316 vs 316L stainless steel: the carbon difference
316 vs 316L stainless: what the L means, why low carbon matters for welding and corrosion, and when to specify each grade.
316 and 316L are the same molybdenum-bearing stainless, except 316L has lower carbon (under 0.03%). That one change matters when the part is welded: low carbon stops chromium carbides forming at the weld, which would otherwise cause intergranular corrosion (weld decay). Spec 316L for welded or corrosion-critical parts; plain 316 is fine, and slightly stronger, for machined parts that are not welded. In practice much stock is dual-certified 316/316L.
What the L means
The L is low carbon. Everything else, including the molybdenum that gives 316 its chloride resistance, is the same.
| Property | 316 | 316L |
|---|---|---|
| Carbon | Up to ~0.08% | Under 0.03% |
| Strength | Slightly higher | Slightly lower |
| Corrosion after welding | Can sensitize | Resists weld decay |
| Cost | Comparable | Comparable |
| Best for | Machined, non-welded parts | Welded and corrosion-critical parts |
Why it matters for welding
Heat the carbon-bearing 316 into the 425 to 815 C range (as welding does) and chromium carbides can form at the grain boundaries, pulling chromium out of the surrounding metal. That chromium-depleted zone then corrodes along the weld, a failure called sensitization or weld decay. 316L has too little carbon for that to happen, so welded 316L keeps its corrosion resistance without a post-weld anneal. For food, pharma and marine weldments, that is why 316L is specified.
When plain 316 is fine
Machined parts that are not welded, where the slightly higher strength of standard carbon is useful and sensitization never comes up. For the bigger stainless decision, 304 versus 316 (the molybdenum), see 304 vs 316.
Finishing
Passivate stainless after machining to restore the corrosion-resistant oxide layer, especially on welded parts.
FAQ
What does the L in 316L mean?
Low carbon: under 0.03%, compared with up to about 0.08% for standard 316.
Is 316 or 316L more corrosion resistant?
In general service they are similar. 316L resists intergranular corrosion at welds because its low carbon prevents chromium carbide formation, so it wins for welded parts.
Which is stronger, 316 or 316L?
Standard 316 is slightly stronger because of its higher carbon, but the difference is small and rarely the deciding factor.
When do I need 316L instead of 316?
For welded parts and corrosion-critical service such as food, pharmaceutical and marine work, where weld decay must be avoided.
What is dual-certified 316/316L?
Stock that meets both the low-carbon limit of 316L and the strength minimums of 316, so it can be used wherever either grade is called for. Much 316 stock is dual-certified.
Last reviewed: October 2026. Related reading: 304 vs 316 stainless steel and what is passivation.
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