spore: profile
id: steel-52100
spore_version: 0.2
family: bearing-steel
name: AISI 52100 bearing steel
abbreviation: 52100 (UNS G52986)
role: High-carbon chromium alloy steel for rolling-element bearings
category: tribology
type: bearing-materials
summary: |
  AISI 52100 is an iron-based, high-carbon chromium alloy steel with 0.980 to 1.10 % carbon and 1.30 to 1.60 % chromium (AZoM composition table). AZoM gives its density as 7.81 g/cm3 and its melting point as 1424 °C. Rockwell C values of 62 to 66 are printed for its quenched conditions. AZoM describes it as used in bearings in rotating machinery. A 2017 ASTM paper ranks 52100 among the bearing steels with the highest corrosion rates in simulated seawater.
best_for: Hard, wear-resistant rolling bearings in rotating machinery (AZoM), where corrosion exposure is limited
weakest_at: Corrosion resistance. In a 2017 electrochemical ranking in simulated seawater, 52100 had one of the highest corrosion rates of the bearing steels tested (ranking only; the abstract gives no corrosion-rate numbers)
identity:
  formula: 'Iron-based steel: Fe 96.5 to 97.32 %, C 0.980 to 1.10 %, Cr 1.30 to 1.60 %, Mn 0.250 to 0.450 %, Si 0.150 to 0.300 %, S 0.0250 max %, P 0.0250 max % (wt%)'
  source: azom-52100
  where: Chemical Composition table (Element and Content columns); totalmateria Composition table gives the same C, Mn, Si, Cr, P and S ranges
  designations:
    - system: UNS
      code: G52986
      source: azom-52100
      where: Page title (AISI 52100 Alloy Steel (UNS G52986))
    - system: AISI
      code: '52100'
      source: azom-52100
      where: Page title
    - system: SAE
      code: E52100
      source: totalmateria-52100
      where: Cross-references list (SAE, United States)
    - system: EN
      code: '1.3505'
      source: totalmateria-52100
      where: Cross-references list (WL, Germany)
    - system: JIS
      code: SUJ 2
      source: totalmateria-52100
      where: Cross-references list (JIS, Japan)
    - system: ASTM
      code: A 295
      note: cross-reference printed as A 295 52100; the specification text itself was not read
      source: totalmateria-52100
      where: Cross-references list (ASTM, United States)
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
properties:
  - benchmark: density
    label: Density, as printed in the physical properties table
    value: 7.81
    unit: g/cm3
    scope: material
    conditions:
      temperature: not printed
      temper: not printed
    method: Physical properties table, metric column, as printed
    status: ground
    source: azom-52100
    where: Physical Properties table, Density row
  - benchmark: density
    label: Density range, 0 to 30 degC
    value: 7.67
    value_high: 7.86
    bound: range
    unit: kg/dm3
    scope: material
    conditions:
      temperature: 0 to 30 °C
      temper: not printed
    method: Physical properties section, as printed (range)
    status: ground
    source: totalmateria-52100
    where: Physical properties, Density row
  - benchmark: elastic_modulus
    label: Elastic modulus, metric range
    value: 190
    value_high: 210
    bound: range
    unit: GPa
    scope: material
    conditions:
      temperature: not printed
      temper: not printed
    method: Mechanical properties table, metric column, as printed (range)
    status: ground
    source: azom-52100
    where: Mechanical properties table, Elastic modulus row
  - benchmark: elastic_modulus
    label: Modulus of elasticity, range at 0 to 30 degC
    value: 190
    value_high: 210
    bound: range
    unit: GPa
    scope: material
    conditions:
      temperature: 0 to 30 °C
      temper: not printed
    method: Physical properties section, as printed (range)
    status: ground
    source: totalmateria-52100
    where: Physical properties, Modulus of Elasticity row
  - benchmark: poissons_ratio
    value: 0.27
    value_high: 0.3
    bound: range
    unit: '-'
    scope: material
    conditions:
      temperature: not printed
      note: dimensionless; the page prints no unit
    method: Mechanical properties table as printed (range)
    status: ground
    source: azom-52100
    where: Mechanical properties table, Poisson's ratio row
  - benchmark: melting_point
    value: 1424
    unit: °C
    scope: material
    conditions:
      basis: single value as printed in the physical properties table
      composition: AISI 52100 as listed by AZoM
    method: Physical properties table, metric column, as printed
    status: ground
    source: azom-52100
    where: Physical Properties table, Melting point row
  - benchmark: cte
    label: Thermal expansion coefficient, 23 to 280 degC, annealed
    value: 11.9
    unit: µm/m°C
    scope: material
    conditions:
      temperature_range: 23 to 280 °C
      temper: annealed
    method: Thermal properties table, metric column, as printed
    status: ground
    source: azom-52100
    where: Thermal properties table, Thermal expansion co-efficient row
  - benchmark: cte
    label: Thermal expansion coefficient, 0 to 100 degC, annealed
    value: 11.9
    unit: 10-6/°C
    scope: material
    conditions:
      temperature_range: 0 to 100 °C
      temper: annealed
    method: Thermal properties section, as printed
    status: ground
    source: totalmateria-52100
    where: Thermal Properties, Thermal Expansion row
  - benchmark: hardness_rockwell_c
    label: Rockwell C hardness, quenched in oil from 150 °C and tempered
    value: 62
    unit: HRC
    scope: material
    conditions:
      treatment: quenched in oil from 150 °C, tempered (as printed)
      scale: Rockwell C
    method: Mechanical properties table, as printed
    status: ground
    source: azom-52100
    where: Mechanical properties table, Hardness Rockwell C (quenched in oil from 150°C tempered) row
  - benchmark: hardness_rockwell_c
    label: Rockwell C hardness, quenched in water from 150 °C and tempered
    value: 64
    unit: HRC
    scope: material
    conditions:
      treatment: quenched in water from 150 °C, tempered (as printed)
      scale: Rockwell C
    method: Mechanical properties table, as printed
    status: ground
    source: azom-52100
    where: Mechanical properties table, Hardness Rockwell C (quenched in water from 150°C tempered) row
  - benchmark: hardness_rockwell_c
    label: Rockwell C hardness, quenched in oil
    value: 64
    unit: HRC
    scope: material
    conditions:
      treatment: quenched in oil (as printed; no tempering stated)
      scale: Rockwell C
    method: Mechanical properties table, as printed
    status: ground
    source: azom-52100
    where: Mechanical properties table, Hardness Rockwell C (quenched in oil) row
  - benchmark: hardness_rockwell_c
    label: Rockwell C hardness, quenched in water
    value: 66
    unit: HRC
    scope: material
    conditions:
      treatment: quenched in water (as printed; no tempering stated)
      scale: Rockwell C
    method: Mechanical properties table, as printed
    status: ground
    source: azom-52100
    where: Mechanical properties table, Hardness Rockwell C (quenched in water) row
  - benchmark: hardness_rockwell_unspecified_scale
    label: Rockwell hardness range, scale letter not printed
    value: 58
    value_high: 65
    bound: range
    unit: HR
    scope: material
    conditions:
      temperature: 0 to 30 °C
      scale: not printed on the page
      treatment: not printed
    method: Mechanical properties section, as printed (range)
    status: ground
    note: The page prints HR without a scale letter, so the scale is unknown. Do not read it as Rockwell C.
    source: totalmateria-52100
    where: Mechanical properties, Rockwell Hardness (HR) row
corrosion:
  - environment: Simulated synthetic seawater, aqueous electrochemical polarisation and impedance tests
    headline: In a seawater electrochemical ranking, AISI 52100 had one of the highest corrosion rates of the bearing steels tested.
    effect: Kvryan et al. (2017) ranked 52100 with CSS-42L as having the highest corrosion rates. 440C, CR30, XD15N and Pyrowear 675 (CN-A) had the lowest. The abstract gives the ranking only. The authors say that salt-spray and immersion standards lack sensitivity for steels with elevated chromium content, which is why they used electrochemistry.
    rating: severe
    conditions:
      basis: aqueous solutions at the free corrosion potential; ranking as printed in the abstract
      electrolyte: simulated synthetic seawater
      heat_treatment: not stated in the abstract
    source: kvryan-2017
    where: Abstract (ASTM STP 1600, pp. 466 to 486)
  - environment: Plain tap water in a rotating spindle test, 100 h (440C races, not 52100)
    headline: In a 100 h tap-water spindle test, 440C races corroded; AISI 52100 was not part of that water test.
    effect: NASA's 2023 test ran hybrid 440C-race bearings and NiTi-Hf bearings in tap water for 100 h. The 440C bearings showed significant corrosion on the races and the adjacent housing spacers, and the NiTi-Hf bearings showed none. In that study 52100 was only the ball material of a separate denting test.
    rating: severe
    conditions:
      bearing: R4 hybrid bearings, 440C races with Si3N4 balls
      duration: 100 h
      environment: plain tap water partly filling the housing, seals partly removed
    source: nasa-tm-2023
    where: Corrosion Test Method and Results section
risks:
  hazards:
    - text: 'Solid steel: the grouped safety data sheet (TW Metals, rev. 01/14/2016) lists 52100 among its alternate names and states that carbon, alloy and tool steels in their solid state present no inhalation, ingestion or contact health hazard.'
      ghs: []
      source: uwo-sds-steels
      where: Section 1.1 (Alternate names) and Section 4.2 (Overview)
    - text: Dust and fume from burning, melting, welding, sawing, brazing, grinding and machining may be hazardous to health. The sheet lists eye, nose and throat irritation and metal fume fever as acute effects, and prolonged exposure to dusts or fumes as a respiratory hazard.
      ghs: []
      source: uwo-sds-steels
      where: Section 4.2 (Overview, Acute and Chronic effects)
  failure_risks:
    - mode: Brinnelling (permanent dents in the raceways) under high static or shock load
      trigger: High radial load on the ball-race contact, tested by NASA with 52100 balls, NiTi-Hf balls and silicon nitride balls
      consequence: NASA reports that the load needed for a given dent depth with NiTi-Hf balls is roughly twice that needed for 52100 balls. The authors state that 52100 is less resistant to brinnelling than NiTi-Hf.
      severity: moderate
      source: nasa-tm-2023
      where: Introduction and Background; Denting Test Method and Results (text around Figure 11)
    - mode: Corrosion pitting in marine or other aqueous environments
      trigger: Exposure to seawater or other aqueous solutions
      consequence: Kvryan et al. (2017) state that premature failure by corrosion pitting is a major concern in aerospace systems operating in marine environments, and they rank 52100 among the steels with the highest corrosion rates in simulated seawater.
      severity: moderate
      source: kvryan-2017
      where: Abstract, first paragraph and ranking sentence
  handling:
    - text: AZoM advises a spheroidising anneal at 649 °C (1200 °F) before machining to improve machinability.
      source: azom-52100
      where: Fabrication and Heat Treatment, Machinability
    - text: AZoM gives normalising at 872 °C (1600 °F) and heating to 816 °C (1500 °F) followed by oil quenching. Normalising is done before machining to reduce machining stress.
      source: azom-52100
      where: Fabrication and Heat Treatment, Heat Treatment and Normalizing text
    - text: efunda gives austenitizing at 816 to 857 °C (1500 to 1575 °F), oil quenching with no more than 1 hour before tempering, and a cold soak to -68 °C (-90 °F) or lower for at least 1 hour.
      source: efunda-52100
      where: Heat treatment section (austenitizing and quench)
  mitigations:
    - text: Use local exhaust ventilation where grinding, welding or burning makes dust or fume, and wear a NIOSH-approved dust, mist or fume respirator when welding or burning this metal.
      source: uwo-sds-steels
      where: Exposure controls and personal protection (respiratory protection); Precautionary statement P261
uses:
  - application: mechanisms
    device: Rolling-element bearings in rotating machinery
    example: AZoM describes AISI 52100 as used in bearings in rotating machinery.
    source: azom-52100
    where: Applications section
  - application: mechanisms
    device: Ball material in small precision test bearings for space-mechanism research (not a flight part)
    example: NASA's 2023 denting tests used 52100 balls as one of three ball materials, alongside NiTi-Hf and silicon nitride, in small precision test bearings.
    source: nasa-tm-2023
    where: Denting Test Method and Results section
supply:
  - subject: Iron
    producers:
      - country: Australia
        share_percent: 37.7
        year: 2025
      - country: Brazil
        share_percent: 16.2
        year: 2025
      - country: India
        share_percent: 11.9
        year: 2025
      - country: China
        share_percent: 11.2
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: false
    recycling: Not read in the iron-ore summary we hold; see gaps.
    substitutes: []
    source: usgs-mcs2026-iron-ore
    where: 'World Mine Production table, usable ore, 2025e (world total 2,600,000 thousand t; shares calculated by Space Mushroom from the Australia 980,000, Brazil 420,000, India 310,000 and China 290,000 values). The table is iron ore, which is the feedstock of the steel''s iron content, not a figure for the steel itself. Critical list: USGS 2025 list page.'
  - subject: Chromium
    producers:
      - country: South Africa
        share_percent: 45.1
        year: 2025
      - country: Turkey
        share_percent: 17.6
        year: 2025
      - country: Kazakhstan
        share_percent: 13.7
        year: 2025
      - country: India
        share_percent: 5.9
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Chromium, used in stainless steel)
        listed: true
    recycling: Recycled chromium, contained in reported stainless-steel scrap receipts, accounted for 21% of apparent US 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 (world total 51,000 thousand t, chromium content per the table header; shares calculated by Space Mushroom from the country values); Recycling; Substitutes; critical list from the USGS 2025 list page
documents:
  - title: 'AZoM: AISI 52100 Alloy Steel (UNS G52986), materials datasheet'
    type: datasheet
    url: https://www.azom.com/article.aspx?ArticleID=6704
    year: 2012
  - title: 'efunda: AISI 52100 alloy steel properties'
    type: database
    url: https://www.efunda.com/materials/alloys/alloy_steels/show_alloy.cfm?ID=AISI_52100&show_prop=all&Page_Title=AISI+52100
  - title: 'Total Materia: AISI 52100 material page'
    type: database
    url: https://www.totalmateria.com/en-us/material/1623479
  - title: 'NASA/TM-20230004311: Shock- and Corrosion-Resistant Bearings for Space Mechanisms'
    type: report
    url: https://ntrs.nasa.gov/api/citations/20230004311/downloads/TM-20230004311.pdf
    year: 2023
  - title: Electrochemical Corrosion Test Methods for Rapid Assessment of Aerospace Bearing Steel Performance (ASTM STP 1600)
    type: paper
    url: https://doi.org/10.1520/STP160020160150
    year: 2017
  - title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Iron Ore'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-ore.pdf
    year: 2026
  - title: 'Safety Data Sheet: Carbon, Alloy and Tool Steels AISI Grades (TW Metals, rev. 01/14/2016), copy hosted by University of Western Ontario'
    type: sds
    url: https://www.eng.uwo.ca/files/departments-units/student-shop/2016/sds-carbon-alloy-and-tool-steels.pdf
    year: 2016
gaps:
  - No tensile strength, yield strength or fatigue strength for 52100 was found in the pages read. AZoM and efunda print hardness and modulus but no strength values.
  - No specific heat capacity for 52100 was found.
  - AZoM's thermal conductivity (46.6 W/mK) and its bulk modulus (140 GPa) and shear modulus (80 GPa) are labelled as typical steel, not 52100, so they are left out.
  - No electrical resistivity, outgassing or vacuum data for 52100 was found. No space-flight use beyond the NASA test-bearing use was found.
  - The Kvryan et al. (2017) abstract gives a corrosion ranking only. The full paper was not opened, so no 52100 corrosion-rate number is listed.
  - No humidity, salt-spray or wet-environment test of 52100 was found. The NASA 2023 water test used 440C and NiTi-Hf bearings only.
  - The totalmateria hardness range (58 to 65 HR) does not print a Rockwell scale letter, so its scale is unknown.
  - The pages read give one composition range for 52100. Vacuum-degassed and other specialist variants were not separated.
  - totalmateria also prints 1.3514 (WL, Germany) as a cross-reference. It is not listed as a designation because the page does not say it is the same grade.
  - The ASTM A 295 and SAE specification texts were not read. Those designations are cross-references only.
  - Manganese is on the USGS 2025 critical list, but no manganese production data were read, so it is not profiled. Carbon supply is not profiled either.
  - No crustal abundance figure for iron or chromium was read.
  - The USGS iron-ore summary recycling entry was not read, so iron recycling is left blank.
  - No image with a verified licence was found, so the profile has no media entry.
  - 'side_effects: no source beyond the dust and fume statement in the hazards section.'
  - Hardness uses the benchmarks hardness_rockwell_c and hardness_rockwell_unspecified_scale. Neither is in property-canon.yaml; add them to the canon before import.
sources:
  azom-52100:
    title: AISI 52100 Alloy Steel (UNS G52986)
    id: AZoM article 6704 (published 26 Sep 2012)
    url: https://www.azom.com/article.aspx?ArticleID=6704
    year: 2012
    kind: datasheet
    license: AZoM terms (cited, not reproduced)
  efunda-52100:
    title: AISI 52100 Alloy Steel, efunda properties page
    id: efunda ID=AISI_52100
    url: https://www.efunda.com/materials/alloys/alloy_steels/show_alloy.cfm?ID=AISI_52100&show_prop=all&Page_Title=AISI+52100
    kind: database
    license: efunda terms (cited, not reproduced)
  totalmateria-52100:
    title: AISI 52100 material page (Total Materia)
    id: totalmateria material 1623479
    url: https://www.totalmateria.com/en-us/material/1623479
    kind: database
    license: Total Materia terms (cited, not reproduced)
  nasa-tm-2023:
    title: Shock- and Corrosion-Resistant Bearings for Space Mechanisms
    id: NASA/TM-20230004311 (Howard and DellaCorte, August 2023)
    url: https://ntrs.nasa.gov/api/citations/20230004311/downloads/TM-20230004311.pdf
    year: 2023
    kind: report
    license: public domain (NASA)
  kvryan-2017:
    title: Electrochemical Corrosion Test Methods for Rapid Assessment of Aerospace Bearing Steel Performance
    id: doi:10.1520/STP160020160150 (ASTM STP 1600, pp. 466 to 486)
    url: https://doi.org/10.1520/STP160020160150
    year: 2017
    kind: paper
    license: publisher copyright (cited, abstract only)
  usgs-mcs2026-chromium:
    title: Mineral Commodity Summaries 2026, Chromium
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-iron-ore:
    title: Mineral Commodity Summaries 2026, Iron Ore
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-ore.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS)
    id: 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  uwo-sds-steels:
    title: 'Safety Data Sheet: Carbon, Alloy and Tool Steels AISI Grades (TW Metals), rev. 01/14/2016'
    id: 'TW Metals MSDS # 300; copy hosted by University of Western Ontario'
    url: https://www.eng.uwo.ca/files/departments-units/student-shop/2016/sds-carbon-alloy-and-tool-steels.pdf
    year: 2016
    kind: datasheet
    license: supplier document, linked not reproduced
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 13
  note: Written by an AI assistant on 2026-11-01 from pages fetched in this run. Values are as printed on AZoM, efunda and Total Materia, and from the NASA 2023 report, the 2017 ASTM abstract, USGS MCS 2026, and the grouped SDS. Supply shares are calculated from the USGS tables. The verify-values run found 13 of 13 values and 6 of 6 designations in the source text.
story:
  recipe:
    line: AISI 52100 is an iron-based steel with 0.980 to 1.10 % carbon and 1.30 to 1.60 % chromium, with small manganese and silicon additions (AZoM composition table). It is heated to 816 to 857 °C, oil quenched, then tempered (efunda).
    parts:
      - name: Iron
        symbol: Fe
        share: 96.5 to 97.32 %
        role: The matrix that makes up nearly all of the steel.
      - name: Carbon
        symbol: C
        share: 0.980 to 1.10 %
        role: The high carbon content is what lets the steel reach its printed hardness after quenching.
      - name: Chromium
        symbol: Cr
        share: 1.30 to 1.60 %
        role: The alloying element that makes this a chromium steel. Corrosion ranking studies still place it near the high-corrosion end.
      - name: Manganese
        symbol: Mn
        share: 0.250 to 0.450 %
        role: Minor alloying element in the composition table.
      - name: Silicon
        symbol: Si
        share: 0.150 to 0.300 %
        role: Minor alloying element in the composition table.
  risk_groups:
    - title: For people
      level: 0
      verdict: Solid steel is not a hazard; dust and fume are.
      lead: The grouped safety data sheet says solid steel presents no inhalation, ingestion or contact hazard. The hazard comes from dust and fume made during processing.
      points:
        - label: The solid metal
          line: The sheet says carbon, alloy and tool steels in their solid state present no inhalation, ingestion or contact health hazard. It lists 52100 among its alternate names.
        - label: Dust and fume
          line: Burning, melting, welding, sawing, brazing, grinding and machining can make dust and fume. The sheet calls these hazardous to health and lists metal fume fever as an acute effect.
        - label: Respiratory protection
          line: Wear a NIOSH-approved dust, mist or fume respirator when welding or burning this metal.
    - title: In service
      lead: 'NASA and ASTM sources describe two service risks for 52100: brinnelling and corrosion.'
      points:
        - label: Brinnelling
          line: In NASA's denting tests, NiTi-Hf balls needed roughly twice the load of 52100 balls to make the same dent depth.
        - label: Corrosion
          line: In a 2017 seawater electrochemical ranking, 52100 had one of the highest corrosion rates of the bearing steels tested.
    - title: Handling
      points:
        - label: Machining
          line: AZoM advises a spheroidising anneal at 649 °C (1200 °F) before machining.
        - label: Heat treatment
          line: efunda gives austenitizing at 816 to 857 °C (1500 to 1575 °F) followed by an oil quench.
  why: AISI 52100 is a high-carbon chromium steel for rolling-element bearings. AZoM describes it as used in bearings in rotating machinery. Its hardness is the reason it is chosen for bearings. NASA's 2023 bearing study used 52100 balls as one of its comparison materials, so it is a reference grade in space-mechanism research. The sources read here do not show a flight application.
  uses:
    - where: Rotating-machinery bearings
      line: AZoM describes AISI 52100 as used in bearings in rotating machinery.
    - where: Space bearing research
      line: NASA's 2023 denting tests used 52100 balls, alongside NiTi-Hf and silicon nitride balls, in small precision test bearings. This is a research use, not a flight part.
  can_do:
    - label: Hardness
      benchmark: hardness_rockwell_c
      value: 62 to 66 HRC
      line: AZoM prints Rockwell C values of 62 and 64 for the oil and water quenched conditions it lists, and 66 for water quench. The conditions are as printed; tempering is only stated for two of the rows.
    - label: Stiffness
      benchmark: elastic_modulus
      value: 190 to 210 GPa
      line: The elastic modulus is 190 to 210 GPa, printed by both AZoM and Total Materia.
    - label: Density
      benchmark: density
      value: 7.81 g/cm3
      line: AZoM gives a density of 7.81 g/cm3 in its physical properties table.
    - label: Melting point
      benchmark: melting_point
      value: 1424 °C
      line: AZoM gives a melting point of 1424 °C for the grade.
  compare: In the 2017 ASTM ranking, AISI 52100 sits at the high-corrosion end of the bearing steels tested, with CSS-42L, while 440C sits at the low end. NASA's 2023 study adds that 440C bearings corroded after 100 h in tap water and NiTi-Hf bearings did not. 52100 was not part of that water test. The ranking therefore favours 440C where corrosion resistance matters, and 52100 where hardness and wear resistance come first.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Elastic modulus
      benchmark: elastic_modulus
    - label: Hardness (Rockwell C)
      benchmark: hardness_rockwell_c
  handling:
    - Grinding, welding or burning makes dust and fume. Use local exhaust and a NIOSH-approved respirator.
    - Spheroidising anneal at 649 °C (1200 °F) before machining, per AZoM.
    - Austenitizing at 816 to 857 °C with an oil quench, per efunda. Cool to -68 °C (-90 °F) or lower after quenching, per efunda.
    - Keep the supplier's own safety data sheet on file. The sheet we hold covers a family of steels, not 52100 alone.
  good_for:
    - Hard, wear-resistant rolling bearings in rotating machinery, per AZoM.
    - Comparison with 440C and other bearing steels, using the 2017 ASTM corrosion ranking and the 2023 NASA bearing tests.
  watch_out:
    - Corrosion. In the 2017 seawater ranking 52100 had one of the highest corrosion rates. It is a poor choice where corrosion resistance is needed.
    - Brinnelling. NiTi-Hf needed roughly twice the load of 52100 for the same dent depth in NASA's tests.
    - Thin data. The pages read give no tensile, yield or fatigue values for 52100.
  verdict: AISI 52100 is a hard, through-hardened bearing steel with a density of 7.81 g/cm3 and a modulus of 190 to 210 GPa (AZoM). Its corrosion record in the sources read here is poor, and its space-relevant data are thin.