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Classification and representative grades of duplex stainless steel
Source:Xinsteel   Date:2020-06-24
The first type is a low alloy type, the representative grade is UNSS32304, the steel does not contain molybdenum, the PREN value is 24-25, and it can be used in place of SS304 or 316 in stress corrosion resistance.
The second type is a medium alloy type, the representative grade is UNSS31803, the PREN value is 32-33, and its corrosion resistance is between SS316L and 6% molybdenum+N austenitic stainless steel.
The third type is a high-alloy type, generally containing 25% Cr, also containing molybdenum and nitrogen, and some also containing copper and tungsten. The standard grades are UNSS32550, PREN value is 38-39, the corrosion resistance of this type of steel is higher than 22 Duplex stainless steel with %Cr.
The fourth type belongs to the super duplex stainless steel type, which contains high molybdenum and nitrogen. The standard grades are UNSS32750, and some also contain tungsten and copper. The PREN value is greater than 40. It can be applied to harsh media conditions and has good corrosion resistance and mechanical synthesis. Performance, comparable to super austenitic stainless steel.