Duplex 2205 — what the data actually supports

Data completeness: partial. Last verified 19 August 2026.

Designations

Roughly equal parts austenite and ferrite. The phase balance is what gives 2205 both its strength and its narrower processing window: heat input outside the qualified range shifts the balance and the properties go with it.

Properties, with what each one rests on

8 sourced values, 1 gap named. Publishing the gaps is more useful than filling them from an aggregator that does not say where its numbers came from. The routes to filling them are the standard itself, a mill datasheet, or a mill certificate for your actual heat — which supersedes both at E5.

Where the numbers come from

Proof strength Rp0.2, minimum (ASTM) is E3, not E5. Claimed as a E5 value, but ASTM A240/A240M was not consulted directly. Under the demotion rule, a claimed level a reader cannot verify from the record alone drops one level. 65 ksi. This is the governing value for strength-driven screening. To restore it: open ASTM A240/A240M and record the edition, table and product form.

Proof strength Rp0.2, minimum (EN). The same property for the same alloy, 11% higher — and NOT directly comparable with the ASTM figure above, because the datasheet quotes EN 10088-2 minima for cold rolled strip while the ASTM figure is for plate. Two standards and two product forms. This is exactly why a value belongs to a document and a form, not to a material.

PREN. Corrected on 20 August 2026. The earlier note said the source stated neither its formula nor its input composition; it states both — PRE = %Cr + 3.3 × %Mo + 16 × %N, and 22.4% Cr, 3.1% Mo, 0.17% N, which give 35.4 against the printed 35. It stays at E3 rather than reaching E2, because the composition is the datasheet’s typical value and not an analysis of any heat: the arithmetic is repeatable, the input is not traceable. Sufficient for screening, not for a corrosion argument.

Thermal conductivity. Typical value from a mill datasheet. No test method or specimen condition stated.

Why we do not just copy an aggregator. Because then this page would be a worse copy of MatWeb with no way for you to tell which rows to trust, and the one thing we have that MatWeb does not is the evidence column. Our coverage and its limits.

What Duplex 2205 is usually chosen for

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.

And what it is usually rejected for

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.

The number to be more careful with than any of the above is the difference between a specified minimum and a typical value — a floor the standard guarantees, versus what a supplier’s production usually does. The full version, and the most expensive routine mistake in material data.

Compare

Duplex 2205 vs 316l · Duplex 2205 vs 2304 · Duplex 2205 vs 254smo

What this page 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.

Generated from data/materials/2205.yaml. Regenerate rather than editing this file by hand — edits here are lost on the next build.