UNS S31803 is also known as grade 2205. The duplex stainless steel family includes a wide range of different materials, however, the duplex 31803 is the most common one. Duplex-grade stainless steel alloys have ferritic/austenitic properties, giving these materials superior strength and excellent resistance to oxidation.
UNS S31803/2205 is a duplex grade with a ferritic-austenitic microstructure. The alloy consists of around 40-50% ferrite in the annealed condition. The duplex microstructure has the high strength of the ferritic grades whilst retaining the corrosion resistance of the austenitic grades. It is not uncommon to see the metal used as a practical solution to chloride-induced stress cracking, which is the Achilles' heel of stainless steel.