Are they straight bars, Salk?
If so, not likely a wagon or buggy axle, but maybe lengths of shafting?
I have some buggy axles here, and they are square-tapered, and round at the ends. they are also dropped at the ends where the wheels mount.
I was always going to make a 'hand gonne' of one of them...
No matter to the folks here what they Were though, if wrought -iron, and they are by sounds of it, they are Very worth saving!!