VIV,
Since I have been working with 321ss I have found that cleaning is a big deal.. I also know that welding it too hot also causes cracking.. We weld 321 that is only .002 thick at 12 amps and sometimes that is too hot..I'm also finding that too much H2 in the gas mixture causes problems.. Arc length become very important dealing with H2. the less H2 you have in the mixture the more forgiving the weld puddle is..We have had to get rid of the good cleaners and it seems that mechanical cleaning is the way to go.. I also am starting to look at tumbling some small parts to clean them.. We also have seen stringers right through the parent metal, does anyone know of a remelt 321ss