Duplex 2205
UNS S31803 / S32205 EN / W.Nr. 1.4462
22Cr-5Ni-3Mo nitrogen-alloyed duplex — the general-purpose grade for chloride environments, with yield strength about twice that of 316L.
Duplex & Super Duplex Steel — Grades & Products
Austenitic-ferritic stainless steels with roughly double the strength of 300-series grades and superior chloride corrosion resistance — for offshore, chemical and desalination duty.
Duplex & Super Duplex Steel — Material Overview
Duplex stainless steels combine a balanced austenite-ferrite microstructure: the ferrite gives yield strength roughly double that of austenitic grades (so thinner walls carry the same pressure), and the mixed structure resists chloride stress-corrosion cracking — the failure mode that limits 300-series steels in hot brines.
Standard duplex 2205 (UNS S31803 / S32205) is the volume grade for chemical, marine and oil-and-gas service. Super duplex grades (S32750, S32760) add chromium, molybdenum and nitrogen for pitting resistance numbers (PREN) above 40 — the entry point for seawater and aggressive oilfield chemistry. Lean duplex S32101 is a lower-nickel structural option with better stress-corrosion resistance than 304/316.
4grades listed
7,800 kg/m³typical density (2205 / super duplex ≈ 7.8 g/cm³)
6product forms
Available Grades
The grades below are the ones most often asked for. Each grade stays on this page — the material-first way to browse.
Super Duplex 2507
UNS S32750 EN / W.Nr. 1.4410
25Cr-7Ni-4Mo super duplex with PREN above 40 — seawater, offshore firewater and chemical service requiring maximum chloride pitting resistance.
Super Duplex S32760
UNS S32760 EN / W.Nr. 1.4501
Tungsten-bearing super duplex (F55) for the most aggressive oilfield and seawater chemistry, with excellent cast-and-weld corrosion properties.
Lean Duplex S32101
UNS S32101
21Cr-1.5Ni low-nickel lean duplex — structural sections, bridges and tanks where 304/316 lack stress-corrosion resistance but full duplex strength is not required.
Chemical Composition (indicative)
Nominal ranges as published in the common product standards. Values are indicative and for comparison only — always purchase against the current ASTM/EN specification and the mill test certificate.
Duplex 2205
| Element | Content |
|---|---|
| Chromium (Cr) | 22.0 – 23.0 |
| Nickel (Ni) | 4.5 – 6.5 |
| Molybdenum (Mo) | 3.0 – 3.5 |
| Nitrogen (N) | 0.14 – 0.20 |
| Carbon (C) | ≤ 0.030 |
Super Duplex 2507
| Element | Content |
|---|---|
| Chromium (Cr) | 24.0 – 26.0 |
| Nickel (Ni) | 6.0 – 8.0 |
| Molybdenum (Mo) | 3.0 – 5.0 |
| Nitrogen (N) | 0.24 – 0.32 |
| Carbon (C) | ≤ 0.030 |
Super Duplex S32760
| Element | Content |
|---|---|
| Chromium (Cr) | 24.0 – 26.0 |
| Nickel (Ni) | 6.0 – 8.0 |
| Molybdenum (Mo) | 3.0 – 4.0 |
| Tungsten (W) | 0.5 – 1.0 |
| Nitrogen (N) | 0.20 – 0.30 |
Lean Duplex S32101
| Element | Content |
|---|---|
| Chromium (Cr) | 20.5 – 22.5 |
| Nickel (Ni) | 1.5 – 3.0 |
| Molybdenum (Mo) | 0.1 – 0.8 |
| Manganese (Mn) | 4.0 – 6.0 |
| Nitrogen (N) | 0.20 – 0.25 |
Mechanical Properties (indicative)
Typical minimum values for the common product forms in the annealed / solution-treated condition. Actual properties depend on product form, specification revision and heat treatment.
Duplex 2205
| Property | Value |
|---|---|
| Tensile strength (min) | 620 – 655 MPa |
| Yield strength (min) | 450 MPa |
| Elongation (min) | 25 % |
| PREN (typical) | 34 – 36 |
Super Duplex 2507
| Property | Value |
|---|---|
| Tensile strength (min) | 795 MPa |
| Yield strength (min) | 550 MPa |
| Elongation (min) | 15 % |
| PREN (typical) | ≥ 40 |
Super Duplex S32760
| Property | Value |
|---|---|
| Tensile strength (min) | 750 MPa |
| Yield strength (min) | 550 MPa |
Lean Duplex S32101
| Property | Value |
|---|---|
| Tensile strength (min) | 650 MPa |
| Yield strength (min) | 450 MPa |
Physical Properties
| Property | Value |
|---|---|
| Density (2205) | 7.8 g/cm³ (≈ 7805 kg/m³) |
| Density (2507 / S32760) | ≈ 7.8 g/cm³ |
| Modulus of elasticity | ≈ 200 GPa |
| Thermal conductivity (20 °C) | ≈ 15 W/m·K |
Available Product Forms
Duplex & Super Duplex Steel is offered in the product forms below. Availability varies by grade and size — confirm the exact combination with our sales desk.
Pipes & Tubes
Seamless and welded pipes and tubes to ASTM/ASME, IS and BS specifications — including boiler, air-preheater and corten tubes.
Sheets, Plates & Coils
Hot-rolled and cold-rolled sheets, plates, coils, circles and flats in standard and cut sizes.
Pipe Fittings
Butt-weld, forged and socket-weld fittings — elbows, tees, reducers, caps, stub ends, olets and nipples.
Flanges
Weld neck, slip-on, blind, lap joint, socket weld, threaded, spectacle, ring joint, orifice and deck flanges to ASME B16.5, 150# – 2500#.
Bars, Rods & Wires
Bright and black round bars, square and hex bars, flats and wires in stainless, duplex, alloy, carbon and nickel-alloy grades.
Fasteners
Bolts, nuts, studs, washers and threaded rods in alloy and stainless grades.
Industrial Applications
- Offshore oil and gas piping, manifolds and umbilicals
- Desalination and brine-handling plants
- Seawater cooling and firewater systems
- Chemical and petrochemical chloride service
- Pulp-mill digesters and bleach-plant equipment
- Structural sections in marine and bridge environments
Applicable Standards
| Standard | Scope |
|---|---|
| ASTM A790 / ASME SA790 | Seamless and welded ferritic/austenitic duplex pipe |
| ASTM A789 / ASME SA789 | Seamless and welded duplex tubes for general service |
| ASTM A240 / ASME SA240 | Duplex plate, sheet and strip |
| ASTM A182 / ASME SA182 | Forged duplex flanges and fittings (F51, F53, F55) |
| ASTM A815 | Wrought duplex fittings |
| ASTM A276 / A479 | Duplex bars and shapes |
| NORSOK M-650 / M-630 | Qualification for offshore duplex delivery |
Quality & Documentation
Duplex material is supplied with EN 10204 Type 3.1 certification, heat-number traceability, and the ferrite/austenite balance and corrosion tests the specification calls for (ASTM A923 for intergranular attack; G48 Method A for pitting). NORSOK-compliant documentation and third-party inspection can be arranged with the enquiry.
Related Engineering Calculators
Pipe Weight Calculator
Theoretical weight of pipe from outside diameter, wall thickness, length and material.
Round Bar Weight Calculator
Theoretical weight of round bars from diameter, length and material.
Sheet & Plate Weight Calculator
Theoretical weight of sheets and plates from length, width, thickness and material.
Technical Flange Calculator
ASME B16.5 dimensions, bolting pattern and weight estimates for 14 flange types.
Unit Conversion Calculator
mm ↔ in, m ↔ ft, kg ↔ t, kg/m ↔ lb/ft and MPa ↔ psi conversions.
Frequently Asked Questions
What is the difference between S31803 and S32205?
They are both "2205", but S32205 is the tightened modern composition with a narrower chromium, molybdenum and nitrogen window that guarantees the corrosion performance buyers actually need. New material is normally ordered to S32205; S31803 remains an accepted UNS for older stock and drawings.
When is super duplex required instead of standard duplex?
When the PREN (pitting resistance equivalent) needs to exceed roughly 40 — typically seawater above ambient temperature, high-chloride oilfield brines with H₂S, or chemical service that pits 2205. Super duplex also carries higher strength.
Can duplex be welded like 316L?
It welds readily with duplex-matching fillers and controlled heat input, but the cooling rate must keep the austenite-ferrite balance — over-heating or excessive travel can raise ferrite. Follow the WPS; the 2507/2250 nitrogen-bearing fillers and 2209/2594 are typical choices.
Is duplex stronger than austenitic stainless steel?
Yes — yield strength is roughly double (450–550 MPa versus 205–240 MPa for annealed 316L), which often allows a thinner wall for the same pressure and can offset the higher per-kg price.
What is PREN?
Pitting Resistance Equivalent Number — PREN = %Cr + 3.3×%Mo + 16×%N. It ranks resistance to chloride pitting: 316L is about 24, 2205 is 34–36, super duplex is above 40.
Need Duplex & Super Duplex Steel Priced?
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