S31803 is almost identical to S32205 in terms of both composition, physical and tensile properties. S32205 is achieved by producing S31803 with certain elements – chromium, nickel and molybdenum, controlled to the upper limit of their range. As these three elements account for the resistance to pitting corrosion S32205 has a slightly improved and more consistent corrosion resistance than S31803. However, in all other aspects, the grades can be considered identical.
S31803 was developed in the 1930s for application in paper and pulp manufacture. A number of the leading manufacturers of duplex stainless steel were consistently producing this grade to the upper end of the allowable specification. This reflected their desire to maximise the corrosion performance of the alloy, aided by the development of the AOD steelmaking process which allowed tighter control of composition. In addition, it also allowed the level of nitrogen additions to be influenced, rather than just present as a background element. Controlling nitrogen, chromium and molybdenum content to the upper end of the allowable specification for S31803 results in better and more consistent corrosion resistance.
To differentiate the duplex stainless steel produced at the top end of the composition range, a further specification was introduced, namely UNS S32205, although this still meets the DIN 1.4462 caption. Duplex stainless steel made to the S32205 (F60) caption will fully meet the S31803 (F51) caption, whereas the reverse is not true. Therefore, S32205 can be dual-certified as S31803.
Langley Alloys stocks S32205 (2205) duplex stainless steels as round bars from 5/8”-20” diameter (15.87-508mm), plate up to 3” (76.2mm) thickness, as well as pipes in scheduled sizes, flanges and fittings.
For more information about our range of alloys, please contact Langley Alloys today.