Try 312. Not much that stuff won’t stick together in a fashion. Obviously a chemical analysis of the parent is the best case scenario but if you don’t know what it is and it’s not cast iron of course cos stainless doesn’t weld cast iron then 312 is your best bet.
They’ll be something hardenable if they’ve got an edge ground on them.
12% Manganese or something with a fair bit of carbon. Preheat it either way.
If it’s a blunt edge then it could be a Wear resistant Steel like Hardox, RAEX, XAR etc. If so weld with an undermatching filler metal then hardfsce with something like ESAB Weartrode 55 HD.