Chromium Cr

spore: profile
id: chromium
spore_version: 0.2
family: transition-metals
name: Chromium
abbreviation: Cr
role: transition metal used mainly as the alloying element that makes stainless steel and nickel superalloys corrosion resistant, and as the hard chrome plating layer on wear surfaces
category: metals
type: heavy-metals
summary: |
  Chromium (Cr, atomic number 24) is a lustrous, hard, silvery-blue body-centred cubic metal with a density of 7.19 g/cm3 at 20 °C and a melting point of 1907 °C (Stanford Advanced Materials SDS; Goodfellow). Most of it is used as an alloying element: the USGS says stainless steels and superalloys require the addition of chromium, and that chromium has no substitute in stainless steel or in superalloys (USGS 2026). Its corrosion resistance comes from a thin self-healing Cr2O3 passive film, which Goodfellow describes as the basis of virtually all industrial chromium applications. The pure metal is not classed as hazardous under CLP in its supplier SDS; the hazard is hexavalent chromium, which is a known carcinogen.
best_for: 'Alloying: stainless steel and nickel superalloys, which the USGS says have no chromium substitute'
weakest_at: Brittle at room temperature in commercial grades (impurities), and volatile CrO3 forms above about 1,000 °C in oxygen (Goodfellow)
identity:
  formula: Cr (element, atomic number 24)
  cas: 7440-47-3
  source: sds-sam-cr
  where: Section 1, product name and CAS number 7440-47-3
  designations: []
tags:
  environments: []
  stresses: []
  applications:
    - structures
    - propulsion-and-tanks
    - mechanisms
properties:
  - benchmark: density
    label: Density, chromium at 20 °C
    value: 7.19
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      form: element, as stated in the datasheet
    method: Value printed in the Goodfellow chromium material page, General Properties table
    status: ground
    source: goodfellow-cr
    where: General Properties table, row Density (20 °C) 7.19 g/cm³
  - benchmark: density
    label: Density, chromium metal at 20 °C (supplier SDS)
    value: 7.19
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      form: chromium metal, CAS 7440-47-3
    method: Value printed in Section 9 of the Stanford Advanced Materials SDS
    status: ground
    source: sds-sam-cr
    where: Section 9 Physical and chemical properties, row Density at 20 °C (68 °F)
  - benchmark: density
    label: Density, chromium (WebElements)
    value: 7140
    unit: kg/m3
    scope: material
    conditions:
      unit_in_source: kg m-3
      temperature: not stated in the row
    method: Value printed in the WebElements chromium physical properties page, Density properties
    status: ground
    source: webelements-cr
    where: Physical properties page, Density properties, row Density of solid 7140 kg m-3
  - benchmark: melting_point
    label: Melting point, chromium (supplier SDS)
    value: 1907
    unit: °C
    scope: material
    conditions:
      form: chromium metal, CAS 7440-47-3
    method: Value printed in Section 9 of the Stanford Advanced Materials SDS
    status: ground
    source: sds-sam-cr
    where: Section 9 Physical and chemical properties, row Melting point/Melting range 1907 °C (3465 °F)
  - benchmark: melting_point
    label: Melting point, chromium (Goodfellow)
    value: 1907
    unit: °C
    scope: material
    conditions:
      form: element, high-purity material page value as printed
    method: Value printed in the Goodfellow chromium material page, General Properties table
    status: ground
    source: goodfellow-cr
    where: General Properties table, row Melting Point 1,907 °C (2,180 K)
  - benchmark: boiling_point
    label: Boiling point, chromium (supplier SDS)
    value: 2671
    unit: °C
    scope: material
    conditions:
      form: chromium metal, CAS 7440-47-3
    method: Value printed in Section 9 of the Stanford Advanced Materials SDS
    status: ground
    source: sds-sam-cr
    where: Section 9 Physical and chemical properties, row Boiling point/Boiling range 2671 °C (4840 °F)
  - benchmark: boiling_point
    label: Boiling point, chromium (Goodfellow)
    value: 2671
    unit: °C
    scope: material
    conditions:
      form: element, as printed
    method: Value printed in the Goodfellow chromium material page, General Properties table
    status: ground
    source: goodfellow-cr
    where: General Properties table, row Boiling Point 2,671 °C (2,944 K)
  - benchmark: thermal_conductivity
    label: Thermal conductivity, chromium
    value: 93.9
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated in the row
      unit_in_source: W/m·K
    method: Value printed in the Goodfellow chromium material page, General Properties table
    status: ground
    source: goodfellow-cr
    where: General Properties table, row Thermal Conductivity 93.9 W/m·K
  - benchmark: cte
    label: Coefficient of linear thermal expansion, chromium
    value: 4.9
    unit: µm/m·°C
    scope: material
    conditions:
      temperature: not stated in the row
      unit_in_source: µm/m·°C
    method: Value printed in the Goodfellow chromium material page, General Properties table
    status: ground
    source: goodfellow-cr
    where: General Properties table, row Coefficient of Thermal Expansion 4.9 µm/m·°C
  - benchmark: elastic_modulus
    label: Young's modulus, chromium (Goodfellow)
    value: 279
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in the row
    method: Value printed in the Goodfellow chromium material page, Mechanical Properties table
    status: ground
    source: goodfellow-cr
    where: Mechanical Properties table, row Elastic (Young's) Modulus 279 GPa
  - benchmark: shear_modulus
    label: Rigidity (shear) modulus, chromium
    value: 115
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in the page
    method: Value printed in the WebElements chromium physical properties page, Elastic properties
    status: ground
    source: webelements-cr
    where: Physical properties page, Elastic properties, row Rigidity modulus 115 GPa
  - benchmark: bulk_modulus
    label: Bulk modulus, chromium
    value: 160
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in the page
    method: Value printed in the WebElements chromium physical properties page, Elastic properties
    status: ground
    source: webelements-cr
    where: Physical properties page, Elastic properties, row Bulk modulus 160 GPa
  - benchmark: poissons_ratio
    label: Poisson's ratio, chromium
    value: 0.21
    unit: '-'
    scope: material
    conditions:
      basis: typical value as printed, no temperature stated
    method: Value printed in the Goodfellow chromium material page, Mechanical Properties table
    status: ground
    source: goodfellow-cr
    where: Mechanical Properties table, row Poisson's Ratio 0.21
  - benchmark: vickers_hardness
    label: Vickers hardness, chromium
    value: 1060
    unit: HV
    scope: material
    conditions:
      basis: approximate value as printed (about 1,060 HV), no load stated
    method: Value printed in the Goodfellow chromium material page, Mechanical Properties table
    status: ground
    note: Custom benchmark name, not in the property canon. The printed value is approximate.
    source: goodfellow-cr
    where: Mechanical Properties table, row Hardness Mohs 8.5; ~1,060 HV
  - benchmark: mohs_hardness
    label: Mohs hardness, chromium
    value: 8.5
    unit: '-'
    scope: material
    conditions:
      basis: Mohs scale, pure metal
    method: Value printed in the Goodfellow chromium material page, Mechanical Properties table
    status: ground
    note: Custom benchmark name, not in the property canon.
    source: goodfellow-cr
    where: Mechanical Properties table, row Hardness Mohs 8.5
  - benchmark: neel_temperature
    label: Néel temperature, chromium (antiferromagnetic transition)
    value: 311
    unit: K
    scope: material
    conditions:
      basis: transition below which chromium is antiferromagnetic, as printed
    method: Value printed in the Goodfellow chromium material page, Magnetic Properties table
    status: ground
    note: Custom benchmark name, not in the property canon.
    source: goodfellow-cr
    where: Magnetic Properties row, antiferromagnetic below 311 K (Néel temp)
corrosion:
  - environment: Air and aqueous environments, bulk metal
    headline: Chromium forms a self-healing passive film that resists air and water.
    effect: The Goodfellow corrosion row says chromium forms a 2 to 3 nm Cr2O3 passive film in air and aqueous environments, which reforms within milliseconds if damaged. The same page says this film is the basis of stainless steel corrosion resistance.
    rating: low
    conditions:
      basis: qualitative statement; no exposure duration or temperature printed
    source: goodfellow-cr
    where: Corrosion Resistance row, value Excellent (self-passivating) and Notes
  - environment: Concentrated nitric acid
    headline: Concentrated nitric acid passivates chromium.
    effect: The Goodfellow acid resistance row says concentrated HNO3 passivates chromium, and that the metal is resistant to dilute HNO3 and acetic acid.
    rating: none
    conditions:
      basis: qualitative statement; no concentration or temperature printed
    source: goodfellow-cr
    where: Chemical Properties, Acid Resistance row, Notes
  - environment: Hydrochloric acid and dilute sulfuric acid
    headline: Reducing acids dissolve the passive film and attack the metal.
    effect: The Goodfellow page says the passive film dissolves in reducing acids such as HCl and dilute H2SO4, exposing the metal to attack, and that chromium is dissolved by HCl.
    rating: severe
    conditions:
      basis: qualitative statement; no concentration or temperature printed
    source: goodfellow-cr
    where: Chemical Properties, Acid Resistance row, Value/Behavior and Notes
  - environment: Oxygen-rich air above about 1,000 °C
    headline: Chromium oxide protects up to about 1,000 °C, then volatile CrO3 forms.
    effect: The Goodfellow high-temperature oxidation row says Cr2O3 protects to about 1,000 °C, and that above this temperature volatile CrO3 forms in high oxygen partial pressure, causing chromium evaporation in SOFC interconnects and turbine parts.
    rating: moderate
    conditions:
      basis: oxygen-rich atmosphere; no exposure time printed
    source: goodfellow-cr
    where: Thermal and Environmental Properties, High-Temperature Oxidation row
risks:
  hazards:
    - text: The Stanford Advanced Materials SDS for chromium metal (CAS 7440-47-3) says the substance is not classified as hazardous to health or the environment under CLP, and gives no hazard statements or signal word.
      ghs: []
      source: sds-sam-cr
      where: Section 2 Hazards identification, Classification according to Regulation (EC) No 1272/2008
    - text: 'PubChem aggregates ECHA notifications for the Chromium record (CID 23976): it reports that the chemical does not meet GHS hazard criteria for 50% (1202 of 2404) of company reports. The most reported statements are H317, H334 and H319, but the aggregate may include chromium compounds, so check the supplier SDS for the metal you handle.'
      ghs:
        - H317
        - H319
        - H334
      source: pubchem-cr
      where: GHS Classification section, ECHA C&L Notifications Summary
    - text: Hexavalent chromium compounds (CrO3, dichromates, chromate pigments) are IARC Group 1 carcinogens and have an OSHA PEL of 5 µg/m3 for Cr(VI). Goodfellow says chromium(III) and chromium metal are not classified as carcinogens.
      ghs: []
      source: goodfellow-cr
      where: Chemical Properties and Toxicology (Cr6+) row
  failure_risks:
    - mode: Chromium evaporation at high temperature
      trigger: Heating above about 1,000 °C in an oxygen-rich atmosphere
      consequence: Volatile CrO3 forms and the metal evaporates, which the Goodfellow page describes as a major problem in SOFC interconnects and high-temperature turbine components.
      severity: moderate
      source: goodfellow-cr
      where: Thermal and Environmental Properties, High-Temperature Oxidation row
    - mode: Loss of the passive film in reducing acids
      trigger: Exposure to hydrochloric acid or dilute sulfuric acid
      consequence: The passive film dissolves and the metal is attacked (Goodfellow).
      severity: high
      source: goodfellow-cr
      where: Chemical Properties, Acid Resistance row
    - mode: Brittle fracture of commercial chromium at room temperature
      trigger: Interstitial impurities (N, O, C) in commercial grades, which pin dislocations
      consequence: Commercial chromium is brittle at room temperature, while high-purity chromium above 99.9% is ductile above about 100 °C (Goodfellow). The Goodfellow table prints the ductile-to-brittle transition as about -20 °C to +200 °C, depending on purity.
      severity: moderate
      source: goodfellow-cr
      where: Mechanical Properties table, row Ductile-to-Brittle Transition
  side_effects: []
  handling:
    - text: Keep the container tightly sealed and store in a cool, dry place (SDS Section 7).
      source: sds-sam-cr
    - text: The SDS asks for no special measures against fire or explosion, and lists toxic metal oxide fume as the hazardous decomposition product (SDS Sections 5 and 10).
      source: sds-sam-cr
    - text: Exposure limits printed in the SDS for chromium metal are a US PEL of 1 mg/m3 and a TLV of 0.5 mg/m3 (Section 8).
      source: sds-sam-cr
  mitigations: []
uses:
  - application: structures
    device: Stainless steel (chromium at 10.5 % or more by weight, with iron)
    example: The USGS says stainless-steel and heat-resisting-steel producers were the leading consumers of ferrochromium in 2025, and that chromium has no substitute in stainless steel, the leading end use.
    source: usgs-mcs2026-chromium
    where: Domestic Production and Use paragraph; Substitutes paragraph
  - application: propulsion-and-tanks
    device: Nickel superalloys for gas turbine hot sections (Inconel 718, 17 to 21 % Cr)
    example: Goodfellow says chromium additions of 10 to 20 wt% to nickel superalloys provide oxidation and hot-corrosion resistance in gas turbine hot sections, and gives Inconel 718 at 17 to 21 % Cr. The USGS calls superalloys the major strategic end use of chromium.
    source: goodfellow-cr
    where: Applications paragraph on nickel superalloys (Inconel 718 entry); USGS Substitutes paragraph
  - application: mechanisms
    device: Hard chrome electroplating on hydraulic cylinder rods and landing gear
    example: Goodfellow says hard chrome electroplating deposits 50 to 250 µm of chromium at 800 to 1,000 HV, and is the standard wear-resistant coating for hydraulic cylinder rods and landing gear, though increasingly challenged by REACH restrictions.
    source: goodfellow-cr
    where: Applications paragraph on hard chrome electroplating; Mechanical Properties table
supply:
  - subject: Chromium (chromite ore mine production, 2025e)
    abundance: 'USGS 2026: world resources are greater than 12 billion tons of shipping-grade chromite, and the USGS says they are heavily concentrated (95 %) in Kazakhstan and southern Africa.'
    producers:
      - country: South Africa (mine production 2025e, 23,000 thousand t of 51,000 thousand t world total)
        share_percent: 45.1
        year: 2025
      - country: Turkey (mine production 2025e, 9,000 thousand t)
        share_percent: 17.6
        year: 2025
      - country: Kazakhstan (mine production 2025e, 7,000 thousand t)
        share_percent: 13.7
        year: 2025
      - country: India (mine production 2025e, 3,000 thousand t)
        share_percent: 5.9
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (IEA page summarising the final list)
        listed: true
    recycling: 'USGS: recycled chromium, contained in reported stainless-steel scrap receipts, accounted for 21 % of apparent U.S. consumption in 2025.'
    substitutes:
      - 'USGS: chromium has no substitute in stainless steel or in superalloys. Chromium-containing scrap can substitute for ferrochromium in some metallurgical uses.'
    source: usgs-mcs2026-chromium
    where: 'World Mine Production and Reserves table (2025e, gross weight; shares calculated by Space Mushroom against the 51,000 thousand t world total, which is rounded by the USGS); Salient Statistics; Recycling; Substitutes. Critical list: IEA page for the USGS final 2025 list.'
  - subject: Chromium (United States import sources, chromium metal)
    abundance: 'USGS 2026: net import reliance was 79 % of apparent U.S. consumption in 2025e.'
    producers:
      - country: China (chromium metal imports, 2021 to 2024)
        share_percent: 40
        year: 2024
      - country: United Kingdom (chromium metal imports, 2021 to 2024)
        share_percent: 26
        year: 2024
      - country: Russia (chromium metal imports, 2021 to 2024)
        share_percent: 15
        year: 2024
      - country: France (chromium metal imports, 2021 to 2024)
        share_percent: 14
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-chromium
    where: Import Sources (2021 to 2024), chromium metal; Salient Statistics, net import reliance row
documents:
  - title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
  - title: Safety data sheet, Chromium Metal (CAS 7440-47-3), Stanford Advanced Materials, revised 16/11/2022
    type: sds
    url: https://samaterials.com/tds/sc/1735205134-CR1292.pdf
    year: 2022
  - title: Goodfellow, Chromium material data page (general, mechanical, corrosion and chemical properties)
    type: datasheet
    url: https://www.goodfellow.com/usa/material/metals/chromium
  - title: WebElements, Chromium physical properties
    type: database
    url: https://www.webelements.com/chromium/physics.html
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements, chromium
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Cr&all=all&ascii=html
  - title: PubChem compound record for chromium (CID 23976), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23976
  - title: IEA summary of the final 2025 List of Critical Minerals (USGS)
    type: report
    url: https://www.iea.org/policies/31799-final-list-of-critical-minerals-2025
    year: 2025
gaps:
  - 'Electrical resistivity: Goodfellow prints 125 nΩ·m at 20 °C and WebElements prints 12.7 × 10−8 Ω m. Neither nΩ·m nor the WebElements exponent form is entered, because the unit is not in the site registry.'
  - 'Ductile-to-brittle transition: Goodfellow prints about -20 °C to +200 °C, depending on purity. It is described in the failure risks only and is not entered as a benchmark, because the range is not a single grade value.'
  - 'Tensile and yield strength, and elongation, for wrought or electroplated chromium: no printed value was read in a source this run.'
  - Electrodeposited hard chrome hardness (800 to 1,000 HV) is a range for a coating, not the pure metal, so it is not entered as a property.
  - 'Atomic weight: not a property-canon benchmark; the NIST value 51.9961(6) is used in the recipe parts only.'
  - 'Designations: no UNS, ASTM, EN or AMS code for unalloyed chromium metal was printed in a source read in this run, so designations is empty.'
  - 'Critical-mineral list status on the EU list: the European Commission page fetched in this run did not show chromium in its readable text, and the list was not confirmed, so no EU list entry is made.'
  - 'Production process: the reduction route for pure chromium was not read from a primary source in this run.'
  - No space-environment data (outgassing, atomic-oxygen erosion, radiation, thermal-vacuum) for chromium metal was found in the sources read.
  - 'Crustal abundance of chromium: the USGS PP 1802-A Table A1 read in this run does not list chromium, and the USGS chromium summary does not print an abundance, so none is entered.'
  - 'Media: no public-domain image of chromium metal was checked in this run, so media is empty.'
sources:
  usgs-mcs2026-chromium:
    title: Mineral Commodity Summaries 2026, Chromium, February 2026
    id: USGS MCS 2026, prepared by Ruth F. Schulte
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  goodfellow-cr:
    title: Goodfellow, Chromium material page (general, mechanical, thermal, environmental and chemical property tables)
    id: Goodfellow material page, metals, chromium
    url: https://www.goodfellow.com/usa/material/metals/chromium
    kind: datasheet
    license: supplier web page (cited, not reproduced)
  sds-sam-cr:
    title: Safety data sheet, Chromium Metal (CAS 7440-47-3), Stanford Advanced Materials, date revised 16/11/2022
    id: CAS 7440-47-3
    url: https://samaterials.com/tds/sc/1735205134-CR1292.pdf
    year: 2022
    kind: datasheet
    license: supplier safety data sheet (cited, not reproduced)
  webelements-cr:
    title: 'WebElements, Chromium: physical properties'
    id: WebElements, University of Sheffield (Mark Winter)
    url: https://www.webelements.com/chromium/physics.html
    kind: database
    license: WebElements (cited, not reproduced)
  nist-atomic-weights-cr:
    title: NIST Atomic Weights and Isotopic Compositions for All Elements, chromium
    id: NIST standard atomic weight 51.9961(6)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Cr&all=all&ascii=html
    kind: database
    license: US government data
  pubchem-cr:
    title: 'PubChem compound record: Chromium (CID 23976), GHS Classification section'
    id: CID 23976, ECHA C&L Inventory aggregated notifications
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23976
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA
  iea-crit-2025:
    title: IEA, Final List of Critical Minerals 2025 (summary of the USGS final list)
    id: IEA policy page 31799
    url: https://www.iea.org/policies/31799-final-list-of-critical-minerals-2025
    year: 2025
    kind: web
    license: IEA terms of use (cited, not reproduced)
  wiki-cr:
    title: Wikipedia, Chromium (history and composition only)
    id: Wikipedia article Chromium
    url: https://en.wikipedia.org/wiki/Chromium
    kind: web
    license: CC BY-SA 4.0 (Wikipedia, cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 16
  unreachable: 0
  caveats: 3
  note: Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. The melting point and boiling point appear in two sources, and both are kept. Shares in the supply section are calculated from printed tonnes, not printed as percentages. Electrical resistivity, the ductile-to-brittle range and the strength values are left as gaps.
story:
  recipe:
    line: Chromium is a single-element metal (Cr, atomic number 24, body-centred cubic per Goodfellow). Its standard atomic weight is 51.9961 (NIST). It is added to iron as ferrochromium, made from chromite ore, or as chromium metal or chromium-containing scrap (USGS 2026).
    parts:
      - name: Chromium
        symbol: Cr
        atoms: 1
        atomic_weight: 51.9961
        role: The base metal. Density 7.19 g/cm3 and melting point 1907 °C (SDS), and it forms a self-healing Cr2O3 passive film that gives stainless steel its corrosion resistance (Goodfellow).
  risk_groups:
    - title: For people
      level: 1
      verdict: Metal is not classed as hazardous under CLP, but…
      lead: The supplier SDS for the metal gives no hazard statement. Hexavalent chromium compounds are a separate and serious hazard, and the PubChem aggregate includes sensitising statements.
      points:
        - label: The metal
          line: The SDS for chromium metal says it is not classified under CLP, and gives a US PEL of 1 mg/m3 and a TLV of 0.5 mg/m3.
        - label: Hexavalent chromium
          line: Goodfellow says Cr(VI) compounds are IARC Group 1 carcinogens, while chromium(III) and the metal are not classified as carcinogens.
    - title: If it fails
      lead: The failure routes are chromium evaporation above about 1,000 °C in oxygen, and loss of the passive film in reducing acids.
      points:
        - label: Evaporation
          line: Volatile CrO3 forms above about 1,000 °C in high oxygen partial pressure, which Goodfellow describes as a major problem in SOFC interconnects and turbine parts.
        - label: Acid attack
          line: The passive film dissolves in HCl and dilute H2SO4, and the metal is then attacked.
  why: Chromium is a hard transition metal whose main value is what it does in alloys. Its density of 7.19 g/cm3 and melting point of 1907 °C come from the supplier SDS. Wikipedia records that Louis Nicolas Vauquelin first isolated it in the late eighteenth century, and that the name comes from the Greek word for colour, because many chromium compounds are intensely coloured. The Cr2O3 passive film is what makes stainless steel and nickel superalloys corrosion resistant, and the USGS says neither stainless steel nor superalloys have a chromium substitute.
  uses:
    - where: Stainless steel
      line: Stainless and heat-resisting steel producers were the leading consumers of ferrochromium in the United States in 2025, and the USGS says chromium has no substitute in stainless steel, the leading end use.
    - where: Gas turbine superalloys
      line: Goodfellow says chromium in nickel superalloys such as Inconel 718 (17 to 21 % Cr) gives oxidation and hot-corrosion resistance in gas turbine hot sections.
    - where: Hard chrome plating
      line: Electroplated hard chrome, 50 to 250 µm thick at 800 to 1,000 HV, is the standard wear coating for hydraulic rods and landing gear, though REACH restrictions increasingly challenge it (Goodfellow).
  can_do:
    - label: Weight
      value: 7.19 g/cm3
      benchmark: density
      line: The SDS prints a density of 7.19 g/cm3 at 20 °C, and Goodfellow prints the same value.
    - label: Melting
      value: 1907 °C
      benchmark: melting_point
      line: The SDS and Goodfellow both print a melting point of 1907 °C, one of the highest among the Period 4 transition metals (Goodfellow).
    - label: Stiffness
      value: 279 GPa
      benchmark: elastic_modulus
      line: Goodfellow prints a Young's modulus of 279 GPa, higher than iron at 200 GPa.
    - label: Hardness
      value: 1060 HV
      benchmark: vickers_hardness
      line: Goodfellow prints about 1,060 HV for the pure metal, and Mohs 8.5.
    - label: Heat carry
      value: 93.9 W/(m·K)
      benchmark: thermal_conductivity
      line: Goodfellow prints a thermal conductivity of 93.9 W/m·K, which is lower than copper or aluminium but higher than stainless steel (about 16 W/m·K, as printed).
  compare: Chromium is a dense, hard, high-melting metal. The SDS gives 7.19 g/cm3 and 1907 °C for the metal, and Goodfellow gives 93.9 W/m·K for thermal conductivity without a temperature. The table compares chromium on the three properties that the two sources print most consistently.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Keep the container sealed and the metal stored cool and dry (SDS Section 7).
    - Avoid breathing dust, and treat the oxide fume as toxic (SDS Section 10).
    - Keep hexavalent chromium compounds out of the workplace where possible; the metal itself is not classed as a carcinogen (Goodfellow).
  good_for:
    - 'Alloying: chromium gives stainless steel and nickel superalloys their corrosion resistance, and the USGS says neither has a substitute.'
    - 'Hard surfaces: hard chrome plating gives wear resistance at 800 to 1,000 HV (Goodfellow).'
    - 'Oxidation protection: the Cr2O3 film protects up to about 1,000 °C (Goodfellow).'
  watch_out:
    - 'Reducing acids: hydrochloric acid and dilute sulfuric acid dissolve the passive film (Goodfellow).'
    - Hexavalent chromium is a carcinogen, and the metal itself is not classed as one (Goodfellow).
    - 'Supply: South Africa produced about 45 % of world chromite ore mine output in 2025e, and the United States had 79 % net import reliance (USGS 2026).'
    - No space outgassing, erosion yield or radiation data for chromium metal were found in the sources read.
  verdict: Chromium is best known as an alloying element that gives stainless steel and superalloys their corrosion resistance. The metal is not classed as hazardous in the supplier SDS, but its hexavalent compounds are carcinogenic, and this profile has no sourced space-environment test data.
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