CO₂ laser welding of tailored 5A02 aluminum alloy sheets with different thickness using filler powder

CO₂ laser was used to weld 5A02 aluminum alloys sheet with different thickness with filler metal powder and without powder.The influences of the filler metal powder on the weld appearance and process stability was studied.Using tensile tests, microscope and SEM, the mechanical and microstructure characteristics of the welded joints were evaluated, and the effect of the weld distribution on the plastic formability of the TWB(tailored welded blanks) were analyzed.The results indicate that the addition of the metal powder can enhance the energy coupling efficiency during laserwelding of 5A02 aluminum alloys sheet with different thickness, and the weld appearance and process stability can be improved greatly.In a wide range of parameters for this alloy sheet with different thickness, the weld appearance is very well.The total elongation in the longitudinal direction for the laser welds decreased greatly.The specimens of the TWB in the transverse direction all fractured on the HAZ of the thinner base metal, the main reason is the thinner base metal of half-harded state was annealed during welding.The ductibility of the TWB is effected by percent of the sheet in a TWB.The total elongation increases with the percent of the sheet with better ductibility. The microstructure of the welds from the fusion line to the weld is cellular dendrite structure, and it is the finer equl-axed grains in the center of fusion zone.