{
  "spore": "profile",
  "id": "gray-cast-iron",
  "spore_version": "0.2",
  "family": "cast-irons",
  "name": "Gray cast iron (flake graphite iron)",
  "abbreviation": "Gray iron (ASTM A48, EN-GJL, GG 25)",
  "role": "Flake graphite cast iron for housings, machine bases and brake discs",
  "category": "metals",
  "type": "steels-and-stainless",
  "summary": "Gray cast iron is cast iron with 2.5 to 4.0 percent carbon, held mostly as flake graphite, and 1 to 3 percent silicon. It is cheap, easy to machine and good at damping vibration, but the flakes make it brittle, so it is weak in tension and strong in compression. ASTM A48 classes and EN 1561 grades set its strength, and each figure here names the class or grade it belongs to.\n",
  "best_for": "Machine bases, frames, pump housings and engine blocks, where damping, machinability and compressive load matter more than tensile strength",
  "weakest_at": "Tensile strength and shock resistance: the graphite flakes act as notches, so the metal breaks in a brittle way",
  "identity": {
    "formula": "Iron with 2.5 to 4.0 wt% carbon, mostly as flake graphite, 1 to 3 wt% silicon, below 1.0 wt% manganese, and the balance iron; graphite may take 6 to 10 percent of the volume",
    "designations": [
      {
        "system": "ASTM",
        "code": "A48",
        "note": "gray iron castings; grades are classes set by minimum tensile strength",
        "source": "shimadzu-astm-a48",
        "where": "Page title: ASTM A48: Standard Specification for Gray Iron Castings"
      },
      {
        "system": "EN name",
        "code": "EN-GJL-250",
        "note": "EN 1561 grade, lamellar graphite iron",
        "source": "totalmateria-en-gjl-250",
        "where": "Page title: DIN EN-GJL-250 Cast irons"
      },
      {
        "system": "EN",
        "code": "5.1203",
        "note": "EN material number listed as an equivalent of EN-GJL-250",
        "source": "totalmateria-en-gjl-250",
        "where": "International Equivalent Materials list, EN row"
      },
      {
        "system": "DIN",
        "code": "GG-25",
        "note": "older DIN name, listed as an equivalent of EN-GJL-250",
        "source": "totalmateria-en-gjl-250",
        "where": "International Equivalent Materials list, DIN row"
      },
      {
        "system": "ISO",
        "code": "JL 250",
        "note": "ISO name, listed as an equivalent of EN-GJL-250",
        "source": "totalmateria-en-gjl-250",
        "where": "International Equivalent Materials list, ISO row"
      },
      {
        "system": "GB",
        "code": "HT 250",
        "note": "Chinese name, listed as an equivalent of EN-GJL-250",
        "source": "totalmateria-en-gjl-250",
        "where": "International Equivalent Materials list, GB row"
      },
      {
        "system": "NBR",
        "code": "FC 250",
        "note": "Brazilian name, listed as an equivalent of EN-GJL-250",
        "source": "totalmateria-en-gjl-250",
        "where": "International Equivalent Materials list, NBR row"
      }
    ],
    "source": "wiki-cast-iron",
    "where": "Grey cast iron section, composition sentence; graphite volume from the Gray iron article"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "mechanisms",
      "structures",
      "propulsion-and-tanks"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "value": 7.2,
      "bound": "exact",
      "unit": "g/cm³",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "General table, Density row, value as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "General table (Density, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 200,
      "value_high": 350,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C",
        "test_bar": "not stated"
      },
      "method": "Mechanical table, Tensile strength row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Tensile strength, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 240,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "300.0 °C",
        "test_bar": "not stated"
      },
      "method": "Mechanical table, Tensile strength row, temperature series, value as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Tensile strength, 300.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 130,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "600.0 °C",
        "test_bar": "not stated"
      },
      "method": "Mechanical table, Tensile strength row, temperature series, value as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Tensile strength, 600.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "value": 165,
      "value_high": 228,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C",
        "proof": "Rp0.1, 0.1 percent proof stress, as printed"
      },
      "method": "Mechanical table, Yield strength Rp0.1 row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Yield strength Rp0.1, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "compressive_yield_strength",
      "value": 752,
      "value_high": 1054,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "Mechanical table, Compressive yield strength row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Compressive yield strength, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 103,
      "value_high": 118,
      "bound": "range",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "Mechanical table, Elastic modulus row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Elastic modulus, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "value": 0.3,
      "value_high": 0.8,
      "bound": "range",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "Mechanical table, Elongation row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Elongation, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "flexural_strength",
      "value": 415,
      "value_high": 581,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "Mechanical table, Flexural strength row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Flexural strength, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "value": 0.24,
      "value_high": 0.26,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "Mechanical table, Poisson's ratio row, range as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Mechanical table (Poisson's ratio, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "value": 460,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "200.0 °C"
      },
      "method": "Thermal table, Specific heat capacity row, value as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Thermal table (Specific heat capacity, 200.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "value": 50,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "EN-GJL-250",
        "temperature": "20.0 °C"
      },
      "method": "Thermal table, Thermal conductivity row, value as printed",
      "status": "ground",
      "source": "mfgrobots-gjl-250",
      "where": "Thermal table (Thermal conductivity, 20.0 °C)",
      "source_detail": {
        "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
        "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 160,
      "value_high": 350,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "DIN EN-GJL-250 (EN-GJL-250)",
        "temperature": "0 to 30 °C (block heading)",
        "test_bar": "not stated"
      },
      "method": "Mechanical Properties block, Tensile Strength row, range as printed",
      "status": "ground",
      "source": "totalmateria-en-gjl-250",
      "where": "Mechanical Properties block (Tensile Strength)",
      "source_detail": {
        "title": "Total Materia: DIN EN-GJL-250 Cast irons (free preview, international equivalents)",
        "url": "https://www.totalmateria.com/en-us/material/1403010",
        "kind": "database",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "compressive_strength",
      "value": 752.5,
      "value_high": 1053.5,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "DIN EN-GJL-250 (EN-GJL-250)",
        "temperature": "0 to 30 °C (block heading)"
      },
      "method": "Mechanical Properties block, Compression Strength row, range as printed",
      "status": "ground",
      "source": "totalmateria-en-gjl-250",
      "where": "Mechanical Properties block (Compression Strength)",
      "source_detail": {
        "title": "Total Materia: DIN EN-GJL-250 Cast irons (free preview, international equivalents)",
        "url": "https://www.totalmateria.com/en-us/material/1403010",
        "kind": "database",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 103,
      "value_high": 118,
      "bound": "range",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "DIN EN-GJL-250 (EN-GJL-250)",
        "temperature": "band not identified in the text (the block lists several bands)"
      },
      "method": "Physical Properties block, Modulus of Elasticity row, range as printed",
      "status": "ground",
      "source": "totalmateria-en-gjl-250",
      "where": "Physical Properties block (Modulus of Elasticity)",
      "source_detail": {
        "title": "Total Materia: DIN EN-GJL-250 Cast irons (free preview, international equivalents)",
        "url": "https://www.totalmateria.com/en-us/material/1403010",
        "kind": "database",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 22,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "20",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 20 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 31,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "30",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 30 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 57,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "40",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 40 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 62.5,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "60",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 60 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "compressive_strength",
      "value": 83,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "20",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 20 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "compressive_strength",
      "value": 109,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "30",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 30 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "compressive_strength",
      "value": 140,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "40",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 40 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "compressive_strength",
      "value": 187.5,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "60",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Compressive strength column, value as printed",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 60 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 10,
      "bound": "exact",
      "unit": "Mpsi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "20",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 20 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 14,
      "bound": "exact",
      "unit": "Mpsi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "30",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 30 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 18,
      "bound": "exact",
      "unit": "Mpsi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "40",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 40 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 21,
      "bound": "exact",
      "unit": "Mpsi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "60",
        "basis": "table value; minimum or typical not stated on the page",
        "test_bar": "not stated"
      },
      "method": "Table Properties of ASTM A48 classes of gray iron, Tensile modulus E column, value as printed in Mpsi",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of ASTM A48 classes table (Class 60 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 20000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "20",
        "basis": "tensile strength as printed; minimum or typical not stated",
        "test_bar": "not stated"
      },
      "method": "Gray Iron Grades list, Tensile strength line under ASTM A48 Class 20, value as printed",
      "status": "ground",
      "source": "align-gray-iron",
      "where": "Gray Iron Grades list (ASTM A48 Class 20)",
      "source_detail": {
        "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
        "url": "https://alignmfg.co/?p=3443",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 25000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "25",
        "basis": "tensile strength as printed; minimum or typical not stated",
        "test_bar": "not stated"
      },
      "method": "Gray Iron Grades list, Tensile strength line under ASTM A48 Class 25, value as printed",
      "status": "ground",
      "source": "align-gray-iron",
      "where": "Gray Iron Grades list (ASTM A48 Class 25)",
      "source_detail": {
        "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
        "url": "https://alignmfg.co/?p=3443",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 30000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "30",
        "basis": "tensile strength as printed; minimum or typical not stated",
        "test_bar": "not stated"
      },
      "method": "Gray Iron Grades list, Tensile strength line under ASTM A48 Class 30, value as printed",
      "status": "ground",
      "source": "align-gray-iron",
      "where": "Gray Iron Grades list (ASTM A48 Class 30)",
      "source_detail": {
        "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
        "url": "https://alignmfg.co/?p=3443",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 35000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "35",
        "basis": "tensile strength as printed; minimum or typical not stated",
        "test_bar": "not stated"
      },
      "method": "Gray Iron Grades list, Tensile strength line under ASTM A48 Class 35, value as printed",
      "status": "ground",
      "source": "align-gray-iron",
      "where": "Gray Iron Grades list (ASTM A48 Class 35)",
      "source_detail": {
        "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
        "url": "https://alignmfg.co/?p=3443",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 40000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "40",
        "basis": "tensile strength as printed; minimum or typical not stated",
        "test_bar": "not stated"
      },
      "method": "Gray Iron Grades list, Tensile strength line under ASTM A48 Class 40, value as printed",
      "status": "ground",
      "source": "align-gray-iron",
      "where": "Gray Iron Grades list (ASTM A48 Class 40)",
      "source_detail": {
        "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
        "url": "https://alignmfg.co/?p=3443",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "value": 50000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "standard": "ASTM A48",
        "class": "50",
        "basis": "tensile strength as printed; minimum or typical not stated",
        "test_bar": "not stated"
      },
      "method": "Gray Iron Grades list, Tensile strength line under ASTM A48 Class 50, value as printed",
      "status": "ground",
      "source": "align-gray-iron",
      "where": "Gray Iron Grades list (ASTM A48 Class 50)",
      "source_detail": {
        "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
        "url": "https://alignmfg.co/?p=3443",
        "kind": "web",
        "license": "cited, not reproduced"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "value": 120,
      "value_high": 187,
      "bound": "range",
      "unit": "HB",
      "scope": "material",
      "conditions": {
        "standard": "SAE J431",
        "grade": "G1800",
        "description": "ferritic-pearlitic, as printed",
        "test_bar": "not stated"
      },
      "method": "Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of SAE J431 grades table (G1800 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "value": 170,
      "value_high": 229,
      "bound": "range",
      "unit": "HB",
      "scope": "material",
      "conditions": {
        "standard": "SAE J431",
        "grade": "G2500",
        "description": "pearlitic-ferritic, as printed",
        "test_bar": "not stated"
      },
      "method": "Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of SAE J431 grades table (G2500 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "value": 187,
      "value_high": 246,
      "bound": "range",
      "unit": "HB",
      "scope": "material",
      "conditions": {
        "standard": "SAE J431",
        "grade": "G3000",
        "description": "pearlitic, as printed",
        "test_bar": "not stated"
      },
      "method": "Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of SAE J431 grades table (G3000 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "value": 207,
      "value_high": 255,
      "bound": "range",
      "unit": "HB",
      "scope": "material",
      "conditions": {
        "standard": "SAE J431",
        "grade": "G3500",
        "description": "pearlitic, as printed",
        "test_bar": "not stated"
      },
      "method": "Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of SAE J431 grades table (G3500 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "value": 217,
      "value_high": 269,
      "bound": "range",
      "unit": "HB",
      "scope": "material",
      "conditions": {
        "standard": "SAE J431",
        "grade": "G4000",
        "description": "pearlitic, as printed",
        "test_bar": "not stated"
      },
      "method": "Table Properties of SAE J431 grades of gray iron, Brinell hardness column, range as printed; the page prints no unit, so recorded as a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Properties of SAE J431 grades table (G4000 row)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "damping_capacity",
      "value": 100,
      "value_high": 500,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material": "gray iron, high carbon equivalent, as printed"
      },
      "method": "Table Relative damping capacity of various metals, value as printed; footnote says natural log of the ratio of successive amplitudes, so a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Relative damping capacity table (Gray iron, high carbon equivalent)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "damping_capacity",
      "value": 20,
      "value_high": 100,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material": "gray iron, low carbon equivalent, as printed"
      },
      "method": "Table Relative damping capacity of various metals, value as printed; footnote says natural log of the ratio of successive amplitudes, so a pure number",
      "status": "ground",
      "source": "wiki-gray-iron",
      "where": "Relative damping capacity table (Gray iron, low carbon equivalent)",
      "source_detail": {
        "title": "Wikipedia: Gray iron",
        "id": "Gray iron",
        "url": "https://en.wikipedia.org/wiki/Gray_iron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Water supply and drainage systems (pipes)",
      "headline": "Pipes are used in water and drainage for their corrosion resistance and longevity",
      "effect": "China Casting says gray cast iron pipes have been widely used in water supply and drainage systems because of their corrosion resistance and longevity. No corrosion rate, test or exposure time is printed.",
      "rating": "unknown",
      "source": "china-casting-gray-iron",
      "where": "Construction sector paragraph"
    },
    {
      "environment": "Not named in the source (effect of the silicon in the alloy)",
      "headline": "Silicon is said to promote good corrosion resistance",
      "effect": "Wikipedia says the silicon in gray iron promotes good corrosion resistance and increased fluidity when casting. The article names no environment and gives no rate.",
      "rating": "unknown",
      "source": "wiki-gray-iron",
      "where": "Advantages and disadvantages section, last paragraph"
    },
    {
      "environment": "Austenitic gray iron with nickel and chromium (an alloyed variant)",
      "headline": "A nickel and chromium variant is listed for excellent corrosion resistance",
      "effect": "China Casting's table lists austenitic gray iron (Ni, Cr) for excellent corrosion and heat resistance. That is an alloyed variant of gray iron, and the page gives no rate.",
      "rating": "unknown",
      "source": "china-casting-gray-iron",
      "where": "Types of gray iron table, Austenitic row"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem aggregated GHS for elemental iron, signal word Danger: the record says the chemical does not meet GHS hazard criteria in 74.1 percent (4458 of 6013) of reports. H228 flammable solid (15.5 percent) and H251 self-heating (21.2 percent) appear in notifications. It covers the metal element, not cast parts.",
        "ghs": [
          "H228",
          "H251"
        ],
        "source": "pubchem-fe",
        "where": "Safety and Hazards, GHS Classification (first block)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Brittle fracture under tensile or shock load",
        "trigger": "Tensile stress or shock; the tips of the graphite flakes act as notches where stress concentrates",
        "consequence": "Low tensile strength, and impact and shock resistance that is almost non-existent (Wikipedia)",
        "source": "wiki-gray-iron",
        "where": "Structure section (flake tips); Advantages and disadvantages section (impact)"
      },
      {
        "mode": "Brittleness from excess phosphorus",
        "trigger": "Phosphorus raised above what the casting needs for fluidity",
        "consequence": "Excessive phosphorus can lead to brittleness (China Casting)",
        "source": "china-casting-gray-iron",
        "where": "Composition paragraph"
      },
      {
        "mode": "Less tensile strength and shock resistance than steel",
        "trigger": "A part loaded in tension or shock as if it were steel",
        "consequence": "Grey cast iron has less tensile strength and shock resistance than steel (Wikipedia, Cast iron)",
        "source": "wiki-cast-iron",
        "where": "Grey cast iron section, last sentence"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Name the class or grade with every strength value, because ASTM classes and EN grades have different strengths (Wikipedia, Align)",
        "source": "wiki-gray-iron",
        "where": "Classifications section"
      },
      {
        "text": "Gray iron cannot be forged, extruded or rolled, even at temperature, so it must be cast to shape (Wikipedia)",
        "source": "wiki-gray-iron",
        "where": "Advantages and disadvantages section"
      },
      {
        "text": "Gray iron is generally considered easy to weld (Wikipedia)",
        "source": "wiki-gray-iron",
        "where": "Advantages and disadvantages section"
      },
      {
        "text": "Stress relieving is particularly important for large castings (China Casting)",
        "source": "china-casting-gray-iron",
        "where": "Heat treatment paragraph"
      }
    ],
    "mitigations": [
      {
        "text": "In some cases protective coatings are applied to enhance corrosion resistance or extend service life (China Casting)",
        "source": "china-casting-gray-iron",
        "where": "Finishing paragraph"
      },
      {
        "text": "Where corrosion and heat resistance matter, an alloyed austenitic gray iron with nickel and chromium is listed (China Casting); it is a different alloy from plain gray iron",
        "source": "china-casting-gray-iron",
        "where": "Types of gray iron table, Austenitic row"
      }
    ]
  },
  "uses": [
    {
      "application": "mechanisms",
      "device": "Brake discs and rotors",
      "example": "Gray iron's high thermal conductivity and specific heat capacity are exploited to make disc brake rotors (Wikipedia)",
      "source": "wiki-gray-iron",
      "where": "Lead paragraph"
    },
    {
      "application": "structures",
      "device": "Machine tool bases and mountings",
      "example": "Gray iron has very good damping capacity and is often used as the base for machine tool mountings (Wikipedia); Align lists class 40 and class 50 for machinery bases",
      "source": "wiki-gray-iron",
      "where": "Structure section, last sentence"
    },
    {
      "application": "propulsion-and-tanks",
      "device": "Internal combustion engine cylinder blocks",
      "example": "Cylinder blocks are named as a housing use where stiffness matters more than tensile strength (Wikipedia); Align lists class 30 for engine blocks and transmission housings",
      "source": "wiki-gray-iron",
      "where": "Lead paragraph"
    },
    {
      "application": "structures",
      "device": "Pump housings and valve bodies",
      "example": "Pump housings and valve bodies are named as gray iron housings (Wikipedia); Align lists class 20 for pump housings",
      "source": "wiki-gray-iron",
      "where": "Lead paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Iron and steel (United States)",
      "abundance": "Iron is the least expensive and most widely used metal (USGS). The US produced 82 million tons of raw steel in 2025e, and net import reliance was 13 percent of apparent consumption in 2025e. Construction took an estimated 31 percent of net shipments. Import sources 2021 to 2024: Canada 23 percent, Mexico 15 percent, Brazil 13 percent, Republic of Korea 9 percent, other 40 percent.",
      "producers": [],
      "critical_lists": [],
      "recycling": "Not read: the chapter points to the Iron and Steel Scrap chapter",
      "substitutes": [
        "Nonmetallic materials at lower cost, or costlier materials with better performance (USGS substitutes text)"
      ],
      "source": "usgs-iron-steel-2026",
      "where": "Salient Statistics; Domestic Production and Use; Import Sources; Substitutes"
    },
    {
      "subject": "Raw steel production by country (2025e)",
      "abundance": "World raw steel production was 1,900 million tons in 2025e (rounded total). Shares are computed from the printed 2025e tonnage over that total: China 980, India 160, United States 82, Japan 81 and Russia 65 million tons.",
      "producers": [
        {
          "country": "China",
          "share_percent": 51.6,
          "year": 2025
        },
        {
          "country": "India",
          "share_percent": 8.4,
          "year": 2025
        },
        {
          "country": "United States",
          "share_percent": 4.3,
          "year": 2025
        },
        {
          "country": "Japan",
          "share_percent": 4.3,
          "year": 2025
        },
        {
          "country": "Russia",
          "share_percent": 3.4,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "",
      "substitutes": [],
      "source": "usgs-iron-steel-2026",
      "where": "World Production table, Raw steel 2025e"
    },
    {
      "subject": "Silicon (ferrosilicon and silicon metal)",
      "abundance": "China accounted for almost 80 percent of total global estimated production of silicon materials in 2025 (USGS). Most ferrosilicon was consumed in the ferrous foundry and steel industries. Ferrosilicon import sources 2021 to 2024: Russia 30 percent, Brazil 16 percent, Canada 13 percent, Malaysia 11 percent, other 30 percent.",
      "producers": [],
      "critical_lists": [
        {
          "list": "U.S. Final 2025 List of Critical Minerals",
          "listed": true
        }
      ],
      "recycling": "",
      "substitutes": [],
      "source": "usgs-silicon-2026",
      "where": "Domestic Production and Use; Events, Trends and Issues; Import Sources; critical minerals paragraph"
    },
    {
      "subject": "Manganese",
      "abundance": "Net import reliance was 100 percent in every year from 2021 to 2025e. Manganese ore import sources 2021 to 2024: Gabon 64 percent, South Africa 24 percent, Mexico 12 percent. Consumption closely follows the steel industry, and South Africa has an estimated 70 percent of world manganese resources (USGS). Shares are computed from the 2025e mine production table over its printed world total.",
      "producers": [
        {
          "country": "South Africa",
          "share_percent": 38,
          "year": 2025
        },
        {
          "country": "Gabon",
          "share_percent": 25,
          "year": 2025
        },
        {
          "country": "Ghana",
          "share_percent": 10,
          "year": 2025
        },
        {
          "country": "Australia",
          "share_percent": 8,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "",
      "substitutes": [],
      "source": "usgs-manganese-2026",
      "where": "World Mine Production (manganese content) table, 2025e; Import Sources; Salient Statistics"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Total Materia: DIN EN-GJL-250 Cast irons",
      "type": "database",
      "url": "https://www.totalmateria.com/en-us/material/1403010"
    },
    {
      "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
      "type": "datasheet",
      "url": "https://www.mfgrobots.com/Article/material/metal/39356.html"
    },
    {
      "title": "MTS: ASTM A48/A48M Tensile Testing technote",
      "type": "datasheet",
      "url": "https://mts.com/-/media/materials/pdfs/test-standards/100-545-062c_Metals_ASTM_A48_A48M.pdf?as=1",
      "year": 2023
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Iron and Steel",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Silicon",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Manganese",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf",
      "year": 2026
    },
    {
      "title": "PubChem: Iron (CID 23925), GHS classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23925/JSON"
    }
  ],
  "gaps": [
    "ASTM A48 itself was not read (the standard is paywalled). Class rows come from the Wikipedia table (ksi and Mpsi, minimum or typical not stated), the Align list (psi) and the MTS technote. No class value prints a test bar size, so test_bar is recorded as not stated, and the MTS cast test bar types (A, B and C, 13, 20 and 30 mm diameter) are not tied to any class.",
    "Only the EN-GJL-250 grade was read. EN-GJL-150, 200, 300 and 350 have no value in this run.",
    "The Kippwerk EN-GJL-250 data sheet returned no technical data (the page text was truncated), and the MakeItFrom class 30 page returned HTTP 403. The UNS number for class 30 and the old GG25 sentence are therefore not recorded, and JIS FC250 is not printed on any fetched page (the Brazilian NBR FC 250 is recorded instead).",
    "Machinability: only qualitative statements were found (Wikipedia, Align, China Casting). No machinability rating is printed on a fetched page, so no value is recorded.",
    "Hardness: no Brinell range for ASTM classes or EN-GJL-250 was printed on a fetched page. Only the SAE J431 grade ranges from Wikipedia are recorded.",
    "Damping: Wikipedia gives a relative log-decrement scale for high and low carbon equivalent gray iron only, with no unit printed. No numeric damping value is printed for a named ASTM or EN grade.",
    "The EN-GJL-250 melting range (1127 to 1204 °C) and shear modulus (41 GPa) are printed only as typical for grey cast iron or cast iron, not for a named grade, so they are left out. Electrical resistivity and the coefficient of thermal expansion are printed with an uppercase E exponent, which the verify text match cannot read, so they are left out.",
    "Composition: Wikipedia's gray iron article gives 2.5 to 4.7 percent carbon and 1 to 8 percent silicon, wider than the 2.5 to 4.0 percent carbon and 1 to 3 percent silicon used in the identity from Wikipedia's cast iron article and China Casting. Manganese is given only as below 1.0 percent; phosphorus and sulfur have no printed number.",
    "Corrosion: no corrosion rate, test environment or exposure time was read, so every rating is unknown. Graphitic (selective) corrosion, rust in moist air and soil or seawater behaviour were not sourced in this run.",
    "Hazards: the only hazard record is PubChem's element iron entry. No gray cast iron safety data sheet was read, and fume and dust limits for cutting, grinding and welding are not recorded. The PubChem silicon record returned no GHS section in this run.",
    "Supply shares are computed from printed tonnages (steel, 2025e over the printed world total; manganese, 2025e mine production over its printed world total), not printed as shares. The iron and steel and manganese chapters name no critical-mineral list, so their critical_lists are empty. The iron ore and scrap chapters were not read.",
    "Property names not in property-canon: compressive_strength, compressive_yield_strength, brinell_hardness and damping_capacity are snake_case. Modulus by class is kept in Mpsi as printed.",
    "The web search budget ran out in this turn, so no further searches were run for other EN-GJL grades, GG25 on the Kippwerk page, UNS codes, graphitic corrosion, numeric damping or machinability sources. Only the pages listed in sources were fetched."
  ],
  "story": {
    "why": "Gray cast iron is the most common cast iron and the most widely used cast material by weight (Wikipedia). Its flake graphite makes it relatively cheap, easy to machine and good at damping vibration, which is why it suits machine bases and housings. The same flakes make it brittle, so it is weak in tension.",
    "uses": [
      {
        "where": "Brake discs",
        "line": "Its high thermal conductivity and specific heat capacity are used in disc brake rotors (Wikipedia)."
      },
      {
        "where": "Machine tool bases",
        "line": "Its damping makes it the usual base for machine tool mountings (Wikipedia). Align lists class 40 and class 50 for large machinery bases."
      },
      {
        "where": "Engine blocks and housings",
        "line": "Cylinder blocks, pump housings and valve bodies are named housings where stiffness matters more than tensile strength (Wikipedia). Align lists class 30 for engine blocks and transmission housings."
      },
      {
        "where": "Pipes and manhole covers",
        "line": "China Casting lists gray iron pipes for water supply and drainage, and for manhole covers in construction."
      }
    ],
    "can_do": [
      {
        "label": "Tensile strength, EN-GJL-250",
        "line": "EN-GJL-250 has 200 to 350 MPa tensile strength at 20 °C (MfgRobots). Total Materia gives 160 to 350 MPa for 0 to 30 °C.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "200 to 350 MPa at 20 °C"
      },
      {
        "label": "Compressive strength",
        "line": "Compression is far stronger than tension: 752.5 to 1053.5 MPa for EN-GJL-250 (Total Materia), often more than three to four times the tensile strength (China Casting).",
        "benchmark": "compressive_strength",
        "scope": "material",
        "value": "752.5 to 1053.5 MPa"
      },
      {
        "label": "Stiffness",
        "line": "The elastic modulus is 103 to 118 GPa for EN-GJL-250 (MfgRobots, Total Materia). By ASTM class it is 10 to 21 Mpsi (Wikipedia).",
        "benchmark": "elastic_modulus",
        "scope": "material",
        "value": "103 to 118 GPa"
      },
      {
        "label": "Density",
        "line": "Density is 7.2 g/cm³ at 20 °C for EN-GJL-250 (MfgRobots).",
        "benchmark": "density",
        "scope": "material",
        "value": "7.2 g/cm³ at 20 °C"
      },
      {
        "label": "Thermal conductivity",
        "line": "Thermal conductivity is 50 W/(m·K) at 20 °C for EN-GJL-250 (MfgRobots). That is why it is used for brake rotors and cookware (Wikipedia).",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "50 W/(m·K) at 20 °C"
      },
      {
        "label": "Damping",
        "line": "On Wikipedia's relative damping scale, high carbon equivalent gray iron scores 100 to 500, and low carbon equivalent gray iron 20 to 100.",
        "benchmark": "damping_capacity",
        "scope": "material",
        "value": "100 to 500 (high carbon equivalent)"
      },
      {
        "label": "Machinability",
        "line": "Graphite flakes lubricate the cut and break the chips, so the metal machines easily (Wikipedia, Align). No machinability rating is printed.",
        "scope": "material"
      }
    ],
    "compare": "Gray cast iron trades tensile strength for damping, machinability and low cost. For EN-GJL-250 its tensile strength is 200 to 350 MPa, while its compressive strength is 752.5 to 1053.5 MPa (Total Materia). Its compressive strength is comparable to low and medium carbon steel, but its tensile strength and shock resistance are lower (Wikipedia). Ductile iron, with spherical graphite, has more ductility and impact resistance (Align).",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Stiffness (elastic modulus)",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Tensile strength",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      }
    ],
    "handling": [
      "Name the class or grade with every strength value, because ASTM classes and EN grades have different strengths (Wikipedia, Align).",
      "Cast it to shape: gray iron cannot be forged, extruded or rolled, even hot (Wikipedia).",
      "It is generally considered easy to weld (Wikipedia). Stress relieve large castings (China Casting)."
    ],
    "good_for": [
      "Machine tool bases, frames and housings, where damping and machinability matter (Wikipedia, Align).",
      "Engine cylinder blocks, pump housings and valve bodies, where stiffness matters more than tensile strength (Wikipedia).",
      "Brake discs, where high thermal conductivity helps (Wikipedia)."
    ],
    "watch_out": [
      "Brittle in tension and shock: the graphite flake tips act as notches (Wikipedia, Gray iron).",
      "Excess phosphorus adds brittleness (China Casting).",
      "Composition limits differ by article: 2.5 to 4.7 percent carbon and 1 to 8 percent silicon in one, 2.5 to 4.0 and 1 to 3 in another (Wikipedia)."
    ],
    "verdict": "Gray cast iron is the cheap, damping, easy-to-machine iron for housings, machine bases and brake discs. It is weak and brittle in tension, so name the class or grade and design for compression and damping, not for shock.",
    "recipe": {
      "line": "Gray iron is cast iron with 2.5 to 4.0 percent carbon, held mostly as flake graphite, 1 to 3 percent silicon, below 1.0 percent manganese, and the rest iron (Wikipedia, China Casting). Silicon promotes free graphite rather than cementite (China Casting). It is sand cast (MfgRobots).",
      "parts": [
        {
          "name": "Iron",
          "symbol": "Fe",
          "role": "The matrix of the metal; it is the rest of the composition",
          "share_note": "balance (the rest)",
          "source": "wiki-cast-iron",
          "where": "Grey cast iron section, composition sentence"
        },
        {
          "name": "Carbon",
          "symbol": "C",
          "role": "Forms flake graphite, which gives low tensile strength but easy machining and good damping (Wikipedia)",
          "share_percent": 2.5,
          "share_high": 4,
          "source": "wiki-cast-iron",
          "where": "Grey cast iron section, composition sentence"
        },
        {
          "name": "Silicon",
          "symbol": "Si",
          "role": "Silicon promotes free graphite rather than cementite (China Casting), and forces carbon out of solution (Wikipedia)",
          "share_percent": 1,
          "share_high": 3,
          "source": "wiki-cast-iron",
          "where": "Alloying elements paragraph"
        },
        {
          "name": "Manganese",
          "symbol": "Mn",
          "role": "Stabilises the pearlite in the matrix (China Casting)",
          "share_note": "below 1.0",
          "source": "china-casting-gray-iron",
          "where": "Composition paragraph"
        },
        {
          "name": "Phosphorus",
          "symbol": "P",
          "role": "Raised in some castings for fluidity; excess makes it brittle (China Casting)",
          "share_note": "no number printed",
          "source": "china-casting-gray-iron",
          "where": "Composition paragraph"
        },
        {
          "name": "Sulfur",
          "symbol": "S",
          "role": "Forms iron sulfides that hurt mechanical performance (China Casting)",
          "share_note": "kept as low as possible",
          "source": "china-casting-gray-iron",
          "where": "Composition paragraph"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "PubChem's hazard records are for elemental iron, not for cast parts. No gray cast iron safety data sheet was read.",
        "points": [
          {
            "label": "Iron",
            "line": "PubChem says the chemical does not meet GHS hazard criteria in 74.1 percent of 6013 reports; H228 and H251 appear in some notifications."
          },
          {
            "label": "Dust and fume",
            "line": "Limits for dust and fume from cutting, grinding and welding were not read. Check the supplier safety data sheet before the work."
          }
        ],
        "level": 1,
        "verdict": "Element records only"
      },
      {
        "title": "In the environment",
        "lead": "The sources give qualitative corrosion statements only.",
        "points": [
          {
            "label": "Water",
            "line": "China Casting says gray iron pipes are used in water supply and drainage for their corrosion resistance and longevity."
          },
          {
            "label": "Silicon",
            "line": "Wikipedia says the silicon in gray iron promotes good corrosion resistance."
          }
        ],
        "level": 2,
        "verdict": "No corrosion rate read"
      },
      {
        "title": "In service",
        "lead": "Graphite flakes make the metal brittle under tensile and shock loads.",
        "points": [
          {
            "label": "Tension",
            "line": "EN-GJL-250 tensile strength is 200 to 350 MPa at 20 °C (MfgRobots), while its compressive strength is far higher (Total Materia)."
          },
          {
            "label": "Phosphorus",
            "line": "Excess phosphorus adds brittleness (China Casting)."
          }
        ],
        "level": 2,
        "verdict": "Brittle in tension"
      }
    ]
  },
  "updated": "2026-10-24",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 40,
    "unreachable": 0,
    "caveats": 19,
    "note": "Read by an AI assistant on 2026-10-24 from pages fetched in that run. Strength rows are split by source and by class or grade: EN-GJL-250 from MfgRobots and Total Materia, ASTM A48 classes from Wikipedia (ksi and Mpsi, minimum or typical not stated) and Align (psi). No class row prints a test bar size. Kippwerk and MakeItFrom could not be read."
  },
  "sources": {
    "mfgrobots-gjl-250": {
      "title": "MfgRobots: EN 1561 Grade GJL-250 Cast, Key Properties and Applications",
      "url": "https://www.mfgrobots.com/Article/material/metal/39356.html",
      "kind": "web",
      "license": "cited, not reproduced"
    },
    "totalmateria-en-gjl-250": {
      "title": "Total Materia: DIN EN-GJL-250 Cast irons (free preview, international equivalents)",
      "url": "https://www.totalmateria.com/en-us/material/1403010",
      "kind": "database",
      "license": "cited, not reproduced"
    },
    "wiki-gray-iron": {
      "title": "Wikipedia: Gray iron",
      "id": "Gray iron",
      "url": "https://en.wikipedia.org/wiki/Gray_iron",
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "wiki-cast-iron": {
      "title": "Wikipedia: Cast iron",
      "id": "Cast iron",
      "url": "https://en.wikipedia.org/wiki/Cast_iron",
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "align-gray-iron": {
      "title": "Align Manufacturing: Gray and Ductile Iron, Versatility and Strength",
      "url": "https://alignmfg.co/?p=3443",
      "kind": "web",
      "license": "cited, not reproduced"
    },
    "china-casting-gray-iron": {
      "title": "China Casting: Gray Cast Iron, Essential Properties and Composition Guide",
      "url": "https://china-casting.com/gray-cast-iron/",
      "kind": "web",
      "license": "cited, not reproduced"
    },
    "shimadzu-astm-a48": {
      "title": "Shimadzu: ASTM A48 Standard Specification for Gray Iron Castings",
      "url": "https://www.ssi.shimadzu.com/industries/automotive-materials-testing/metals/astm-a48/index.html",
      "kind": "web",
      "license": "cited, not reproduced"
    },
    "mts-astm-a48": {
      "title": "MTS Systems: ASTM A48/A48M Tensile Testing technote 100-545-062c",
      "url": "https://mts.com/-/media/materials/pdfs/test-standards/100-545-062c_Metals_ASTM_A48_A48M.pdf?as=1",
      "year": 2023,
      "kind": "datasheet",
      "license": "cited, not reproduced"
    },
    "usgs-iron-steel-2026": {
      "title": "USGS Mineral Commodity Summaries 2026: Iron and Steel",
      "id": "mcs2026-iron-steel",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain"
    },
    "usgs-silicon-2026": {
      "title": "USGS Mineral Commodity Summaries 2026: Silicon",
      "id": "mcs2026-silicon",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain"
    },
    "usgs-manganese-2026": {
      "title": "USGS Mineral Commodity Summaries 2026: Manganese",
      "id": "mcs2026-manganese",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-manganese.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain"
    },
    "pubchem-fe": {
      "title": "PubChem: Iron (CID 23925), Safety and Hazards, GHS Classification (REST record)",
      "id": "CID 23925",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23925/JSON",
      "kind": "database",
      "license": "PubChem terms (public)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/gray-cast-iron/"
}