You can run regular 7018 with AC. I've done it with a 110v Craftsman buzzbox that went up to 100a with 3/16" rods on both cast iron and a rusted car frame.
I don't advise it unless you like pain, however.
The aforementioned welder is what I have in my shop at home. It works, but again, I don't advise it unless you like pain. I've put together my share of sheet and plate with it.
At my day job I get to use a Miller Syncrowave.