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Duplex & Super Duplex Stainless Steel Products

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Super Duplex stainless Steels are made from an alloying of 25% chromium and duplex stainless are made from an alloying of 22%. The level of resistance to pitting corrosion is increased by increasing the chromium content. The Pitting Resistance Equivalent number (PREN), is calculated as PREN = Cr + 3.3x Mo + 16x%N, where Cr=chromium and Mo=molybdenum, respectively. The PREN can be increased by increasing the chromium content to increase its resistance to pitting corrosion from 34 to 40. This indicates a superior resistance over a wide range of environments. Because of their long-lasting performance in seawater, super duplex grades are preferred for marine and subsea applications. Use alloying additives in a cost-efficient manner To maintain the favorable balance of austenitic, ferritic microstructures, an increase in chromium would normally require the addition expensive alloying elements like nickel. Super duplex stainless steels are made with nitrogen, which serves this purpose. This allows for a highly attractive combination of strength, corrosion resistance, and pricing that is competitive against other grades with higher alloying content. The Super Duplex stainless steels feature a two-phase microstructure called "duplex" that includes both ferritic and austenitic grains. This gives them an attractive combination of properties. They are generally twice as strong than austenitic stainless stees. They are somewhere in the middle of ferritic and austenitic grades and have good toughness and flexibility. Their resistance to stress corrosion cracking is another advantage over austenitic stainless Steels. Hyper duplex stainless steels, also known as hyper-duplex stainless steels, are being developed. They have a 27% and 29% chromium composition, which increases the resistance to corrosion. They are however more difficult to produce and only readily available in tube form. We stock 40 sizes of super-duplex solid bars, ranging in size from 0.5" (12.7mm to 406.4mm) We stock plate up to 3 inches (76.2mm) in a variety of grades.
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