UNS S32550 : SUPER DUPLEX : A276 (VO1.03), A479 (VO1.03) The characteristic features of high strength and corrosion resistance exhibited by the dual microstructure (austenite, ferrite) associated with duplex stainless steels are found in UNS S32550. It is similar in composition to the more widely used super duplex grade UNS S32760. UNS S32550 has a slightly higher copper level, lower nickel and no deliberate tungsten additions, and is normally supplied to achieve the UNS S32760 PREN requirement of 40.Super duplex 255 is a super duplex stainless steel supplied in the hot worked and annealed condition. It achieves higher strengths than most stainless steels and alternative corrosion resistant alloys, offering the potential to reduce section size and therefore weight and cost.As a 25% Cr alloy, with significant additions of copper, Ferralium® 255 offers excellent corrosion resistance in a wide variety of corrosive chemicals including sulphuric, nitric and phosphoric acid. In seawater and other chloride containing environments it also provides outstanding resistance to pitting and crevice corrosion, with Critical Pitting Temperature exceeding 50°C. Excellent ductility and impact strength at both ambient and sub-zero temperatures combine with a high resistance to abrasion, erosion and cavitation erosion.