °C before welding and avoiding cooling below 200 °C during welding.
      source: team-1-4057
      where: Schweißeignung row
    - text: Team Edelstahl says tempering colours must be removed chemically or mechanically after welding to keep corrosion resistance in the weld.
      source: team-1-4057
      where: Schweißeignung row
  mitigations:
    - text: Preheat before welding, and keep the weld below 200 °C while it is made (Team Edelstahl). Smiths High Performance and Smith Metal also recommend preheat.
      source: team-1-4057
      where: Schweißeignung row
uses:
  - application: mechanisms
    device: Pump and propeller shafts, outboard drive shafts, valve stems and axles
    example: Smith Metal lists marine systems, pump and propeller shafts, outboard motor drive shafts, valve stems, aircraft components and axles as typical applications.
    source: smith-metal-431
    where: Typical Applications list
  - application: mechanisms
    device: Pumps, valves, piston rods and compressor impellers
    example: Team Edelstahl says the grade is often used for heavily loaded machine parts such as pumps, valves, piston rods and compressor impellers, and lists automotive, chemical and petrochemical, power plant and aerospace uses.
    source: team-1-4057
    where: Kurzbeschreibung paragraph and Anwendungsgebiete row
  - application: structures
    device: Bolts, fasteners and bearings
    example: Smiths High Performance lists bolts and fasteners, bearings, pump shafts and valve stems among motorsport applications for 431.
    source: smiths-431
    where: Motorsport Applications list
supply:
  - subject: Chromium
    abundance: World mine production of chromite was 51,000 thousand t gross weight in 2025 (estimated). World resources are greater than 12 billion t of shipping-grade chromite, 95 percent in Kazakhstan and southern Africa (USGS 2026).
    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: Zimbabwe
        share_percent: 3.9
        year: 2025
      - country: Brazil
        share_percent: 3.9
        year: 2025
    critical_lists: []
    recycling: USGS says recycled chromium, contained in reported stainless-steel scrap receipts, accounted for 21 percent of the chromium total in 2025.
    substitutes: []
    source: usgs-chromium-2026
    where: World Mine Production and Reserves table, column 2025e, world total 51,000 (gross weight); shares calculated by Space Mushroom as country value over world total; Domestic Production and Use and Recycling paragraphs
  - subject: Nickel
    abundance: World mine production of nickel was an estimated 3.9 million t in 2025, and world reserves are greater than 140 million t (USGS 2026).
    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
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-nickel-2026
    where: World Mine Production and Reserves table, column 2025e, world total 3,900,000 t; shares calculated by Space Mushroom as country value over world total
media: []
documents:
  - title: Stainless Steel 431 product page, Aircraft Materials (composition, typical mechanical properties, designations)
    type: datasheet
    url: https://www.aircraftmaterials.com/data/alstst/alstst/431.html
  - title: 431 Stainless Steel Technical Datasheet, Smiths High Performance, revision 12.02.2025
    type: datasheet
    url: https://www.smithshp.com/assets/pdf/stainless-steel/high-performance-stainless-steel/431-stainless-steel-english.pdf
    year: 2025
  - title: AISI 431 / 1.4057 / UNS43100 datasheet, voestalpine High Performance Metals Australia
    type: datasheet
    url: https://www.voestalpine.com/highperformancemetals/australia/app/uploads/sites/265/2026/07/Datasheet-431-2026-v2.pdf
    year: 2026
  - title: 431 Stainless Technical Datasheet, Smiths Metal Centres
    type: datasheet
    url: https://www.smithmetal.com/pdf/stainless/431-stainless.pdf
    year: 2023
  - title: 'Abrams Premium Steel: steel grade 1.4057 (AISI/SAE 431) datasheet'
    type: datasheet
    url: https://files.abrams-industries.com/steel/en_eu/1.4057.pdf
  - title: 'Team Edelstahl: Werkstoff Datenblatt 1.4057 X17CrNi16-2'
    type: datasheet
    url: https://www.teamedelstahl.de/wp-content/uploads/2021/04/1.4057.pdf
  - title: Swiss Steel Group stainless steel bar programme (2018-0010 DEW Lagerkatalog RSH EN), pages 10 to 11
    type: datasheet
    url: https://swisssteel-group.com/content-media/documents/Brochures/Stainless-Steel/2018-0010_DEW_Lagerkatalog_RSH_EN.pdf
    year: 2018
  - 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: Nickel'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.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
gaps:
  - No safety data sheet for 431 itself was read. The hazard entry uses the PubChem aggregate for elemental chromium, and a search for welding-fume SDS returned only other filler metals, so welding fume exposure limits are not recorded.
  - 'Density: Team Edelstahl prints 7.0 kg/dm3 at 20 °C, which conflicts with 7800 kg/m3 from Smiths High Performance. Only the Smiths value is recorded, and the conflict is not resolved.'
  - 'Electrical resistivity: Smiths High Performance prints 720 with the unit ''n. Ω.m''. It is not recorded because the printed unit is unusual. The Team Edelstahl value of 0.70 ohm mm2/m is recorded instead.'
  - 'Composition limits differ: Smiths High Performance, Team Edelstahl and Abrams give nickel 1.5 to 2.5 percent and manganese up to 1.5 percent; Swiss Steel and Smith Metal give nickel 1.25 minimum and Smith Metal gives manganese up to 1.0 percent. The EN limits are used in the recipe, and both are noted. Aircraft Materials gives chromium 15.50 to 16.50 and nickel 2 to 3 percent (its own AMS-type limits), not used.'
  - 'Tempering temperature conflicts: Voestalpine prints 600 to 650 °C with a one-hour minimum hold, and Team Edelstahl and Abrams print 600 to 800 °C (Team) and 950 to 1050 °C hardening only (Abrams). Both ranges are recorded in the recipe line, and no single value is used as a property.'
  - 'Hardness: Team Edelstahl prints a maximum of 295 HB at 20 °C without a condition, which is not recorded as a property because the condition is not stated. Swiss Steel gives a maximum of 321 HBW for QT800, and Abrams gives 331 HB for the delivery condition.'
  - 'Designation conflict: the Aircraft Materials page title says AMS 5682 while its tables and designations list say AMS 5628, so only AMS 5628 is recorded. The Voestalpine nearest-standards table prints X20CrNi16-2 for the EN name, which is not recorded; Team Edelstahl''s X17CrNi16-2 is used instead.'
  - Tensile and yield values from manufacturers are typical or minimum values for one heat treatment each. Strength by product size and temper is not verified against a specification, and no ASTM A276 or AMS 5628 minimum table was opened.
  - Corrosion rate, salt spray and atmospheric exposure results were not found. The ratings in the corrosion section are from manufacturer statements only.
  - Hardness and impact are not in the canonical property list used by the import (hardness_brinell and impact_energy are short names chosen for this profile). Impact test temperatures were not printed in the sources.
  - 'Cold working: Voestalpine says the grade cannot be readily worked cold, but no cold-working limit or reduction figure was printed.'
  - 'Supply: no critical-mineral listing for chromium or nickel was found in the USGS text opened. Chromium recycling is recorded from the USGS 2026 text, and nickel recycling was not read.'
  - Atomic oxygen, radiation, outgassing and cryogenic toughness were not looked up for this grade; Team Edelstahl gives service only down to -40 °C.
  - Thermal expansion 20 to 400 °C (10.6 ppm/K) is printed in the Abrams table with a decimal comma, which the value check could not match, so it was removed. The 20 to 100 °C value (10.0) is kept.
  - 'Aalco 431 datasheet: the Aalco page returned 404 and no Aalco 431 datasheet was found by search, so Aalco is not cited. The makeitfrom and AZoM pages were blocked or were for another material and are not used.'
sources:
  aircraftmaterials-431:
    title: Stainless Steel Grade 431 (Aircraft Materials)
    url: https://www.aircraftmaterials.com/data/alstst/alstst/431.html
    kind: datasheet
    license: web page (cited, not reproduced)
  smiths-431:
    title: 431 Stainless Steel Technical Datasheet, Smiths High Performance, revision 12.02.2025
    url: https://www.smithshp.com/assets/pdf/stainless-steel/high-performance-stainless-steel/431-stainless-steel-english.pdf
    year: 2025
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  voest-431:
    title: AISI 431 / 1.4057 / UNS43100, voestalpine High Performance Metals Australia
    url: https://www.voestalpine.com/highperformancemetals/australia/app/uploads/sites/265/2026/07/Datasheet-431-2026-v2.pdf
    year: 2026
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  smith-metal-431:
    title: 431 Stainless Technical Datasheet, Smiths Metal Centres
    url: https://www.smithmetal.com/pdf/stainless/431-stainless.pdf
    year: 2023
    kind: datasheet
    license: Stockholder datasheet (cited, not reproduced)
  abrams-1-4057:
    title: Abrams Premium Steel, steel grade 1.4057 (AISI/SAE 431)
    url: https://files.abrams-industries.com/steel/en_eu/1.4057.pdf
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  team-1-4057:
    title: Team Edelstahl, Werkstoff Datenblatt 1.4057 X17CrNi16-2
    url: https://www.teamedelstahl.de/wp-content/uploads/2021/04/1.4057.pdf
    kind: datasheet
    license: Distributor datasheet (cited, not reproduced)
  swiss-dew-2018:
    title: Swiss Steel Group stainless steel bar programme (2018-0010 DEW Lagerkatalog RSH EN)
    url: https://swisssteel-group.com/content-media/documents/Brochures/Stainless-Steel/2018-0010_DEW_Lagerkatalog_RSH_EN.pdf
    year: 2018
    kind: datasheet
    license: Manufacturer catalogue (cited, not reproduced)
  usgs-chromium-2026:
    title: 'Mineral Commodity Summaries 2026: Chromium'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-nickel-2026:
    title: 'Mineral Commodity Summaries 2026: Nickel'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-chromium:
    title: 'PubChem: Chromium (CID 23976), GHS classification'
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
    kind: database
    license: PubChem terms (public)
license: CC-BY-4.0
updated: '2026-10-25'
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 0
  caveats: 4
  note: 'Read by an AI assistant on 2026-10-25 from the pages and PDFs named in each entry. Caveats: the strength values are manufacturer typical or minimum values for different heat treatments and product forms, not a specification; the datasheets disagree on composition limits, tempering range and density; the hazard entry is the PubChem chromium record, not a 431 safety data sheet; the supply shares are calculated from the USGS printed values.'
story:
  recipe:
    line: Type 431 is an iron-chromium-nickel martensitic steel, supplied as bar, plate, sheet and tube (Smith Metal). Voestalpine recommends a soft anneal with slow furnace cooling, hardening in oil or air, and tempering with at least one hour at temperature followed by air cooling. Team Edelstahl gives the same EN ranges as Smiths High Performance.
    parts:
      - name: Iron
        symbol: Fe
        share_note: balance (the rest)
        role: The matrix of the alloy. Quench and tempering turn it into martensite, which gives the high strength.
      - name: Chromium
        symbol: Cr
        share_percent: 15
        share_high: 17
        role: Forms the passive oxide film that gives corrosion resistance. Voestalpine's average analysis sits in the upper part of this range.
      - name: Nickel
        symbol: Ni
        share_percent: 1.5
        share_high: 2.5
        role: Adds toughness and corrosion resistance over 13 percent chromium steels (Team Edelstahl). Swiss Steel and Smith Metal print a minimum of 1.25 percent.
      - name: Carbon
        symbol: C
        share_percent: 0.12
        share_high: 0.22
        role: Gives the hardness that hardening produces. Voestalpine's average analysis is at the upper end of this range.
      - name: Manganese
        symbol: Mn
        share_percent: 0
        share_high: 1.5
        role: Deoxidiser held at up to 1.5 percent in the EN limits; Smith Metal prints a lower upper limit.
      - name: Silicon
        symbol: Si
        share_percent: 0
        share_high: 1
        role: Deoxidiser held at up to 1.0 percent.
      - name: Phosphorus
        symbol: P
        share_percent: 0
        share_high: 0.04
        role: Impurity held at up to 0.04 percent.
      - name: Sulfur
        symbol: S
        share_percent: 0
        share_high: 0.03
        role: Impurity held at up to 0.03 percent.
  risk_groups:
    - title: For people
      level: 1
      verdict: Chromium and nickel alloy, not a safety data sheet
      lead: No 431 safety data sheet was read. The hazard record is for elemental chromium, and it does not name the alloy.
      points:
        - label: Chromium
          line: PubChem lists sensitisation codes H317 and H334 and eye irritation code H319 for elemental chromium in its aggregated notifications.
    - title: In the environment
      level: 2
      verdict: Marine use is the common case
      lead: Smith Metal calls the alloy resistant to salt water and widely used in marine equipment, and Smiths High Performance says it has the highest corrosion resistance of the martensitic grades.
      points:
        - label: Salt water
          line: Smith Metal says the alloy offers considerable resistance to saltwater, similar to Type 304. No salt-spray result is printed.
        - label: Nitriding
          line: Smiths High Performance says nitriding raises hardness and fatigue resistance, but corrosion resistance reduces once the material is nitrided.
    - title: Welding and heat
      level: 3
      verdict: Preheat and avoid carbide precipitation
      lead: Welds crack without preheat and can lose corrosion resistance through carbide formation.
      points:
        - label: Weld
          line: Team Edelstahl recommends heating to 100 to 300 °C before welding and avoiding cooling below 200 °C while welding. Smith Metal also recommends preheat.
        - label: Carbides
          line: Team Edelstahl says chromium carbide formation depletes chromium in some areas and makes the grade prone to intergranular corrosion.
  why: Type 431 is a martensitic stainless steel that combines high tensile and torsional strength with reasonable corrosion resistance and toughness. Smith Metal and Smiths High Performance name shafts, valve stems and pump parts as typical uses. Its chemistry is 15 to 17 percent chromium and 1.5 to 2.5 percent nickel, and after heat treatment it reaches 850 to 1000 MPa tensile strength (Voestalpine, Smith Metal). Welding and cold forming are its limits, and Team Edelstahl notes the chromium carbide route to intergranular corrosion.
  uses:
    - where: Shafts, valve stems and axles
      line: Smith Metal lists pump and propeller shafts, outboard drive shafts, valve stems and axles among typical applications.
    - where: Pumps, valves and compressor parts
      line: Team Edelstahl says it is often used for heavily loaded parts such as pumps, valves, piston rods and compressor impellers.
    - where: Motorsport and fasteners
      line: Smiths High Performance lists valve stems, bolts and fasteners, bearings and pump shafts as motorsport applications.
  can_do:
    - label: Strength
      value: 850 to 1000 MPa
      benchmark: ultimate_tensile_strength
      line: Heat treated, the tensile strength is 850 to 1000 MPa with a yield strength of 600 MPa and 12 percent elongation (Voestalpine). Smiths High Performance gives 800 to 950 MPa for QT800 at 60 to 160 mm.
    - label: Toughness
      value: 25 J
      benchmark: impact_energy
      line: Voestalpine gives 25 J impact toughness for the heat-treated condition, and Swiss Steel gives a minimum of 27 J ISO-V for QT800 at 20 to 160 mm.
    - label: Weight
      value: 7800 kg/m3
      benchmark: density
      line: Smiths High Performance gives a density of 7800 kg/m3. Team Edelstahl prints 7.0 kg/dm3, which conflicts with it and is not used.
    - label: Thermal
      value: 25 W/(m·K)
      benchmark: thermal_conductivity
      line: Thermal conductivity is 25 W/(m·K) at 20 °C (Abrams) and 20.2 W/(m·K) at 100 °C (Smiths High Performance).
    - label: Usable range
      value: '-40 to 400 °C'
      benchmark: max_service_temp
      line: Team Edelstahl says the grade can be used from -40 °C to 400 °C.
  compare: Team Edelstahl says 1.4057 has better toughness and corrosion resistance than comparable 13 percent chromium steels, and is widely used where heavily loaded machine parts need strength. Smith Metal compares its corrosion resistance with Type 304 and Smiths High Performance says it is the most corrosion resistant of the martensitic grades. Voestalpine says it can not be readily cold worked, which limits forming compared with more ductile grades.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Preheat to 100 to 300 °C before welding, and do not let the weld cool below 200 °C while it is made (Team Edelstahl).
    - Remove tempering colours from welds chemically or mechanically to keep corrosion resistance (Team Edelstahl).
    - Do not cold head or bend the material, since it cannot be readily cold worked (Voestalpine).
    - Keep welding gases free of hydrogen and nitrogen, which harm the weld properties (Team Edelstahl).
  good_for:
    - Shafts, valve stems and pump parts that need high strength and torsional capacity (Smith Metal, Smiths High Performance).
    - Heavily loaded machine parts, such as pumps, valves and piston rods (Team Edelstahl).
    - Parts that will be nitrided for surface hardness, though corrosion resistance drops after nitriding (Smiths High Performance).
  watch_out:
    - Welding cracks without preheat (Smiths High Performance, Smith Metal).
    - Carbide formation can cause intergranular corrosion (Team Edelstahl).
    - Nitriding lowers corrosion resistance (Smiths High Performance).
    - No salt-spray result, corrosion rate or cryogenic toughness figure was found, and service is quoted only to -40 °C (Team Edelstahl).
  verdict: Type 431 is the high-strength martensitic grade for shafts, valve stems and pump parts. It reaches 850 to 1000 MPa tensile strength when heat treated and resists salt water reasonably well. Welding needs preheat, cold forming is limited, and carbides can cause intergranular corrosion. Its strength figures are manufacturer values for specific heat treatments and forms, and it has no 431 safety data sheet in this profile.