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.

3 Answers 3


A railing ( tubular or angle) it it very likely to be "mild" steel , aka -carbon steel. It contains 0.1 to 0.2 % carbon , a little manganese and silicon. Highly weldable with standard filler metal . MIG is the easiest , gas shielded solid steel wire or flux cored steel wire ( the flux generates gas to shield the weld.). You want the most common standard steel filler wire. You do not have the skill necessary to weld any type of cast iron; the railing is very unlikely to be cast iron." Wrought iron" is an archaic name for very low carbon steel ; unlikely to be in your railing but it would weld the same as mild steel.


If a magnet sticks to it use the flex core at the proper diameter for your welder as long as the steel/ iron is clean it will work I usually have a roll that I pick up at big box store, welding shop or harbor freight for when I run out of gas. If aluminum flux core won't work it will require aluminum wire and a shield gas like helium or co2 or argon. I use C02 as it is cheap at work they use a mix but I don't remember what is in the mix.

  • Thanks -- do people actually use aluminum wire to weld to iron? That seems weird, but I am not experienced in this so I wouldn't know otherwise.
    – Dave
    Jul 17, 2018 at 20:19
  • No I thought you were not sure of the type of metal so I gave info for both most common types.
    – Ed Beal
    Jul 17, 2018 at 20:31
  • Ok, gotcha, thanks! It's ferrous, so now I know.
    – Dave
    Jul 17, 2018 at 21:17

Wrought Iron is basically your traditional steel, (wrought into a particular shape) - you will have no problem welding this with the traditional filler rods/wire...

you mention cast iron... now thats a bit of a different animal when welding... since its an alloy (not just pig iron, but added "stuff" to make it melt at a lower temp (like silica, carbon, etc) .. The "blend" of these materials can get damaged when welding and you can create brittle section -- for this reason, you need to pre-heat cast iron, and typically weld with a cast iron rod -- but... technically you can weld cast iron with regular rods... (just keep clean and do some surface preparation (i.e. grid a bevel/groove along the weld seam)

hope this helps

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