Super Duplex Sheets & Plates
Giriraj Impex stocks, supplies and exports super duplex sheets and plates in UNS S32750 (2507) and UNS S32760 to ASTM A240 / ASME SA240. We supply super duplex sheets and plates from approved mills, cold-rolled sheets and hot-rolled plates, solution annealed and pickled, with mill test certificates giving composition, PREN and mechanical properties.
Super duplex plate is used where structures and pressure equipment must resist seawater and strong chloride solutions while carrying high loads – heat-exchanger tube sheets and channels, seawater-cooled equipment, desalination vessels, scrubbers and offshore and marine components.
Specifications
| Item | Details |
|---|---|
| Standard | ASTM A240 / ASME SA240; general requirements ASTM A480 |
| Grades | UNS S32750 (2507), UNS S32760 |
| Products | Cold-rolled sheet; 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, ASTM G48, 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.
The high chromium, molybdenum and nitrogen give super duplex a PREN of 40 or more, compared with the mid-30s for 2205 – see 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.
Super duplex plate has a minimum yield strength of 550 MPa, more than three times that of 316L, so tube sheets, shells and structural members can be made noticeably thinner.
Where super duplex plate is used
In seawater-cooled heat exchangers, super duplex tube sheets and channels pair with super duplex or titanium tubes so that every wetted part resists crevice corrosion. In desalination plants, super duplex plate is used for high-pressure vessels and pump components. Offshore, it is used for seawater filters, deluge and firewater equipment, and structural parts in splash zones. In chemical plants, it handles chloride-contaminated acids and brines that would pit 316L and challenge 2205. Because the material cost is higher than 2205, it is normally selected where 2205 would be at the edge of its capability.
Fabrication and testing
Super duplex plate is welded with strict heat-input control, over-alloyed filler metal and suitable shielding and backing gas, using procedures qualified with ferrite, impact and corrosion tests. Hot forming must be followed by solution annealing and rapid cooling. Projects commonly specify ASTM A923 testing for intermetallic phases and ASTM G48 pitting tests at a set temperature on the plate as delivered. Plates should be stored and handled apart from carbon steel and pickled after welding.
Ordering
Please give the UNS grade, thickness, width, length and quantity, minimum PREN, supplementary tests, design code and inspection required.
Super duplex compared with alternatives
For seawater and high-chloride plate applications, super duplex competes with 6% molybdenum austenitic grades such as 254 SMO, with nickel alloys and with titanium. Super duplex offers the highest strength of these, which suits pressure-bearing tube sheets, vessels and structures; 254 SMO is easier to form and weld; titanium has excellent seawater resistance but different fabrication requirements and lower stiffness; and nickel alloys such as 625 are used where temperature or chemistry goes beyond the duplex range. Materials engineers weigh these options against cost, weight and fabrication. See SMO 254 and titanium for those alternatives.
When super duplex plate is chosen, the fabricator's welding procedures and the plate's supplementary tests carry as much weight as the grade itself, because poorly controlled heat input can undo the material's corrosion resistance in the weld zone.
Applications and related products
Super duplex sheets and plates are used for heat-exchanger tube sheets and channels, desalination pressure vessels, seawater filters, scrubbers, chemical process vessels and offshore and marine structures. To complete a super duplex project we also supply super duplex pipes and tubes, super duplex flanges, super duplex pipe fittings, super duplex round bars and super 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 super duplex stainless steel plate, sheet and strip, including UNS S32750 and S32760.
Super duplex grades are specified with a PREN of 40 or more, calculated as %Cr + 3.3 × %Mo + 16 × %N from the actual composition on the mill test certificate.
Yes. Under ASTM A240, super duplex plate has a minimum yield strength of 550 MPa compared with 450 MPa for 2205, and much higher than 316L.
Commonly ASTM A923 for intermetallic phases, ASTM G48 pitting tests at a set temperature, impact tests and ultrasonic testing. They are agreed with the order.
Yes, but it must be solution annealed and rapidly cooled afterwards to restore its phase balance and corrosion resistance.
Super duplex is chosen for seawater and higher-temperature or higher-chloride service where 2205 would be close to its limits for pitting and crevice corrosion.
Request a Quote for Super Duplex Sheets & Plates
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254 SMO® is a trademark of Outokumpu.