I need to weld a railing and am not sure what kind of metal it is made from. For the time being, I'm going to assume it's iron until I can do a magnet test. But short of getting a sample tested in a lab or doing the "spark test", I don't know how to identify the iron used. I was planning on using a flux core MIG welder, but need to pick a proper wire composition. Is there a general purpose wire I can use that would work reasonably well on wrought and cast iron?
EDIT - it is ferrous metal.