Not trying to teach me granny to suck eggs, but you shouldn't need to look for alternative if you know it does the job.
This material should not be hard to get hold of. Perhaps it is because you are asking suppliers for '254SMO'and they don't recognise that this is a tradename of Avesta Polarit for what is essentially a bog standard duplex grade.
Try 'F44', or 'UNS S31254', or Werkstoff Numbers 1.4547 or 1.4529, or even another tradename (Krupp Hoesch) - '1925hMo'.
You should always check the chemis and mechis of these before ploughing ahead and ordering - just ask to see the test certificates. Easy Peasy!
It is common in virtually all forms over here in the UK.
These are 6%Mo SuperAustinitic stainless steels, not duplex.
Even though there are some chemistry differences the only performance differences that I have ever seen are at the very limits of use. In general S31245 is the weakest of the alloys.
I would suggest that you only use UNS numbers to specify grades. After all, even EN has agreed to start using them.
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Corrosion never sleeps, but it can be managed.
DUH! Sorry Ed, I stand erected! I did mean to say 6% MoSA
Was just trying to say this should be a diddly job to get hold of - look at the more common names for a material. Matweb is good - go on there and do a sequential search and it will give you a whole ruck of tradenames specs, grades etc for all the same material!
Don't forget the casting equivalent (ASTM A351 CK3MCuN)although if you ask any foundry for 254SMO or 6Mo stainless, they should know what you mean. If they don't, don't bother.