F55: A super duplex stainless steel

F55 is a kind of super duplex stainless steel, superior to the 2205 in overall performance. “Super” refers to the high alloying of its components. Compared with other duplex stainless steels, the high alloying of super duplex steels mainly refers to high molybdenum and nitrogen.

The characteristics performance are (1) excellent resistance to stress corrosion cracking, excellent resistance to pitting and crevice corrosion, resistance to various inorganic acids and organic acids, excellent resistance to non-oxidizing acid corrosion, strong alkali corrosion; (2) good weldability, excellent mechanical properties, can reduce the weight of the structure, with design advantages; (3) in the working temperature above 300°C for a long time service, the toughness of the material will decline significantly.

F55 has been included in the specification for metal materials and ASME boilers and pressure vessels resistant to sulfide stress cracking for NACE MR 0175 oil field equipment. Its main applications include submarine pipelines, flue gas desulfurization, osmotic desalination equipment, sulfuric acid plants, and fasteners for Marine engineering.