(i'm not an expert or any sort, but)
if it were Ni-Cr-Mo, it's basically a low alloy steel sort widely used in the welding world? could this be relevant?
sorry if i confuses it more here.
*edit. this guess was completely incorrect and irrelevant, it turned out.
it seems some alloy formular, close to stain-less but not quite, if i am not mistaken.