S32550 is the Unified Numbering System (UNS) designation for the original super duplex stainless steel, best known as Ferralium® 255.
The UNS system was created by a group of trade bodies working together in the 1970s to reduce confusion caused by the same alloy being called different things, or different alloys sharing a name. Each metal is indicated by a letter followed by five numbers, where the letter shows the family - S for stainless steels.
Ferralium® 255 (UNS S32550, DIN 1.4507, F61) is the original super duplex stainless steel (SDSS), developed by Langley Alloys in the 1960s. It is still the only super duplex to provide a yield strength >85ksi, while its increased copper content (2%) gives greater resistance to acids.
We carry an extensive stock of Ferralium® 255, with bar up to 16" (406.4mm) diameter, plate up to 3" (76.2mm) thickness, and a variety of pipes and fittings available ex-stock from our warehouses in the UK and USA.