Study on ultrasonic regulation of the welding performance and defects of 7A52 aluminum alloy plate

The welding performance and defects of thick aluminum alloy plates with medium and high strength are always a hot research topic. In this study, ultrasonic technology was used to regulate the properties and defects of welded joints of a 7A52 aluminum alloy plate during double-sided welding, and these welded joints were compared with conventional welded joints. X rays were used to macroscopically detect the defects of welded joints. An optical microscope was used to analyze the grain structure and microdefects in each zone of welded joints. The tensile and impact tests were carried out on the joints. The fracture morphology of tensile and impact specimens was observed using a scanning electron microscope, and the defects and slag inclusions were analyzed by energy dispersive spectroscopy. In the process of ultrasonic welding, the crystallization process of the molten metal pool was changed, and the solidification and heat transfer environment under ultrasonic influence directly led to the change in the properties and defects of welded joints. The experimental results show that the 7A52 aluminum alloy joints can produce deep penetration and very few macroscopic defects after ultrasonic adjustment. Ultrasonic waves can refine the grains in the weld zone, heat-affected zone, and fusion zone and reduce the microdefects in each zone. The tensile and impact properties of ultrasonic welds have been improved by 84% and 87%, respectively. Therefore, ultrasonic waves can regulate the welding performance and defects of 7A52 aluminum alloy plates and other aluminum alloy plates with a similar structural composition. This study provides guidance for the selection of a double-sided welding method with low cost, high efficiency, and good joint performance for aluminum alloy plates.