Have you cut one, they might be hollow with powdered flux in and the ends have been sealed?The rods are in a tube marked Sifbronze No3 Nickle rod is 500mm long & aprox 4mm square with a rough finish could not find a reference to them, all the ends look like those in the picture View attachment 155740 View attachment 155741 View attachment 155742
Not zinc then, they would just melt, do you have a tig set, I would see if they would puddle / melt with a DC arc, probably wouldn't help to identify them thoughHad the end cherry red no sigh of softening
I've used cast iron rods with oxy acetylene, these look a bit too shiny though, thats why I suggested running a tig arc on it, the ones I used to use were a trapezoidal section rather than square.I once used similar looking rods, years ago, to gas weld some cast iron.
I dont have any means to test them any more.....so no pointNon magnetic, would not think Stellite. Can file the puddles they are hard but not like the stellite rods I have used on buckets.
Will send you a sample if you pm address cant leave it alone now