UNS S32750, commonly known as Super Duplex 2507®, is very similar to UNS S31803 Duplex. The difference between the two is the contents of chromium and nitrogen are higher in the Super Duplex Grade which in turn creates higher corrosion resistance as well as a longer lifespan. Super Duplex is composed of between 24% to 26% chromium, 6% to 8% nickel, 3% molybdenum, and 1.2% manganese, with the balance being iron. Also found in Super Duplex are trace amounts of carbon, phosphorus, sulfur, silicon, nitrogen, and copper. Benefits include: good weldability and workability, a high level of thermal
conductivity and low coefficient of thermal expansion, high resistance to corrosion, fatigue, high resistance to pitting and crevice corrosion, high resistance to stress corrosion cracking (especially chloride stress corrosion cracking), high energy absorption, high strength, and erosion. Essentially, the Duplex alloys are a compromise; possessing some of the ferritic stress corrosion cracking resistance and much of the superior formability of the common austenitic stainless alloys, more cost effectively than the high nickel alloys.