Short answer: 304L is the low-carbon version of 304 and is normally preferred for welded fabrications that will not receive solution heat treatment. For unwelded sheet products, 304 often performs similarly; many commercial products are dual certified when chemistry and properties satisfy both specifications.
This guide is written for stainless steel buyers, sourcing teams, engineers and product manufacturers. The purpose is not to declare one universal winner, but to turn a broad material question into a specification that a mill or service center can quote, process and inspect consistently.
Quick Comparison
| Option | Key point | Typical use or decision |
|---|---|---|
| 304 / S30400 | Higher permitted carbon than 304L | General forming and fabrication |
| 304L / S30403 | Maximum carbon typically 0.03% | Welded tanks, sinks, pipework and corrosion-sensitive fabrications |
The table is a starting point. Actual performance depends on the governing standard, delivered condition, dimensions, surface finish, fabrication route and service environment. Commercial names should never replace a complete purchase specification.
What Buyers Should Evaluate
- Review section thickness, heat input and post-weld heat treatment.
- Check the exact EN designation: 304L can correspond to 1.4307 or 1.4306 depending on specification.
- Do not assume dual certification without checking the MTC.
For production orders, share the end use rather than requesting a grade or finish in isolation. A supplier can then review corrosion exposure, forming severity, welding, visual requirements and packing before material is cut. This early review is usually less expensive than correcting a rejected shipment or unstable production trial.
Common Purchasing Mistakes
- Treating 304L as universally stronger
- Using the grade name without a governing standard
- Ignoring weld heat tint because low carbon was specified
These mistakes are avoidable when drawings, approved samples, inspection methods and certificate requirements are agreed before production. For visual products, retain a signed master sample. For functional dimensions, define where and how measurements will be taken.
Recommended RFQ Wording
For welded work, specify 304L, the relevant product standard, certificate type, finish and post-weld cleaning expectation. Ask whether the offered material is dual certified.
Also include order quantity, acceptable quantity variation, destination, required delivery date and whether partial shipments are allowed. If a requirement is critical, make it measurable and place it on the purchase order rather than only in an email conversation.
How Still Steel Supports the Project
Still Steel supplies stainless steel coil, strip and sheet and provides slitting, cut-to-length, brushing, polishing and protective-film services. We can compare available mill material with your drawing, prepare trial quantities and preserve heat-number traceability through service-center processing.
Send the grade, dimensions, annual volume and application to vip@still-steel.com, or discuss the requirement on WhatsApp.
Frequently Asked Questions
Is 304L more corrosion resistant than 304?
Their general corrosion resistance is similar, but 304L better resists sensitization-related intergranular corrosion after welding.
Can 304 be welded?
Yes. The decision depends on section thickness, service environment, welding procedure and whether heat treatment is possible.
What does dual certified mean?
It means the supplied heat satisfies the stated requirements of both grade designations shown on the certificate.
Technical References
Reference documents support general selection and fabrication principles. The final material decision must follow the applicable contract, standard, regulation and engineering review for the specific product.