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.
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
  source: wiki-cast-iron
  where: Grey cast iron section, composition sentence; graphite volume from the Gray iron article
  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
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
    - structures
    - propulsion-and-tanks
properties:
  - benchmark: density
    value: 7.2
    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)
  - 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)
  - benchmark: ultimate_tensile_strength
    value: 240
    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)
  - benchmark: ultimate_tensile_strength
    value: 130
    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)
  - 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)
  - 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)
  - 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)
  - 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)
  - 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)
  - 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)
  - benchmark: specific_heat
    value: 460
    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)
  - benchmark: thermal_conductivity
    value: 50
    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)
  - 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)
  - 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)
  - 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)
  - benchmark: ultimate_tensile_strength
    value: 22
    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)
  - benchmark: ultimate_tensile_strength
    value: 31
    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)
  - benchmark: ultimate_tensile_strength
    value: 57
    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)
  - benchmark: ultimate_tensile_strength
    value: 62.5
    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)
  - benchmark: compressive_strength
    value: 83
    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)
  - benchmark: compressive_strength
    value: 109
    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)
  - benchmark: compressive_strength
    value: 140
    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)
  - benchmark: compressive_strength
    value: 187.5
    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)
  - benchmark: elastic_modulus
    value: 10
    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)
  - benchmark: elastic_modulus
    value: 14
    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)
  - benchmark: elastic_modulus
    value: 18
    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)
  - benchmark: elastic_modulus
    value: 21
    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)
  - benchmark: ultimate_tensile_strength
    value: 20000
    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)
  - benchmark: ultimate_tensile_strength
    value: 25000
    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)
  - benchmark: ultimate_tensile_strength
    value: 30000
    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)
  - benchmark: ultimate_tensile_strength
    value: 35000
    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)
  - benchmark: ultimate_tensile_strength
    value: 40000
    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)
  - benchmark: ultimate_tensile_strength
    value: 50000
    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)
  - 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)
  - 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)
  - 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)
  - 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)
  - 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)
  - 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)
  - 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)
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.
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
    kind: datasheet
    year: 2023
    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
    kind: report
    year: 2026
    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
    kind: report
    year: 2026
    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
    kind: report
    year: 2026
    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
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.'
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.
  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
        share_note: balance (the rest)
        role: The matrix of the metal; it is the rest of the composition
        source: wiki-cast-iron
        where: Grey cast iron section, composition sentence
      - name: Carbon
        symbol: C
        share_percent: 2.5
        share_high: 4
        role: Forms flake graphite, which gives low tensile strength but easy machining and good damping (Wikipedia)
        source: wiki-cast-iron
        where: Grey cast iron section, composition sentence
      - name: Silicon
        symbol: Si
        share_percent: 1
        share_high: 3
        role: Silicon promotes free graphite rather than cementite (China Casting), and forces carbon out of solution (Wikipedia)
        source: wiki-cast-iron
        where: Alloying elements paragraph
      - name: Manganese
        symbol: Mn
        share_note: below 1.0
        role: Stabilises the pearlite in the matrix (China Casting)
        source: china-casting-gray-iron
        where: Composition paragraph
      - name: Phosphorus
        symbol: P
        share_note: no number printed
        role: Raised in some castings for fluidity; excess makes it brittle (China Casting)
        source: china-casting-gray-iron
        where: Composition paragraph
      - name: Sulfur
        symbol: S
        share_note: kept as low as possible
        role: Forms iron sulfides that hurt mechanical performance (China Casting)
        source: china-casting-gray-iron
        where: Composition paragraph
  risk_groups:
    - title: For people
      level: 1
      verdict: Element records only
      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.
    - title: In the environment
      level: 2
      verdict: No corrosion rate read
      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.
    - title: In service
      level: 2
      verdict: Brittle in tension
      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).
  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
      benchmark: ultimate_tensile_strength
      value: 200 to 350 MPa at 20 °C
      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.
    - label: Compressive strength
      benchmark: compressive_strength
      value: 752.5 to 1053.5 MPa
      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).'
    - label: Stiffness
      benchmark: elastic_modulus
      value: 103 to 118 GPa
      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).
    - label: Density
      benchmark: density
      value: 7.2 g/cm³ at 20 °C
      line: Density is 7.2 g/cm³ at 20 °C for EN-GJL-250 (MfgRobots).
    - label: Thermal conductivity
      benchmark: thermal_conductivity
      value: 50 W/(m·K) at 20 °C
      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).
    - label: Damping
      benchmark: damping_capacity
      value: 100 to 500 (high carbon equivalent)
      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.
    - label: Machinability
      line: Graphite flakes lubricate the cut and break the chips, so the metal machines easily (Wikipedia, Align). No machinability rating is printed.
  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.