Michinori Ohkubo

Effects of zirconium on mechanical properties of 7050 aluminum alloy welds by electron beam welding.

7050 aluminum alloy extruded plates 12mm in thickness were electron beam welded. Effects of Zr up to 0.16% in the base metal on the microstructures and mechanical properties of welds were investigated. Tensile strength, ductility and fatigue strength of the welded joints naturally aged after welding are affected by Zr contents. The welds of Zr added base metal show higher tensile strength and elongation than those of Zr free one owing to refined grain size in the fusion zone. The properties of welded joints T7-tempered after welding are, however, above 90% irrespective of Zr contents. Nevertheless, T7-tempered welds show considerably lower ductility and impact absorbed energy than the base metal. The optimum Zr content 0.12% in the base metal is recommended.