Case Hardening Steels Official identity plus sourced composition

Material / Grade

8CrMnMo15-4

Quench-and-temper steel for tunable strength, toughness and wear resistance; actual heat-treatment response depends on section size and composition.

Hardness potential84 / 100Comparison index

Toughness78 / 100Comparison index

Impact resistance80 / 100Comparison index

Bending resistance76 / 100Comparison index

Abrasive wear76 / 100Comparison index

Steel Overview

Complete introduction and metallurgical analysis

8CrMnMo15-4 belongs to Case Hardening Steels and selection centres on a hard wear-resistant case combined with a tougher load-bearing core.

Quench-and-temper steel for tunable strength, toughness and wear resistance; actual heat-treatment response depends on section size and composition.

The principal recorded elements are C≈0.08%, Si≈0.3%, Mn≈1%, Cr≈4%, Mo≈0.5%. Mid-range values support engineering interpretation and do not replace purchase limits.

The expected microstructure is a high-carbon martensitic case over a lower-carbon tough core after carburising, quenching and tempering; delivery condition, section size, melt quality and processing history can change that state.

Comparison indices are hardness 84/100, toughness 78/100, impact 80/100, wear 76/100 and bending 76/100. These are internal indices, not standard test results.

The screening temperature range is 120–250 °C; strength or hardness loss, oxidation, exposure time and creep must be assessed separately.

A representative process route is carburising or carbonitriding followed by grade-specific hardening, quenching, tempering and case-depth verification. Obtain actual temperatures, times and cooling media from the grade and product data sheet.

Manufacturing indices are weldability 12/100, machinability 63/100, corrosion resistance 18/100 and fatigue resistance 82/100; use them for screening only.

The principal risk is case cracking, distortion, retained austenite or inadequate effective case depth when the cycle is not controlled. 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: 8CrMnMo15-4 is a rational candidate when high surface hardness and contact-wear resistance without sacrificing core toughness matches the real load, environment and certified product condition.

Recorded standards:Ovako designation; EN 10027 naming rules (not an official EN standard grade)

International Equivalents

International equivalents and designations

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

EN / DIN / ISOOfficial designation for the same grade

8CrMnMo15-4

A registered identity within the same grade record.

PrimaryOfficial designation for the same grade

8CrMnMo15-4

A registered identity within the same grade record.

JISConditional application alternative

SCM415

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

JISConditional application alternative

SCr415

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≈0.08%, Si≈0.3%, Mn≈1%, Cr≈4%, Mo≈0.5%. 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	≈ 0.08 %	Carbon raises hardness, strength and carbide potential; excessive carbon can reduce toughness and weldability.
Si	≈ 0.3 %	Silicon supports deoxidation and solid-solution strength and can influence tempering or oxidation response.
Mn	≈ 1 %	Manganese contributes to hardenability and sulfur control; its final effect depends on amount and processing.
Cr	≈ 4 %	Chromium promotes hardenability and carbide formation and, at sufficient levels, corrosion or oxidation resistance.
Mo	≈ 0.5 %	Molybdenum improves hardenability and temper resistance and can support hot strength or pitting resistance.

Ovako family table – typical analysis, not formal standard limits Sourced with conditions

Engineering Behaviour

Engineering behaviour and selection response

Hardness potential84 / 100

Hardness must be reported with delivery/heat-treatment condition; no single grade-wide value applies. Internal comparison index: 84/100.

Engineering analysis

Toughness78 / 100

Toughness has an internal index of 78/100 (high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Impact resistance80 / 100

Impact resistance has an internal index of 80/100 (high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Bending resistance76 / 100

Bending resistance has an internal index of 76/100 (high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Abrasive wear76 / 100

Wear resistance depends on final hardness, microstructure and wear mode; grade name alone is insufficient for substitution. Internal comparison index: 76/100.

Engineering analysis

Corrosion resistance18 / 100

Not stainless; surface protection is generally required in moist/corrosive service. Internal comparison index: 18/100.

Engineering analysis

Weldability12 / 100

Weldability has an internal index of 12/100 (very low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Machinability63 / 100

Machinability has an internal index of 63/100 (moderate). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

High-temperature strength27 / 100

Temperature-dependent behavior varies with condition, exposure time, environment and product form; use sourced values for design. Internal comparison index: 27/100.

Engineering analysis

Creep resistance19 / 100

Creep resistance has an internal index of 19/100 (very low). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Fatigue resistance82 / 100

Fatigue resistance has an internal index of 82/100 (very 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

Hardness must be reported with delivery/heat-treatment condition; no single grade-wide value applies. Internal screening index: 84/100 (very high).

84/100

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 80/100 and toughness at 78/100. These are not Charpy or Izod energy values; temperature, orientation, geometry and actual microstructure govern component behaviour.

80/100highComparison 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

Temperature-dependent behavior varies with condition, exposure time, environment and product form; use sourced values for design. 120–250 °C is a screening range or sourced limit according to its evidence label. Check strength loss, oxidation, creep, exposure time and environment.

Continuous service

120–250 °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 resistance19/100Comparison index

The relative creep index is 19/100 (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

Wear resistance depends on final hardness, microstructure and wear mode; grade name alone is insufficient for substitution. The abrasive-wear index is 76/100; 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

No complete sourced numerical mechanical set is stored for this condition; labelled comparison indices are shown instead of invented test values.

Comparative property	Internal index	Information type
Hardness potential	84 / 100	Comparison index
Toughness	78 / 100	Comparison index
Impact resistance	80 / 100	Comparison index
Bending resistance	76 / 100	Comparison index
Abrasive wear	76 / 100	Comparison index
Corrosion resistance	18 / 100	Comparison index
Weldability	12 / 100	Comparison index
Machinability	63 / 100	Comparison index
High-temperature strength	27 / 100	Comparison index
Creep resistance	19 / 100	Comparison index
Fatigue resistance	82 / 100	Comparison index

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 carburising or carbonitriding followed by grade-specific hardening, quenching, tempering and case-depth verification. 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- 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

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

Comparison index

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

case cracking, distortion, retained austenite or inadequate effective case depth when the cycle is not controlled.
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 84, toughness 78, impact 80 and wear 76 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.

Derived calculations

Carbon equivalent CE(IIW)1.147 Calculated

Calculated from recorded inputs; apply only within the stated formula scope and limitations.

Weld-cracking composition parameter Pcm0.373 Calculated

Calculated from recorded inputs; apply only within the stated formula scope and limitations.

Advantages & Limitations

Advantages, limitations and unsuitable applications

Advantages

high surface hardness and contact-wear resistance without sacrificing core toughness.
A clearly labelled engineering profile supports comparison with related grades.
Grade identity, chemistry, counterparts and references remain traceable in one dossier.

Limitations and weaknesses

case cracking, distortion, retained austenite or inadequate effective case depth when the cycle is not controlled.
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 datacase cracking, distortion, retained austenite or inadequate effective case depth when the cycle is not controlled

Applications & Processing

Industrial applications and processing

Typical applications

Gears and power-transmission components
Pinions and highly loaded gear-train parts
Shafts, axles and rotating machine components
High-strength fasteners and mechanical connections
Highly loaded heavy-machinery components
Case-hardened components requiring a hard surface and tough core
Splined shafts, keys and surface-contact parts
Wear-resistant machine and surface-contact components

Manufacture, welding and surface engineering

Weldability has an internal index of 12/100 (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

8CrMnMo15-4 is worth evaluating when the principal need is high surface hardness and contact-wear resistance without sacrificing core toughness. Internal indices of hardness 84/100, toughness 78/100, impact 80/100 and wear 76/100 must be aligned with the real failure mechanism. The leading risk is case cracking, distortion, retained austenite or inadequate effective case depth when the cycle is not controlled. Final approval requires the current standard, product form, dimensions, delivery condition, heat treatment and heat-specific MTC.

Engineering analysis

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Frequently Asked Questions

Frequently asked questions

What is 8CrMnMo15-4 steel?

Quench-and-temper steel for tunable strength, toughness and wear resistance; actual heat-treatment response depends on section size and composition.

What are the main applications of 8CrMnMo15-4?

Application contexts include Gears and power-transmission components, Pinions and highly loaded gear-train parts, Shafts, axles and rotating machine components and High-strength fasteners and mechanical connections, subject to the product standard and actual condition.

How hard can 8CrMnMo15-4 be?

Hardness must be reported with delivery/heat-treatment condition; no single grade-wide value applies. Internal screening index: 84/100 (very high).

Is 8CrMnMo15-4 suitable for impact loading?

Impact resistance is indexed at 80/100 and toughness at 78/100. These are not Charpy or Izod energy values; temperature, orientation, geometry and actual microstructure govern component behaviour.

What is the service-temperature limit of 8CrMnMo15-4?

Can 8CrMnMo15-4 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 grade8CrMnMo15-4Case Hardening Steels

Selected grade1.5715 / 16NiCrS4Case Hardening 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

Ovako – Quenching and Tempering SteelManufacturer Family Table · Tier A

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

View source

Ovako Product CatalogManufacturer catalog · Tier A

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

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Ovako Steel Navigator – Material Data Sheets indexDatasheet Discovery · Tier A

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

View source