304L Stainless Steel
metalaustenitic stainless steel
UNS S30403EN 1.4307AISI 304LSS 304LDIN X2CrNi18-9
Composition — UNS S30403 / ASTM A276 / EN 1.4307
| Element | Min % | Max % | Notes |
|---|---|---|---|
| Fe | bal. | balance | |
| Cr | 18.00 | 20.000 | Higher Cr range than 316L (16–18%) compensates for absence of Mo in general corrosion resistance |
| Ni | 8.00 | 12.000 | Austenite stabiliser; maintains FCC structure through all temperatures down to cryogenic |
| Mn | — | 2.000 | |
| Si | — | 0.750 | |
| C | — | 0.030 | Low carbon ('L') reduces sensitisation — prevents Cr carbide precipitation at grain boundaries during AM thermal cycles |
| P | — | 0.045 | |
| S | — | 0.030 | |
| N | — | 0.100 | Nitrogen stabilises austenite and provides solid-solution strengthening |
Mechanical & thermal properties — 4 conditions
| Property | LPBF as-built (XY) | LPBF as-built (Z) | LPBF annealed (XY) | Binder Jetting sintered (isotropic) |
|---|---|---|---|---|
| Elastic modulus | 193 GPa | — | — | — |
| Yield strength (0.2%) | 400–520 MPa | 360–480 MPa | 180–270 MPa | 140–230 MPa |
| Ultimate tensile strength | 560–680 MPa | 520–640 MPa | 490–600 MPa | 380–530 MPa |
| Elongation at break | 25.0–50.0 % | 20.0–45.0 % | 40.0–65.0 % | 15.0–45.0 % |
| Hardness (HV) | 190–260 HV10 | — | — | — |
| Density | 8.00 g/cm³ | — | — | — |
| Relative density | — | — | — | 96.5–99.5 % |
| As-built surface Ra | 7.0–18.0 µm | — | — | — |
Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.
Engineering considerations
- 316L vs 304L selection: the primary decision criterion is chloride exposure. If the part will contact seawater, body fluids, de-icing chemicals, swimming pool water, or any saline solution, specify 316L. 304L is appropriate for food contact (non-acidic), architectural, and general industrial use in dry or low-humidity environments.
- Sensitisation prevention: always specify 304L (not 304) to ensure C ≤ 0.03%. During LPBF, the rapid cooling cycle reduces sensitisation risk. Post-build welding or heat treatment between 425–870°C should be avoided or followed by solution annealing.
- Binder jetting selection: use BJ 304L when geometric complexity is the primary driver and structural performance is secondary. Verify sintered density ≥98% by Archimedes method; density <97% significantly impairs corrosion resistance as well as strength.
- Post-processing corrosion: electropolish or passivation treatment (citric acid or nitric acid per ASTM A380) recommended after LPBF to remove iron contamination from build substrate and improve corrosion resistance.
- TRIP effect awareness: 304L (unlike 316L) may undergo some deformation-induced martensite transformation under high plastic strain. This increases work hardening rate and can introduce slight magnetic response. For fully non-magnetic applications, verify magnetic permeability after any cold working.
- Surface finish: LPBF as-built Ra ~10 µm is insufficient for most food-contact applications. Specify electropolishing to Ra <0.8 µm for hygienic applications; verify with Ra measurement per ISO 4288.
Advantages
- Lower cost than 316L — 15–20% less expensive powder, no Mo premium
- Similar tensile properties to 316L in LPBF as-built condition — Mo contribution to strength is modest
- Excellent ductility and toughness from austenitic FCC structure — survives forming and post-AM processing
- Non-magnetic (fully austenitic) — suitable for sensor housings and MRI-adjacent applications
- Binder jetting option enables complex geometries at lower cost than LPBF for lower-performance applications
- Good weldability — low C content prevents sensitisation during post-build welding or repair
- Wide availability of powder from multiple suppliers; well-established processing parameters
Limitations
- No molybdenum — significantly lower pitting corrosion resistance in chloride environments vs 316L. PREN (Pitting Resistance Equivalent Number) for 304L ≈18 vs 316L ≈24
- Not suitable for marine, offshore, medical implant, pharmaceutical, or any chloride-rich application — specify 316L for these
- As-built LPBF cellular substructure may be sensitisation risk in weld heat-affected zones — specify low-carbon 'L' grade and verify with ASTM A262
- Binder jetting produces lower and more variable properties than LPBF — not recommended for structural applications
- No AM-specific ASTM material standard for 304L (only 316L has ASTM F3184)
- Susceptible to stress corrosion cracking in chloride + tensile stress conditions — 316L is preferred even in mildly challenging environments
Typical applications
Food processing equipment (hoppers, valves, mixers) — FDA-compliant, no Mo required in non-chloride food environmentsArchitectural metalwork and cladding with complex geometriesGeneral industrial enclosures, housings, and bracketsCryogenic storage components (vessels, piping — austenite stable at -196°C)Chemical processing vessels in non-chloride serviceAutomotive exhaust components and decorative trimWater treatment infrastructure (non-chloride-rich environments)Prototype and low-volume production functional parts where corrosion resistance required
Industries
food-processingarchitectureindustrialautomotiveenergy
Standards & certifications
ASTM-F3184established
316L SS powder bed fusion — 304L can be assessed against this standard's methodology; no equivalent 304L AM standard exists
aerospaceindustrial
No direct ASTM AM standard for 304L. Use ASTM F3184 methodology (316L) as a framework, applying 304L composition limits. Most AM suppliers qualify 304L to customer-specific or internal specifications.
Compatible AM processes (3)
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Last reviewed: 2026-05-13 · v1 · Sources: outokumpu-304l-2022, tolosa-2018-304l-lpbf, yan-2017-304l-bj
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