304
Typical reasons to choose 304
- Household appliances and consumer goods
- Kitchen equipment
- Food and beverage equipment
- Storage tanks
- Indoor and mild outdoor cladding
- General flanges and valves
Stainless steel grade comparison
304 vs 347 Stainless Steel
Compare 304 and 347 stainless steel by chemistry, mechanical properties, intergranular corrosion resistance, high-temperature behavior, welding, fabrication, product forms and procurement cost.
Quick answer:
choose 304 for general-purpose equipment, food service,
architectural components and fabrication where repeated
high-temperature exposure is not a design requirement.
Choose 347 when niobium stabilization is needed to reduce
sensitization and intergranular-corrosion risk after welding
or repeated exposure to approximately 400–900°C.
The stabilization difference that drives the selection
304
EN 1.4301 · UNS S30400
- Typical Cr 18.1%
- Typical Ni 8.1%
- Stabilizer None
- Primary role General purpose
347
EN 1.4550 · UNS S34700
- Typical Cr 17.5%
- Typical Ni 9.5%
- Stabilizer Niobium
- Primary role High-temp stability
Typical chemistry basis: Outokumpu Core 304/4301 and Core 347/4550. Actual heat chemistry must be confirmed from the governing standard and material certificate.
M03 · Decision summary
304 or 347 stainless steel: which one should you specify?
Both are Cr-Ni austenitic stainless steels with similar room-temperature physical properties. The real reason to move from 304 to 347 is usually niobium stabilization and the need to maintain resistance to intergranular corrosion after welding or elevated-temperature exposure.
| Decision factor | 304 stainless steel | 347 stainless steel |
|---|---|---|
| General-purpose service |
Excellent all-purpose choice with broad supply
and fabrication experience.
Preferred |
Can perform well, but stabilization may add cost without benefit in ordinary service. |
| Intergranular corrosion | Standard 304 can become sensitized after unsuitable thermal exposure; 304L is often evaluated for welding. |
Niobium stabilization is specifically used to reduce
sensitization and grain-boundary attack.
Stabilized |
| Intermittent 400–900°C exposure | Not normally selected specifically for repeated exposure in the sensitization range. |
Designed for applications where repeated elevated-temperature
exposure and intergranular-corrosion resistance matter.
Preferred |
| Welding | Excellent general weldability. 304L may be preferred when post-weld sensitization is a concern. | Excellent weldability with stabilization intended to preserve intergranular-corrosion resistance. |
| Room-temperature strength | Slightly higher EN cold-rolled proof and tensile values in the compared condition. | Similar overall room-temperature strength class. |
| Physical properties | Density, modulus, thermal expansion and conductivity are essentially the same as 347 in the cited data. | Very similar to 304. |
| Availability |
Extremely broad global availability across many
product forms.
Supply advantage |
More specialized supply, especially when exact high-temperature or certification requirements apply. |
| Relative material cost | Usually the more economical general-purpose option. | Typically carries a premium for stabilization and more specialized supply. |
Selection rule: do not specify 347 merely because it sounds like a higher grade. Specify it when stabilization, welding history or repeated elevated-temperature exposure creates a real engineering need.
M04 · Technical data
304 vs 347 stainless steel properties
Room-temperature properties are relatively close. The more important difference is the niobium stabilization of Type 347 and the resulting behavior after thermal exposure.
Typical chemical composition
Typical Outokumpu values by mass. Use the actual material standard and MTC for acceptance.
| Element / feature | 304 / S30400 | 347 / S34700 | Selection significance | Source |
|---|---|---|---|---|
| Carbon | 0.04% | 0.05% | Typical values only; specification limits control purchasing. | Outokumpu Core |
| Chromium | 18.1% | 17.5% | Both belong to the standard Cr-Ni austenitic family. | Outokumpu Core |
| Nickel | 8.1% | 9.5% | 347 has somewhat more nickel in the cited typical chemistry. | Outokumpu Core |
| Niobium | Not stabilized | Niobium stabilized | Niobium preferentially forms stable carbides and reduces chromium-carbide-related sensitization. | Outokumpu Core |
| PRE | 18 | 18 | Their basic composition-based pitting indicator is similar; stabilization is the important distinction. | Outokumpu Core |
Mechanical properties at 20°C
EN 10088-2 cold-rolled coil and sheet values.
| Property | 304 / 1.4301 | 347 / 1.4550 | Interpretation | Condition |
|---|---|---|---|---|
| 0.2% proof strength | 230 MPa | 220 MPa | Room-temperature proof strengths are close. | Cold-rolled sheet / coil |
| 1.0% proof strength | 260 MPa | 250 MPa | Again, only a small difference in the cited condition. | Cold-rolled sheet / coil |
| Tensile strength | 540–750 MPa | 520–720 MPa | 304 has a slightly higher specified range here. | Cold-rolled sheet / coil |
| Elongation | 45% | 40% | Both retain high austenitic ductility. | EN 10088-2 |
Typical physical properties
Reference data according to EN 10088-1 / Outokumpu Core.
| Property | 304 | 347 | Selection effect | Condition |
|---|---|---|---|---|
| Density | 7.9 kg/dm³ | 7.9 kg/dm³ | Essentially identical. | Reference value |
| Elastic modulus | 200 GPa | 200 GPa | No practical difference in the cited value. | 20°C |
| Thermal expansion | 16.0 ×10⁻⁶/K | 16.0 ×10⁻⁶/K | The stabilization difference does not change this cited value. | 20–100°C |
| Thermal conductivity | 15 W/m·K | 15 W/m·K | Essentially identical. | 20°C |
| Specific heat | 500 J/kg·K | 500 J/kg·K | Essentially identical. | 20°C |
| Electrical resistivity | 0.73 Ω·mm²/m | 0.73 Ω·mm²/m | No difference in the cited reference value. | 20°C |
| Magnetizable | Normally no | Normally no | Both are austenitic; fabrication can still create some magnetic response. | Annealed reference |
Key point:
304 and 347 are much closer at room temperature than their
different grade numbers suggest. The procurement reason for 347
is normally stabilization and elevated-temperature service,
not a major improvement in ordinary tensile or physical properties.
M05 · Product form matrix
Product forms and supply routes for 304 and 347
304 is one of the most broadly available stainless grades. 347 is also commercially established, but supply is more specialized and frequently linked to high-temperature, aerospace, refinery and chemical applications.
Availability note:
this matrix describes typical product routes and does not
claim live inventory. Confirm dimensions, condition,
quantity and specification in the RFQ.
| Product form | 304 | 347 | Procurement note |
|---|---|---|---|
| Cold-rolled coil & sheet | Common | Available | Published Outokumpu product form for both grades. |
| Hot-rolled coil & sheet | Common | Available | Confirm actual thickness range and heat-treatment condition. |
| Quarto plate | Common | Available | 347 plate is commonly tied to specialist industrial requirements. |
| Precision strip | Common | Verify source | 304 has broader standard precision-strip availability. |
| Tube & pipe | Widely available | Specialist supply | 347 tubes are used in refinery, chemical and high-temperature service. |
| Standard mill finishes | Broad range | Available | Specify required finish by product form and applicable standard. |
M06 · Grade selector
Use thermal exposure and fabrication to choose 304 or 347
Check the conditions that apply to your component. The result is a preliminary screening recommendation.
Preliminary result
Start with 304
For ordinary general-purpose service without a stabilization or elevated-temperature requirement, 304 is normally the more economical and widely available starting point.
Send Conditions to an Engineer
STEP 01
Define temperature
Normal service, repeated heating or sustained high-temperature operation.
STEP 02
Check welding
Gauge, weld heat input, post-weld exposure and corrosion environment.
STEP 03
Check corrosion mode
General corrosion, intergranular attack or chloride pitting.
STEP 04
Specify the purchase condition
Grade, product form, dimensions, finish, standard and certificate.
M08 · Applications & limitations
Where 304 works, where 347 is justified, and where neither is enough
304 is the broad general-purpose grade. 347 becomes valuable when the component sees welding plus corrosive service, repeated thermal cycles or elevated-temperature conditions that make stabilization important.
347
Typical reasons to choose 347
- High-temperature gaskets
- Expansion joints
- Aircraft collector rings
- Exhaust manifolds
- Rocket-engine components
- High-temperature chemical equipment
!
Conditions requiring another alloy review
- Seawater service
- Severe chloride pitting environments
- Strong reducing acids
- Applications requiring much higher creep strength
- Extremely high oxidation temperatures
- Code-controlled service requiring another specified alloy
Thermal and fabrication decision matrix
The key distinction is what happens after heat enters the component.
| Condition | 304 | 347 | Decision |
|---|---|---|---|
| Normal room-temperature fabrication | Excellent general-purpose choice. | Also workable, but stabilization may add unnecessary cost. | 304 usually makes more commercial sense. |
| Heavy welding + corrosion concern | Evaluate 304L or welding procedure carefully. | Niobium stabilization provides a specific advantage. | 347 may be justified. |
| Intermittent 400–900°C service | Not specifically optimized for this condition. | Published as particularly useful in this temperature range. | 347 is the stronger starting point. |
| Ordinary food-service equipment | Widely used and economical. | Usually no stabilization benefit. | 304 generally preferred. |
| Severe chlorides | May pit or crevice corrode. | Niobium does not provide molybdenum-style chloride resistance. | Consider 316 or another higher-alloy grade. |
Important:
347 stabilization primarily addresses carbide precipitation
and intergranular-corrosion risk. It should not be marketed
as a universal improvement in pitting, seawater or acid resistance.
Material image comparison
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M10 · Standards & equivalence
304 and 347 grade designations
These are related Cr-Ni austenitic stainless steels, but 347's niobium stabilization is a deliberate metallurgical difference and must not be ignored during substitution.
| System | 304 | 347 | Procurement note |
|---|---|---|---|
| ASTM / AISI type | 304 | 347 | Common North American type designation. |
| UNS | S30400 | S34700 | Use UNS when exact alloy identity matters. |
| EN material number | 1.4301 | 1.4550 | European grade references used on this page. |
| Microstructure | Austenitic | Austenitic | Both retain high ductility and toughness. |
| Stabilization | Not stabilized | Niobium stabilized | This is the principal metallurgical distinction. |
| High-temperature variant | 304H / S30409 | 347H / S34709 | H grades are separate purchase grades and should not be assumed from standard 304 or 347. |
ASTM A240/A240M
Common flat-product specification route.
EN 10088-2
Mechanical-property reference for stainless flat products.
UNS S34700
Standard Type 347 niobium-stabilized alloy identity.
UNS S34709
347H high-carbon variant for specific elevated-temperature requirements.
Do not treat 347, 347H and 304H as interchangeable names. The exact chemistry, carbon range, heat treatment, product standard and design temperature must be verified.
M11 · Direct answers
304 vs 347 stainless steel FAQ
Direct answers to the main procurement and engineering questions behind the 304 versus 347 decision.
What is the main difference between 304 and 347?
347 is a niobium-stabilized Cr-Ni austenitic stainless steel. The stabilization reduces susceptibility to intergranular corrosion after certain welding and elevated-temperature exposures. 304 is the broader general-purpose grade.
Is 347 more corrosion resistant than 304?
Not universally. Their basic PRE values are similar. 347's important advantage is improved resistance to intergranular corrosion associated with sensitization, not a major improvement in chloride pitting resistance.
Why is niobium added to 347 stainless steel?
Niobium forms stable carbides preferentially, reducing the chromium depletion at grain boundaries that can otherwise occur during sensitizing thermal exposure.
Is 347 better for high-temperature use?
347 is specifically used where elevated-temperature stability and intergranular-corrosion resistance are important. Outokumpu identifies intermittent heating around 400–900°C as an important application range.
Which is stronger, 304 or 347?
At room temperature they are in a similar strength class. In the cited EN cold-rolled condition, 304 has slightly higher proof and tensile values, but this is normally not the reason for choosing between the grades.
Can 304 be welded instead of using 347?
304 is readily weldable, but the correct grade depends on gauge, carbon content, post-weld environment and later thermal exposure. 304L is also commonly evaluated where sensitization after welding is a concern.
Is 347 stainless steel magnetic?
347 is an austenitic stainless steel and normally has low magnetic response in the solution-annealed condition. Some magnetic response may appear after fabrication or welding.
Is 347 more expensive than 304?
It is generally a more specialized material and normally carries a premium. Actual cost depends on product form, dimensions, quantity, alloy surcharges, certification and availability.
Should I use 347 or 347H?
347H is a separate high-carbon variant used where specific high-temperature strength requirements apply. Do not substitute 347H for standard 347 without checking the applicable design code and purchase specification.
M13 · Sources & technical review
Technical basis for this 304 vs 347 comparison
The comparison separates ordinary room-temperature properties from the stabilization and elevated-temperature behavior that actually differentiates Type 347.
Primary technical references
- Outokumpu Core Range Datasheet 304/4301 and 347/4550 chemistry, mechanical properties, physical properties, applications and product forms.
- Outokumpu Core 347/4550 Product Information Niobium stabilization, intergranular-corrosion resistance and intermittent 400–900°C application guidance.
- ASTM A240/A240M Flat-product grade requirements for Types 304 and 347.
- EN 10088-2 Mechanical-property reference for stainless flat products.
- Aperam 347/347H – 1.4550 Independent manufacturer reference for niobium stabilization, high-temperature corrosion behavior and typical applications.
- Nickel Institute technical guidance Background on stabilized austenitic grades and high-temperature/intergranular-corrosion considerations.
Page accountability
Author
Stainless Steel Market Technical Editorial Team
Comparison structured from standards, manufacturer datasheets and procurement requirements.
Technical review
Stainless Steel Market Materials Review
Review scope includes chemistry, stabilization, mechanical properties, welding and high-temperature selection.
Reviewed
23 September 2026
Data checked against published manufacturer and standards-reference information.
M14 · Ask an engineer
Still deciding between 304 and 347?
Send the actual temperature cycle, welding condition and corrosion environment so the grade can be selected against the real service requirement.
- 304, 347 or another grade under consideration
- Operating, peak and cycling temperature
- Time spent in elevated-temperature service
- Sheet, plate, coil, pipe, tube or other form
- Dimensions and thickness
- Welding procedure and post-weld condition
- Corrosion environment and process chemistry
- Applicable ASTM, ASME, EN or customer specification
- 347 or 347H requirement where relevant
- Quantity, destination, delivery date and MTC requirements
Send your material requirement
Include temperature, environment, welding, product form, dimensions, standard and quantity for a more useful technical review.