{
  "spore": "profile",
  "id": "stainless-321",
  "spore_version": "0.2",
  "family": "stainless-austenitic",
  "name": "AISI 321 stainless steel (UNS S32100, EN 1.4541)",
  "abbreviation": "321",
  "role": "titanium-stabilised austenitic stainless steel for high-temperature and welded service",
  "category": "metals",
  "type": "steels-and-stainless",
  "summary": "AISI 321 (UNS S32100, EN 1.4541) is an austenitic stainless steel with 17 to 19 % chromium and 9 to 12 % nickel, stabilised with titanium. Its datasheets give a density of 7.92 g/cm3 and an elastic modulus of 193 GPa, and a mean thermal expansion of 16.6 ppm/K from 20 to 100 degC. Sheet to ASTM A240 has a minimum 0.2 % proof stress of 205 MPa and a minimum tensile strength of 515 MPa. The titanium keeps the carbon tied up, so the steel resists carbide precipitation in the 800 to 1500 degF (427 to 815 degC) range, which is the reason for the grade.\n",
  "best_for": "Welded parts that run hot in oxidising air, from 427 to 850 degC: titanium holds the grade against carbide precipitation in the 800 to 1500 degF range",
  "weakest_at": "Strength when annealed (about 241 MPa typical yield) and cold-work strength only, plus exposure of 900 to 1500 degF for long periods, which lowers general corrosion resistance",
  "identity": {
    "formula": "Fe balance, with Cr 17.0 to 19.0 wt %, Ni 9.0 to 12.0 wt %, C max 0.08 wt %, Mn max 2.00 wt %, Si max 0.75 wt %, N max 0.10 wt % and Ti 5x(C+N) to 0.70 wt % (ATI 321 composition table)",
    "designations": [
      {
        "system": "UNS",
        "code": "S32100",
        "source": "upmet-321",
        "where": "Header line, AMS 5510 / AMS 5645 / UNS S32100"
      },
      {
        "system": "EN",
        "code": "1.4541",
        "source": "righton-321",
        "where": "Specifications block, Commercial 321, EN 1.4541"
      },
      {
        "system": "EN name",
        "code": "X6CrNiTi18-10",
        "source": "righton-321",
        "where": "Alloy designations list, first bullet"
      },
      {
        "system": "AISI",
        "code": "321",
        "source": "righton-321",
        "where": "Alloy designations list, AISI 321"
      },
      {
        "system": "ASTM",
        "code": "A240",
        "note": "plate, sheet and strip",
        "source": "ati-321",
        "where": "Specifications line, ASTM A240 / ASME SA-240"
      },
      {
        "system": "AMS",
        "code": "5510",
        "note": "sheet, strip and plate",
        "source": "ati-321",
        "where": "Specifications line, AMS 5510"
      },
      {
        "system": "AMS",
        "code": "5645",
        "note": "bar, wire and forging",
        "source": "upmet-321",
        "where": "Header line, AMS 5510 / AMS 5645 / UNS S32100"
      },
      {
        "system": "BS",
        "code": "321S31",
        "source": "aircraftmaterials-ams5510",
        "where": "Specifications list, BS 970 321S31"
      },
      {
        "system": "BS",
        "code": "321 S51",
        "source": "swiss-4541",
        "where": "Relevant current and obsolete standards list, BS : 321 S51"
      },
      {
        "system": "AFNOR",
        "code": "Z6CNT 18-10",
        "source": "swiss-4541",
        "where": "Relevant current and obsolete standards list, AFNOR : Z6CNT 18-10"
      },
      {
        "system": "Trade name",
        "code": "ATI 321",
        "source": "ati-321",
        "where": "Page title, ATI 321 Austenitic Stainless Steel (UNS S32100)"
      }
    ],
    "source": "ati-321",
    "where": "Composition table, Minimum and Maximum (wt %) columns, rows Cr, Ni, C, Ti and Fe"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "structures",
      "propulsion-and-tanks",
      "heat-shields"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, 321 (United Performance Metals datasheet)",
      "value": 7.92,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "not stated",
        "unit_in_source": "0.286 lb/in3"
      },
      "method": "Value printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "source": "upmet-321",
      "where": "Physical Properties of 321 table, Density g/cm3 column, grade 321 row",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, UNS S32100 at 20 °C (Combined Metals datasheet)",
      "value": 8.09,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "UNS S32100",
        "temperature": "20 °C",
        "unit_in_source": "0.29 lb/in3 at 70 °F"
      },
      "method": "Value printed in a distributor datasheet; the page says the figures come mainly from third-party melting mills and are for reference only",
      "status": "ground",
      "note": "The other datasheet figure, 7.92 g/cm3, is 0.17 g/cm3 lower; both are kept because the sources do not state their test basis in the same way.",
      "source": "combmet-321",
      "where": "Physical Properties table, Density row, At 20°C column",
      "source_detail": {
        "title": "Combined Metals of Chicago, Alloy 321 Stainless Steel material datasheet",
        "id": "UNS S32100, EN DIN 1.4541, REV 2022 08 05",
        "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_321_data_sheet.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "Distributor datasheet, reference only, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting range, 321",
      "value": 1398,
      "value_high": 1446,
      "bound": "range",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "unit_in_source": "2550 to 2635 °F",
        "form": "not stated"
      },
      "method": "Range printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "source": "upmet-321",
      "where": "Physical Properties of 321 table, Melting Range °C column",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Modulus of elasticity in tension, 321",
      "value": 193,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "not stated",
        "unit_in_source": "28 x 10^6 psi"
      },
      "method": "Value printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "source": "upmet-321",
      "where": "Physical Properties of 321 table, Modulus of Elasticity in Tension GPa column",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "cte",
      "label": "Mean coefficient of linear thermal expansion, 20 to 100 °C",
      "value": 16.6,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "20 to 100 °C",
        "unit_in_source": "16.6 x 10-6 cm/cm/°C; 9.2 x 10-6 in/in/°F"
      },
      "method": "Mean coefficient printed in a supplier datasheet table",
      "status": "ground",
      "source": "upmet-321",
      "where": "Mean Coefficient of Linear Thermal Expansion table, row 20-100 °C",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "cte",
      "label": "Mean coefficient of linear thermal expansion, 20 to 1000 °C",
      "value": 20.5,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "20 to 1000 °C",
        "unit_in_source": "20.5 x 10-6 cm/cm/°C; 11.4 x 10-6 in/in/°F"
      },
      "method": "Mean coefficient printed in a supplier datasheet table",
      "status": "ground",
      "source": "upmet-321",
      "where": "Mean Coefficient of Linear Thermal Expansion table, row 20-1000 °C",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, 321, 20 to 100 °C",
      "value": 16.3,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "20 to 100 °C",
        "unit_in_source": "112.5 Btu·in/(hr·ft2·°F)"
      },
      "method": "Value printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "source": "upmet-321",
      "where": "Thermal Conductivity table, row 20-100 °C, W/m·K column",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, 321, 20 to 500 °C",
      "value": 21.4,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "20 to 500 °C",
        "unit_in_source": "147.7 Btu·in/(hr·ft2·°F)"
      },
      "method": "Value printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "source": "upmet-321",
      "where": "Thermal Conductivity table, row 20-500 °C, W/m·K column",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, 1.4541 at 20 °C (Swiss Steel Group datasheet)",
      "value": 15,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "1.4541",
        "temperature": "20 °C",
        "unit_in_source": "W/m K"
      },
      "method": "Value printed in a manufacturer datasheet, Physical Properties block",
      "status": "ground",
      "note": "Lower than the 16.3 W/(m·K) of the 20 to 100 °C range in the other datasheet; the two use different temperature bases.",
      "source": "swiss-4541",
      "where": "Physical Properties block, thermal conductivity at 20°C (W/m K) row",
      "source_detail": {
        "title": "Swiss Steel Group, Data sheet 1.4541 X6CrNiTi 18-10",
        "id": "Revision 4541-0, created 21.02.2000",
        "url": "https://swisssteel-group.com/content-media/documents/Data-Sheets/Stainless-Steel/w_4541engl.pdf",
        "year": 2000,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, 321, 0 to 100 °C",
      "value": 500,
      "bound": "exact",
      "unit": "J/kg K",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "0 to 100 °C",
        "unit_in_source": "0.12 Btu/lb·°F, 32 to 212 °F"
      },
      "method": "Value printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "source": "upmet-321",
      "where": "Specific Heat table, row 0-100 °C, J/kg K column",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity, 321 at 20 °C",
      "value": 72,
      "bound": "exact",
      "unit": "microhm·cm",
      "scope": "material",
      "conditions": {
        "grade": "321",
        "temperature": "20 °C",
        "unit_in_source": "microhm·cm"
      },
      "method": "Value printed in a supplier datasheet table of physical properties",
      "status": "ground",
      "note": "The same table gives 78 microhm·cm at 100 °C and 126 microhm·cm at 900 °C.",
      "source": "upmet-321",
      "where": "Electrical Resistivity table, row 20 °C, microhm·cm column",
      "source_detail": {
        "title": "321 Stainless Steel Datasheet, United Performance Metals",
        "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, 0.2 % proof, sheet (ASTM A240 minimum)",
      "value": 205,
      "bound": "lower",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "form": "sheet",
        "specification": "ASTM A240",
        "measure": "0.2 % proof stress",
        "temper": "not printed",
        "unit_in_source": "205 Min MPa"
      },
      "method": "Minimum value printed in a distributor datasheet, sheet row of the ASTM A240 table",
      "status": "ground",
      "source": "righton-321",
      "where": "Mechanical properties, ASTM A240 Sheet table, row Proof Stress",
      "source_detail": {
        "title": "Righton Blackburns Ltd, Stainless Steel 1.4541 (321) datasheet",
        "id": "Datasheet updated 05 August 2021",
        "url": "https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Stainless-Steel-14541-321-Bar_462.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Distributor datasheet, indicative only, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, sheet (ASTM A240 minimum)",
      "value": 515,
      "bound": "lower",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "form": "sheet",
        "specification": "ASTM A240",
        "temper": "not printed",
        "unit_in_source": "515 Min MPa"
      },
      "method": "Minimum value printed in a distributor datasheet, sheet row of the ASTM A240 table",
      "status": "ground",
      "source": "righton-321",
      "where": "Mechanical properties, ASTM A240 Sheet table, row Tensile Strength",
      "source_detail": {
        "title": "Righton Blackburns Ltd, Stainless Steel 1.4541 (321) datasheet",
        "id": "Datasheet updated 05 August 2021",
        "url": "https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Stainless-Steel-14541-321-Bar_462.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Distributor datasheet, indicative only, cited not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation A50 mm, sheet (ASTM A240 minimum)",
      "value": 35,
      "bound": "lower",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "form": "sheet",
        "specification": "ASTM A240",
        "gauge_length": "A50 mm",
        "unit_in_source": "35 Min %"
      },
      "method": "Minimum value printed in a distributor datasheet, sheet row of the ASTM A240 table",
      "status": "ground",
      "source": "righton-321",
      "where": "Mechanical properties, ASTM A240 Sheet table, row Elongation A50 mm",
      "source_detail": {
        "title": "Righton Blackburns Ltd, Stainless Steel 1.4541 (321) datasheet",
        "id": "Datasheet updated 05 August 2021",
        "url": "https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Stainless-Steel-14541-321-Bar_462.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Distributor datasheet, indicative only, cited not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, annealed, typical",
      "value": 241,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "annealed",
        "basis": "typical, based on ASTM A240",
        "unit_in_source": "35 ksi"
      },
      "method": "Typical value printed in a distributor datasheet, Typical Room Temperature Mechanical Properties table",
      "status": "ground",
      "note": "Typical, not a minimum. A specification minimum of 205 MPa is recorded separately for sheet.",
      "source": "combmet-321",
      "where": "Typical Room Temperature Mechanical Properties table, row Annealed, 0.2% Offset Yield column",
      "source_detail": {
        "title": "Combined Metals of Chicago, Alloy 321 Stainless Steel material datasheet",
        "id": "UNS S32100, EN DIN 1.4541, REV 2022 08 05",
        "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_321_data_sheet.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "Distributor datasheet, reference only, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, annealed, typical",
      "value": 586,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "annealed",
        "basis": "typical, based on ASTM A240",
        "unit_in_source": "85 ksi"
      },
      "method": "Typical value printed in a distributor datasheet",
      "status": "ground",
      "source": "combmet-321",
      "where": "Typical Room Temperature Mechanical Properties table, row Annealed, Tensile Strength (UTS) column",
      "source_detail": {
        "title": "Combined Metals of Chicago, Alloy 321 Stainless Steel material datasheet",
        "id": "UNS S32100, EN DIN 1.4541, REV 2022 08 05",
        "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_321_data_sheet.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "Distributor datasheet, reference only, cited not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation in 2 in, annealed, typical",
      "value": 55,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "temper": "annealed",
        "gauge_length": "2 in (50.8 mm)",
        "basis": "typical, based on ASTM A240"
      },
      "method": "Typical value printed in a distributor datasheet",
      "status": "ground",
      "source": "combmet-321",
      "where": "Typical Room Temperature Mechanical Properties table, row Annealed, Elongation in 2 in column",
      "source_detail": {
        "title": "Combined Metals of Chicago, Alloy 321 Stainless Steel material datasheet",
        "id": "UNS S32100, EN DIN 1.4541, REV 2022 08 05",
        "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_321_data_sheet.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "Distributor datasheet, reference only, cited not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Rp0.2 yield, solution annealed, typical (Swiss Steel Group)",
      "value": 320,
      "bound": "exact",
      "unit": "N/mm2",
      "scope": "material",
      "conditions": {
        "temper": "solution annealed",
        "basis": "typical",
        "specification_minimum_as_printed": "190 N/mm2 (EN 10088-3)"
      },
      "method": "Typical value printed in a manufacturer datasheet, mechanical properties table",
      "status": "ground",
      "note": "This typical value is well above the 205 MPa minimum in the ASTM A240 sheet table. The two are different product forms and standards, so they are not averaged.",
      "source": "swiss-4541",
      "where": "Heat treatment / mechanical properties table, row yield strength, Typical column",
      "source_detail": {
        "title": "Swiss Steel Group, Data sheet 1.4541 X6CrNiTi 18-10",
        "id": "Revision 4541-0, created 21.02.2000",
        "url": "https://swisssteel-group.com/content-media/documents/Data-Sheets/Stainless-Steel/w_4541engl.pdf",
        "year": 2000,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum continuous service temperature in oxidising atmosphere",
      "value": 850,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "exposure": "continuous, oxidising atmosphere",
        "sulphur_bearing_atmosphere": "750 °C (printed separately)"
      },
      "method": "Maximum temperature printed in a manufacturer datasheet for continuous exposure",
      "status": "ground",
      "source": "swiss-4541",
      "where": "Resistance to high temperature exposure section, first two bullets",
      "source_detail": {
        "title": "Swiss Steel Group, Data sheet 1.4541 X6CrNiTi 18-10",
        "id": "Revision 4541-0, created 21.02.2000",
        "url": "https://swisssteel-group.com/content-media/documents/Data-Sheets/Stainless-Steel/w_4541engl.pdf",
        "year": 2000,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited not reproduced"
      }
    },
    {
      "benchmark": "hardness_brinell",
      "label": "Hardness, Brinell maximum, bar",
      "value": 217,
      "bound": "upper",
      "unit": "HB",
      "scope": "material",
      "conditions": {
        "form": "bar",
        "unit_in_source": "217 max HB"
      },
      "method": "Maximum value printed in a distributor datasheet, Bar table",
      "status": "ground",
      "note": "hardness_brinell is not a canonical name in spores/property-canon.yaml; see gaps.",
      "source": "righton-321",
      "where": "Mechanical properties, Bar table, row Hardness Brinell",
      "source_detail": {
        "title": "Righton Blackburns Ltd, Stainless Steel 1.4541 (321) datasheet",
        "id": "Datasheet updated 05 August 2021",
        "url": "https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Stainless-Steel-14541-321-Bar_462.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Distributor datasheet, indicative only, cited not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Natural waters (rural and industrial)",
      "headline": "Excellent resistance in most natural waters, provided chloride, salt and hydrochloric or organic acid levels are low.",
      "effect": "The Swiss Steel Group datasheet says 1.4541 shows excellent resistance to corrosion in most natural waters, rural and industrial, provided the chloride, salt and concentrations of hydrochloric and organic acids are low. It also says the grade stays resistant to intergranular corrosion after welding.",
      "rating": "low",
      "conditions": {
        "basis": "qualitative statement, no test result or rate given"
      },
      "source": "swiss-4541",
      "where": "Corrosion resistance section, first paragraph"
    },
    {
      "environment": "Carbide precipitation range, 800 to 1500 °F (427 to 815 °C)",
      "headline": "Titanium stabilises the grade against chromium carbide precipitation in the 800 to 1500 °F range.",
      "effect": "The titanium addition reduces or prevents carbide precipitation during welding and in 800 to 1500 °F service, according to the NKS datasheet. Long-time exposure in the 900 to 1500 °F range may lower its general corrosion resistance, but the grade still shows better intergranular corrosion resistance than unstabilised grades.",
      "rating": "moderate",
      "conditions": {
        "exposure": "long-time, 900 to 1500 °F",
        "basis": "datasheet statement, no rate given"
      },
      "source": "nks-321",
      "where": "Description paragraph and Corrosion paragraph"
    },
    {
      "environment": "Oxidising air at high temperature",
      "headline": "The grade has good oxidation resistance and is rated for continuous service up to 850 °C in oxidising atmospheres.",
      "effect": "The Combined Metals datasheet says the grade has excellent resistance to oxidation and intergranular corrosion. The Swiss Steel Group datasheet gives continuous exposure limits of 850 °C in oxidising atmospheres and 750 °C in oxidising atmospheres that contain sulphur.",
      "rating": "low",
      "conditions": {
        "basis": "datasheet limits for continuous exposure; no scaling rate given"
      },
      "source": "swiss-4541",
      "where": "Resistance to high temperature exposure section"
    },
    {
      "environment": "Nitric and sulphur acids",
      "headline": "Good resistance to nitric acid and moderate resistance to sulphur acids.",
      "effect": "The NKS datasheet says Type 321 resists nitric acid well and the sulphur acids moderately, and shows excellent resistance to organic chemicals and a wide range of inorganic chemicals.",
      "rating": "low",
      "conditions": {
        "basis": "qualitative statement, no concentration or temperature given"
      },
      "source": "nks-321",
      "where": "Corrosion paragraph"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "NIST SRM 1171 (AISI 321) safety data sheet: not classified as a physical or health hazard under OSHA 29 CFR 1910.1200, with no pictograms, hazard statements or signal word. The material is an article under 1910.1200(c) and no SDS is required.",
        "ghs": [],
        "source": "nist-srm1171",
        "where": "Opening paragraph and Exemption paragraph"
      }
    ],
    "failure_risks": [
      {
        "mode": "Loss of general corrosion resistance after long exposure at 900 to 1500 °F",
        "trigger": "Long-time service in the 900 to 1500 °F range",
        "consequence": "The NKS datasheet says general corrosion resistance may be lowered, although intergranular corrosion resistance is still better than unstabilised grades. No rate is given.",
        "severity": "moderate",
        "source": "nks-321",
        "where": "Corrosion paragraph"
      },
      {
        "mode": "Attack in natural waters with high chloride, salt or acid content",
        "trigger": "Waters or acids where chloride, salt, hydrochloric or organic acid concentrations are not low",
        "consequence": "The Swiss Steel Group datasheet gives excellent corrosion resistance only when these are low. It gives no pitting or crevice test result.",
        "severity": "moderate",
        "source": "swiss-4541",
        "where": "Corrosion resistance section, first paragraph"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Weldable with all processes except gas welding; filler metal Novonit 4316 or 4551 is recommended (Swiss). NKS says AWS E/ER 347 or E/ER 321 filler is most often specified. Maximum inter-pass temperature 200 °C; heat tint must be removed by pickling or mechanical means and the surface passivated.",
        "source": "swiss-4541",
        "where": "Welding section"
      },
      {
        "text": "Machinability is poor, and titanium carbo-nitrides change the machining behaviour compared with low-carbon grades such as 1.4307 (Swiss Steel Group datasheet).",
        "source": "swiss-4541",
        "where": "Machining section and general properties list"
      },
      {
        "text": "Solution anneal at 1075 to 1125 °C followed by rapid cooling in air or water for optimum properties (Swiss); NKS gives an annealing range of 1750 to 2050 °F, water quench or air cool.",
        "source": "nks-321",
        "where": "Processing paragraph"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "propulsion-and-tanks",
      "device": "Aircraft exhaust stacks and jet engine parts",
      "example": "United Performance Metals lists aircraft exhaust stacks, manifolds and jet engine parts among the industry applications of alloy 321.",
      "source": "upmet-321",
      "where": "Industry Applications list"
    },
    {
      "application": "structures",
      "device": "Welded pressure vessels and boiler casings",
      "example": "Combined Metals lists welded pressure vessels, boiler casings, firewalls and stack liners among the applications of Type 321.",
      "source": "combmet-321",
      "where": "Description, Applications include paragraph"
    },
    {
      "application": "heat-shields",
      "device": "Annealing covers and high-temperature tempering equipment",
      "example": "Combined Metals lists annealing covers and high-temperature tempering equipment, for continuous or intermittent service at 800 to 1500 °F (427 to 816 °C).",
      "source": "combmet-321",
      "where": "Description paragraph and Applications include list"
    }
  ],
  "supply": [
    {
      "subject": "Nickel (mine production, 9 to 12 wt % of the grade)",
      "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
        }
      ],
      "critical_lists": [],
      "recycling": "The USGS nickel summary gives US nickel-containing scrap, including stainless-steel scrap, as an import source, but no recycling share for global nickel was read.",
      "substitutes": [
        "USGS: low-nickel, duplex or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction; titanium alloys can substitute for nickel-base alloys in corrosive environments."
      ],
      "source": "usgs-mcs2026-nickel",
      "where": "World Mine Production and Reserves table, 2025e world total 3,900,000 t; shares calculated by Space Mushroom from the country values 2,600,000 (Indonesia), 270,000 (Philippines), 200,000 (Russia) and 140,000 (New Caledonia); Substitutes paragraph"
    },
    {
      "subject": "Chromium (mine production, 17 to 19 wt % of the grade)",
      "producers": [
        {
          "country": "South Africa",
          "share_percent": 45.1,
          "year": 2025
        },
        {
          "country": "Turkey",
          "share_percent": 17.6,
          "year": 2025
        },
        {
          "country": "Kazakhstan",
          "share_percent": 13.7,
          "year": 2025
        },
        {
          "country": "India",
          "share_percent": 5.9,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: recycled chromium, contained in reported stainless-steel scrap receipts, accounted for 21 % of US apparent consumption in 2025.",
      "substitutes": [
        "USGS: chromium has no substitute in stainless steel, the leading end use."
      ],
      "source": "usgs-mcs2026-chromium",
      "where": "World Mine Production and Reserves table, 2025e world total 51,000 thousand t chromium content; shares calculated by Space Mushroom from the country values 23,000 (South Africa), 9,000 (Turkey), 7,000 (Kazakhstan) and 3,000 (India); Domestic Production and Use and Substitutes paragraphs"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "United Performance Metals, 321 Stainless Steel Datasheet (AMS 5510, AMS 5645, UNS S32100)",
      "type": "datasheet",
      "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
      "year": 2026
    },
    {
      "title": "Righton Blackburns, Stainless Steel 1.4541 (321) datasheet, updated 05 August 2021",
      "type": "datasheet",
      "url": "https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Stainless-Steel-14541-321-Bar_462.pdf",
      "year": 2021
    },
    {
      "title": "Combined Metals of Chicago, Alloy 321 Stainless Steel material datasheet (UNS S32100), REV 2022 08 05",
      "type": "datasheet",
      "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_321_data_sheet.pdf",
      "year": 2022
    },
    {
      "title": "NKS, 321 Stainless Steel product datasheet",
      "type": "datasheet",
      "url": "https://nks.com/wp-content/uploads/321-Stainless-Steel.pdf"
    },
    {
      "title": "Swiss Steel Group, Data sheet 1.4541 X6CrNiTi 18-10 (revision 4541-0)",
      "type": "datasheet",
      "url": "https://swisssteel-group.com/content-media/documents/Data-Sheets/Stainless-Steel/w_4541engl.pdf",
      "year": 2000
    },
    {
      "title": "Aircraft Materials, AMS 5510 Stainless Steel 321 page",
      "type": "database",
      "url": "https://aircraftmaterials.com/data/alstst/ams5510.html"
    },
    {
      "title": "ATI 321 Austenitic Stainless Steel (UNS S32100) product page",
      "type": "datasheet",
      "url": "https://atimaterials.com/Products/ati-321"
    },
    {
      "title": "NIST SRM 1171 (AISI 321) Material Safety Data Sheet, dated 29 October 2014",
      "type": "sds",
      "url": "https://tsapps.nist.gov/srmext/MSDS/1171-MSDS.pdf",
      "year": 2014
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Nickel",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Chromium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf",
      "year": 2026
    }
  ],
  "gaps": [
    "No outgassing, total mass loss, atomic oxygen erosion, radiation or thermal-cycling data for AISI 321 was found in an opened source, so the space-environment section is empty.",
    "Pitting resistance number, critical pitting temperature and stress-corrosion data were not found in the opened sources; the corrosion section is qualitative.",
    "Titanium supply (sponge, ferrotitanium) was not read; supply covers nickel and chromium only.",
    "Critical-mineral list membership for nickel and chromium was not printed in the USGS 2026 summaries opened for this run, so critical_lists is empty.",
    "Silicon limit disagrees between sources: AMS 5510 (aircraftmaterials page) prints 0.25 to 1.00 %, while the ATI page prints a maximum of 0.75 %. Neither is entered as a property.",
    "Density, modulus and expansion values differ slightly between the datasheets, and the Swiss Steel Group datasheet gives density as 7.9 kg/dm3 (no temperature). The Swiss value is not entered as a property.",
    "The Swiss Steel Group datasheet gives electrical resistivity as 0.73 with the unit printed as W mm2/m, which is not a standard unit form; it is not entered.",
    "hardness_brinell is not in spores/property-canon.yaml; it is used as a short name for the Brinell maximum of 217 HB from the Righton bar table.",
    "Impact energy (Swiss Steel Group typical 200 J at 25 °C, specification 100 J minimum) and the sheet and plate hardness values from the United Performance Metals table were not entered, to keep one value per property.",
    "The ATI page gives sheet and strip density as 0.286 lb/in3 and plate as 0.29 lb/in3 without a g/cm3 value printed on the fetched page; no conversion was made.",
    "Chemical resistance to specific organic acids, and the creep and stress-rupture values the NKS and Swiss sources describe as better than 304, were not found as numbers.",
    "The Aperam 1.4541 product page prints typical composition values with no unit and was used only for designations, not for numbers."
  ],
  "story": {
    "why": "AISI 321 is a titanium-stabilised 18-8 austenitic stainless steel. Its datasheets give a density of 7.92 g/cm3 and an elastic modulus of 193 GPa, and a mean thermal expansion of 16.6 ppm/K from 20 to 100 °C. The titanium addition is the reason to choose it over 304 for welded parts that run in the 800 to 1500 °F range, since it reduces carbide precipitation there.",
    "uses": [
      {
        "where": "Hot exhaust and jet parts",
        "line": "United Performance Metals lists aircraft exhaust stacks, manifolds and jet engine parts among the applications of alloy 321."
      },
      {
        "where": "Welded pressure equipment",
        "line": "Combined Metals lists welded pressure vessels, boiler casings, firewalls and stack liners. The datasheet says the grade is used for continuous or intermittent service at 800 to 1500 °F (427 to 816 °C)."
      },
      {
        "where": "Annealing and tempering equipment",
        "line": "Annealing covers and high-temperature tempering equipment are listed as typical applications by Combined Metals and NKS."
      }
    ],
    "can_do": [
      {
        "label": "Carry heat",
        "line": "Thermal conductivity is 16.3 W/(m·K) from 20 to 100 °C and 21.4 W/(m·K) from 20 to 500 °C in the United Performance Metals table.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "16.3 W/(m·K)"
      },
      {
        "label": "Stay in shape when hot",
        "line": "The mean coefficient of thermal expansion is 16.6 ppm/K from 20 to 100 °C and 20.5 ppm/K from 20 to 1000 °C.",
        "benchmark": "cte",
        "scope": "material",
        "value": "20.5 ppm/K"
      },
      {
        "label": "Hold load at sheet strength",
        "line": "Sheet to ASTM A240 has a minimum 0.2 % proof stress of 205 MPa and a minimum tensile strength of 515 MPa, with at least 35 % elongation over 50 mm.",
        "benchmark": "yield_strength",
        "scope": "material",
        "value": "205 MPa minimum yield"
      },
      {
        "label": "Survive continuous heat",
        "line": "The Swiss Steel Group datasheet gives 850 °C as the maximum for continuous exposure in oxidising atmospheres, and 750 °C where the atmosphere contains sulphur.",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "850 °C"
      }
    ],
    "compare": "The datasheets for AISI 321 agree closely on density (7.92 and 8.09 g/cm3 at different stated bases) and on modulus (193 GPa), but they differ on thermal conductivity (15 W/(m·K) at 20 °C from Swiss Steel Group, 16.3 W/(m·K) from 20 to 100 °C from United Performance Metals) and on annealed strength. The values are for the grade as printed in each source and should be read as examples of spread, not a ranking.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Thermal expansion",
        "benchmark": "cte",
        "scope": "material"
      }
    ],
    "handling": [
      "Specify the product form and temper, since the sheet minimums and annealed typical values differ.",
      "Use the filler metal and inter-pass limit from the welding section of the datasheet.",
      "Remove heat tint and passivate after welding."
    ],
    "good_for": [
      "Welded hot parts: titanium stabilisation against carbide precipitation in the 800 to 1500 °F range (NKS datasheet).",
      "Continuous service up to 850 °C in oxidising atmospheres (Swiss Steel Group datasheet).",
      "Non-magnetic annealed stainless steel with 193 GPa modulus (datasheets)."
    ],
    "watch_out": [
      "Long exposure at 900 to 1500 °F can lower general corrosion resistance (NKS datasheet).",
      "Chloride and strong acid content must be low for the stated corrosion resistance (Swiss Steel Group datasheet).",
      "Machinability is poor compared with low-carbon grades (Swiss Steel Group datasheet).",
      "No space-environment data (outgassing, atomic oxygen, radiation) was found for this grade in the sources read."
    ],
    "verdict": "AISI 321 is a titanium-stabilised 18-8 stainless steel for welded parts that run hot. It has a density of 7.92 g/cm3, a modulus of 193 GPa, and a 205 MPa minimum yield in sheet, and it is rated to 850 °C in oxidising air for continuous service. Its weak points are the long exposure at 900 to 1500 °F and the chloride limits, and this profile has no sourced space-environment data.",
    "recipe": {
      "line": "AISI 321 is an iron-based alloy of chromium and nickel, stabilised with titanium so that the carbon is tied up as carbides or carbo-nitrides rather than as chromium carbide at grain boundaries (Swiss Steel Group datasheet). The composition ranges are the ASTM A240 limits printed in the ATI composition table, in weight percent.",
      "parts": [
        {
          "name": "Iron",
          "symbol": "Fe",
          "role": "The matrix of the alloy; the other elements are dissolved in it."
        },
        {
          "name": "Chromium",
          "symbol": "Cr",
          "role": "Gives the stainless steel its corrosion and oxidation resistance (Swiss and NKS datasheets)."
        },
        {
          "name": "Nickel",
          "symbol": "Ni",
          "role": "Keeps the structure austenitic; NKS describes the alloy as non-magnetic."
        },
        {
          "name": "Titanium",
          "symbol": "Ti",
          "role": "The stabilising element that reduces or prevents carbide precipitation in the 800 to 1500 °F range (NKS datasheet)."
        },
        {
          "name": "Carbon",
          "symbol": "C",
          "role": "Kept low; titanium binds the carbon that remains."
        },
        {
          "name": "Manganese",
          "symbol": "Mn",
          "role": "Minor element, listed as a maximum in the ATI composition table."
        },
        {
          "name": "Silicon",
          "symbol": "Si",
          "role": "Minor element, listed as a maximum in the ATI composition table; AMS 5510 lists 0.25 to 1.00 %."
        },
        {
          "name": "Nitrogen",
          "symbol": "N",
          "role": "Minor element that also enters the titanium requirement, 5x(C+N)."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The only hazard statement in the sources is the NIST SRM 1171 safety data sheet for AISI 321, which classifies the material as an article.",
        "points": [
          {
            "label": "Solid alloy",
            "line": "The NIST SRM 1171 safety data sheet for AISI 321 is not classified as a physical or health hazard under OSHA and carries no pictogram or signal word."
          },
          {
            "label": "Processing",
            "line": "The sources read here cover the solid alloy only. Grinding, cutting and welding fumes were not read from a source in this run."
          }
        ],
        "level": 1,
        "verdict": "Not classified"
      },
      {
        "title": "If it fails",
        "lead": "The failure routes in these sources are qualitative: long exposure at 900 to 1500 °F, and waters or acids with high chloride or acid content.",
        "points": [
          {
            "label": "Long-time heat",
            "line": "The NKS datasheet says long-time exposure at 900 to 1500 °F may lower general corrosion resistance, though the grade still resists intergranular corrosion better than unstabilised grades."
          },
          {
            "label": "Chloride and acids",
            "line": "The Swiss Steel Group datasheet gives excellent corrosion resistance only when chloride, salt, hydrochloric and organic acid concentrations are low."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Welding",
            "line": "Weldable with all processes except gas welding. Filler metal 4316 or 4551 is recommended, and the maximum inter-pass temperature is 200 °C."
          },
          {
            "label": "Heat tint",
            "line": "Heat tint from welding must be removed by pickling or mechanical means and the surface passivated, to restore corrosion resistance."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-25",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 20,
    "unreachable": 2,
    "caveats": 4,
    "note": "Values read by an AI assistant on 2026-10-25 from the pages and PDFs named in each entry. Unreachable: Aubert and Duval alloy page (404), MakeItFrom (403), Alloys International (403). Caveats: the datasheets disagree on density, thermal conductivity and typical yield; the Swiss Steel Group sheet dates from 2000; the NIST SRM is a single reference material for the grade; supply shares are calculated from USGS tonnages."
  },
  "sources": {
    "upmet-321": {
      "title": "321 Stainless Steel Datasheet, United Performance Metals",
      "id": "AMS 5510 / AMS 5645 / UNS S32100 datasheet, text on page 1",
      "url": "https://www.upmet.com/sites/default/files/products/datasheet/321-datasheet.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "Supplier datasheet, cited not reproduced; states the data are for information only"
    },
    "righton-321": {
      "title": "Righton Blackburns Ltd, Stainless Steel 1.4541 (321) datasheet",
      "id": "Datasheet updated 05 August 2021",
      "url": "https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Stainless-Steel-14541-321-Bar_462.pdf",
      "year": 2021,
      "kind": "datasheet",
      "license": "Distributor datasheet, indicative only, cited not reproduced"
    },
    "combmet-321": {
      "title": "Combined Metals of Chicago, Alloy 321 Stainless Steel material datasheet",
      "id": "UNS S32100, EN DIN 1.4541, REV 2022 08 05",
      "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_321_data_sheet.pdf",
      "year": 2022,
      "kind": "datasheet",
      "license": "Distributor datasheet, reference only, cited not reproduced"
    },
    "nks-321": {
      "title": "NKS, 321 Stainless Steel datasheet",
      "id": "ASTM A240 product datasheet",
      "url": "https://nks.com/wp-content/uploads/321-Stainless-Steel.pdf",
      "kind": "datasheet",
      "license": "Supplier datasheet, cited not reproduced"
    },
    "swiss-4541": {
      "title": "Swiss Steel Group, Data sheet 1.4541 X6CrNiTi 18-10",
      "id": "Revision 4541-0, created 21.02.2000",
      "url": "https://swisssteel-group.com/content-media/documents/Data-Sheets/Stainless-Steel/w_4541engl.pdf",
      "year": 2000,
      "kind": "datasheet",
      "license": "Manufacturer datasheet, cited not reproduced"
    },
    "aircraftmaterials-ams5510": {
      "title": "Stainless Steel 321 (AMS 5510 / AMS 5645), Aircraft Materials",
      "id": "Specifications list and typical properties table",
      "url": "https://aircraftmaterials.com/data/alstst/ams5510.html",
      "kind": "web",
      "license": "Web reference, cited not reproduced; says specifications are a guideline only"
    },
    "ati-321": {
      "title": "ATI 321 Austenitic Stainless Steel (UNS S32100), ATI",
      "id": "Product page, plate, sheet and strip",
      "url": "https://atimaterials.com/Products/ati-321",
      "kind": "datasheet",
      "license": "Manufacturer product page, cited not reproduced"
    },
    "nist-srm1171": {
      "title": "NIST SRM 1171 (AISI 321) Material Safety Data Sheet",
      "id": "Stainless Steel (Cr 17-Ni 11-Ti 0.3), dated 29 October 2014",
      "url": "https://tsapps.nist.gov/srmext/MSDS/1171-MSDS.pdf",
      "year": 2014,
      "kind": "datasheet",
      "license": "US government document, public domain"
    },
    "usgs-mcs2026-nickel": {
      "title": "Mineral Commodity Summaries 2026: Nickel, USGS",
      "id": "USGS MCS 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf",
      "year": 2026,
      "kind": "report",
      "license": "US government, public domain"
    },
    "usgs-mcs2026-chromium": {
      "title": "Mineral Commodity Summaries 2026: Chromium, USGS",
      "id": "USGS MCS 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "US government, public domain"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/stainless-321/"
}