Effects of interface gap and shielding gas on the quality of alloy AA6061 fiber laser lap weldings

Abstract Analyzing the perpendicular and longitudinal sections of the laser welded joints of AA6061-T6, it was confirmed that adding an interface gap between two plates could improve the esthetic appearance and reduce porosity formation. The use of helium as shielding gas yielded a further increase of the weld seam quality in terms of porosity and mechanical properties. The resultant microstructure in the weld zone was analyzed in terms of cooling rate and temperature gradient calculated from the predictive 3D welding model. The failure mechanisms during tensile-shear and cross-tension tests are also analyzed via finite element modeling based on the measured micro-hardness distributions.