AISI 52100 bearing steel 52100 (UNS G52986)
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%)
Also known as UNS G52986, EN 1.3505, AISI 52100, SAE E52100, JIS SUJ 2, ASTM A 295
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).
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Hardness
62 to 66 HRC
Stiffness
190 to 210 GPa
Density
7.81 g/cm3
Melting point
1424 °C
Recipe, share of the weight
- Fe not statedIron
- C not statedCarbon
- Cr not statedChromium
- Mn not statedManganese
- Si not statedSilicon
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)
Risk at a glance
- People None found. Solid steel is not a hazard; dust and fume are.
- If it fails Moderate. Brinnelling (permanent dents in the raceways) under high static or shock load
- Corrosion Severe. In a seawater electrochemical ranking, AISI 52100 had one of the highest corrosion rates of the bearing steels tested.
Quick facts: 52100 (UNS G52986)
| Property | Value | Basis |
|---|---|---|
| Density | 7.67 to 7.86 g/cm³ | 2 sourced values across conditions |
| Young's modulus | 190 to 210 GPa | 2 sourced values across conditions |
| Thermal expansion (CTE) | 11.9 ppm/K | 2 sourced values across conditions |
| Melting point | 1,424 °C | 1 sourced value |
What is the density of AISI 52100 bearing steel?
AISI 52100 bearing steel has a density of 7.67 to 7.86 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the coefficient of thermal expansion of AISI 52100 bearing steel?
AISI 52100 bearing steel has a coefficient of thermal expansion of 11.9 ppm/K. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the melting point of AISI 52100 bearing steel?
AISI 52100 bearing steel has a melting point of 1,424 °C. The source and test conditions are listed in the properties table on this page.
What is the Young's modulus of AISI 52100 bearing steel?
AISI 52100 bearing steel has a Young's modulus of 190 to 210 GPa. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for AISI 52100 bearing steel?
AISI 52100 bearing steel is also written as UNS G52986, EN 1.3505, AISI 52100, SAE E52100, JIS SUJ 2, ASTM A 295. Each code is printed in the source listed beside it in the designations table.
What is AISI 52100 bearing steel used for?
Uses recorded in the sources include Rolling-element bearings in rotating machinery; Ball material in small precision test bearings for space-mechanism research (not a flight part).
Why it exists
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.
Where it's used
Rotating-machinery bearings
AZoM describes AISI 52100 as used in bearings in rotating machinery.
Space bearing research
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.
Recipe
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%)
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).
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Iron Fe | not stated | The matrix that makes up nearly all of the steel. |
| Carbon C | not stated | The high carbon content is what lets the steel reach its printed hardness after quenching. |
| Chromium Cr | not stated | The alloying element that makes this a chromium steel. Corrosion ranking studies still place it near the high-corrosion end. |
| Manganese Mn | not stated | Minor alloying element in the composition table. |
| Silicon Si | not stated | Minor alloying element in the composition table. |
Weight shares are as printed in the sources.
What it can do
Hardness
62 to 66 HRC
measured
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.
Stiffness
190 to 210 GPa
measured
The elastic modulus is 190 to 210 GPa, printed by both AZoM and Total Materia.
Density
7.81 g/cm3
measured
AZoM gives a density of 7.81 g/cm3 in its physical properties table.
Melting point
1424 °C
measured
AZoM gives a melting point of 1424 °C for the grade.
How it compares
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.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | 52100 (UNS G52986) |
|---|---|
| Thermal behavior and safety | |
| melting point | 1424 °C3 |
| Physical and electrical | |
| Density, as printed in the physical properties table | 7.81 g/cm³1 |
| Density range, 0 to 30 degCPhysical properties section, as printed (range) | 7.67 to 7.86 kg/dm3 |
| Rockwell C hardness, quenched in oil from 150 °C and temperedMechanical properties table, as printed | 62 HRC |
| Rockwell C hardness, quenched in water from 150 °C and temperedMechanical properties table, as printed | 64 HRC |
| Rockwell C hardness, quenched in oilMechanical properties table, as printed | 64 HRC |
| Rockwell C hardness, quenched in waterMechanical properties table, as printed | 66 HRC |
| Rockwell hardness range, scale letter not printed | 58 to 65 HR5 |
| Other measurements | |
| Elastic modulus, metric range | 190 to 210 GPa2 |
| Modulus of elasticity, range at 0 to 30 degCPhysical properties section, as printed (range) | 190 to 210 GPa |
| poissons ratioMechanical properties table as printed (range) | 0.27 to 0.3 - |
| Thermal expansion coefficient, 23 to 280 degC, annealed | 11.9 µm/m°C4 |
| Thermal expansion coefficient, 0 to 100 degC, annealedThermal properties section, as printed | 11.9 10-6/°C |
Why choose it, and why not
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 for
- 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.
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.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| UNS | G52986 |
| EN | 1.3505 |
| AISI | 52100 |
| SAE | E52100 |
| JIS | SUJ 2 |
| ASTM | A 295 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, as printed in the physical properties table | Physical properties table, metric column, as printed | temperature not printedtemper not printed | — |
| 2 | Elastic modulus, metric range | Mechanical properties table, metric column, as printed (range) | temperature not printedtemper not printed | — |
| 3 | melting point | Physical properties table, metric column, as printed | basis single value as printed in the physical properties tablecomposition AISI 52100 as listed by AZoM | — |
| 4 | Thermal expansion coefficient, 23 to 280 degC, annealed | Thermal properties table, metric column, as printed | temperature range 23 to 280 °Ctemper annealed | — |
| 5 | Rockwell hardness range, scale letter not printed | Mechanical properties section, as printed (range) | temperature 0 to 30 °Cscale not printed on the pagetreatment not printed | The page prints HR without a scale letter, so the scale is unknown. Do not read it as Rockwell C. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Simulated synthetic seawater, aqueous electrochemical polarisation and impedance tests | severe | In a seawater electrochemical ranking, AISI 52100 had one of the highest corrosion rates of the bearing steels tested.1 |
| Plain tap water in a rotating spindle test, 100 h (440C races, not 52100) | severe | In a 100 h tap-water spindle test, 440C races corroded; AISI 52100 was not part of that water test.2 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Simulated synthetic seawater, aqueous electrochemical polarisation and impedance tests | 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. | basis aqueous solutions at the free corrosion potential; ranking as printed in the abstractelectrolyte simulated synthetic seawaterheat treatment not stated in the abstract |
| 2 | Plain tap water in a rotating spindle test, 100 h (440C races, not 52100) | 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. | bearing R4 hybrid bearings, 440C races with Si3N4 ballsduration 100 henvironment plain tap water partly filling the housing, seals partly removed |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
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.
- The solid metal
- 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.
- Dust and fume
- 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.
- Respiratory protection
- Wear a NIOSH-approved dust, mist or fume respirator when welding or burning this metal.
In service
NASA and ASTM sources describe two service risks for 52100: brinnelling and corrosion.
- Brinnelling
- In NASA's denting tests, NiTi-Hf balls needed roughly twice the load of 52100 balls to make the same dent depth.
- Corrosion
- In a 2017 seawater electrochemical ranking, 52100 had one of the highest corrosion rates of the bearing steels tested.
Handling
- Machining
- AZoM advises a spheroidising anneal at 649 °C (1200 °F) before machining.
- Heat treatment
- efunda gives austenitizing at 816 to 857 °C (1500 to 1575 °F) followed by an oil quench.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Brinnelling (permanent dents in the raceways) under high static or shock loadmoderate severity | High radial load on the ball-race contact, tested by NASA with 52100 balls, NiTi-Hf balls and silicon nitride ballsNASA 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. |
| Corrosion pitting in marine or other aqueous environmentsmoderate severity | Exposure to seawater or other aqueous solutionsKvryan 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. |
Handling and storage
- AZoM advises a spheroidising anneal at 649 °C (1200 °F) before machining to improve machinability.
- 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.
- 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.
Mitigations
- 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.
Supply and geography
How common the raw materials are and where they come from.
Iron
- Top producers (2025)
- Australia 37.7%, Brazil 16.2%, India 11.9%, China 11.2%
- Critical mineral lists
- US: not listed
- Recycling
- Not read in the iron-ore summary we hold; see gaps.
Chromium
- Top producers (2025)
- South Africa 45.1%, Turkey 17.6%, Kazakhstan 13.7%, India 5.9%
- Critical mineral lists
- US: listed
- 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.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
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.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| AISI 52100 Alloy Steel (UNS G52986) | datasheet | 2012 | 13 values | |
| AISI 52100 Alloy Steel, efunda properties page | database | 1 value | ||
| AISI 52100 material page (Total Materia) | database | 4 values | ||
| Shock- and Corrosion-Resistant Bearings for Space Mechanisms | report | 2023 | 3 values | |
| Electrochemical Corrosion Test Methods for Rapid Assessment of Aerospace Bearing Steel Performance | paper | 2017 | 2 values | |
| Mineral Commodity Summaries 2026, Chromium | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Iron Ore | report | 2026 | 1 value | |
| About the 2025 List of Critical Minerals (USGS) | web | 2025 | 0 values | |
| Safety Data Sheet: Carbon, Alloy and Tool Steels AISI Grades (TW Metals), rev. 01/14/2016 | datasheet | 2016 | 3 values |
Updated