This invention relates to the field of welding high strength aluminum structures, and more particularly to the alloy filler metal composition, its resultant microstructure, and the physical and mechanical properties which are obtained in the weld bead during fusion welding. A composition for producing small diameter aluminum welding filler metal wires having a chemistry comprising Si varying from approximately 0.3 to 0.9 wt. %, Mn varying from approximately 0.05 to 1.2 wt. %, Mg varying from approximately 2.0 to 7.0 wt. %, Cr varying from approximately 0.05 to 0.30 wt. %, Zr varying from approximately 0.05 to 0.30 wt. %, Ti varying from approximately 0.003 to 0.20 wt. %, and B varying from approximately 0.0010 to 0.030 wt. %, and a remainder of aluminum and various trace elements.