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GRADE PROFILE

Duplex 2205 — 1.4462 / X2CrNiMoN22-5-3

2205 is the reference duplex: half austenitic, half ferritic, PREN 34 to 36, and a yield strength close to twice that of a 316L. It holds brackish water and often allows thinner walls — which is why it costs less than it looks.

When to choose it

In brackish water, moderate-salinity desalination, petrochemicals and pulp and paper. And above all wherever chloride stress corrosion cracking is the dominant risk: that is the point at which duplex does not compare with 316L but replaces it, because its two-phase structure resists a mechanism to which austenitics give way suddenly.

On vessels and piping under load, the argument is economic as much as metallurgical. Double the yield strength allows thinner walls, which offsets part of the material premium and lightens the supporting structure.

When not to choose it

In continuous service above 300 °C. Sigma phase precipitates and embrittles the alloy irreversibly. That is a hard limit, not a precaution.

In cryogenic service, where the ferritic phase loses its ductility.

In hot seawater without reservation. A PREN of 35 is not enough for that medium: it is the domain of 2507 or 254 SMO.

And on sites without a qualified welding procedure. The austenite/ferrite balance is set on cooling; poorly controlled heat input gives a weld that is too ferritic and less resistant than the parent metal. Duplex does not forgive improvised welding.

Composition

Chemical composition (% by mass)
Element %
C ≤ 0.03
Cr 21–23
Ni 4.5–6.5
Mo 2.5–3.5
N 0.1–0.22
Mn ≤ 2
Si ≤ 1

Mechanical properties

We only publish mechanical properties tied to a specific standard and product form — welded tube, seamless tube and bar do not share the same values, and the gap routinely exceeds 30%. The figures that apply to your specification appear on the material certificate; ask us at enquiry stage.

Designations and standards

Equivalent normative designations
Reference Designation
EN (numeric) 1.4462
EN (symbolic) X2CrNiMoN22-5-3
ASTM / AISI 2205
UNS S32205, S31803
JIS SUS329J3L
AFNOR —

Tube product standards :

  • EN 10216-5
  • EN 10217-7
  • ASTM A790
  • ASTM A789

Availability

Welded, seamless and heat exchanger tube, Ø 10 to 610 mm, plus fittings, flanges and bar. Partner stock or mill depending on the size and quantity. EN 10204 3.1 material certificates carrying the heat chemistry supplied with the goods.

Related grades

  • 2304 (S32304) — duplex without molybdenum, cheaper, for lighter waters.
  • 2507 (1.4410) — super duplex, PREN 42.5, for seawater and offshore.
  • 316L (1.4404) — the austenitic reference, worth comparing where mechanical loading is not an issue.

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Frequently asked questions

Are S32205 and S31803 the same thing?
Both correspond to 1.4462, but S32205 imposes tighter chromium, molybdenum and nitrogen ranges than S31803. On a borderline application the difference shows in the actual PREN of the heat. If your specification names S32205, an S31803 is not automatically compliant.
Is 2205 really cheaper than 316L?
By weight, no: cost index 175 against 130. At equal service, often yes, because the yield strength allows a thinner wall. The calculation is done on the finished item, not on the material price.
What is the maximum service temperature?
In continuous service, around 300 °C. Beyond that, sigma phase precipitation embrittles the alloy irreversibly, and the loss of toughness cannot be recovered by heat treatment.