Welding can be normally defined as the join the two metal pieces. MIG welding, mostly, uses heat to melt the two pieces together along with a wire. This third, filler metal is fed through the gun into the weld. The melted metals cool together, then creat the strong joint. Now a days any combination of metals can be joined by MIG welding, but the strength and durability of the joint is determined by the wire used. A careful examination of the metal being welded will lead to the best choice of wire, also known as the electrode, for the welding. Common Metals for MIG Welding: MIG Wires can weld most metals and metal alloys. The three most commonly used metals in MIG welding projects are stainless steel, carbon steel and aluminum, although aluminum requires a special setup and is not nearly as common than the other two. The metals being welded together are often referred to the base metals. The composition and thickness of the base metals are determine the proper composition and t...