316 Stainless Steel vs 316L Stainless
316 and 316L are molybdenum-bearing austenitic stainless steels with near-identical corrosion resistance. The only meaningful difference is carbon: 316L caps C at 0.03% to prevent sensitisation during welding.
316 Stainless Steel
UNS S31600
Composition (wt %)
| Element | Min | Max |
|---|---|---|
| Fe | 60.0 | 75.0 |
| Cr | 16.0 | 18.0 |
| Ni | 10.0 | 14.0 |
| Mo | 2.0 | 3.0 |
| Mn | 0.0 | 2.0 |
| C | 0.0 | 0.08 |
316L Stainless
UNS S31603
Composition (wt %)
| Element | Min | Max |
|---|---|---|
| Fe | 60.0 | 72.0 |
| Cr | 16.0 | 18.0 |
| Ni | 10.0 | 14.0 |
| Mo | 2.0 | 3.0 |
| Mn | 0.0 | 2.0 |
| C | 0.0 | 0.03 |
Key differences
| Aspect | 316 Stainless Steel | 316L Stainless | Engineering impact |
|---|---|---|---|
| Maximum carbon | 0.08% C max | 0.03% C max | 316L resists intergranular corrosion in the heat-affected zone after welding without post-weld anneal. 316 can sensitise between 425-870 C if not annealed. |
| Mechanical strength (annealed) | Slightly higher yield (~205 MPa) | Slightly lower yield (~170 MPa) | For unwelded structural parts, 316 offers marginal strength benefit. For most wrought service the difference is immaterial. |
| Weldability | Requires PWHT for thick sections | Weld-and-forget up to typical structural thicknesses | 316L is the default choice for welded vessels, tanks, and piping in chloride-bearing service. |
| Typical specification | ASTM A240 Type 316, UNS S31600 | ASTM A240 Type 316L, UNS S31603 | Dual-certified 316/316L plate is widely available and satisfies both specs simultaneously. |
When to choose 316 Stainless Steel
- Bar stock for machined fittings used un-welded
- Fastener applications where slightly higher yield matters
- Service temperatures above 500 C (L-grade creep is lower)
When to choose 316L Stainless
- Welded pressure vessels and pipework
- Food, pharma, and semiconductor process lines
- Marine fittings exposed to chloride after production
Frequently asked questions
Is dual-certified 316/316L the same as 316L?
Dual-certified stock meets both specifications - C <= 0.03% plus the higher mechanical minima of 316. For welded service it behaves as 316L.
Can I substitute 316L for 316 on a drawing that calls out 316?
Usually yes for corrosion service below 500 C. Check drawing notes for yield-strength callouts - 316L minimum yield is lower.
Does 316L need post-weld heat treatment?
Not for the purpose of preventing sensitisation - that is the point of the low-carbon grade. PWHT may still be specified for stress relief in heavy sections.