Welding a 1.5" d barstock of nitronic 50

I’m looking at welding a 1.5" d barstock of nitronic 50. The material is Austenetic 209 SS. I’ve decided on a welding rod of 309L SS. From doing a carbon equivalency calculation it looks like this material should be preheated between 400 and 700F (calc from ASM #6 welding book). Post heat is going to be wrapped in blankets to cool slowly. My one concern is the possibility of sensitization (C = 0.06% in XM19) through the 850-450 range. Thoughts suggestions. The part cannot be put into a furnace as the length of the barstock in the end will exceed the furnace size. I suppose we could torch the part as well for a post heat, just like the pre heat. I’m thinking of keeping the part at the low end of the pre heat (400F) as I have also read the preheating stainless can cause more problems.
Also, this part has a CE of 8.5 and from what i read in the ASM book it suggested a pre heat. i turned the bar in half and beveled the edges for R & D purposes and cost. That was my thought as well for filler. However, I don’t think the supplier stocks it.


Why would you use any preheat on an austenitic alloy? What are you welding to? The bar to itself? Why not the ER209 filler?
Your CE does not apply to an austenitic alloy. You don’t get hardening so it does not matter. It is more important to keep temps as low as possible. And, make sure that everything is very clean. Use good Ar for purge.

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@edstainless, Thank you for using forums to help others.