Microstructure homogenization of 2A14 aluminum alloy weld seam by ultrasonic irradiation in metal inert gas welding

The quality of welded joints is affected by microstructure heterogeneity of the weld seam. In this work, the microstructure homogenization of 2A14 aluminum alloy weld seam was achieved by adding ultrasonic irradiation in the metal-inert gas welding (U-MIG). Compared with the traditional MIG, the width and penetration of the weld seam in the U-MIG increased by 1 mm and 1.7 mm, respectively. Ultrasonic cavitation was the main reason for the microstructure homogenization of the weld seam. The columnar grains near the fusion line in the conventional MIG were completely transformed into the equiaxed grains under the action of ultrasonic irradiation. The size of equiaxed grains was more refined than that of the initial columnar grains.