Question About Welding
 

Question:

I need to know if I can weld decorative cast iron to steel tubing with a mig welder or arc welder.

The weld does not need to be very strong because it won't have to hold any load, but how it looks will matter.

Its decorative wrought iron for a fence.

That should work. Both your Items Are basicly the same thing. Just a little more carbon in the steel.:D

Welding cast iron is an art and requires some special expertise and special material. Apparently, nickel electrodes for arc welding are available at welding supply houses. See here for an example... http://www.weldmark.com/products/wl-sae72000.pdf
I have always heard that brazing is the way to go where cast iron is concerned and there is a wide variety of products available for that as well.

It may not be pretty but, can it be done?

You would get the best appearing weld if you TIG weld the joint. I have welded Axle housings (GM 12 bolt) using Crown's Royal 220Tig welding wire. This is a high Nickel content for welding dissimilar metals. Tensile Strength (as welded) 120,000 psi. Should be strong enough to hold fencing together. If you do not have acces to a TIG welder, Crown also makes Royal-220M for arc welders. You'll want to preheat the pieces if they are large for either welding type. If you cannot find Crown welding wires in your area, I would use a filler that has a high nickel content in a similar brand. Hope this helps.:cool:

Brazing
 

I also suggest Brazing as the way to go, not only will it look better, but welding cast is tough and expensive.

Re: Question About Welding
 

TIG all the way!!!!