QUESTION: Wire versus stick for strength and or penetration
There are a lot of variations of wire welding like flux core with gas or no gas but I am going to assume you are talking about bare wire mig welding vs stick welding. I am still going to have to break this answer down into a few random thoughts because there are so many variables:
• The 70 in E70s6 bare wire and the 70 in 7018 stick rods means they are the same strength. 70,000 psi tensile strength is as strong or stronger than most steels you will weld.
Penetration is another subject in mig bare wire vs stick welding. For downhill welding on 3/16 and thicker a 6011 stick rod will penetrate much deeper than bare wire.
• For Vertical uphill welding Mig will penetrate just as well as stick if it is set hot enough and the wire stickout is kept short. But that’s the thing, with stick welding, there is a built in safety net in that you have to set the machine at least hot enough to keep the rod lit. With Wire, or mig welding there is no such limit and it is possible to set the machine really cold and make a pretty weld that does not even nip through the mill scale on hot rolled steel.