The influence of laser separation distance on the mechanical properties of 2219 aluminum alloy T joint in double-sided laser beam oscillation filler welding

The laser separation distance (distance between the two lasers in welding direction) in double-sided laser beam oscillation filler welding is difficult to precisely control. To evaluate the effect of laser separation distance on the mechanical properties of T joints, 2219 aluminum alloy double-sided laser beam oscillation filler welding experiments with different laser separation distances were conducted in this work. With laser separation, the symmetry of fusion zone was weakened. The keyhole stability at latter welding side was weakened. The number of pores in the T joint increased. The laser separation distance promoted the formation of porosity at latter welding side and the formation of porosity in the stringer. Most of the cracks in the tensile tests at the weld foot propagated in the partially melted zone. Porosity has no significant influence on the tensile strength of T joints. When laser separation distance was 3 mm, the mechanical performance of T joint was the best. The hoop tensile strength was 370.0 MPa. The T-pull tensile strength was 309.5 MPa. Based on the results of tensile strength testing, the mechanical performance of T joints welded by double-sided laser beam oscillation filler welding did not deteriorate with the laser separation distance less than or equal to 3 mm, which showed a good tolerance of laser separation distance for the welding process.