Duplex 2205 chemical composition.PDF

Duplex 2205 stainless steel is a ferritic-austenitic duplex steel, typically designated as UNS S31803/S32205 or EN 1.4462. Its alloy composition generally includes 22%–23% chromium, 4.5%–6.5% nickel, and 3.0%–3.5% molybdenum; under the stricter S32205 specification, it also contains 0.14%–0.20% nitrogen. In appropriate operating environments, these elements enable the material to outperform many conventional austenitic stainless steels in terms of resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking.
Compared to 316L stainless steel, Duplex 2205 stainless steel-in standard plate specifications-typically offers a minimum yield strength approximately twice as high. Furthermore, it demonstrates superior resistance to chloride-induced stress corrosion cracking and localized corrosion across a wide range of environments.

 

Click to download the Duplex 2205 specification.PDF

Item	Technical information
Common grade name	Duplex 2205
UNS designations	S31803 / S32205
EN material number	1.4462
EN designation	X2CrNiMoN22-5-3
Material family	Ferritic-austenitic duplex stainless steel
Typical alloy system	22Cr–5Ni–3Mo–N
Common plate standard	ASTM A240 / ASME SA-240
Common pipe standard	ASTM A790 / ASME SA-790
Common tube standard	ASTM A789 / ASME SA-789
Common bar standards	ASTM A276 / ASTM A479
Common forging standard	ASTM A182, with grade and class confirmed in the order

Procurement note: S31803 and S32205 are closely related designations, but their specification limits are not identical. In particular, S32205 has tighter minimum chromium, molybdenum, and nitrogen requirements than the original S31803 composition range. If the project specifically requires S32205, the purchase order and MTC should identify compliance with S32205 rather than simply stating "2205."

 

The following table shows the commonly specified chemical composition limits for UNS S32205 under ASTM A240 for plate, sheet, and strip, expressed as weight percentages. Buyers ordering pipe, tube, bar, or forgings should verify the requirements of the applicable product standard and its specified edition.

Chemical element	Symbol	Minimum (wt.%)	Maximum (wt.%)
Carbon	C	-	0.030
Chromium	Cr	22.00	23.00
Nickel	Ni	4.50	6.50
Molybdenum	Mo	3.00	3.50
Nitrogen	N	0.14	0.20
Manganese	Mn	-	2.00
Silicon	Si	-	1.00
Phosphorus	P	-	0.030
Sulfur	S	-	0.020
Iron	Fe	Balance	-

 

What is the difference between S31803 and S32205 chemical composition?

This distinction matters when evaluating certificates and supplier quotations.

Element	UNS S31803, commonly specified range (%)	UNS S32205, commonly specified range (%)
Chromium (Cr)	21.00–23.00	22.00–23.00
Nickel (Ni)	4.50–6.50	4.50–6.50
Molybdenum (Mo)	2.50–3.50	3.00–3.50
Nitrogen (N)	0.08–0.20	0.14–0.20
Carbon (C)	≤0.030	≤0.030
Manganese (Mn)	≤2.00	≤2.00
Silicon (Si)	≤1.00	≤1.00
Phosphorus (P)	≤0.030	≤0.030
Sulfur (S)	≤0.020	≤0.020

The ranges above are commonly published for these designations, but the applicable product specification takes precedence. A heat meeting the tighter S32205 limits may also satisfy S31803 chemistry, but buyers should not assume that every product marked S31803 meets all S32205 requirements, including mechanical properties.

 

What is the PREN of Duplex 2205?

The Pitting Resistance Equivalent Number (PREN) is commonly used as a comparative metric for evaluating a material's resistance to pitting corrosion. For 2205 duplex stainless steel, a widely adopted formula is:
PREN = %Cr + 3.3(%Mo) + 16(%N)
Using representative values-22.5% chromium (Cr), 3.25% molybdenum (Mo), and 0.17% nitrogen (N)-the calculated PREN is approximately 35.9. Consequently, its typical value generally falls between 35 and 36, depending on the specific chemical composition and the formula employed for the calculation.

 

The following are common minimum requirements for UNS S32205 plate under ASTM A240. Other product forms and standards may have different requirements.

Mechanical property	Typical ASTM A240 minimum or limit	Unit
Tensile strength	655 minimum	MPa
0.2% yield strength	450 minimum	MPa
Elongation	25 minimum	%
Hardness	31 maximum	HRC
Density	Approximately 7.8	g/cm³

 

Duplex 2205 vs. 316L: performance comparison

Property	Duplex 2205	316L stainless steel
Typical chromium content	22–23%	16–18%
Typical molybdenum content	3.0–3.5% for S32205	2–3%
Minimum yield strength under common plate specifications	450 MPa	170 MPa

 

Duplex 2205 is available in multiple product forms. The appropriate ASTM specification depends on whether the buyer needs flat products, piping, bar stock, or forged components.

Product form	Common specification	Typical applications
Plate, sheet and strip	ASTM A240 / ASME SA-240	Pressure vessels, tanks, chemical equipment, structural components
Seamless and welded pipe	ASTM A790 / ASME SA-790	Process piping, offshore systems, corrosive-fluid transport
Seamless and welded tube	ASTM A789 / ASME SA-789	Heat exchangers and general-service tubing
Bar and shapes	ASTM A276 / ASTM A479	Shafts, machined parts, industrial components
Forged flanges and fittings	ASTM A182, with grade confirmed	Piping systems and pressure components
Wrought butt-welding fittings	ASTM A815	Elbows, tees, reducers and other piping fittings

Are you looking for specific product forms (such as plates, pipes, or round bars) or welding and fabrication guidelines for Duplex 2205?

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Duplex 2205 RFQ checklist

Information required	Example
Material grade	UNS S32205 or S31803
Product form	Plate, sheet, coil, pipe, tube, bar, flange or fitting
Material standard	ASTM A240, A790, A789, A276, or another applicable standard
Dimensions	Thickness × width × length, or OD × wall thickness × length
Quantity	Pieces, meters, or metric tons
Delivery condition	As required by the applicable specification
Certificate	Heat-specific MTC; EN 10204 Type 3.1 if specified
Inspection	Chemical analysis, mechanical tests, dimensional inspection, PMI or other agreed tests
Delivery requirements	Destination, Incoterm, packing, and target delivery date

FAQ

How does 2205 compare to 316L?
Its yield strength is approximately twice that of 316L (450 MPa vs. ~270 MPa), and it has a Pitting Resistance Equivalent Number (PREN) of 34–40 (compared to 24–26 for 316L), offering superior resistance to chloride pitting and stress corrosion cracking (SCC).

 

What is the maximum service temperature for 2205?
The continuous service temperature is approximately 300 °C (572 °F); the ASME standard sets an upper limit of 315 °C. Exceeding this temperature can trigger "α' (alpha-prime) phase embrittlement," leading to an irreversible loss of material toughness.

 

What filler metal is recommended for welding 2205?
ER2209 / E2209 (filler metals matched to duplex stainless steel) are recommended. During welding, the interpass temperature should be kept at ≤ 150 °C, and the heat input should be maintained between 0.5–1.5 kJ/mm to prevent the formation of the detrimental "σ (sigma) phase."

 

Is duplex 2205 magnetic?
Yes, it is magnetic-due to the presence of a ferritic phase, it exhibits ferromagnetism (magnetic permeability μ ≈ 1.5–3.0), unlike the fully austenitic structure of 304/316L.

 

How should 2205 be machined?
It is more difficult to machine than 316L. Use rigid tooling and fixtures, and reduce cutting speeds by 20%–30%. Employ sharp cutting tools and increase the feed rate to ensure the depth of cut penetrates beyond the work-hardened layer.