| Résumé | Extending applications of thick aluminum alloys in various industrial market segments necessitates the development of advanced welding technologies to ensure high integrity welds. In the present work, single pass laser cold-wire welding of 4.8 mm thick AA6061-T6 aluminum plates was carried out in the butt joint configuration. The effect of laser welding parameters such as welding speed, continuous-wave (CW) and pulse-wave (PW) modes (Table 1) on weld integrity, microstructure and mechanical properties was evaluated. Porosity, underfill and excessive penetration were observed as the main imperfections in the fusion zone as displayed in X-Ray photographs (Figure 1) and metallographic pictures (Figure 2). However, the underfill depth and excessive penetration height in the joints manufactured at different welding conditions met the specifications of ISO 13919 standard. Porosity qualifications i.e., Max. porosity and cluster dimensions, and porosity area fraction, in PW mode passed the minimum requirement criteria of the stringent ISO 13919-2 standard quality class (level B), while these porosity qualifications in CW, at 3 m/min welding speed just passed the quality level C criteria as displayed in Table 2. By increasing the welding speed from 3 m/min to 4.5 m/min in CW mode, the maximum single and cluster porosity dimensions, and porosity area fraction are reduced significantly. These results indicate that both laser mode and travel speed can influence the porosity formation during laser cold-wire welding of AA6061-T6 aluminum plate. Welding in PW mode versus CW mode, at the same travel speed and at a similar average power can reduce the porosity area fraction by ~64%. Increasing the welding speed from 3 to 4.5 m/min in CW laser mode reduce the porosity area fraction by ~75%. This can be due to an increase in keyhole stability at higher welding speed. |
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