Last verified 19 August 2026.
The comparison
| Property | Duplex 2205 | 316L | Evidence |
|---|---|---|---|
| Proof strength Rp0.2, minimum (ASTM) | 450 MPa | 170 MPa | E3 E3 |
| Proof strength Rp0.2, minimum (EN) | 500 MPa | 240 MPa | E3 E3 |
| PREN | 35 — | 24 — | E3 E3 |
| Modulus of elasticity | 200 GPa | 200 GPa | E3 E3 |
| Density | 7.8 g/cm³ | 8.0 g/cm³ | E3 E3 |
| Thermal conductivity | 15 W/(m·K) | 15 W/(m·K) | E3 E3 |
| Tensile strength Rm, minimum | 700 MPa | 530 MPa | E3 E3 |
| Elongation A80, minimum | 20 % | 40 % | E3 E3 |
PREN — different documents — Outokumpu Forta range datasheet against Outokumpu Supra range datasheet
Modulus of elasticity — different documents — Outokumpu Forta range datasheet against Outokumpu Supra range datasheet
Density — different documents — Outokumpu Forta range datasheet against Outokumpu Supra range datasheet
Thermal conductivity — different documents — Outokumpu Forta range datasheet against Outokumpu Supra range datasheet
The trap on this comparison
Proof strength Rp0.2 is specified twice: 450 MPa (ASTM A240/A240M, plate, 20 °C) and 500 MPa (EN 10088-2, cold rolled strip, 20 °C) — 11% apart. Both correct. Which one governs is a question about your drawing and your product form, not about the material.
Proof strength Rp0.2 is specified twice: 170 MPa (ASTM A240/A240M, plate, annealed, 20 °C) and 240 MPa (EN 10088-2, cold rolled coil and sheet, 20 °C) — 41% apart. Both correct. Which one governs is a question about your drawing and your product form, not about the material.
Where each side’s numbers come from
See Duplex 2205 and 316L — each page lists every source, every demotion and every gap. Nothing on this page is derived from anything not on those two, and our coverage limits are stated separately.
Where a PREN appears above, read it as a ranking number rather than a qualification: what PREN can and cannot tell you.
When to choose which
Duplex 2205. Where strength sets the section or chlorides set the material. At the 450 MPa ASTM A240 minimum against 170 for 316L, a strength-driven part in 2205 is dramatically thinner, and for a plate in bending that compounds. The higher PREN also moves you out of the range where 316L is marginal in warm chloride service.
316L. It is the default molybdenum-bearing austenitic, and the reasons are practical rather than exceptional. Single phase, so no phase balance to manage in welding. Forgiving heat input. Formable. Stocked by everyone in every product form. Every fabricator has qualified procedures for it. When a design is not strength-driven and the environment is not aggressive, 316L is chosen because choosing anything else has to be justified.
Against Duplex 2205: Fabrication and supply, not properties. Duplex has a narrower heat-input window, needs procedures qualified for it, and is not on every stockist’s shelf in every thickness. A shop with qualified duplex procedures treats 2205 as ordinary; a shop without them faces a new PQR and an eight-week lead time, and that is frequently decisive regardless of what the property table says.
Against 316L: Two things. Strength: at the 170 MPa ASTM A240 plate minimum it is weak for a structural section, and a strength-driven part in 316L is thick. Chlorides: the molybdenum helps against pitting relative to 304, but 316L is marginal in warm chloride service, and the failure mode that usually appears is crevice corrosion at gaskets and joints, which PREN does not predict.
What this comparison does not cover
- Crevice corrosion, the usual failure mode in seawater service, which PREN does not predict.
- Elevated temperature: 2205 has a service ceiling that 316L does not share, driven by 475 °C embrittlement and sigma-phase formation. Not sourced here.
- Cryogenic behaviour.
- Fatigue, fracture toughness and stress corrosion cracking.
- Cost, which moves with alloy surcharges and is not a fixed ratio.
- Composition limits, not established.
- Composition limits are not established, and they are what a purchase order actually specifies.
- Elevated and cryogenic temperature behaviour.
- Welding procedure guidance, filler selection and post-weld treatment.
- Product forms other than plate, where minima differ.
- Whether 316L suits your application. No page can answer that.
Generated from data/materials/2205.yaml and 316l.yaml.