Multi-objective response evaluation for carbon emission and welding performance of laser welding process

Characterized by the advantages of high quality, flexibility, and productivity, laser welding of aluminum alloys is extensively applied in manufacturing fields such as automobile, aerospace, and railway. However, due to the low energy conversion efficiency and high carbon emission, the impact of laser welding on the environment cannot be ignored. Therefore, the environmental impact of the laser welding process should be quantified and a comprehensive evaluation considering both carbon emission and welding performance should be conducted. In this paper, the carbon emission characteristics of each subsystem (i.e., laser device, cooling device, motion device, and gas device) are analyzed, and a laser welding carbon emission model is established. In addition, deformation modeled via finite element method and tensile strength measured through orthogonal experiments are selected as welding performance evaluation indicators. Furthermore, the impacts of process parameters (i.e., welding speed, laser power, and defocus) on carbon emission, tensile strength, and deformation are implemented by Taguchi analysis. The results demonstrate that the welding speed is the dominant parameter affecting the carbon emission, followed by defocus, and lastly by the laser power. Moreover, the welding speed is also the dominant parameter impacting tensile strength and deformation. It is once again followed by defocus and laser power. Based on the TOPSIS (technique for order preference by similarity to ideal solution) method, the best-combined group is the 9th group with 75.8% relative closeness, while the worst is the 14th group with 7.9% relative closeness. The optimal combination is identified for the laser welding of 2670 W, welding speed of 9 mm/s, and defocus of -0.3 mm. The corresponding carbon emission, tensile strength, and deformation are 52.50 gCO(2)-eq, 181.78 MPa, and 1.21 mm, respectively.