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Stainless steel grade comparison

301 vs 309S Stainless Steel

Compare 301 and 309S stainless steel by chemistry, room-temperature strength, cold-work response, oxidation resistance, elevated-temperature behavior, thermal expansion, fabrication, product form and application environment.

Quick answer: choose 301 when high room-temperature strength, spring performance and cold-work strengthening control the design. Choose 309S when sustained high-temperature oxidation resistance, furnace service or hot-process equipment is the governing requirement. They are not direct substitutes.

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Cold-work strength vs high-temperature oxidation resistance

301

EN 1.4310 · UNS S30100

Structure Austenitic
Typical C 0.10%
Typical Cr 17.0%
Typical Ni 7.0%
Main strength Work hardening
Typical role Spring / forming

309S

EN 1.4833 · UNS S30908

Structure Austenitic
Typical C 0.06%
Typical Cr 22.3%
Typical Ni 12.3%
Air guidance Up to ~1000°C*
Typical role Furnace service

*High-temperature limit is guidance for air service, not a universal design temperature. Atmosphere, water vapor, cycling, load and exposure time must be evaluated separately.

M03 · Decision summary

301 or 309S stainless steel: which one should you specify?

These two grades solve different engineering problems. 301 uses cold deformation to create high room-temperature strength, while 309S uses higher chromium and nickel to provide improved oxidation resistance at elevated temperature.

Decision first: start with 301 for springs, precision strip and high-strength cold-formed parts operating at normal or moderate temperatures. Start with 309S for furnace components and hot-process equipment where oxidation and elevated-temperature behavior control service life.

Choose 301

Cold-worked strength is the primary requirement

Best for Springs, precision strip, stamped parts and mechanically loaded cold-formed components.

Not recommended for Sustained furnace-temperature oxidation service.

Key trade-off Strong work hardening increases forming load, springback and machining difficulty.

Alternative Consider 301LN where a lower-carbon, nitrogen-strengthened 301-family solution fits the specification.

Choose 309S

High-temperature oxidation controls the design

Best for Furnace equipment, annealing boxes, thermowells, baffle plates and other hot-process components.

Not recommended for Low-temperature commodity sheet where its high Cr/Ni content provides no useful thermal benefit.

Key trade-off Higher alloy content and cost; creep, atmosphere and structural stability still require design review.

Alternative Consider 310S or another specialized heat-resistant grade when the 309S temperature envelope is insufficient.

Reconsider both

The service environment falls outside both grades

Review when Severe wet chlorides, aggressive acids, sulfur-rich hot gas, carburizing conditions or critical creep-loaded pressure service apply.

Why 309S is optimized primarily for elevated-temperature service, not universal aqueous corrosion.

Alternative 316L, duplex, higher-nickel or specialized heat-resistant alloys depending on the controlling environment.

Engineering reversal conditions: temperature alone is not enough. Atmosphere composition, water vapor, thermal cycling, applied stress, creep duration, deposits and wet shutdown conditions can change the preferred alloy.

M04 · Technical data

301 vs 309S stainless steel properties

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Room-temperature values and high-temperature values must not be mixed. 301 is commonly specified by cold-rolled or temper-rolled strength, while 309S selection requires oxidation, elevated-temperature yield, creep and atmosphere data.

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Typical chemical composition

Typical manufacturer values. Use the governing standard and MTC for acceptance.

Element / feature	301 / S30100	309S / S30908	Selection significance	Basis
Carbon, C	0.10%	0.06%	309S uses a lower-carbon heat-resistant composition.	Typical manufacturer chemistry
Chromium, Cr	17.0%	22.3%	The higher chromium level is central to 309S oxidation resistance.	Typical manufacturer chemistry
Nickel, Ni	7.0%	12.3%	309S uses substantially more nickel for high-temperature austenitic stability.	Typical manufacturer chemistry
Silicon, Si	Standard grade level	Approx. 0.3%	309S is not a high-silicon 314-style heat-resistant alloy.	Therma range typical value
Molybdenum, Mo	No intentional addition	No intentional addition	Neither is a Mo-alloyed chloride-pitting grade.	Grade design
Microstructure	Austenitic	Austenitic	Similar broad crystal structure, but very different alloy balance and service objective.	Grade classification

ASTM flat-product room-temperature reference

Minimum annealed flat-product values. Final 301 temper can be significantly stronger.

Property	301	309S	Unit / condition	Engineering note
Minimum yield strength	205 MPa	205 MPa	Annealed ASTM flat-product reference	This comparison does not show 301's temper-rolled capability.
Minimum tensile strength	515 MPa	515 MPa	Annealed ASTM flat-product reference	Same minimum value does not imply equal service behavior.
Minimum elongation	40%	40%	Annealed ASTM reference	Product thickness and standard details still apply.

301 cold-rolled EN reference

EN 10088-2 cold-rolled coil / sheet values for 301/1.4310.

Property	301 value	Unit	Condition	Selection effect
Rp0.2	250	MPa	Cold rolled	Useful baseline before additional temper rolling.
Rp1.0	280	MPa	Cold rolled	Higher proof strength than many general-purpose austenitic grades.
Rm	600–950	MPa	Cold rolled	Broad strength range reflects 301's high-strength character.
Minimum elongation	40	%	Cold rolled	Useful forming ductility before stronger cold-work tempers.

309S elevated-temperature strength reference

Outokumpu values based on EN 10028-7. At higher temperatures, creep data rather than room-temperature strength must govern design.

Temperature	Rp0.2	Rp1.0	Rm minimum	Design note
100°C	140 MPa	185 MPa	470 MPa	Elevated-temperature reference.
200°C	116 MPa	154 MPa	430 MPa	Strength decreases with temperature.
300°C	100 MPa	139 MPa	410 MPa	Use actual design standard.
400°C	91 MPa	126 MPa	400 MPa	Do not extrapolate room-temperature values.
450°C	86 MPa	123 MPa	385 MPa	Approaching the range where long-duration behavior becomes increasingly important.

Temperature and oxidation selection

Temperature guidance is atmosphere-dependent and must not be treated as an allowable-stress limit.

Condition	301	309S	Source condition	Procurement implication
Sustained high-temperature oxidation	Not the intended grade family	Improved oxidation resistance	Heat-resistant alloy design	309S is the logical starting point of these two.
Maximum application-temperature guidance	Do not use as furnace design basis	Approx. 1000°C in air*	EN 10095 / manufacturer guidance	Atmosphere, cycling and load can lower the usable temperature.
Water vapor	High-temperature review required	Can reduce oxidation limit	Manufacturer guidance	Maximum service temperature may be reduced by up to ~100°C.
Continuous 600–900°C exposure	Not primary use envelope	Slight embrittlement susceptibility	Therma 309S guidance	Inspect structural stability and room-temperature toughness after exposure.
Above creep-controlled range	Alternative alloy review	Use creep data	Long-duration high-temperature service	Do not size using room-temperature yield strength.

Typical physical properties

Values are reference data and are temperature-specific where stated.

Property	301	309S	Condition	Engineering effect
Density	7.9 kg/dm³	7.8 kg/dm³	Reference	Very small mass difference.
Elastic modulus	200 GPa	196 GPa	20°C	Similar room-temperature stiffness.
309S elastic modulus	—	150 GPa	600°C	High-temperature stiffness is lower than at room temperature.
Thermal expansion	Approx. 16 ×10⁻⁶/K	18.8 ×10⁻⁶/K	301: low-temperature reference; 309S: 20–600°C	309S hot-service design requires allowance for expansion.
Thermal conductivity	15 W/m·K	15 W/m·K	20°C	Similar room-temperature value.
309S thermal conductivity	—	25 W/m·K	800°C	Temperature changes thermal-property values.
Specific heat	500 J/kg·K	472 J/kg·K	20°C reference	Use temperature-specific data for modelling.
Electrical resistivity	0.73 Ω·mm²/m	0.87 Ω·mm²/m	20°C	309S has higher cited resistivity.

Important: 309S's approximate 1000°C guidance is an oxidation / application-temperature reference for air service. It is not the same as an allowable structural design temperature. Load-bearing components must use the applicable creep or high-temperature design data.

M05 · Product form matrix

Product forms and manufacturing routes for 301 and 309S

301 is strongly associated with cold-rolled and precision-strip applications. 309S is available through high-temperature flat-product routes including cold-rolled coil, hot-rolled coil and quarto plate.

Availability note: this is a technical form guide, not live inventory. Actual thickness, width, finish, temper, quantity and delivery route must be confirmed before quotation.

Product / application route	301	309S	Status language	Procurement note
Cold-rolled coil & sheet	Typical product form	Published product form	Typical product form	Confirm gauge, width, finish and mechanical condition.
Hot-rolled coil & sheet	Supplier-dependent	Published product form	Confirm availability	For 309S, define scale condition, pickling and final fabrication.
Quarto plate	Supplier-dependent	Published product form	Confirm availability	Useful for furnace and fabricated hot-process components.
Precision strip	Important product route	Published product route	Supplier-dependent	For 301, specify final tensile or temper requirement.
Spring / temper-rolled strip	Key 301 route	Not primary selection basis	Project-specific	301 final strength must be tied to the temper.
Furnace fabricated components	Not recommended as normal basis	Typical application family	Project-specific	Define temperature, atmosphere, duration and load.
Annealing boxes / baffle plates	Not primary route	Typical 309S application	Project-specific	Thermal cycling and scale spalling should be reviewed.
Thermowells / hot-process parts	Alternative grade review	Typical application family	Project-specific	Actual form may be plate, tube or machined product from another governing standard.

M08 · Applications & limitations

Where 301 works, where 309S is justified, and where another alloy is required

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301 belongs primarily to high-strength cold-worked component design. 309S belongs to the heat-resistant stainless-steel family and should be selected by temperature, atmosphere, load and exposure duration.

301

Typical reasons to choose 301

Springs
Press plates
Conveyor chains
Mixer blades
Automotive gaskets
Precision strip
High-strength stamped components

309S

Typical reasons to choose 309S

Furnace equipment
Annealing boxes
Thermowells
Baffle plates
Quenching-salt pots
Valves and flanges
Hot-process fabricated components

Review

Conditions that can require another alloy

Above the practical 309S oxidation envelope
Strong sulfur-bearing hot gases
Severe carburizing or reducing atmosphere
Warm concentrated chlorides
Critical creep-loaded pressure service
Aggressive reducing acids
Combined high temperature and severe corrosion

Failure modes that can reverse the recommendation

Oxidation and scale growth

301 is not primarily designed as a furnace-temperature oxidation grade. 309S uses substantially higher chromium to create a more protective oxide scale. Actual scale life still depends on temperature, atmosphere and thermal cycling.

Water vapor and thermal cycling

Water vapor can reduce the oxidation resistance of heat-resistant stainless steels and may lower the practical maximum service temperature. Thermal cycling can also crack or detach protective scale.

Creep deformation at high temperature

Above the creep-controlled temperature range, long-duration stress can cause time-dependent deformation even when the applied load is well below room-temperature yield strength. Use approved creep and code data.

Structural embrittlement after long exposure

309S has a slight susceptibility to embrittlement during continuous exposure around 600–900°C. Material exposed for long periods should be assessed for structural stability and post-service toughness requirements.

Sulfur-bearing and reducing hot gases

High nickel does not guarantee good performance in every hot-gas environment. Sulfur compounds, oxygen potential and reducing conditions can significantly change corrosion behavior. The furnace atmosphere must be identified.

Wet chloride attack

Neither 301 nor 309S contains an intentional molybdenum addition. 309S's high chromium content does not make it a seawater-grade alloy. Consider 316L, duplex or another corrosion-resistant alloy when wet chlorides dominate.

301 work hardening and springback

301 gains strength rapidly during cold deformation. This can be beneficial for final strength, but it also increases forming forces, springback and tooling demand. The final temper should be part of the drawing and purchase specification.

Inspection guidance: high-temperature 309S components should be checked for scale condition, cracking, distortion, weld condition and wall-thickness loss. Cold-worked 301 components should be checked for fatigue cracking, excessive springback and local forming damage.

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301 stainless steel

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309s stainless steel

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M10 · Standards & equivalence

301 and 309S stainless steel grade designations

Cross-standard grade names are useful for procurement searches, but equivalence must be confirmed against chemistry, product form, heat treatment, mechanical condition and service standard.

Designation / standard	301	309S	Procurement caveat
ASTM / AISI type	301	309S	Grade type alone does not define product form or final condition.
UNS	S30100	S30908	Useful for exact alloy identification.
EN material number	1.4310	1.4833 in the Therma 309S product mapping	Confirm the exact current EN product and heat-resistant material specification.
301 EN name	X10CrNi18-8	—	301 identification supported by international grade tables.
JIS cross-reference	SUS301	SUS309S — verify against project standard	Do not assume every EN / ASTM / JIS grade is chemically identical without checking limits.
GB cross-reference	Verify against current project standard	Verify against current project standard	Use the specified current GB product standard rather than an informal equivalence chart.
ASTM A240/A240M	Applicable flat-product reference	Applicable flat-product reference	Check current revision, thickness and delivery condition.
ASTM A666	Relevant to austenitic sheet / strip applications	Product-specific verification	Especially relevant where 301 structural / temper-rolled flat product is specified.
EN 10088-2	Key flat-product reference	Verify product route	301 cold-rolled mechanical values should stay attached to this product condition.
EN 10151	Relevant to spring strip	Not primary 309S route	Important for 301 spring and temper classes.
EN 10095	Not primary 301 selection basis	Heat-resistant steel reference	Relevant to 309S high-temperature application data.

301 · ASTM A666 Austenitic stainless flat-product reference for structural and architectural applications.

301 · EN 10151 Relevant to stainless spring strip and strength-controlled conditions.

309S · ASTM A240/A240M Common plate, sheet and strip specification family.

309S · EN 10095 Relevant heat-resistant steel reference for high-temperature selection.

309S cross-standard naming can differ between EN heat-resistant product families and international equivalence tables. Specify the exact UNS, chemistry, product standard and required properties rather than relying only on a grade nickname.

M11 · Direct answers

301 vs 309S stainless steel FAQ

Direct answers to common material-selection and procurement questions about 301 versus 309S stainless steel.

What is the main difference between 301 and 309S stainless steel?

301 is primarily a high-work-hardening austenitic stainless steel used for springs and high-strength cold-formed components. 309S is a high-chromium, high-nickel heat-resistant grade designed for improved oxidation resistance at elevated temperature.

Which is stronger at room temperature?

In basic ASTM annealed flat-product minimum values, both can have 205 MPa minimum yield strength and 515 MPa minimum tensile strength. However, 301 can be strongly cold worked to much higher strength levels and is specifically used for that purpose.

Is 309S better for high temperature than 301?

Yes. 309S is specifically a heat-resistant alloy with improved oxidation resistance. Outokumpu provides an application-temperature guidance value of approximately 1000°C in air, subject to atmosphere and service conditions.

Is 1000°C the absolute maximum temperature for 309S?

No. The value is guidance for oxidation resistance in air, not a universal allowable temperature. Water vapor, aggressive gases, thermal cycling, applied stress and required service life can lower the practical limit.

Can 301 replace 309S in a furnace?

Normally not when high-temperature oxidation resistance is the reason 309S was specified. 301 contains much less chromium and nickel and is not positioned as a dedicated heat-resistant furnace grade.

Can 309S replace 301 in a spring?

Not automatically. 301 is selected specifically for high work-hardening capacity and strength-controlled spring strip. Changing to 309S can alter spring force, forming behavior, thickness and cost.

Does 309S resist seawater better because it has more chromium?

High chromium improves oxidation resistance, but 309S is not a molybdenum-bearing seawater grade. Wet chloride pitting and crevice corrosion should be evaluated separately from high-temperature oxidation.

What happens to 309S during long exposure around 600–900°C?

Manufacturer guidance notes a slight susceptibility to embrittlement during continuous exposure in approximately this temperature range. Structural stability and post-service toughness should therefore be considered.

M13 · Sources & technical review

Technical basis for this 301 vs 309S comparison

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This page separates room-temperature cold-work strength from high-temperature oxidation, creep and atmosphere performance. Those properties should not be reduced to a single “stronger grade” comparison.

Primary technical references

Outokumpu Core Range Datasheet 301/4310 chemistry, cold-rolled mechanical properties, physical data and product-form guidance.
Outokumpu Forta 301/4310 High work-hardening capacity, springs, press plates, conveyor chains and high mechanical-load applications.
Outokumpu Therma Range Datasheet 309S/4833 chemistry, maximum application-temperature guidance, elevated-temperature properties, creep data, physical properties and high-temperature corrosion guidance.
Outokumpu Therma 309S/4833 Furnace equipment, annealing boxes, thermowells, baffle plates, quenching-salt pots and product-form guidance.
ATI 301 UNS S30100 ASTM flat-product chemistry and room-temperature minimum-property reference.
ATI 309S UNS S30908 chemistry, ASTM A240 flat-product room-temperature properties and product specifications.
EN 10088-2 / EN 10151 Relevant to 301 flat products and stainless spring strip.
EN 10095 Heat-resistant steel reference relevant to 309S high-temperature selection.

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M14 · Ask an engineer

Still deciding between 301 and 309S?

Send the actual operating temperature, atmosphere, mechanical load and fabrication requirements so the material can be reviewed against the finished component.

301, 309S or alternative grade under consideration
Sheet, coil, precision strip, plate or fabricated component
Thickness, width and dimensional tolerance
Required room-temperature strength
301 temper or final cold-work condition
Continuous operating temperature
Peak operating temperature
Time at maximum temperature
Thermal-cycle frequency
Air, water vapor or process-gas atmosphere
Sulfur, carburizing or reducing conditions
Static, fatigue or creep loading
Welding process and joint details
Wet shutdown or condensate exposure
Required surface condition / finish
Applicable ASTM, EN or customer standard
Quantity, destination and due date
MTC, inspection and documentation requirements

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