Journal of Materials Research and Technology (Sep 2021)
Effect of focal position offset on joint integrity of AA1050 battery busbar assembly during remote laser welding
Abstract
This paper aims at studying the impact of focal position offset on joint integrity of AA1050 battery busbar during remote laser welding. Welding experiments were conducted at different focal position offsets in the AA1050 L-joint with the integration of laser beam oscillation. The impact of focal position offset was evaluated by multiple joint indicators including weld geometry, thermal profile, weld porosity and mechanical strength. Results showed that defocusing of the laser beam tends to be favourable for the reduction of peak temperatures and weld porosity. However, a defocusing more than 3 mm can lead to 60% drop in bonding integrity and 40% loss of joint strength. A tolerance window of [-2 1] mm was determined for the focal position offset, corresponding to 70% and 30% of the Rayleigh length. This result is a useful reference to inform precise focal position control with respect to the accumulated variations of part tolerance, part-to-part gap and part positioning errors. This study also indicated that the thermal measurement can be a potential approach for in-process monitoring of joint integrity. Indeed, the peak temperature near the weld zone showed good linear correlation with off-line detectable joint indicators including weld depth, weld width at interface, weld tensile strength and weld porosity.
