Bearing Steels Sourced numerical data plus engineering analysis

Material / Grade

SUJ2

SUJ2 is a Bearing Steels grade centred on high hardness, metallurgical cleanliness and rolling-contact fatigue resistance. This dossier separates sourced values from engineering guidance and comparison indices.

Hardness potential98 / 100Comparison index

Toughness42 / 100Comparison index

Impact resistance34 / 100Comparison index

Bending resistance60 / 100Comparison index

Abrasive wear98 / 100Comparison index

Steel Overview

Complete introduction and metallurgical analysis

SUJ2 belongs to Bearing Steels and selection centres on high hardness, metallurgical cleanliness and rolling-contact fatigue resistance.

The expected microstructure is tempered martensite with a controlled fine-carbide population and tightly controlled inclusions; delivery condition, section size, melt quality and processing history can change that state.

Comparison indices are hardness 98/100, toughness 42/100, impact 34/100, wear 98/100 and bending 60/100. These are internal indices, not standard test results.

The screening temperature range is 100–200 °C; strength or hardness loss, oxidation, exposure time and creep must be assessed separately.

A representative process route is spheroidizing or soft annealing, controlled austenitising, quenching and tempering, with a bainitic route where the product data sheet permits it. Obtain actual temperatures, times and cooling media from the grade and product data sheet.

Manufacturing indices are weldability 20/100, machinability 44/100, corrosion resistance 18/100 and fatigue resistance 65/100; use them for screening only.

The principal risk is edge chipping, brittle fracture or contact-fatigue spalling when hardness, cleanliness, lubrication or geometry is unsuitable. Evaluate geometry, surface condition, environment and the governing failure mechanism together.

A similar name or calculated relationship is not proof of interchangeability; match chemistry, specification, condition, heat treatment and MTC.

Engineering conclusion: SUJ2 is a rational candidate when high surface and through-section hardness for rolling contact and wear matches the real load, environment and certified product condition.

Recorded standards:JIS

International Equivalents

International equivalents and designations

A close counterpart is not automatically interchangeable. Confirm chemistry, product standard, delivery condition, dimensions and heat treatment.

JISOfficial designation for the same grade

SUJ2

A registered identity within the same grade record.

EN / ISOClose counterpart requiring verification

100Cr6

Match chemistry, product standard, delivery condition, heat treatment and MTC before substitution.

EN / W.NrClose counterpart requiring verification

1.3505

Match chemistry, product standard, delivery condition, heat treatment and MTC before substitution.

SAE / AISIClose counterpart requiring verification

SAE 52100

Match chemistry, product standard, delivery condition, heat treatment and MTC before substitution.

JISClose counterpart requiring verification

JIS SUJ2

Match chemistry, product standard, delivery condition, heat treatment and MTC before substitution.

Chemical Composition

Chemical composition and the role of each element

The principal recorded elements are C≈1.025%, Si≈0.25%, Mn≈0.5%, P≈0.025%, S≈0.025%, Cu≈0.25%, Ni≈0.25%, Cr≈1.45%, Mo≈0.08%. Mid-range values support engineering interpretation and do not replace purchase limits. Composition is shown for screening and traceability. The current purchase standard and the heat-specific MTC remain authoritative.

Element	Weight-percent range	Metallurgical role and effect
C	0.95–1.1 %	Carbon raises hardness, strength and carbide potential; excessive carbon can reduce toughness and weldability.
Si	0.15–0.35 %	Silicon supports deoxidation and solid-solution strength and can influence tempering or oxidation response.
Mn	≤ 0.5 %	Manganese contributes to hardenability and sulfur control; its final effect depends on amount and processing.
P	≤ 0.025 %	Phosphorus is normally restricted because higher content can promote embrittlement and reduce toughness.
S	≤ 0.025 %	Sulfur may improve chip control in free-cutting grades but can reduce transverse toughness and weldability.
Cu	≤ 0.25 %	Copper can improve atmospheric corrosion resistance or precipitation response in selected alloy systems.
Ni	≤ 0.25 %	Nickel generally improves toughness and through-section response and stabilises austenite in stainless systems.
Cr	1.3–1.6 %	Chromium promotes hardenability and carbide formation and, at sufficient levels, corrosion or oxidation resistance.
Mo	≤ 0.08 %	Molybdenum improves hardenability and temper resistance and can support hot strength or pitting resistance.

JIS special steel strip listing Sourced with conditions

Engineering Behaviour

Engineering behaviour and selection response

Hardness potential98 / 100

Hardness potential has an internal index of 98/100 (very high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Toughness42 / 100

Toughness has an internal index of 42/100 (low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Impact resistance34 / 100

Impact resistance has an internal index of 34/100 (low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Bending resistance60 / 100

Bending resistance has an internal index of 60/100 (moderate). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Abrasive wear98 / 100

Abrasive wear has an internal index of 98/100 (very high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Corrosion resistance18 / 100

Corrosion resistance has an internal index of 18/100 (very low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Weldability20 / 100

Weldability has an internal index of 20/100 (very low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Machinability44 / 100

Machinability has an internal index of 44/100 (low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

High-temperature strength20 / 100

The source catalog does not provide a universal temperature-property curve for this designation. Internal comparison index: 20/100.

Engineering analysis

Creep resistance8 / 100

Creep resistance has an internal index of 8/100 (very low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Fatigue resistance65 / 100

Fatigue resistance has an internal index of 65/100 (high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Numerical scores are internal comparison indices. They are not standard test results, allowable design stresses or a manufacturer guarantee. Data Method

Hardness & Hardenability

Hardness and hardenability

The internal hardness-potential index is 98/100 (very high). Actual hardness depends on chemistry, section size, austenitising, quenching, tempering and test method.

98/100

very high

Comparison index

Governing factors

Chemistry and section size
Austenitising and quench severity
Tempering temperature and time
Test method and surface preparation

Data limits

Final acceptance requires the current standard, product form, dimensions, delivery condition and heat-specific MTC.

Impact & Toughness

Toughness, impact and fracture behaviour

Impact resistance is indexed at 34/100 and toughness at 42/100. These are not Charpy or Izod energy values; temperature, orientation, geometry and actual microstructure govern component behaviour.

34/100lowComparison index

Microstructure, hardness and grain size influence impact tolerance.
Sharp radii, notches and surface defects reduce fracture resistance.
Test temperature, specimen direction and section must be identified.
For critical parts, accept impact energy only from a documented test of the same condition.

Temperature & Creep

Service temperature, thermal stability and creep

The source catalog does not provide a universal temperature-property curve for this designation. 100–200 °C is a screening range or sourced limit according to its evidence label. Check strength loss, oxidation, creep, exposure time and environment.

Continuous service

100–200 °CEngineering guidance

Review the limit against strength or hardness loss and exposure time.

Intermittent service

Do not assign an intermittent limit without product-specific source data.

Tempering and phase stability

Working and coating temperatures must remain compatible with the tempering condition and required microstructure.

Oxidation and environment

Oxidation or corrosion may become limiting before the strength criterion.

Relative creep resistance8/100Comparison index

The relative creep index is 8/100 (very low). It is not an allowable creep stress or rupture-life value.

Do not select this grade for long-term static high-temperature loading from the internal index alone.

Wear & Surface Behaviour

Wear resistance and surface behaviour

Abrasive wear

The abrasive-wear index is 98/100; final hardness, carbides, microstructure, contact mode and lubrication govern actual resistance.

Comparison index

Adhesive wear

Assess adhesive wear with the counterface material, lubrication, roughness, pressure and temperature.

Engineering analysis

Surface improvement

Evaluate surface treatment or coating only after confirming compatibility with chemistry, substrate and process temperature.

Engineering guidance

Mechanical & Physical Properties

Mechanical and physical properties

The record contains 1 sourced mechanical-property rows; each applies only to its stated condition, dimensions and test temperature.

Property	Value	Condition	Dimension	Test temperature
Hardness	85–98 HRB	Annealed as cited	According to the product data sheet	20 °C

Sourced with conditions

Physical properties

Density, elastic modulus, expansion and conductivity depend on family, temperature and product condition. Use grade- and product-specific values for precise calculations.

Obtain density and expansion data from the product data sheet for dimensional calculations.
Elastic modulus and conductivity vary with temperature.

Engineering analysis

Heat Treatment

Heat-treatment stages and process controls

The representative family route is spheroidizing or soft annealing, controlled austenitising, quenching and tempering, with a bainitic route where the product data sheet permits it. Numerical temperatures are shown only when supported by the record.

Annealing / stress relief

Engineering guidance

Assess the supply condition, residual stress, section size and prior machining before selecting time and temperature.

Cooling: Grade-specific

Annealing / stress relief

Engineering guidance

Assess the supply condition, residual stress, section size and prior machining before selecting time and temperature.

Cooling: Grade- and process-specific cooling

Preheating and austenitising

Engineering guidance

Set preheat steps and austenitising parameters from the grade/product data sheet and actual section size.

Cooling: Grade- and process-specific cooling

Quenching / controlled cooling

Engineering guidance

Choose the quench medium and cooling severity against hardenability, geometry, distortion and crack risk.

Cooling: Grade- and process-specific cooling

Tempering / property adjustment

Engineering guidance

Set tempering or ageing to the required hardness, toughness and service-temperature balance.

Cooling: Grade- and process-specific cooling

Tempering / property adjustment

Engineering guidance

Set tempering or ageing to the required hardness, toughness and service-temperature balance.

Cooling: Grade- and process-specific cooling

Process control: Review delivery condition, actual section, equipment capability, crack and distortion risk and target hardness before approving the cycle.

Engineering Charts

Hardness, toughness, impact, temperature and process charts

Chemistry data retain their evidence label; 0–100 charts are internal indices and stages without temperature are process sequences.

Multi-axis engineering profile

Comparison index

Chemical composition

Derived from source data

Hardness–toughness balance

Comparison index

Toughness, impact and fatigue

Comparison index

Wear and surface response

Comparison index

Mechanical properties or comparison indices

Sourced with conditions

Service temperature

Engineering guidance

Heat treatment

Engineering guidance

Related-grade similarity

Comparison index

All comparison indices

Comparison index

Failure Modes & Selection

Potential failure modes and selection guidance

Potential failure mechanisms

edge chipping, brittle fracture or contact-fatigue spalling when hardness, cleanliness, lubrication or geometry is unsuitable.
Fatigue initiation from surface defects, section transitions or stress concentration.
Property loss after unsuitable heat treatment, cooling or finishing.
Corrosion, oxidation or environmental attack when protection is inadequate.

Selection and design notes

Match designation, material number, product standard and supply form before purchase.
Compare the governing failure mechanism with hardness 98, toughness 42, impact 34 and wear 98 indices out of 100.
Use mechanical values only within their cited condition, dimensions and test temperature.
Confirm the heat-treatment route and target hardness with the processor before final machining.
Review the heat number, MTC and required test results before release.

Advantages & Limitations

Advantages, limitations and unsuitable applications

Advantages

high surface and through-section hardness for rolling contact and wear.
A clearly labelled engineering profile supports comparison with related grades.
Grade identity, chemistry, counterparts and references remain traceable in one dossier.

Limitations and weaknesses

edge chipping, brittle fracture or contact-fatigue spalling when hardness, cleanliness, lubrication or geometry is unsuitable.
A 0–100 index cannot be converted into design stress, impact energy or creep life.
Hardness and toughness depend on section, delivery condition and actual processing.
Do not approve a substitute before checking the product standard and heat-specific MTC.

Cases requiring caution or an alternative material

Critical design without condition- and section-specific test dataDirect substitution based only on name or similarity scoreLong-term creep service without sourced time–stress–temperature dataedge chipping, brittle fracture or contact-fatigue spalling when hardness, cleanliness, lubrication or geometry is unsuitable

Applications & Processing

Industrial applications and processing

Typical applications

Bearing rings, races, rollers and rolling-contact components
Components under fatigue, torsion or cyclic loading
Wear-resistant machine and surface-contact components
bearing rings and raceways
rolling elements where the product form is qualified
precision wear-resistant components
parts exposed to repeated rolling-contact stress

Manufacture, welding and surface engineering

Weldability has an internal index of 20/100 (very low). Actual performance requires a documented product condition, heat treatment and test context.

Forming and forging depend on steel family, delivery condition and the grade-specific qualified temperature range.

Select nitriding, induction hardening or coating against chemistry, substrate hardness and application.
Keep coating-deposition temperature compatible with the tempering condition and substrate.
Control hydrogen embrittlement, residual stress and distortion in high-strength components.

Engineering Conclusion

Engineering conclusion and selection recommendation

SUJ2 is worth evaluating when the principal need is high surface and through-section hardness for rolling contact and wear. Internal indices of hardness 98/100, toughness 42/100, impact 34/100 and wear 98/100 must be aligned with the real failure mechanism. The leading risk is edge chipping, brittle fracture or contact-fatigue spalling when hardness, cleanliness, lubrication or geometry is unsuitable. Final approval requires the current standard, product form, dimensions, delivery condition, heat treatment and heat-specific MTC.

Engineering analysis

Shaygan Steel — the right choice in alloy steel

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Frequently Asked Questions

Frequently asked questions

What is SUJ2 steel?

What are the main applications of SUJ2?

Application contexts include Bearing rings, races, rollers and rolling-contact components, Components under fatigue, torsion or cyclic loading, Wear-resistant machine and surface-contact components and bearing rings and raceways, subject to the product standard and actual condition.

How hard can SUJ2 be?

The internal hardness-potential index is 98/100 (very high). Actual hardness depends on chemistry, section size, austenitising, quenching, tempering and test method.

Is SUJ2 suitable for impact loading?

Impact resistance is indexed at 34/100 and toughness at 42/100. These are not Charpy or Izod energy values; temperature, orientation, geometry and actual microstructure govern component behaviour.

What is the service-temperature limit of SUJ2?

Can SUJ2 be replaced by a close grade?

Approve substitution only after matching chemistry, specification, product form, condition, heat treatment and MTC.

Steel Comparison

Engineering steel comparison

Compare this grade with any other dossier. Scores from 0 to 100 are internal screening indices, not laboratory values or allowable design stresses.

Close suggestions:

Search for the second steel

Current gradeSUJ2Bearing Steels

Selected grade1.3537 / 100CrMo7Bearing Steels

Current-grade chemistry

Second-grade chemistry

Current-grade heat treatment

Second-grade heat treatment

Current-grade applications

Limitations

Second-grade applications

Limitations

Select a second grade to update the comparison.

Sources & Evidence

Sources, methodology and evidence

Sources support grade identity, recorded values or the engineering method. General guidance does not replace product-specific certification.

Grade-specific sources

Nippon Steel Special Steel StripManufacturer catalog · Tier A

Reference supporting grade identity or recorded values; interpret it within the cited product and condition context. Role: manufacturer catalog.

View source

Nippon Steel Special Steel Strip — composition tablesManufacturer catalog · Tier A

Reference supporting grade identity or recorded values; interpret it within the cited product and condition context. Role: manufacturer catalog.

View source

Ovako — 100Cr6 producer material sheetManufacturer Grade Sheet · Tier A

Reference supporting grade identity or recorded values; interpret it within the cited product and condition context. Role: manufacturer grade sheet.

View source