Austenitic Stainless Steels Sourced numerical data plus engineering analysis

Material / Grade

AISI 304

Austenitic stainless steel; generally not hardenable by quenching and strengthened by cold work.

Hardness potential39 / 100Comparison index

Toughness94 / 100Comparison index

Impact resistance97 / 100Comparison index

Bending resistance86 / 100Comparison index

Abrasive wear42 / 100Comparison index

Steel Overview

Complete introduction and metallurgical analysis

AISI 304 belongs to Austenitic Stainless Steels and selection centres on corrosion resistance, ductility and fabrication capability in an austenitic stainless structure.

Austenitic stainless steel; generally not hardenable by quenching and strengthened by cold work.

The expected microstructure is predominantly austenitic matrix, with ferrite or secondary phases controlled by composition and thermal history; delivery condition, section size, melt quality and processing history can change that state.

Comparison indices are hardness 39/100, toughness 94/100, impact 97/100, wear 42/100 and bending 86/100. These are internal indices, not standard test results.

The screening temperature range is 400–800 °C; strength or hardness loss, oxidation, exposure time and creep must be assessed separately.

A representative process route is solution annealing, rapid cooling and suitable post-fabrication cleaning or passivation. Obtain actual temperatures, times and cooling media from the grade and product data sheet.

Manufacturing indices are weldability 88/100, machinability 34/100, corrosion resistance 70/100 and fatigue resistance 73/100; use them for screening only.

The principal risk is chloride pitting, crevice corrosion, stress-corrosion cracking or sensitisation in an unsuitable environment or thermal cycle. 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: AISI 304 is a rational candidate when broad corrosion resistance with good forming and welding behaviour matches the real load, environment and certified product condition.

Recorded standards:AISI tool/stainless designation — verify governing ASTM/SAE/product specification

International Equivalents

International equivalents and designations

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

AISI / SAEOfficial designation for the same grade

AISI 304

A registered identity within the same grade record.

PrimaryOfficial designation for the same grade

AISI 304

A registered identity within the same grade record.

AISI shorthandOfficial designation for the same grade

304

A registered identity within the same grade record.

UNSClose counterpart requiring verification

UNS S30400

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

ENClose counterpart requiring verification

EN 1.4301 / X5CrNi18-10

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

JISClose counterpart requiring verification

JIS SUS304

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%, Mn≈2%, Si≈0.75%, Cr≈19%, Ni≈9.25%, N≈0.1%, S≈0.03%, P≈0.045%. 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.
Mn	≤ 2 %	Manganese contributes to hardenability and sulfur control; its final effect depends on amount and processing.
Si	≤ 0.75 %	Silicon supports deoxidation and solid-solution strength and can influence tempering or oxidation response.
Cr	18–20 %	Chromium promotes hardenability and carbide formation and, at sufficient levels, corrosion or oxidation resistance.
Ni	8–10.5 %	Nickel generally improves toughness and through-section response and stabilises austenite in stainless systems.
N	≤ 0.1 %	Nitrogen strengthens austenitic stainless steel and contributes strongly to pitting resistance and phase balance.
S	≤ 0.03 %	Sulfur may improve chip control in free-cutting grades but can reduce transverse toughness and weldability.
P	≤ 0.045 %	Phosphorus is normally restricted because higher content can promote embrittlement and reduce toughness.

Laxcon open grade reference; stainless composition limits Sourced with conditions

Engineering Behaviour

Engineering behaviour and selection response

Hardness potential39 / 100

Hardness and hardenability are condition-dependent; numeric values require grade-specific heat-treatment context. Internal comparison index: 39/100.

Engineering analysis

Toughness94 / 100

Toughness has an internal index of 94/100 (very high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Impact resistance97 / 100

Impact resistance has an internal index of 97/100 (very high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Bending resistance86 / 100

Bending resistance has an internal index of 86/100 (very high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Abrasive wear42 / 100

Wear resistance depends on hardness, microstructure/carbides and the wear mechanism. Internal comparison index: 42/100.

Engineering analysis

Corrosion resistance70 / 100

Generally good corrosion resistance; environment and chemistry control actual performance. Internal comparison index: 70/100.

Engineering analysis

Weldability88 / 100

Weldability has an internal index of 88/100 (very high). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Machinability34 / 100

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

Engineering analysis

High-temperature strength58 / 100

Temperature-dependent properties require grade-specific condition and test data. Internal comparison index: 58/100.

Engineering analysis

Creep resistance57 / 100

Creep resistance has an internal index of 57/100 (moderate). Actual performance requires a documented product condition, heat treatment and test context.

Engineering analysis

Fatigue resistance73 / 100

Fatigue resistance has an internal index of 73/100 (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

Hardness and hardenability are condition-dependent; numeric values require grade-specific heat-treatment context. Internal screening index: 39/100 (low).

39/100

low

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 97/100 and toughness at 94/100. These are not Charpy or Izod energy values; temperature, orientation, geometry and actual microstructure govern component behaviour.

97/100very highComparison 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 properties require grade-specific condition and test data. 400–800 °C is a screening range or sourced limit according to its evidence label. Check strength loss, oxidation, creep, exposure time and environment.

Continuous service

400–800 °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 resistance57/100Comparison index

The relative creep index is 57/100 (moderate). 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 hardness, microstructure/carbides and the wear mechanism. The abrasive-wear index is 42/100; 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 4 sourced mechanical-property rows; each applies only to its stated condition, dimensions and test temperature.

Property	Value	Condition	Dimension	Test temperature
Tensile strength	≥ 515 MPa	Annealed as cited	According to the product data sheet	20 °C
Yield strength Rp0.2	≥ 205 MPa	Annealed as cited	According to the product data sheet	20 °C
Elongation	≥ 40 %	Annealed as cited	According to the product data sheet	20 °C
Reduction of area	≥ 50 %	Annealed as cited	According to the product data sheet	20 °C

Sourced with conditions

Physical properties

Density≈ 7900 kg/m³Sourced with conditions

Young modulus≈ 193 GPaSourced with conditions

Heat Treatment

Heat-treatment stages and process controls

The representative family route is solution annealing, rapid cooling and suitable post-fabrication cleaning or passivation. Numerical temperatures are shown only when supported by the record.

Preheating and austenitising

1010–1120 °CSourced with conditions

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

Cooling: Grade- and process-specific cooling

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

Sourced with conditions

Service temperature

Engineering guidance

Heat treatment

Sourced with conditions

Related-grade similarity

Comparison index

All comparison indices

Comparison index

Failure Modes & Selection

Potential failure modes and selection guidance

Potential failure mechanisms

chloride pitting, crevice corrosion, stress-corrosion cracking or sensitisation in an unsuitable environment or thermal cycle.
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 39, toughness 94, impact 97 and wear 42 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

Pitting-resistance equivalent PREN (indicative)20.4 Calculated

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

Advantages & Limitations

Advantages, limitations and unsuitable applications

Advantages

broad corrosion resistance with good forming and welding behaviour.
A clearly labelled engineering profile supports comparison with related grades.
Grade identity, chemistry, counterparts and references remain traceable in one dossier.

Limitations and weaknesses

chloride pitting, crevice corrosion, stress-corrosion cracking or sensitisation in an unsuitable environment or thermal cycle.
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 datachloride pitting, crevice corrosion, stress-corrosion cracking or sensitisation in an unsuitable environment or thermal cycle

Applications & Processing

Industrial applications and processing

Typical applications

Food, beverage, hygienic and pharmaceutical equipment
Chemical and process equipment, tanks and piping
Plate, sheet and tubular products to the applicable product standard
Architectural and formed components
process and food equipment
corrosion-resistant tanks, piping and fittings
architectural and general stainless fabrication
components needing good formability and cleanliness

Manufacture, welding and surface engineering

Weldability has an internal index of 88/100 (very high). 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.

Clean and passivate after fabrication or welding where the specification requires it.
Electropolishing may be used where cleanliness or corrosion performance requires it.
Prevent free-iron contamination and preserve the specified surface condition.

Engineering Conclusion

Engineering conclusion and selection recommendation

AISI 304 is worth evaluating when the principal need is broad corrosion resistance with good forming and welding behaviour. Internal indices of hardness 39/100, toughness 94/100, impact 97/100 and wear 42/100 must be aligned with the real failure mechanism. The leading risk is chloride pitting, crevice corrosion, stress-corrosion cracking or sensitisation in an unsuitable environment or thermal cycle. 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 AISI 304 steel?

Austenitic stainless steel; generally not hardenable by quenching and strengthened by cold work.

What are the main applications of AISI 304?

Application contexts include Food, beverage, hygienic and pharmaceutical equipment, Chemical and process equipment, tanks and piping, Plate, sheet and tubular products to the applicable product standard and Architectural and formed components, subject to the product standard and actual condition.

How hard can AISI 304 be?

Hardness and hardenability are condition-dependent; numeric values require grade-specific heat-treatment context. Internal screening index: 39/100 (low).

Is AISI 304 suitable for impact loading?

Impact resistance is indexed at 97/100 and toughness at 94/100. These are not Charpy or Izod energy values; temperature, orientation, geometry and actual microstructure govern component behaviour.

What is the service-temperature limit of AISI 304?

Can AISI 304 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 gradeAISI 304Austenitic Stainless Steels

Selected grade1.4420 / Supra 316plusAustenitic Stainless 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 Heat Treatment Guide — International grade listIdentity And Heat Treatment Model Reference · Tier A

Reference supporting grade identity or recorded values; interpret it within the cited product and condition context. Role: identity and heat treatment model reference.

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Laxcon austenitic stainless family and open grade datasetFamily Context And Composition Reference · Tier A-open-data

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

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Laxcon Steel grade reference — StainlessGrade Composition · Tier A-open-data

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

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Laxcon — AISI 304 grade pageGrade Composition · Tier A-open-data

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

View source