201
Typical reasons to choose 201
- Household appliances
- Kitchen utensils
- Sinks in suitable environments
- Doors and windows
- Railroad cars
- High-strength formed sheet parts
Stainless steel grade comparison
201 vs 409 Stainless Steel
Compare 201 and 409 stainless steel by microstructure, chemistry, strength, wet-corrosion resistance, oxidation behavior, magnetism, thermal expansion, welding, forming, exhaust-system suitability and relative alloy cost.
Quick answer:
choose 201 when higher room-temperature strength,
austenitic ductility and better composition-based
wet-corrosion resistance are important.
Choose 409 when low alloy cost, magnetic ferritic
behavior, low thermal expansion and automotive
or industrial exhaust service are the real priorities.
Two completely different alloy strategies
201
EN 1.4372 · UNS S20100
- Structure Austenitic
- Typical Cr 16.1%
- Typical Ni 3.6%
- Typical Mn 6.6%
- Typical N 0.08%
- PRE ≈17
409
EN 1.4512 · 409 family
- Structure Ferritic
- Typical Cr 11.5%
- Typical Ni 0.2%
- Typical Ti 0.30%
- Magnetic Yes
- PRE ≈12
Technical basis: Outokumpu Core 201/4372 and Moda 409/4512. 409-family UNS designation can vary with the exact low-carbon product route; confirm the purchase specification and MTC.
M03 · Decision summary
201 or 409 stainless steel: which one should you specify?
201 and 409 are not close substitutes. 201 is a high-strength austenitic Cr-Mn-N stainless steel, while 409 is a low-alloy titanium-stabilized ferritic stainless steel developed around economical exhaust, thermal cycling and mildly corrosive service.
Decision first:
start with 201 if mechanical strength, austenitic formability
and wet-corrosion performance are more important.
Start with 409 if the component is an exhaust part
where low thermal expansion, magnetic ferritic behavior,
deep drawing, oxidation resistance in dry air
and low alloy cost matter more.
Best for 201
High-strength formed components
201 provides high annealed proof strength, strong work hardening and greater composition-based pitting resistance than 409.
Best for 409
Automotive and industrial exhaust
409 combines Ti stabilization, ferritic thermal behavior, low expansion and good oxidation resistance in dry air at low alloy cost.
Recommendation reverser
Aggressive wet corrosion changes the answer
409 has only about 11.5% Cr and PRE around 12. If appearance, wet chloride corrosion or aggressive outdoor exposure is critical, a higher-Cr or Mo-alloyed grade should be reviewed.
| Decision factor | 201 stainless steel | 409 stainless steel |
|---|---|---|
| Microstructure | Austenitic. | Ferritic. |
| Room-temperature strength |
High proof and tensile strength.
Strength advantage |
Lower tensile range, optimized more for exhaust fabrication and thermal behavior. |
| PRE |
Approximately 17.
Higher |
Approximately 12. |
| Atmospheric appearance | Better starting point where clean stainless appearance is important. | Best for non-severe environments; surface discoloration can be acceptable in exhaust applications. |
| Dry-air oxidation | Not the primary selection reason for 201. |
Good oxidation resistance
in dry air.
409 advantage |
| Thermal expansion | Austenitic behavior; higher expansion. |
10.5 ×10⁻⁶/K at 20–100°C.
Lower expansion |
| Thermal conductivity | 15 W/m·K. |
25 W/m·K.
Higher conductivity |
| Magnetism | Nominally non-magnetic in the annealed condition; cold work can increase response. | Ferritic and magnetic. |
| Chloride SCC | Austenitic structure requires SCC review when chloride, stress and temperature combine. |
Ferritic structure provides
strong resistance to chloride-induced SCC.
Structural advantage |
| Relative alloy cost | Low-nickel austenitic route. |
Very low nickel and lower chromium;
often a lower alloy-cost structure.
Cost advantage |
Selection rule:
201 is normally the stronger choice for
strength plus general stainless appearance.
409 is normally the more logical choice
when the component is engineered specifically
for economical exhaust or similar thermal service.
M04 · Technical data
201 vs 409 stainless steel properties
The comparison below keeps chemistry, room-temperature mechanical properties, corrosion indicators and thermal behavior separate. That matters because 201 and 409 have different microstructures and are normally selected for different service conditions.
Typical chemical composition
Typical manufacturer values by mass. Actual heat acceptance must follow the governing product specification and MTC.
| Element / indicator | 201 / S20100 | 409 / 1.4512 | Selection significance | Basis |
|---|---|---|---|---|
| Carbon, C | 0.05% | 0.02% | 409 combines low carbon with titanium stabilization. | Typical manufacturer chemistry |
| Chromium, Cr | 16.1% | 11.5% | 201 has substantially more chromium for wet-corrosion resistance. | Outokumpu typical values |
| Nickel, Ni | 3.6% | 0.2% | 409 is essentially a very-low-nickel ferritic route. | Outokumpu typical values |
| Manganese, Mn | 6.6% | Conventional ferritic level | High Mn helps 201 maintain its austenitic Cr-Mn-N structure. | Grade design |
| Nitrogen, N | 0.08% | Low interstitial design | Nitrogen contributes to 201's high mechanical strength. | Typical chemistry / grade family |
| Titanium, Ti | Not intentionally stabilized | Approx. 0.30% | Ti improves 409 resistance to sensitization during welding. | Outokumpu typical values |
| Molybdenum, Mo | No intentional addition | No intentional addition | Neither grade has a 316-style Mo pitting advantage. | Grade chemistry |
| PRE | ≈17 | ≈12 | 201 has the higher composition-based pitting-resistance indicator. | Cr + 3.3Mo + 16N |
Mechanical properties at 20°C
EN 10088-2 cold-rolled coil / sheet values for an equivalent product-condition comparison.
| Property | 201 / 1.4372 | 409 / 1.4512 | Condition | Interpretation |
|---|---|---|---|---|
| 0.2% proof strength | 350 MPa | 220 MPa | Cold-rolled coil / sheet | 201 has substantially higher annealed proof strength. |
| 1.0% proof strength | 380 MPa | Not stated | EN cold-rolled reference | Do not invent a 409 Rp1.0 value where the cited table does not provide one. |
| Tensile strength | 680–880 MPa | 380–560 MPa | Cold-rolled coil / sheet | 201 has the much higher tensile-strength range. |
| Elongation | 45% | 25% | EN cold-rolled reference | 201 retains greater tensile ductility in this comparison. |
| Work hardening | High | Lower ferritic response | Fabrication dependent | 201 gains strength rapidly during cold deformation. |
| Deep drawing | Good, but high work hardening | Particularly suitable | Sheet forming | 409's stabilized ferritic structure is attractive for deep-drawn exhaust parts. |
Hot-rolled product comparison
Mechanical requirements change with product form and delivery condition.
| Property | 201 hot rolled | 409 hot rolled | Unit | Selection note |
|---|---|---|---|---|
| Rp0.2 | 330 | 220 | MPa | 201 retains the higher hot-rolled proof strength. |
| Rp1.0 | 370 | Not stated | MPa | Use the actual grade table in the purchase specification. |
| Tensile strength | 680–880 | 380–560 | MPa | 201 remains the stronger room-temperature material. |
| Elongation | 45 | 25 | % | Different microstructures produce very different strength/ductility combinations. |
ASTM A240 minimum-property reference
ASTM values are shown separately from EN requirements to avoid mixing different specification systems.
| Property | 201 | 409 family reference | Condition | Important note |
|---|---|---|---|---|
| Minimum yield strength | 269 MPa | 170 MPa | ASTM A240 flat-product basis | Exact 409 UNS / low-carbon variant must match the purchase specification. |
| Minimum tensile strength | 515 MPa | 380 MPa | ASTM A240 flat-product basis | 201 has the higher minimum tensile requirement. |
| Minimum elongation | 40% | 20% | ASTM reference | The two grades should not be treated as structural equivalents. |
Typical physical and thermal properties
Metric reference values at or near 20°C unless otherwise stated.
| Property | 201 | 409 | Condition | Engineering effect |
|---|---|---|---|---|
| Density | 7.8 kg/dm³ | 7.7 kg/dm³ | Reference value | 409 is slightly less dense. |
| Elastic modulus | 200 GPa | 220 GPa | 20°C | 409 has the higher cited elastic modulus. |
| Thermal expansion | Verify for project calculation | 10.5 ×10⁻⁶/K | 20–100°C for 409 | Low ferritic expansion can reduce thermal-growth and weld-distortion concerns. |
| Thermal conductivity | 15 W/m·K | 25 W/m·K | 20°C | 409 transfers heat more readily. |
| Specific heat | Verify for project calculation | 460 J/kg·K | 20°C | Use condition-specific values for thermal modelling. |
| Electrical resistivity | 0.70 Ω·mm²/m | 0.60 Ω·mm²/m | 20°C | 409 has lower electrical resistivity. |
| Magnetizable | No* | Yes | Annealed reference | 409 is inherently magnetic; 201 can become more magnetic after cold work. |
Key point:
201 is clearly stronger at room temperature
and has the higher PRE.
409 is not intended to win that comparison:
its value comes from ferritic thermal behavior,
low alloy cost, deep drawability,
Ti stabilization and exhaust-service performance.
M05 · Product form matrix
Product forms and application routes for 201 and 409
Both grades are commercially associated with hot- and cold-rolled flat products, but they normally go into very different finished components.
Availability note:
this is a technical product-form guide,
not a statement of current inventory.
Confirm thickness, width, finish,
quantity, standard and MTC
before placing an order.
| Product form / application | 201 | 409 | Procurement note |
|---|---|---|---|
| Cold-rolled coil & sheet | Common | Common | Published product route for both grades. |
| Hot-rolled coil & sheet | Common | Common | Confirm thickness, pickling and surface condition. |
| Deep-drawn components | Good formability | Particularly suitable | 201 work-hardens strongly; 409 has ferritic deep-drawing behavior. |
| Automotive exhaust parts | Not primary route | Core application | 409 was developed around this type of thermal application. |
| Industrial exhaust systems | Review required | Typical application | Verify gas chemistry, condensation and service temperature. |
| Decorative exposed sheet | More suitable | Environment dependent | 409 is often selected where appearance is secondary. |
| Wet chloride service | Review exposure | Limited pitting resistance | Consider a higher-alloy grade if localized corrosion controls. |
| Magnetic component requirement | Not reliable as primary feature | Magnetic | 409's ferritic structure provides predictable magnetism. |
M06 · Grade selector
Use strength, corrosion and exhaust conditions to choose 201 or 409
Check the conditions that actually control the component. The result is a preliminary selection direction rather than final material approval.
Preliminary result
Start with 409
For automotive or industrial exhaust components, 409 is normally the logical starting point because its ferritic structure, low thermal expansion and Ti stabilization match the application better than 201.
Send Conditions to an Engineer
STEP 01
Define environment
Dry gas, condensate, water, chlorides and road salt.
STEP 02
Define temperature
Normal, peak and cyclic exhaust temperatures.
STEP 03
Define fabrication
Deep drawing, welding, bending and dimensional stability.
STEP 04
Define appearance
Is staining acceptable, or must the surface remain decorative?
M08 · Applications & limitations
Where 201 works, where 409 makes more sense, and where neither grade is enough
The best application split is not simply “201 is stronger” or “409 is cheaper.” 201 is a high-strength Cr-Mn austenitic grade, while 409 is engineered around economical, thermally cycled ferritic exhaust service.
409
Typical reasons to choose 409
- Automotive exhaust systems
- Industrial exhaust systems
- Deep-drawn exhaust shells
- Muffler components
- Heat shields
- Components where staining is acceptable
!
Conditions requiring another grade
- Marine decorative surfaces
- Continuous wet chloride exposure
- Severe pitting or crevice conditions
- Aggressive acids
- High-temperature exhaust beyond 409 capability
- Applications requiring high polish and severe corrosion resistance
Failure modes that can reverse the recommendation
Why can 409 show staining even though it is stainless steel?
409 contains only about 11.5% chromium
and belongs to a mildly corrosive
service family. It can provide useful
service while developing visible
oxidation or staining that would be
unacceptable on decorative equipment.
Why is 409 popular in exhaust systems?
It combines low alloy cost,
low thermal expansion,
higher thermal conductivity,
Ti stabilization, useful deep drawability
and good oxidation resistance in dry air.
Is 201 always more corrosion resistant than 409?
201 has more chromium and a higher
PRE, so it has the stronger
composition-based pitting position.
However, corrosion selection also depends
on stress, temperature and exposure.
Ferritic 409 has excellent resistance
to chloride-induced stress-corrosion cracking.
Can 409 be welded?
Yes. Its titanium stabilization
reduces sensitivity to intergranular corrosion,
and manufacturer guidance identifies
409/4512 as weldable across dimensions.
Actual welding procedure still needs
to control distortion, heat input and joint design.
Does magnetic 409 mean it is lower quality?
No. Magnetism results from
the ferritic crystal structure.
It is a material characteristic,
not a quality rating.
409 is intentionally ferritic
because that structure provides
useful thermal and SCC behavior.
Can 201 replace 409 in an exhaust system?
Not automatically. 201 may offer
higher room-temperature strength,
but it also has different thermal expansion,
thermal conductivity, microstructure
and cost. The exhaust thermal cycle
and condensation environment must be reviewed.
Important:
409's excellent chloride-SCC resistance
does not mean that it has high chloride-pitting resistance.
Stress-corrosion cracking and localized
pitting are different corrosion mechanisms.
Material image comparison
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M10 · Standards & equivalence
201 and 409 stainless steel grade designations
201 belongs to the austenitic low-Ni Cr-Mn-N family. 409 / 1.4512 belongs to the stabilized low-chromium ferritic family. Always confirm whether a project specifies 409, 409L or a particular UNS composition.
| Designation system | 201 | 409 family | Procurement note |
|---|---|---|---|
| ASTM / AISI type | 201 | 409 / 409L family | Confirm carbon level and exact UNS for 409 orders. |
| UNS | S20100 | S40910 commonly used for low-C 409 route | Do not assume all materials marked “409” have identical chemistry. |
| EN material number | 1.4372 | 1.4512 | Primary EN material numbers used on this comparison page. |
| EN name | X12CrMnNiN17-7-5 | X2CrTi12 | Composition families are fundamentally different. |
| JIS reference | SUS201 | SUS409L | Treat as cross-standard references and verify chemistry before substitution. |
| GB reference | 12Cr17Mn6Ni5N | 022Cr11Ti | Confirm the exact current GB product standard and condition. |
| Microstructure | Austenitic | Ferritic | This difference affects magnetism, SCC, thermal expansion and fabrication behavior. |
| ASTM A240/A240M | Flat-product reference | Flat-product reference | Mechanical and chemical requirements must be tied to the exact UNS. |
| EN 10088-1 | Designation / physical data | Designation / physical data | Use current standard revision. |
| EN 10088-2 | Flat-product mechanical reference | Flat-product mechanical reference | Product form and delivery condition change mechanical requirements. |
ASTM A240/A240M
Common stainless plate,
sheet and strip specification family.
EN 10088-1
Grade designation and
physical-property reference.
EN 10088-2
Mechanical and delivery-condition
reference for stainless flat products.
GB / JIS cross-reference
Use only after chemistry,
product form and current
purchase-standard requirements align.
The 409 family contains several closely related designations and low-carbon variants. Do not approve a substitution solely because a supplier describes a material as “409.”
M11 · Direct answers
201 vs 409 stainless steel FAQ
Direct answers to common engineering and procurement questions about 201 versus 409 stainless steel.
What is the main difference between 201 and 409 stainless steel?
201 is a high-strength austenitic Cr-Mn-N stainless steel. 409 is a low-chromium, Ti-stabilized ferritic stainless designed primarily for economical automotive and industrial exhaust service.
Which is stronger, 201 or 409?
201 is significantly stronger in the cited EN cold-rolled condition: 350 MPa Rp0.2 and 680–880 MPa tensile strength compared with 220 MPa and 380–560 MPa for 409.
Which has better corrosion resistance?
For general wet-corrosion and composition-based pitting resistance, 201 has the stronger starting position with PRE around 17 versus roughly 12 for 409. 409 is intended for mildly corrosive environments where appearance may be secondary.
Why is 409 commonly used for exhaust systems?
409 offers low alloy cost, good dry-air oxidation resistance, Ti stabilization, good deep drawability, low thermal expansion and higher thermal conductivity than austenitic grades.
Is 409 magnetic?
Yes. 409 is ferritic and therefore magnetic. Annealed 201 is nominally non-magnetic, although cold working can increase its magnetic response.
Is 409 rust-proof?
No stainless steel is universally rust-proof. 409 has relatively low chromium content and can develop staining or visible oxidation, especially in wet or aggressive environments. It is often acceptable in exhaust systems where cosmetic appearance is not the priority.
Which is better for chloride stress-corrosion cracking?
Ferritic 409 has a structural advantage against chloride-induced stress-corrosion cracking. That does not mean it has better pitting resistance; SCC and pitting are different corrosion mechanisms.
Can 409 be welded?
Yes. Its low interstitial content and titanium stabilization improve welding behavior and reduce sensitization risk. Actual procedure still depends on gauge, joint geometry and service conditions.
Can 201 replace 409 in automotive exhaust components?
Not automatically. 201 is stronger but has very different thermal expansion, conductivity, microstructure and alloy cost. The exhaust temperature cycle, condensation chemistry and dimensional stability must be reviewed first.
M13 · Sources & technical review
Technical basis for this 201 vs 409 comparison
This comparison keeps room-temperature strength, wet corrosion, chloride SCC, thermal behavior and exhaust performance separate because 201 and 409 have fundamentally different microstructures.
Primary technical references
- Outokumpu Core Range Datasheet 201/4372 chemistry, PRE, EN mechanical values, ASTM reference properties, physical data and applications.
- Outokumpu Core 201/4372 Low-nickel Cr-Mn-N alloy design, high work hardening, product forms and applications.
- Outokumpu Moda Range Datasheet 409/4512 chemistry, PRE, mechanical properties, thermal properties, corrosion behavior, formability and welding guidance.
- Outokumpu Moda 409/4512 Automotive and industrial exhaust use, Ti stabilization, dry-air oxidation resistance and product forms.
- ASTM A240/A240M Flat-product chemical and mechanical requirements.
- EN 10088-1 Designation and physical-property reference.
- EN 10088-2 Cold-rolled and hot-rolled flat-product mechanical references.
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Update note
Initial T09 comparison prepared with condition-labelled mechanical data, microstructure comparison, corrosion reversal conditions, exhaust-service guidance and interactive selection logic.
M14 · Ask an engineer
Still deciding between 201 and 409?
Send the actual strength, exhaust temperature, corrosion, forming and welding requirements so the grade can be reviewed against the finished component.
- 201, 409, 409L or alternative grade under consideration
- Cold-rolled or hot-rolled product form
- Thickness, width, length and tolerance
- Required yield and tensile strength
- Deep drawing, stamping or bending requirement
- Work-hardening constraints
- Welding process and section thickness
- Normal exhaust temperature
- Peak exhaust temperature
- Thermal cycling frequency
- Dry gas or condensate exposure
- Road salt or chloride exposure
- Required visual surface appearance
- Magnetic / non-magnetic requirement
- Applicable ASTM, EN, JIS, GB or customer specification
- Quantity, destination, due date and MTC requirement
Send your material requirement
For 409 applications, include exhaust temperature, thermal cycling, condensate or road-salt exposure, welding, forming method and required appearance.