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GRADE PROFILE

Duplex 2205 — S31803 (historical designation)

S31803 and S32205 share the same commercial name "2205" and, historically, the same EN number 1.4462. But their composition ranges do not coincide: S32205 tightens chromium and, above all, nitrogen upward, which raises its nominal PREN to 35 against 34 for S31803. The market has shipped S32205 for around twenty years — yet a good number of purchase specifications and material certificates still in circulation name S31803 specifically.

Metal value describes alloy content, not a purchase price: it ignores process, form (welded or seamless), quantity and availability.

When to choose it

When a document you did not write yourself — a purchase specification, drawing, or existing EN 10204 material certificate — names S31803 or UNS S31803 specifically, not S32205. That is this page's real use: checking that a heat labelled "2205" actually falls within S31803's wider range, rather than judging it against S32205's narrower one — an easy point to miss once the two grades are lumped together under the single commercial name "2205".

It also helps explain a heat that falls outside the S32205 range but stays within the S31803 range: the heat is not out of spec, it simply matches the older designation.

When not to choose it

Whenever nothing specifically requires S31803. S32205 is what the market ships today, with a higher PREN floor and therefore a wider safety margin on pitting resistance, for a price difference that is not significant at purchase. Defaulting to S31803 with nothing requiring it has no metallurgical justification — use the S32205 page instead.

And whenever a precise mechanical value is load-bearing for a calculation. This page has no mechanical source of its own — see the FAQ below.

Composition

ASTM A789/A790
Element %
C ≤ 0.03
Cr 21–23
Ni 4.5–6.5
Mo 2.5–3.5
N 0.08–0.2
Mn ≤ 2
Si ≤ 1
P ≤ 0.03
S ≤ 0.02

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) —
EN (symbolic) —
ASTM / AISI 2205
UNS S31803
JIS —
AFNOR —

Tube product standards :

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

Availability

The same forms as S32205 (welded, seamless and heat exchanger tube, Ø 10 to 610 mm, plus fittings, flanges and bar) are expected for this grade, without independent confirmation: an order placed without further detail is filled with S32205 today. If your need is specifically for S31803, say so at enquiry stage — we will check actual availability rather than assume it.

Related grades

  • 2205 (1.4462) — the modern designation of the same 2205, the one the market ships — see that page for sourced composition, mechanical properties and applications.
  • 2304 (S32304) — duplex without molybdenum, cheaper, for lighter waters.
  • 316L (1.4404) — the austenitic reference, if mechanical loading is not the issue.

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Frequently asked questions

Are S31803 and S32205 the same grade?
No. Same commercial name "2205", historically the same EN number 1.4462, but two different composition ranges — nitrogen in particular, whose minimum rises from 0.08% (S31803) to 0.14% (S32205). Nominal PREN 34 against 35.
Should I order S31803 or S32205?
Unless an existing document (specification, drawing, certificate) names S31803 specifically, order S32205: that is what the market ships, with a higher pitting-resistance margin for a comparable cost. This page exists to check compliance against an older document, not to steer a new purchase.
Why are the mechanical properties and applications identical to S32205's?
Because they are carried over from that page for lack of a source dedicated to S31803 specifically — the two grades belong to the same product family and behave very similarly in service, but the claim has not been verified grade by grade. Only this page's composition and PREN are independently sourced.