Experimentally-guided finite element modeling on global tensile responses of AA6061-T6 aluminum alloy joints by laser welding

Abstract

There are still some technical issues involved in laser welding of aluminum alloys, such as porosity, cracking, deformation, and so forth. In this study, AA6061-T6 sheets of 2.54 mm in thickness were welded by a disk laser in the bead-on-plate with two different welding parameter sets. Full penetration depths were achieved with decent surface appearances for both cases. The digital image correlation method was successfully applied in experiments to identify material model parameters of tensile welded specimens from various weldment regions. The identified parameters were utilized to numerically simulate the uniaxial tensile tests of laser-welded specimens. The effect of welded joint geometry on global tensile responses was investigated in experimentally-guided finite element modeling. With the help of X-ray computed microtomography, internal defects of the welded bead were detected and used as an input variable in the simulations. Strain development was observed through experimental and numerical data. The results showed that axial deformation was initiated at the top surface of welded metals. The considerable axial deformation occurred at the bottom surface (weld root) of the welded joint just before failure. The numerical results indicated that the geometry of welded joints greatly affected tensile responses. The results also concluded that the diameter of a single void significantly influenced tensile responses compared to its distributed location and the total volume of multiple voids with smaller sizes. Compared between the two sets of welding parameter sets used in this study, the welded joints of this particular AA6061-T6 material with the first parameter set of 2.40 kW laser power and 1.27 m/min traveling speed employed could give better tensile properties and be verified by both experimental and numerical results.