Ferrite levels in materials are important for all of the reasons already mentioned. Measurement of ferrite using a Ferritscope or Severn Gauge is a good idea - especially for duplex materials.
Cast austenitic stainless steels typically have anywhere from 8-18% ferrite in them. This is due to...
I concur with some of the information you have already. I think that the Superaustenitic grades (6Mo or higher) would be a great stepping stone. A concern will be critical crevice temperature and I do not know how you would work to avoid it at 98C - high, obviously.
I would look into CK3MCuN...
There are stainless steels that have alloyed copper and do much hetter in Microbially Induced Corrosion (MIC) attack, if that is of concern. I would look into something like Ferralium (duplex stainless steel with Cu) as an option if you want to look into Ferralium.
Looking at the combination of temperatures and solutes, I would be concerned about 410ss. An issue that may be of consideration is the Critical Crevice Temperature - I believe the chloride concentration is high enough that you need to think about crevice corrosion (and pitting) and the...
