26-1, E-Brite, S44627
It is a high puity super ferritic. It is a pain to weld. It must be quenched hard from anneal. The thickness is limited to about 0.100" (due to heat treating). Like all super ferritics it suffers from 885F Embrittlement, but you are hot enough that that won't matter. You are above the temp range.
At room temp it has limited ductility, and the DBTT isn't too far below room temp.
On the other hand, it cannot be chloride stress cracked. Being a high purity grade it has almost no grain boundary phases so IGA isn't an issue either. It is the workhorse in hot, concentrated caustic, esp if there are chlorides. It is more corrosion resistant than Ni200 and it will resist erosion.
To be honest, alloys like HR-120 and HR-160 would prob work better. A cast Co-Cr would be great, but you prob can't afford it. Some aircraft alloys might come close, like L-605.
Some Ni doesn't hurt too much, but in order to keep a 25-35% Cr alloy austenitic you need a lot, unless you use some Co instead.
High Si also helps.
How about R30023 (Stellite 23) or R30031 (Stellite 31), maybe as an overlay. Other similar alloys are R31233.
The more that I think about it the more that I like the idea of a weld overlay.
The kinetics of sulfidation are well defined. There are low melting eutectics formed with the metals and S. If the sulfide is liquid or gas, you get rapid corrosion. If it is solid then corrosion is slower. Each alloy has limits were you go from slow predictible corrosion to rapid attack. The breakaway is usually defined in terms of both time and temp.
= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
