Effect of beam oscillating pattern on weld characterization of laser welding of AA6061-T6 aluminum alloy

Laser oscillating welding was employed to join 4 mm-thick AA6061-T6 aluminum alloy in butt configuration. Three beam oscillating patterns that are transversal, longitudinal and circular were studied. The beam oscillation improved the weld morphologies and promoted the formation of equiaxed grain within the fusion zone due to stirring effect. The circular oscillation obtained the soundest weld, the finest grain and the most amount of equiaxed grains within the weld. The beam oscillation almost had no effect on the tensile strength of the weld, but increased the ductility obviously. The strain of circularly oscillating weld was up to 8%, 38% higher than the weld without beam oscillation. The ductility improvement was attributed to the decrease of weld morphological defects and the increase of equiaxed grains. Besides, the improving mechanisms of weld characterization were discussed by the beam oscillating effect on the behaviors of laser keyhole and melt flow. (C) 2016 Elsevier Ltd. All rights reserved.