SAF Duplex 2205 Stainless Steel (UNS S32205 S31803) Alloy Material SAF Duplex 2205 stainless steel (UNS S32205 formerly known as UNS S31803 and commonly known as "alloy 2205") has a mixed microstructure of austenite and ferrite, and is a two-phase alloy based on the Fe-Cr-Ni series.
S32205: Distinguishable Differences. UNS S31803 and S32205 represent alloys with more characteristics in common than distinct differences are that firstly it is both stainless steels with similar elemental compositions. Both UNS S31803 and S32205 belong to the duplex 2205 family, which means they comprise almost equal parts austenite and ferrite.