S31803 is a duplex stainless steel based on a chromium content of 22%. It can also be referenced as DIN 1.4462 and, when supplied as round bar, ASTM A182 F51. Its closest equivalent is the tighter-controlled UNS S32205 (F60), which meets the same caption and can be dual-certified as S31803.
Background
Developed in the 1930s for paper and pulp manufacture, S31803 offered twice the strength and a significant uplift in corrosion resistance compared with general 304/316 stainless steel. The Pitting Resistance Equivalent Number (PREN), calculated from chromium, molybdenum and nitrogen content, is a convenient way to compare the corrosion resistance of different alloys. S31803 has a PREN of up to 34, against 25 for 316, reflecting much better corrosion resistance. This made it an excellent choice for corrosive environments, and its use has broadened into marine applications, food and chemical processing and general engineering.
S32205: the tighter-controlled equivalent
The alloy can be produced to a tighter composition range that always achieves the best possible corrosion resistance, by controlling chromium, molybdenum and nitrogen to the upper end of the specification. This version is referenced S32205 and ASTM A182 F60, though still DIN 1.4462.
What we stock
We stock S32205, which can also be supplied as S31803, effectively dual-certified. We hold S32205 (2205) duplex stainless steel as round bar from 5/8" to 20" diameter (15.87-508mm), plate up to 3" (76.2mm) thick, plus pipes in scheduled sizes, flanges and fittings. S32750 and S32760 are available ex-stock in a similar size range.