Study on laser wire-filling welding process of 5052 aluminum alloy: Effects of wire feed speed, laser power, defocus distance, and duty cycle

Based on the laser wire filling welding process of a 5052 aluminum alloy, this paper investigates the effects of wire feed speed, laser power, defocus distance, and duty cycle on the macroscopic and microscopic structure of the weld. The results indicate that when the wire feed speed is too low, the weld surface is narrow and elongated, lacking fullness; when it is too high, local discontinuities and bulges begin to appear. At a defocus distance of −5 to 0 mm, the molten depth is relatively large, and the molten width fluctuates little overall. As the defocus distance increases from 0 to 3 mm, the molten depth decreases sharply, with the reduction exceeding twofold. As the duty cycle decreases, the grain cooling rate increases, leading to gradual grain refinement in the fusion zone. The optimal process parameters obtained through adjustment are wire feed speed 245 cm/min, laser power 1650 W, defocus distance 0 mm, and duty cycle 95%. At this time, the droplet transition mode is liquid bridge transfer, and the hardness curve shows a symmetrical “double concave valley” shape. The influence of process parameters on weld deposition size is verified through regression models and response surfaces. The synergistic effect of laser power and duty cycle is the strongest, and when combined, they can greatly increase the molten width and the molten depth. In finite element simulations, the temperature field and the stress field exhibit essentially consistent variations, reflecting the inherent nature of thermomechanical coupling.