Last verified 19 August 2026.
The comparison
| Property | Duplex 2205 | Super duplex 2507 | Evidence |
|---|---|---|---|
| Proof strength Rp0.2, minimum (EN) | 500 MPa | 550 MPa | E3 E3 |
| PREN | 35 — | 43 — | E3 E3 |
| Modulus of elasticity | 200 GPa | 200 GPa | E3 E3 |
| Density | 7.8 g/cm³ | 7.8 g/cm³ | E3 E3 |
| Thermal conductivity | 15 W/(m·K) | 15 W/(m·K) | E3 E3 |
| Tensile strength Rm, minimum | 700 MPa | 750 MPa | E3 E3 |
| Elongation A80, minimum | 20 % | 20 % | E3 E3 |
| Proof strength Rp0.2, minimum (ASTM) | 450 MPa | not established here | E3 / — |
All shared rows compare like for like.
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.
Where each side’s numbers come from
See Duplex 2205 and Super duplex 2507 — 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.
Super duplex 2507. Seawater and the aggressive end of chloride service, where 2205 is marginal. At the 550 MPa EN 10088-2 minimum it is also the strongest of the stainless grades on this site, so a strength-driven section in 2507 is thinner again than in 2205.
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 Super duplex 2507: Fabrication and supply, almost always. A narrower heat-input window than 2205, procedures that must be qualified specifically for it, and availability that is thin outside common thicknesses. A shop without a qualified procedure faces a new PQR and a lead time measured in weeks, and that is frequently decisive regardless of what the property table says.
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.
- The ASTM plate minimum is not established here.
- Crevice corrosion, which PREN does not predict and which usually decides seawater work.
- Elevated temperature: super duplex carries the same 475 °C embrittlement and sigma-phase constraints as 2205, and they arrive sooner. Not sourced here.
- Cost, which is materially above 2205 and moves with alloy surcharges.
Generated from data/materials/2205.yaml and 2507.yaml.