Duplex Steel Sheets & Plates
Giriraj Impex stocks, supplies and exports duplex sheets and plates in duplex 2205 – UNS S31803 and S32205 – to ASTM A240 / ASME SA240. We supply duplex sheets and plates from approved mills, cold-rolled sheets in 2B finish and hot-rolled plates solution annealed and pickled, with mill test certificates and supplementary corrosion and impact tests on request.
Duplex plate lets designers build lighter, thinner-walled vessels, tanks and structures that also resist chloride stress corrosion cracking and pitting better than 316L. It is used for storage tanks, pressure vessels, heat-exchanger shells, scrubbers, chemical tankers, offshore structures and bridges.
Specifications
| Item | Details |
|---|---|
| Standard | ASTM A240 / ASME SA240; general requirements ASTM A480 |
| Grades | UNS S31803, S32205 (duplex 2205); dual certified S31803/S32205 |
| Products | Cold-rolled sheet (below 4.76 mm) and hot-rolled plate |
| Finish | Sheet: 2B; plate: hot rolled, annealed and pickled |
| Condition | Solution annealed and rapidly cooled |
| Sizes | Thickness, width and length to mill range; confirmed on enquiry |
| Optional tests | ASTM A923 (intermetallic phases), ASTM G48 (pitting), impact test, ultrasonic test, ferrite count |
| Documents | Mill test certificate (MTC) with PREN; third-party inspection on request |
Composition
| UNS | Grade | C | Mn | P | S | Si | Cr | Ni | Mo | N | Other elements |
|---|---|---|---|---|---|---|---|---|---|---|---|
| S31803 | 2205 | 0.030 | 2.00 | 0.030 | 0.020 | 1.00 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | 0.08–0.20 | – |
| S32205 | 2205 | 0.030 | 2.00 | 0.030 | 0.020 | 1.00 | 22.0–23.0 | 4.5–6.5 | 3.0–3.5 | 0.14–0.20 | – |
| S32750 | 2507 | 0.030 | 1.20 | 0.035 | 0.020 | 0.80 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 | Cu 0.50 |
| S32760 | Zeron 100 type | 0.030 | 1.00 | 0.030 | 0.010 | 1.00 | 24.0–26.0 | 6.0–8.0 | 3.0–4.0 | 0.20–0.30 | Cu 0.50–1.00, W 0.50–1.00 |
S32760 also requires a minimum PREN of 40. Footnotes as given in the standards.
For seawater and the most aggressive chloride service, see super duplex sheets and plates.
Mechanical properties to ASTM A240
| UNS | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) | Elongation in 50 mm, % |
|---|---|---|---|
| S31803 | 620 (90) | 450 (65) | 25 |
| S32205 | 655 (95) | 450 (65) | 25 |
| S32750 | 795 (116) | 550 (80) | 15 |
| S32760 | 750 (108) | 550 (80) | 25 |
Hardness limits as given in the standard.
The minimum yield strength of 2205 plate is about two and a half times that of 316L plate (170 MPa), which is why duplex allows thinner shells and lighter structures for the same design pressure or load.
Designing with duplex plate
Because duplex is stronger than austenitic stainless steel, vessels and tanks can often be designed with thinner walls, saving weight and partly offsetting the material cost. The design code sets the allowable stresses and the upper temperature limit, which for duplex is lower than for austenitic grades. For storage tanks and structural uses, duplex's combination of strength and chloride resistance can replace coated carbon steel, avoiding painting and maintenance. Where plates will be cold formed into heads or shells, the higher strength means more forming force and springback, so the fabricator should plan the forming accordingly.
Welding and fabrication
Duplex plate is welded with controlled heat input and interpass temperature and with over-alloyed filler metal, so that the weld and heat-affected zone keep a balanced ferrite–austenite structure. Welding procedures are commonly qualified with ferrite measurement, impact testing and corrosion testing. Hot forming requires solution annealing afterwards. Plates should be stored apart from carbon steel and handled with clean tools, and welds pickled and passivated after fabrication.
Ordering
Please give the grade, thickness, width, length and quantity, sheet finish, and any supplementary tests (A923, G48, impact, ultrasonic), design code and inspection required.
Duplex plate for tanks and structures
Large atmospheric storage tanks for chemicals, fertiliser solutions and pulp liquors are a classic duplex plate application: the higher strength lets shell courses be thinner than in 316L, and resistance to stress corrosion cracking removes a common failure mode. In structures, duplex plate is used for offshore walkways, blast walls and splash-zone members, and for bridge decks and architectural elements in coastal cities, where it avoids repainting. In all these uses, plate thickness, welding details and the design code allowable stresses are set by the designer; we supply the plate with the certification and tests the design calls for.
Duplex sheet is used for smaller vessels, ducting and scrubber internals, and as cladding over carbon steel in some designs. Sheets and plates of the same grade can be supplied together for a project, each with its mill test certificate.
Applications and related products
Duplex sheets and plates are used for chemical and fertiliser storage tanks, pressure vessels and columns, heat-exchanger shells and tube sheets, flue gas desulphurisation scrubbers, pulp and paper digesters and bleach towers, desalination evaporators, chemical tanker cargo tanks, offshore topside structures and blast walls, and bridges. To complete a duplex project we also supply duplex pipes and tubes, duplex flanges, duplex pipe fittings, duplex round bars and duplex fasteners. Other plate and sheet materials are on the plates and sheets pages, and grade guidance on the duplex and super duplex steel page.
Frequently Asked Questions
ASTM A240 (ASME SA240) covers duplex stainless steel plate, sheet and strip, including UNS S31803 and S32205. General requirements such as tolerances and finishes are in ASTM A480.
Under ASTM A240, duplex 2205 plate has a minimum yield strength of 450 MPa, compared with 170 MPa for 316L. This allows thinner, lighter vessels and structures.
Common additions are ASTM A923 testing for intermetallic phases, ASTM G48 pitting tests, Charpy impact tests and ultrasonic testing. They are specified on the order.
Duplex 2205 performs well in many chloride environments, but for warm seawater and the most demanding conditions super duplex grades such as UNS S32750 are usually specified.
Yes, but after hot forming the part must be solution annealed and rapidly cooled to restore the correct phase balance and corrosion resistance.
Yes. Cold-rolled duplex sheets are supplied in 2B finish, and hot-rolled plates annealed and pickled.
Request a Quote for Duplex Steel Sheets & Plates
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