S21800 is the Unified Numbering System (UNS) designation for a higher-alloyed stainless steel, most commonly known as Nitronic® 60. We stock it as Fermonic® 60.
The UNS system was created by a number of trade groups in the 1970s to reduce confusion caused by the same alloy being called different things, or different alloys sharing a name. Each metal is given a letter followed by five numbers, where the letter indicates the family - S for stainless steels.
What is Nitronic 60?
Nitronic 60 (Fermonic® 60, UNS S21800) is a fully austenitic stainless steel, supplied in the hot worked and annealed condition.
Its general corrosion resistance sits between Alloy 304 and Alloy 316: better than Alloy 304 in most environments, and superior to Alloy 316 for chloride pitting resistance.
Wear and galling resistance
Additions of silicon and manganese give it superior wear, galling and fretting resistance compared with many other corrosion-resistant alloys. This makes it a strong choice for applications involving repeated movement or sliding, or frequent assembly and disassembly.
Connectors and couplings make particular use of this galling resistance, operating reliably even when left for extended periods.
Strength
The same compositional additions provide almost double the yield strength of Alloys 304 and 316, and higher strength can be achieved through cold working. It remains fully austenitic - and therefore fully non-magnetic - even after severe cold working, although cold working brings no further improvement in galling performance.