Super Duplex Stainless Steel

Super Duplex Steel is a high-performance stainless steel with great strength and corrosion resistance, making it perfect for usage in tough and demanding environments. It contains about 25% chromium, nickel, molybdenum, and nitrogen. Palgotta Metal offers premium Super Duplex Steel materials designed to deliver reliability, durability, and performance across a wide range of industrial applications. This alloy has a unique duplex microstructure with a balanced mix of austenitic and ferritic phases, providing an excellent combination of mechanical and physical qualities. This dual-phase structure is very resistant to pitting, crevice corrosion and stress corrosion cracking, especially in chloride-rich and marine environments.

History of Super Duplex Stainless Steel

Duplex stainless steel was initially introduced in Sweden to address corrosion problems in the sulfite paper industry. Early versions were a step ahead, but they had limits. The need for a stronger and more corrosion-resistant alloy led to the development of Super Duplex Stainless Steel. The first known Super Duplex grade, Ferralium 255, was developed in the 1960s by Langley Alloys. The phrase "Super Duplex" was not frequently used until the 1980s. It was defined for grades with higher alloy content and a Pitting Resistance Equivalent Number (PREN) > 40. Since then, more powerful grades have been introduced, like Super Duplex F61, designed for the most aggressive environments.

Benefits of Super Duplex Stainless Steel

Super Duplex offers several key benefits that make it ideal for high-demand industrial applications:

Stronger & Durable

Super Duplex is built to handle extreme environments. It’s stronger than most standard stainless steels and holds up against wear, corrosion, and pressure.

High Strength and Durability

Its strong tensile and yield strength enable it to withstand heavy mechanical loads without cracking or deforming. It’s a long-lasting material choice for structural and pressure-related applications.

Weldability and Fabrication

Despite its strength, it is relatively easy to weld and fabricate. With proper welding procedures, it retains its corrosion resistance and mechanical properties.

Cost-Effective

Even while the initial cost is more than normal steel, its extended service life and low maintenance requirements, make it a more cost-effective option in the long term. Less downtime, fewer repairs, and extended equipment life help reduce total project costs.

Different Forms of Super Duplex Stainless Steel

Super Duplex is available in a wide range of forms to suit different industries and applications:

Plates and Sheets

Used in tanks, pressure vessels, and structural components due to their high strength and corrosion resistance.

Bars and Rods

Ideal for machined components, shafts, and fasteners. Common in the marine, offshore and chemical sectors.

Pipes and Tubes

Used for fluid transport in oil and gas, desalination, and petrochemical plants. They maintain integrity under pressure and in corrosive environments.

Flanges and Fittings

Essential for connecting pipe systems in high-pressure and high-corrosion settings.

Wire and Coil

Often used in welding, spring manufacturing, and fastening solutions. Combines flexibility with high strength.

Why Choose Us for Super Duplex Steel Needs?

As a leading Super Duplex Stainless Steel supplier, Palgotta Metal supplies top-grade materials trusted by industries around the world. We supply a wide range of popular grades and custom sizes at competitive prices. With a focus on quality assurance, prompt delivery, and industry-standard packaging, we've established ourselves as a dependable supplier of Super Duplex items. Whether you need raw materials or finished components, we have you covered.

Specification of Super Duplex Stainless Steel

Understanding the technical specifications of Super Duplex Stainless Steel is essential for assessing its suitability in various demanding environments. This section provides insights into its chemical and mechanical characteristics, both of which contribute to the alloy’s superior performance.

Chemical Composition of Super Duplex Stainless Steel

The strength and corrosion resistance of Super Duplex Stainless Steel comes from its precise chemical composition. It includes between 24 and 26% chromium, which provides a passive coating that protects the surface from rust and chemical attack. Molybdenum, present at 3-5%, improves pitting and crevice corrosion resistance, especially in chloride-rich conditions. Nickel, ranging from 6–8%, improves toughness and ensures a stable duplex microstructure. Nitrogen, in the range of 0.2–0.3%, further boosts strength and prevents pitting. Low carbon content (less than 0.03%) keeps the alloy corrosion-resistant by lowering the chance of carbide precipitation during welding. Small additions of manganese (up to 2%) and silicon (up to 1%) help improve toughness, deoxidation, and oxidation resistance at high temperatures.

Mechanical Composition of Super Duplex Stainless Steel

Super Duplex Stainless Steel offers high tensile strength, typically ranging between 600–900 MPa, making it capable of withstanding heavy loads and pressure. Its high yield strength ensures that the material preserves its shape under stress, and its amazing toughness allows it to perform even in freezing temperatures. The alloy's surface hardness enables it to withstand wear, dents, and mechanical impact. It also has high fatigue strength making it appropriate for applications that need constant motion or stress. Moderate ductility means it can bend without cracking, sufficient for forming and fabrication.

Super Duplex Stainless Steel Temperature Limits

Super Duplex Stainless Steel performs exceptionally well in both low and moderately high-temperature environments. Typically, its recommended operational temperature range is from -50°C to approximately 300°C (or -58°F to 572°F). At these temperatures, it keeps its excellent strength, hardness and corrosion resistance, making it perfect for cryogenic and marine use. However, Super Duplex is not appropriate for long-term service above 300 degrees Celsius. Prolonged exposure to elevated temperatures can lead to the formation of harmful intermetallic phases like sigma and chi, which significantly reduce toughness, corrosion resistance, and structural stability.

Various Grades of Super Duplex Stainless Steel

Super Duplex Stainless Steel is available in multiple grades, each engineered for specific industrial demands and environmental conditions.

Duplex 2205 (UNS S31803 / S32205)

Duplex 2205 is the most often used Super Duplex grade, because of its great mix of high strength, and corrosion resistance. With a balanced mix of chromium (22%), nickel (5–6%), and molybdenum (3%), it resists pitting and stress corrosion cracking in chloride-bearing environments.

Super Duplex 2507 (UNS S32750)

Super Duplex 2507 offers superior corrosion resistance and mechanical strength, making it ideal for highly corrosive and high-pressure applications. This grade contains 25% chromium, 4% molybdenum, and 7% nickel, and performs particularly well in seawater, offshore platforms, heat exchangers, and desalination systems.

Super Duplex 32760 (Zeron 100 / UNS S32760)

UNS S32760, commercially known as Zeron 100, was originally developed for use in the North Sea oil and gas industry. It offers enhanced corrosion resistance with added tungsten, along with 25% chromium, 7% nickel, and 3.5% molybdenum.

Duplex 2101 (UNS S32101)

Duplex 2101 is a lean duplex grade that offers a cost-effective alternative to traditional stainless steels like 304 and 316. It contains lower nickel and molybdenum content, making it more economical while still delivering improved strength and moderate corrosion resistance.

Duplex 2304 (UNS S32304)

Duplex 2304 provides a good balance of strength and corrosion resistance at a more affordable price. It has a lower molybdenum and nickel percentage than other super duplex grades, making it suitable for mildly corrosive situations.

Applications of Super Duplex Stainless Steel

Super Duplex Stainless Steel is used across industries that demand both high strength and corrosion resistance. In the oil and gas sector, it's used for subsea pipelines, risers, and platforms. In desalination plants, it is employed for evaporators, piping systems, and heat exchangers. It is used in tanks, pressure vessels and reactors that handle harsh media like acids and chlorides in the chemical processing sector. It is used in bleaching equipment and digesters in pulp and paper factories. It is used in saltwater cooling systems, rudders, and propeller shafts in the marine sector. Super Duplex is particularly useful in architecture and construction for buildings exposed to corrosive or marine environments. In pollution control, it’s used in flue gas scrubbers and waste treatment units.

Applications of Duplex Stainless Steel

Duplex stainless steel is utilized in many different industries where durability and resistance to corrosion are essential. It is used in chemical pressure vessels, tanks, pipelines, and heat exchangers. The oil and gas sector uses it for pipelines, risers and processing systems. It works effectively in coastal environments and high-chloride places like desalination facilities. In pulp and paper mills, duplex steels are used in digesters and bleach systems. You’ll also find it in food processing equipment, biofuel plants, and cargo tanks for ships and trucks.

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