[Dominik]

hi Nick,

okay: I try another one.
when working with stainless (welding as well), never use tools that have been used with mild steel.
stainless will attract the rust from mild steel and start to corrode.

after welding stainless clean the heat affected zone generously at least with distilled water or better yet with a suitable cleaning agent.

otherwise you will get rust close to where you welded and not only at the weld!

dominik