304 vs 304L Stainless Steel
Side-by-side comparison · Composition · Properties · Selection guide
304 and 304L differ in one number: the carbon limit, 0.08% versus 0.030%. Lower carbon stops chromium carbides from forming along grain boundaries when the steel is welded, so 304L keeps full corrosion resistance in the weld zone without any post-weld heat treatment. In exchange, its specified minimum strength is slightly lower.
Full datasheets:304 Stainless Steel·304L Stainless Steel
At a Glance
| 304 | 304L | |
|---|---|---|
| Type | Austenitic | Austenitic (low carbon) |
| UNS | S30400 | S30403 |
| Standard | ASTM A240/A240M | ASTM A240/A240M |
| Density | 7.93 g/cm³ | 7.93 g/cm³ |
Corrosion Resistance and Service Limits
304
- General corrosion resistance comes from the chromium-rich passive film; nickel, molybdenum, nitrogen and copper change performance by grade.
- Check chlorides, temperature, crevices, deposits, process chemistry and cleaning conditions. A grade designation alone is not a service-life guarantee.
304L
- General corrosion resistance comes from the chromium-rich passive film; nickel, molybdenum, nitrogen and copper change performance by grade.
- Check chlorides, temperature, crevices, deposits, process chemistry and cleaning conditions. A grade designation alone is not a service-life guarantee.
Fabrication and Heat Treatment
| Operation | 304 | 304L |
|---|---|---|
| Welding | Generally weldable with a qualified procedure and matching or over-alloyed filler where required; remove heat tint when corrosion service demands it. | Generally weldable with a qualified procedure and matching or over-alloyed filler where required; remove heat tint when corrosion service demands it. |
| Forming | Good ductility is typical, but rapid work hardening increases forming load and springback; bend radius and intermediate annealing depend on grade and reduction. | Good ductility is typical, but rapid work hardening increases forming load and springback; bend radius and intermediate annealing depend on grade and reduction. |
| Machining | Use rigid tooling, positive feeds and controlled heat because the material work-hardens; free-machining grades require separate corrosion and welding review. | Use rigid tooling, positive feeds and controlled heat because the material work-hardens; free-machining grades require separate corrosion and welding review. |
| Heat treatment | Solution annealing and rapid cooling restore the intended condition where applicable. Austenitic grades are not hardened by conventional quench-and-temper treatment. | Solution annealing and rapid cooling restore the intended condition where applicable. Austenitic grades are not hardened by conventional quench-and-temper treatment. |
Chemical Composition (wt%)
| Element | 304 | 304L |
|---|---|---|
| C | ≤0.08 | ≤0.030 |
| Mn | ≤2.00 | ≤2.00 |
| Si | ≤0.75 | ≤0.75 |
| Cr | 17.5–19.5 | 17.5–19.5 |
| Ni | 8.0–10.5 | 8.0–12.0 |
| P | ≤0.045 | ≤0.045 |
| S | ≤0.030 | ≤0.030 |
| N | ≤0.10 | ≤0.10 |
Mechanical Properties
| Property | 304 | 304L |
|---|---|---|
| Tensile strength | ≥515 MPa (75 ksi) | ≥485 MPa (70 ksi) |
| Yield strength (0.2%) | ≥205 MPa (30 ksi) | ≥170 MPa (25 ksi) |
| Elongation (50 mm) | ≥40% | ≥40% |
| Hardness | ≤201 HBW | ≤201 HBW |
Which One Should You Choose?
Choose 304 for:
- Parts that are not welded, or are annealed after welding
- Applications where the extra 35 MPa of specified strength matters
- General stock where dual-certified material is available anyway
Choose 304L for:
- Welded tanks, vessels and pipe left in the as-welded condition
- Multi-pass or heavy-section welding
- Service between 425–815 °C is expected around welds
- Corrosive service where weld-zone attack has been seen before
Our verdict
Dual-certified 304/304L can satisfy the low-carbon chemistry and 304 strength requirements at once, but it must be confirmed on the MTC for the ordered product and standard. Specify 304L or verified dual-certified material when welding and corrosion conditions require it.
Cost and Availability
Compare the current stock position, mill route, minimum production quantity, processing yield, testing and delivered cost for 304 and 304L at quotation time. A fixed price ratio would be misleading because product form, size, condition and market timing can change the commercial result.
Do Not Substitute Without Review
Do not replace 304 with 304L, or the reverse, from the grade name alone. Recheck chemistry, mechanical-property condition, product standard, dimensions, corrosion environment, welding procedure and project approval before substitution.
304 & 304L Products We Export
304 Stainless Steel Sheet
304/304L stainless steel sheet in 2B, BA, No.4 and mirror finish, in quotation-confirmed dimensions, cut to size, with ordered documentation.
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304 Stainless Steel Welded Pipe
304 welded stainless steel pipe and tube to ASTM A312, A249 and A554 — industrial, sanitary and polished decorative, round, square and rectangular sections.
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304 Stainless Steel Round Bar
304/304L stainless steel round bar, in quotation-confirmed dimensions, bright drawn h9/h11 or peeled, cut to length — machining stock with full heat traceability.
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Frequently Asked Questions
Is 304L weaker than 304?
The specified annealed minimums differ. Material certified to both designations must meet both sets of requirements, but dual certification should be confirmed on the MTC rather than inferred from normal market practice.
Do I need 304L if my parts are not welded?
Sensitization risk is mainly associated with welding and prolonged exposure in the applicable temperature range. For unwelded, annealed service, compare 304 and 304L against the governing standard and current quotation; the L suffix alone does not establish a fixed price difference.
Is dual-certified 304/304L acceptable?
Often yes when the certificate satisfies both chemistry and mechanical requirements, but the governing product standard and project specification must explicitly permit the dual certification.
RFQ
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Technical content updated: 2026-07-29
Organizational author: Tsingshan (Shandong) Iron & Steel Co., Ltd..Review method, status and limitations.