Grade dossier
304H Stainless Steel for Elevated-Temperature Service
The controlled higher-carbon 304 variant used where elevated-temperature strength and creep considerations govern the specification.
Identity before substitution
Define the grade, product and condition together
A familiar grade name is not a complete purchase specification. Product form, controlling standard, dimensions, condition, finish, certification and service environment determine whether the delivered material is suitable.
Composition control
ASTM A240/A240M flat-product chemistry
Limits are not heat analysis targets
The table summarizes grade limits commonly used for plate, sheet and strip. Pipe, tube, bar, forgings and cast products can be governed by different specifications. Always place the product standard and edition on the purchase order.
| C | 0.04-0.10 |
|---|---|
| Mn | 2.00 max |
| Si | 0.75 max |
| P | 0.045 max |
| S | 0.030 max |
| Cr | 18.00-20.00 |
| Ni | 8.00-10.50 |
| N | 0.10 max |
Properties with context
Minimums, typical indicators and delivered condition
Specified annealed flat-product values
| Room-temperature tensile strength | 515 MPa min |
|---|---|
| Room-temperature 0.2% yield | 205 MPa min |
| Elongation | 40% min |
| Hardness | 92 HRBW max |
Selection indicators
| Density | about 7.9-8.0 g/cm3 |
|---|---|
| Primary purpose | Improved elevated-temperature strength versus low-carbon variants |
| Design basis | Use code allowable stress and creep data |
| Corrosion note | Higher carbon is not a general corrosion upgrade |
Values depend on product form, thickness, test orientation, condition and governing edition. Use the mill test certificate and the purchase specification for acceptance, not a web table alone.
Selection boundary
Where 304H belongs and where to escalate
Grade selection is an environmental decision, not a popularity contest. Review the complete medium, temperature, geometry, fabrication, cleaning and inspection requirements.
Good reasons to evaluate it
Pressure-vessel and boiler components under an approved code
High-temperature process equipment
Heat-resistant plate and vessel internals
Projects explicitly requiring UNS S30409 certification
Reasons to stop and review
Substituting 304H for 304L in wet welded service
Using room-temperature values for creep design
Quoting a maximum service temperature without atmosphere and load
Assuming dual certification without checking carbon range
Fabrication route
Protect properties through cutting, forming and welding
Match welding procedure and filler to elevated-temperature service.
Control heat treatment and intergranular-corrosion risk where shutdown condensation occurs.
Use the design code for allowable stress and service life.
Document carbon, grain size or supplementary requirements when the code calls for them.
Supply definition
Product form changes the applicable requirements
Do not send an RFQ that names only the grade. State form, governing standard, dimensions, tolerances, finish, edge or end condition, quantity, certification and inspection.
Plate, sheet and strip to ASTM A240/A240M
Pressure-vessel plate to the governing code
Pipe and tube under product-specific high-temperature standards
Bar or forgings under their applicable specifications
Certificate checkpoint
Request heat identity, chemical analysis, mechanical results and compliance to the exact product specification. Add PMI, corrosion testing or supplementary examination only when the application requires it.
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Interactive selection check
Test 304H against the controlling question
Procurement FAQ
Questions to close before placing the order
Is 304H stainless steel magnetic?
Magnetic response depends on microstructure and delivered condition.
Can 304H replace another grade?
Only after checking the governing standard, composition, mechanical properties, corrosion exposure, fabrication route and certification. A commercial name is not a substitution approval.
Does the table apply to every product form?
Not automatically. The values shown use flat-product requirements as a reference. Other forms can use different product standards, dimensions and tests.
What should a 304H RFQ include?
Product form, standard and edition, UNS or EN designation, dimensions, tolerances, finish, quantity, service, fabrication, certificate and inspection requirements.
Sources, scope and RFQ
Use traceable grade data, then specify the actual product
ASTM A240/A240M requirements for UNS S30409
Outokumpu Therma 304H/4948 technical data
ASME material identity and elevated-temperature design framework
ASSDA guidance on L, standard and H stainless grades