Originally Posted by
unterhausen
anyone know if 953 is magnetic?
on edit: unfortunately it is, otherwise it would be easier to tell what the material was, or wasn't
You might be able to tell with a bore-scope. 953 and XCr should both have been back-purged which ought to make the back of the welds look a bit different than regular CrMo welds. So that tells you it's one of those two. XCr is fully seamless but 953 is DOM, so there may be a faint trace of an original weld seam visible inside the tube running down its length if you look closely. But you'd need a reference tube to confirm. And this is assuming we know it's not 931 which is stainless and seamless just like XCr.
Otherwise I guess you need an X-ray fluorescence gun.
Columbus do suggest a slightly different welding rod for XCr. But it would be worth investigating whether there's really that much difference.