Actually, SS will rust if it’s not prepped and welded properly.
Also it’s highly likely to rust without the correct filler rod. Welding SS to mild steel (even if it’s not mild steel. It sure isn’t SS) will create corrosion if the right filler rod isn’t used. I bet there are only 4-5 people on this site that know what the correct filler rod is. I also bet those same poeple are the only ones who could actually do this job right.
And have you ever TIG welded in, what would be in this case,
the 4F, 3G, and possibly 4G positions?