UNS S31803 is a duplex stainless steel based on a 22% chromium content. It is also identified as DIN 1.4462 and ASTM A182 F51.
Developed in the 1930s for paper and pulp manufacture, it offered twice the strength and a significant uplift in corrosion resistance compared with general 304/316 stainless steel. This made it an excellent choice for corrosive environments, and its use has broadened into marine applications, food and chemical processing and general engineering.
S31803 and S32205
UNS S32205 is a very similar grade to S31803 and is widely offered. A number of the leading duplex producers were consistently making the grade to the upper end of the allowable specification to maximise corrosion performance. This was aided by the AOD steelmaking process, which allowed tighter control of composition and let producers influence nitrogen additions rather than leaving nitrogen as a background element. Controlling nitrogen, chromium and molybdenum to the top of the S31803 range gives better and more consistent corrosion resistance.
To distinguish this top-of-range material, the further specification UNS S32205 was introduced, though it still meets the DIN 1.4462 caption. Material made to S32205 (F60) fully meets S31803 (F51), but the reverse is not true, so S32205 can be dual-certified as S31803.
What we stock
We stock 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.