Our molybdenum-bearing stainless is stocked as 316 / 316L dual-certified material. As with our 304L / 304 / 302, that isn’t two different products — it is one material whose mill-certified chemistry and mechanical properties satisfy both alloys at once.
Only one element differs
316 and 316L are chemically identical except for one element: carbon. Chromium, nickel and molybdenum share the same ranges in both. We buy material with carbon held to the 316L maximum of 0.030%, which automatically places it inside the 316 limits as well. That lets the mill certify the same material to AMS 5524 (316) and AMS 5507 (316L), along with ASTM A240 and ASTM A666.
Chemical Requirements — Type 316 & 316L (weight %)
| Element | 316UNS S31600 | 316LUNS S31603 | Dual-CertifiedOverlap Range |
|---|---|---|---|
| Covering specs | AMS 5524 A240 · A666 | AMS 5507 A240 · A666 | Meets both |
| Carbon (C) | 0.08 max | 0.030 max | 0.030 max |
| Manganese (Mn) | 2.00 max | 2.00 max | 2.00 max |
| Silicon (Si) | 0.75 max | 0.75 max | 0.75 max |
| Phosphorus (P) | 0.045 max | 0.045 max | 0.045 max |
| Sulfur (S) | 0.030 max | 0.030 max | 0.030 max |
| Chromium (Cr) | 16.0–18.0 | 16.0–18.0 | 16.0–18.0 |
| Nickel (Ni) | 10.0–14.0 | 10.0–14.0 | 10.0–14.0 |
| Molybdenum (Mo) | 2.00–3.00 | 2.00–3.00 | 2.00–3.00 |
| Nitrogen (N) | 0.10 max | 0.10 max | 0.10 max |
| Iron (Fe) | Balance | Balance | Balance |
Meeting the higher strength
The second half of a dual certification is strength. Lowering carbon also lowers strength, so 316L carries lower mechanical minimums than 316. Dual-certified material has to meet the higher 316 minimums while still meeting 316L chemistry.
Mechanical Requirements — Annealed (minimum, ASTM A240 / A666)
| Property | 316 | 316L | Dual-CertifiedMust Meet |
|---|---|---|---|
| Tensile strength, psi | 75,000 | 70,000 | 75,000 |
| Yield strength (0.2%), psi | 30,000 | 25,000 | 30,000 |
| Elongation in 2″ | 40% | 40% | 40% |
The short version: 316L chemistry, 316 strength. Carbon is the only element that differs between the two grades, and holding it to the 316L maximum satisfies both — provided the material still tests to 316's higher tensile and yield minimums.
What about the hard tempers?
- 1/8 Hard, Quarter Hard and Half Hard 316 / 316L is certified to ASTM A666.
- Full Hard 316 / 316L is certified to the 316 / 316L annealed AMS and ASTM specifications for chemistry only — the mechanical requirements of those specifications don’t apply to Full Hard. You’ll see it marked “chemistry only” on the Stock List and the Specification Cross Reference.
Values shown are specification limits, not a mill analysis — actual chemistry and test results appear on the certified mill test report supplied with your order. This article is educational information only; always order to the current revision of the governing specification.