In this study, 7A52 aluminum alloy sheets of 4 mm in thickness were welded by tungsten inert gas welding using microalloying welding wires containing traces of Zr and Er. The influence of rare earth elements Zr and Er on the microstructure and mechanical properties of the welded joints was analyzed by optical microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, hardness testing, and tensile mechanical properties testing. Systematic analyses indicate that the addition of trace amounts of Er and Zr leads to the formation of fine Al3 Er, Al3 Zr, and Al3(Zr,Er) phases that favor significant grain refinement in the weld zone. Besides, the tensile strength and hardness of the welded joints were obviously improved with the addition of Er and Zr, as evidenced by the increase in tensile strength and elongation by 40 MPa and 1.4%, respectively, and by the welding coefficient of 73%. In this study, 7A52 aluminum alloy sheets of 4 mm in thickness were welded by tungsten inert gas welding using microalloying welding wires containing traces of Zr and Er. The influence of rare earth elements Zr and Er on the microstructure and mechanical properties of the welded joints was analyzed by optical microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, hardness testing, and tensile mechanical properties testing. Systematic analyzes that that the addition of trace amounts of Er and Zr leads to the formation of fine Al3Er, Al3Zr , and Al3 (Zr, Er) phases that favor significant grain refinement in the weld zone. Besides, the tensile strength and hardness of the welded joints were significantly improved with the addition of Er and Zr, as evidenced by the increase in tensile strength and elongation by 40 MPa and 1.4%, respectively, and by the welding coefficient of 73%.