Role of bypass current on pores in double-electrode gas metal arc additive manufactured 2219 aluminum alloy

High porosity has been one of the main issues that limit the application of high-strength aluminum alloys produced by wire and arc additive manufacturing. This study attempts to reduce pores in 2219 aluminum alloys fabricated using double-electrode gas metal arc additive manufacturing (DE-GMA-AM). The effects of bypass current ratio on layer dimension, remelting area, and the number of pores were studied based on single-layer tests. Moreover, the influences of bypass current ratio on mean diameter, mean area, area percentage, radius ratio, and the number of porosities were investigated via depositing thin-walled parts. As the bypass current ratio increases, the layer height increases, and the layer width, the remelted area, and the number of the pores decrease. Pores are mainly distributed in the vicinity of the strips, and the quantity and area percentage in the middle region decrease first and then increase as the bypass current ratio increases. By increasing the bypass current ratio from 0 to 70%, the number of the pores and the area percentage in the middle region decrease by 68.6% and 72.6%, respectively. Porosity in the aluminum alloy parts fabricated using DE-GMA-AM can be significantly alleviated within a certain bypass current range.