Is duplex stainless steel also a general term?

 　　Duplex stainless steel can be divided into the following categories: the first type belongs to the low alloy type, representing the grade UNS S32304 (23Cr-4Ni-0.1N). The steel does not contain molybdenum, and the PREN value is 24-25. It can replace AISI304 or 316 in stress corrosion resistance. The second type belongs to the medium alloy type, represented by UNS S31803 (22Cr-5Ni-3Mo-0.15N), with a PREN value of 32-33. Its corrosion resistance is between AISI 316L and 6% Mo+N austenitic stainless steel. The third type belongs to the high alloy type, generally containing 25% Cr, as well as molybdenum and nitrogen, and some also contain copper and tungsten. The standard grade UNSS32550 (25Cr-6Ni-3Mo-2Cu-0.2N) has a PREN value of 38-39, and this type of steel has higher corrosion resistance than 22% Cr duplex stainless steel. The fourth type belongs to the super duplex stainless steel type, containing high molybdenum and nitrogen. The standard grade is UNS S32750 (25Cr-7Ni-3.7Mo-0.3N), and some also contain tungsten and copper. The PREN value is greater than 40, which is suitable for harsh medium conditions. It has good corrosion resistance and mechanical comprehensive properties, which can be comparable to super austenitic stainless steel.



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Japanese Standard (1)

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National Standard Properties of 304 Stainless Steel Plate

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Similarities and Differences in Performance between N08367 and N08926

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