Aluminum structures, such as tactical vehicle hulls, include plural aluminum components formed from a first alloy composition and joined by one or more welded seam(s). The welded seam(s) may be formed by friction stir welding and/or gas metal arc welding using welding wire made from the first alloy composition. In this manner, all component parts are made from the same alloy composition, providing a more homogeneous structure. The welded component parts then may be placed in a heat treatment furnace to temper the structure. Because essentially all of the aluminum structure before heat treating—the welded seam(s) and the individual component parts—is formed of the same starting material and these parts/seam(s) are simultaneously and evenly heat treated, the resultant hardened, heat-treated part (e.g., a vehicle hull) has a more homogeneous hardened/heat treated structure in the individual parts and across the welded seam(s).