Stainless steel 316 and 316L

Stainless steel 316 and 316L are molybdenum-bearing, austenitic (300-series) stainless steels. Adding 2–3% Mo to the 18Cr-10Ni base improves resistance to chloride pitting and crevice corrosion and boosts performance versus 304 in marine, chemical, and wash-down environments. The “L” grade has low carbon (≤0.03%) for superior weldability and resistance to weld-decay (intergranular corrosion).

Names & Specifications

• UNS: 316 = S31600; 316L = S31603

• EN/DIN: 316 = 1.4401; 316L = 1.4404

• Common product standards: plate/sheet ASTM A240; bar ASTM A276; pipe/tube ASTM A312; wire ASTM A580 (or regional equivalents)

Composition (typical ranges, wt.%)

What changes: The lower carbon in 316L minimizes chromium-carbide precipitation during welding, protecting corrosion resistance in the heat-affected zone.

316 vs 316L — Practical Differences

• Welding: Choose 316L for heavy welds or thick sections; it reduces the risk of intergranular attack.

• High-temperature strength: Standard 316 has a slight edge; for sustained high temps, some projects specify 316H (higher carbon).

• Supply: Many mills dual-certify products as 316/316L when chemistry and properties meet both.

Corrosion Behavior

• Why they beat 304: Molybdenum significantly raises resistance to chloride-induced pitting/crevice corrosion, making 316/316L a common upgrade for coastal, marine, and chemical service.

• Limits: Warm, concentrated chlorides or stagnant crevices can still cause attack—consider duplex or super-austenitic alloys in such cases.

• Rule of thumb: Keep surfaces clean, avoid chloride contamination, and design out tight crevices where possible.

Properties (room temperature, typical)

• Tensile / Yield (min, sheet/plate): ~515 MPa / ~205 MPa; Elongation ~40%

• Density: ~7.98 g/cm³

• Thermal conductivity: ~14–16 W·m⁻¹·K⁻¹

• Magnetism: Essentially non-magnetic when annealed (can become slightly magnetic after cold work)

Common Forms & Finishes Stainless steel 316

Coil, sheet/plate, strip, bar, pipe/tube, wire, and woven or welded wire mesh. Finishes include 2B, pickled, polished, and electropolished for hygienic or ultra-clean service.

Typical Applications Stainless steel 316

• Marine & coastal: architectural fixings, fasteners, splash-zone fabrications

• Process & chemical: heat exchangers, evaporators, pumps/valves, tanks

• Food & pharma: wash-down equipment, tubing, trays, wire cloth/mesh

• Energy & HVAC: flue-gas components, high-temp fixtures (verify temp limits)

Fabrication Tips Stainless steel 316

• Prefer 316L filler (e.g., ER316L) for welded fabrications.

• Clean, pickle, and passivate welds to restore the passive film.

• Avoid chloride cross-contamination during fabrication; rinse and dry after exposure.

Quick Selector

• General duty with chlorides present: 316 or 316L

• Heavy welding / thick sections: 316L

• Higher-temperature service: consider 316H

• Hot, concentrated chlorides: evaluate duplex or super-austenitic grades

FAQs: Stainless steel 316 vs 316L (no links)

1) What’s the main difference between 316 and 316L?
Carbon content. 316 has a maximum of 0.08% C; 316L has a maximum of 0.03% C, which cuts the risk of weld sensitization.

2) Which grade is better for welding?
316L. The lower carbon helps protect the heat-affected zone from intergranular corrosion, especially on thick or multi-pass welds.

3) Is corrosion resistance different between 316 and 316L?
In most environments, general corrosion resistance is similar; 316L mainly excels in welded conditions.

4) Which is better for marine or coastal use?
Both 316 and 316L are common “marine-grade” choices thanks to molybdenum. They resist chloride attack better than 304 but are not immune in stagnant, warm, or highly concentrated chlorides.

5) What are the typical compositions?
Both grades: 16–18% Cr, 10–14% Ni, 2.0–3.0% Mo. The primary difference is carbon (316 ≤0.08%, 316L ≤0.03%).

6) Are 316/316L magnetic?
Essentially non-magnetic when annealed; slight magnetism can appear after cold work.

7) Can 316/316L be hardened by heat treatment?
No. They are austenitic grades and can only be strengthened by cold working.

8) What are typical mechanical properties (sheet/plate minimums)?
316: tensile ~515 MPa, yield ~205 MPa, elongation ~40%.
316L: tensile ~485 MPa, yield ~170 MPa, elongation ~40%.

9) What temperature limits apply?
Good high-temperature oxidation resistance; for sustained higher-temperature strength some specifications use 316H (higher carbon).

10) Can 316L replace 316?
Often yes. Many products are dual-certified 316/316L. Check high-temperature strength requirements before substituting.

11) How do 316/316L compare to 304?
They add 2–3% molybdenum, improving resistance to chloride pitting and crevice corrosion versus 304.

12) Are they suitable for drinking water systems?
Generally yes, provided chloride levels are controlled and good design/maintenance practices are followed.

13) What filler metal should I use for welding?
Use 316L filler (e.g., ER316L) to reduce sensitization risk.

14) What are the common standards and designations?
UNS S31600 (316), UNS S31603 (316L); EN 1.4401 (316), EN 1.4404 (316L). Typical product standards include ASTM A240 (plate/sheet), A276 (bar), A312 (pipe/tube), A580 (wire).

15) When should I consider something beyond 316/316L?
For hot, concentrated chlorides or tight crevices, look at duplex or super-austenitic grades with higher pitting resistance.

Bottom Line

316/316L are the go-to “step up” from 304L when chloride resistance, hygiene, and reliability matter. Choose 316L for welded structures, specify the product form standard, and confirm the service environment to ensure long, trouble-free performance.