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Stainless steel grade comparison

304 vs 304L Stainless Steel

Compare 304 and 304L stainless steel by carbon content, mechanical properties, weldability, sensitization risk, intergranular corrosion resistance, product form, fabrication route and procurement certification.

Quick answer: choose 304 when standard 18Cr-8Ni performance and slightly higher EN minimum strength are sufficient. Choose 304L when welding, thicker fabricated sections or resistance to sensitization-related intergranular corrosion makes low carbon the safer specification.

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Standard 18/8 grade vs low-carbon 18/8 grade

304

EN 1.4301 · UNS S30400

Structure Austenitic
Typical C 0.04%
Typical Cr 18.1%
Typical Ni 8.1%
PRE ≈18
Key role General purpose

304L

EN 1.4307 · UNS S30403

Structure Austenitic
Typical C 0.02%
Typical Cr 18.1%
Typical Ni 8.1%
PRE ≈18
Key role Welded service

304 and 304L have very similar Cr-Ni chemistry. The principal grade distinction is the lower carbon level of 304L and its effect on carbide precipitation after heat input.

M03 · Decision summary

304 or 304L stainless steel: which one should you specify?

The two grades are much closer than most stainless comparisons. Their chromium, nickel, physical properties and general corrosion behavior are similar. The key question is whether carbon content, welding heat input and sensitization risk matter to the finished component.

Decision first: use 304 when the project permits standard S30400 chemistry and its mechanical-property requirements. Use 304L when the specification requires S30403 or when welded-service resistance to carbide precipitation and intergranular corrosion is an important design criterion.

Choose 304

Standard 18Cr-8Ni service without a low-carbon requirement

Best for General-purpose sheet, kitchen equipment, appliances, cladding, handrails and non-critical welded or formed components.

Not recommended for Projects that explicitly require S30403 / 304L chemistry or low-carbon welded service.

Key trade-off Slightly higher EN minimum room-temperature strength, but less carbon margin against sensitization.

Alternative 304L when extensive welding or as-welded corrosion resistance is important.

Choose 304L

Welding and low-carbon chemistry control the specification

Best for Welded tanks, heat exchangers, pipework, food equipment and chemical or pharmaceutical fabrication in mild to medium environments.

Not recommended for Applications that need molybdenum-enhanced chloride resistance or specialist high-temperature strength.

Key trade-off Lower carbon reduces carbide precipitation, while EN minimum strength is slightly lower than 304.

Alternative 316L where chloride pitting or more aggressive process corrosion controls selection.

Check dual certification

The material may satisfy both 304 and 304L

Best approach Check the actual mill certificate for chemistry and mechanical properties.

Do not assume A product described commercially as 304 or 304L is automatically dual certified.

Key requirement The material must satisfy the specified requirements for both grades when dual certification is required.

Buyer action Verify grade designation, heat number, chemistry, mechanical values and applicable specification on the MTC.

Engineering reversal conditions: do not choose 304L simply because it contains less carbon and assume it is “better” in every application. If high-temperature strength, chloride corrosion, pressure-code allowable stress or another specialized requirement controls the design, a different grade or code-specific review may be required.

M04 · Technical data

304 vs 304L stainless steel properties

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The chemistry and physical properties are very similar. The most useful comparison is carbon content, same-condition mechanical properties and behavior after welding or other sensitizing heat input.

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Typical chemical composition

Typical manufacturer values by mass. The actual heat chemistry and governing standard control acceptance.

Element / feature	304 / S30400	304L / S30403	Selection significance	Basis
Carbon, C	0.04%	0.02%	This is the primary practical chemistry difference. Lower carbon reduces carbide precipitation after heat input.	Typical manufacturer chemistry
Chromium, Cr	18.1%	18.1%	Essentially the same typical chromium level.	Typical manufacturer chemistry
Nickel, Ni	8.1%	8.1%	Essentially the same typical nickel level.	Typical manufacturer chemistry
Molybdenum, Mo	No intentional addition	No intentional addition	Neither has the chloride-pitting advantage of 316L.	Grade design
PRE	≈18	≈18	General pitting-resistance alloy balance is similar.	Manufacturer comparison
Microstructure	Austenitic	Austenitic	Both share similar general forming and welding characteristics.	Grade classification

Cold-rolled mechanical properties at 20°C

EN 10088-2 reference values for the same cold-rolled product condition.

Property	304 / 1.4301	304L / 1.4307	Unit	Selection meaning
Rp0.2	230	220	MPa	304 has a slightly higher EN minimum value.
Rp1.0	260	250	MPa	Small difference in the cold-rolled condition.
Rm	540–750	520–700	MPa	304 has the higher cited tensile range.
Minimum elongation	45	45	%	Same cited minimum elongation.

Mechanical properties by flat-product condition

Values remain attached to the specified product form and condition.

Grade / product form	Rp0.2	Rp1.0	Rm	Elongation
304 · cold rolled	230 MPa	260 MPa	540–750 MPa	45%
304 · hot rolled	210 MPa	250 MPa	520–720 MPa	45%
304 · quarto plate	210 MPa	250 MPa	520–720 MPa	45%
304L · cold rolled	220 MPa	250 MPa	520–700 MPa	45%
304L · hot rolled	200 MPa	240 MPa	520–700 MPa	45%
304L · quarto plate	200 MPa	240 MPa	500–700 MPa	45%

Welding and corrosion comparison

The difference between 304 and 304L becomes more important after heat input.

Factor	304	304L	Engineering significance	Buyer action
General corrosion	Good	Good	Their basic Cr-Ni alloy balance is very similar.	Define the actual process environment.
Conventional welding	Excellent weldability	Excellent weldability	Both can be welded by conventional processes.	Specify joint, thickness and filler.
Carbide precipitation	Higher carbon allowance	Reduced by low carbon	This is the central 304L advantage.	Review heat input and service corrosion requirement.
Intergranular corrosion after heat input	More sensitization-dependent	Improved resistance	304L is commonly preferred where welded corrosion performance is important.	Specify 304L where required by design or code.
Post-weld oxide / heat tint	Remove when corrosion requires	Remove when corrosion requires	Low carbon does not eliminate surface oxide effects.	Define pickling, cleaning or passivation.
Severe chlorides	Alternative grade review	Alternative grade review	304L is not a molybdenum-bearing grade.	Consider 316L, duplex or higher alloy.

Typical physical properties

Metric EN 10088-1 reference values.

Property	304	304L	Condition	Selection significance
Density	7.9 kg/dm³	7.9 kg/dm³	Reference	No meaningful difference.
Elastic modulus	200 GPa	200 GPa	20°C	Same cited stiffness.
Thermal expansion	16.0 ×10⁻⁶/K	16.0 ×10⁻⁶/K	20–100°C	Same cited thermal movement.
Thermal conductivity	15 W/m·K	15 W/m·K	20°C	No selection difference.
Specific heat	500 J/kg·K	500 J/kg·K	20°C	Same cited value.
Electrical resistivity	0.73 Ω·mm²/m	0.73 Ω·mm²/m	20°C	Same cited value.
Magnetizable	No*	No*	Annealed reference	Cold work can increase magnetic response in austenitic grades.

Key point: if a comparison table shows major differences in density, thermal expansion or basic Cr-Ni content between 304 and 304L, investigate the source. The major practical distinction is carbon, sensitization resistance and the mechanical requirements attached to the specified standard.

M05 · Product form matrix

Product forms and supply routes for 304 and 304L

Both grades are widely used across stainless flat products. The practical difference often appears at certification and fabrication stage rather than in basic product geometry.

Availability note: this table describes common product and procurement routes only. It is not live inventory. Always confirm grade, dimensions, finish, product standard and certification on the actual quotation and MTC.

Product / route	304	304L	Status	Procurement note
Cold-rolled coil & sheet	Typical product form	Typical product form	Typical product form	Confirm thickness, width, finish and mechanical condition.
Hot-rolled coil & sheet	Typical product form	Typical product form	Typical product form	Confirm annealed / pickled condition and tolerance.
Quarto plate	Published product form	Published product form	Confirm availability	For welded plate fabrication, low-carbon requirements should be checked explicitly.
Precision strip	Published product route	Published product route	Supplier-dependent	Confirm final temper, surface and width range.
Welded storage tanks	Possible after specification review	Common low-carbon selection	Project-specific	State corrosion medium, thickness and welding procedure.
Heat exchangers	Application-dependent	Established application family	Project-specific	Confirm fluid chemistry, product standard and weld details.
Pipes / tubes	Product-standard dependent	Common application family	Confirm product standard	Flat-product values should not be applied to pipe or tube automatically.
304 / 304L dual-certified material	Possible	Possible	Verify MTC	Do not assume dual certification. The certificate must demonstrate compliance with both required grades.
Flanges / valves	Common alloy family	Common alloy family	Product-specific	Confirm whether forged, cast or wrought standards apply.

M08 · Applications & limitations

Where 304 works, where 304L is preferred, and where neither grade is enough

Discuss Your Application

Both grades are general-purpose austenitic stainless steels. 304L becomes more important when welding heat input and intergranular-corrosion resistance are part of the service requirement.

304

Typical reasons to choose 304

Household appliances
Consumer goods
Kitchen equipment
Cladding and handrails
Window frames
Food and beverage equipment
General storage tanks

304L

Typical reasons to choose 304L

Welded food equipment
Chemical equipment in mild to medium service
Pharmaceutical equipment
Heat exchangers
Storage tanks
Tank containers
Pipes and tubes

Review

Conditions requiring another grade or review

Warm seawater
High chloride concentration
Severe crevice conditions
Chloride stress-corrosion cracking risk
Strong reducing acids
High-temperature creep-controlled service
Projects requiring Mo-alloyed corrosion resistance

Failure modes that can reverse the recommendation

Chromium-carbide precipitation during welding

Heat exposure can allow chromium-rich carbides to form at grain boundaries. This can locally reduce chromium available for corrosion protection. 304L's lower carbon content reduces this risk.

Intergranular corrosion

A sensitized region near a weld can become more susceptible to corrosion along grain boundaries. Low-carbon 304L provides additional resistance to this mechanism.

Weld heat tint and oxide scale

Selecting 304L does not make post-weld surface condition irrelevant. Heat tint can reduce local corrosion resistance and may require appropriate cleaning or pickling.

Chloride pitting

304 and 304L have essentially the same basic pitting-resistance alloy balance because neither contains intentional molybdenum. Lower carbon does not turn 304L into a 316L-type chloride grade.

Crevice corrosion

Stagnant chloride solution, gaskets, deposits and tight joints can create conditions that exceed the practical corrosion resistance of both 304 and 304L.

Chloride stress-corrosion cracking

Both grades are austenitic and can become susceptible to chloride stress-corrosion cracking when temperature, tensile stress and chloride concentration are sufficient.

Assuming dual certification without checking the MTC

304/304L dual-certified material exists, but acceptance depends on the actual material certificate and the applicable specification. A sales description alone is not sufficient evidence.

Using 304L where elevated-temperature strength governs

Low carbon is useful for sensitization resistance, but high-temperature structural or pressure design can be governed by code-specific allowable stresses. Use the grade and data required by the governing design code.

Inspection guidance: on welded equipment, inspect weld heat tint, crevices, deposits and local corrosion. For dual-certified procurement, confirm the material designation, heat chemistry and required mechanical values on the actual MTC before acceptance.

Material image comparison

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304 stainless steel

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304L stainless steel

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M10 · Standards & equivalence

304 and 304L stainless steel grade designations

304 and 304L are closely related, but their designations remain distinct. Do not replace S30400 with S30403 or accept dual certification without checking the governing specification and material certificate.

Designation / standard	304	304L	Procurement caveat
ASTM / AISI type	304	304L	The L suffix identifies the low-carbon grade.
UNS	S30400	S30403	Use the exact UNS when grade identity matters.
EN material number	1.4301	1.4307	Do not treat the two material numbers as automatically interchangeable.
JIS reference	SUS304	SUS304L	Verify the applicable JIS product specification.
GB reference	Verify against project standard	Verify against project standard	Do not publish or accept an assumed equivalence without the actual standard.
ASTM A240/A240M	Flat-product specification family	Flat-product specification family	Check current revision, chemistry and mechanical requirements.
EN 10088-2	Flat-product reference	Flat-product reference	Mechanical values change with cold rolled, hot rolled and plate conditions.
Dual certification	Possible when all requirements are met	Possible when all requirements are met	Verify the actual MTC. Never assume dual certification.
PRE family	Approx. 18	Approx. 18	Low carbon does not significantly change the basic pitting-resistance index.

304 · S30400 Standard 18Cr-8Ni austenitic stainless-steel grade.

304L · S30403 Low-carbon counterpart for improved resistance to sensitization after heat input.

ASTM A240/A240M Common plate, sheet and strip specification family.

Dual-certified 304/304L Accept only when the actual certificate demonstrates compliance with both required grade criteria.

A cross-reference name is not enough to prove equivalence. Check chemistry, mechanical properties, product form, standard revision and certification required by the project.

M11 · Direct answers

304 vs 304L stainless steel FAQ

Direct answers to common engineering and procurement questions about 304 versus 304L stainless steel.

What is the main difference between 304 and 304L stainless steel?

The key difference is carbon. 304L is the low-carbon version of the 304 alloy family. The lower carbon content reduces chromium-carbide precipitation caused by welding or other heat input.

Does 304L have better corrosion resistance than 304?

In the solution-annealed condition, their basic corrosion behavior is very similar because their chromium and nickel contents are closely matched. 304L's main corrosion advantage appears when heat input could otherwise cause sensitization and intergranular corrosion.

Which is better for welding, 304 or 304L?

Both have excellent weldability, but 304L is commonly preferred when welded-service corrosion performance is important because its lower carbon content reduces carbide precipitation.

Is 304 stronger than 304L?

In the cited EN 10088-2 cold-rolled condition, 304 has slightly higher minimum proof strength and a higher tensile-strength range: 230 MPa Rp0.2 and 540–750 MPa Rm versus 220 MPa and 520–700 MPa for 304L.

Can 304 and 304L have the same chromium and nickel content?

Yes. Manufacturer typical values for Core 304/4301 and 304L/4307 are both approximately 18.1% chromium and 8.1% nickel. The important difference is carbon.

What does dual-certified 304/304L mean?

It means the material satisfies the applicable requirements for both grades under the relevant specification and is certified accordingly. Do not assume a product is dual certified; check the actual MTC or MTR.

Is 304L better than 304 for seawater?

Not in the same way that 316L is. 304 and 304L have essentially the same chromium-nickel alloy balance and neither contains intentional molybdenum. Severe chloride or seawater conditions can require 316L, duplex or a higher-alloy grade.

Can I replace 304 with 304L?

Only when the applicable specification, mechanical-property requirements and project approval permit the substitution. If dual-certified material is proposed, verify compliance on the actual certificate instead of relying on the commercial grade name.

M13 · Sources & technical review

Technical basis for this 304 vs 304L comparison

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This comparison keeps the difference between basic alloy corrosion resistance and sensitization-related welded-service performance explicit, while separating grade designation from dual certification.

Primary technical references

Outokumpu Core Range Datasheet 304/4301 and 304L/4307 typical chemistry, EN mechanical properties, physical properties, applications and product forms.
Outokumpu Core 304/4301 General-purpose 18Cr-8Ni austenitic stainless steel, formability, weldability and typical application guidance.
Outokumpu Core 304L/4307 Low-carbon alternative, carbide-precipitation guidance and intergranular-corrosion resistance after heat input.
ASTM A240/A240M Plate, sheet and strip material specification family.
EN 10088-1 Grade and physical-property reference framework.
EN 10088-2 Cold-rolled, hot-rolled and plate mechanical-property reference.
Nippon Steel SUS304 / SUS304L data JIS grade identification and comparative chemistry / mechanical-property reference.
American Welding Society technical guidance Dual certification means the material satisfies the required chemical and mechanical criteria for both specified grades.

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M14 · Ask an engineer

Still deciding between 304 and 304L?

Send the actual product standard, welding, dimensions and service environment so the grade and certification can be reviewed against the finished component.

304, 304L or dual-certified 304/304L under consideration
UNS S30400 or S30403 requirement
Sheet, coil, strip, plate, tube, pipe or fabricated component
Thickness, width, diameter and dimensional tolerance
Cold-rolled, hot-rolled or plate condition
Required yield and tensile properties
Welding process and joint details
Section thickness and expected heat input
As-welded corrosion requirement
Pickling, cleaning or passivation requirement
Process media and chloride exposure
Normal and peak operating temperature
Surface finish
ASTM, EN, JIS or customer specification
Dual-certification requirement
Quantity, destination and due date
MTC, inspection and documentation requirement

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For a useful 304 vs 304L review, include the required grade or UNS, product form, dimensions, weld details, corrosion environment, quantity, destination and MTC / dual-certification requirements.