Does solder stick to galvanized steel?
Accordingly, how do you glue galvanized steel?
Most common Types of Adhesive for hot-dip galvanized steel: two-part mix acrylics (Loctite AA H8600, and other industrial formulations) two-part epoxies (metal-bonding or industrial formulations) polyurethane glues (Gorilla Glue, Grizzly Glue, Elmers Polyurethane Glue, and other industrial formulations)
Correspondingly, will JB Weld stick to galvanized metal?
The JB should work fine. Just remember to do what Ice suggested about making sure all of the surfaces are totally clean and grease free. If your going to leave a large gap in the joints then work the JB down into the crack and add some on both sides of the metal if possible.
Johnson J-33 Galvanized Steel Flux - Gallon Johnson's "J-33 Galvanized Flux" is the superior choice for soldering sheet metal seams. This flux for soldering galvanized steel is an active chloride formulation with more strength than just plain muriatic acid.