Laser–arc hybrid welding (LAHW) is known to achieve more stable processes, better mechanical properties, and greater adaptability through the synergy of a laser and an arc. Numerical simulations play a crucial role in deepening our understanding of this interaction mechanism. In this paper, we review the current work on numerical simulations of LAHW, including heat source selection laws, temperature field, flow field, and stress field results. We also discuss the influence of laser–arc interaction on weld defects and mechanical properties and provide suggestions for the development of numerical simulations of LAHW.

To overcome the instability of the traditional magnesium alloy additive process, the research on oscillating laser-arc hybrid additive manufacturing (O-LHAM) for AZ31 Mg alloy was developed first, and it focused on the effect of beam oscillation on process characteristics, such as macroscopic morphology, porosity defects, microstructure, and mechanical properties of thin-walled components. The increasing oscillation frequency was effective in suppressing the defects, including lack of fusion, wavy hump, internal porosity, etc. Compared with the case without oscillation, the average grain size of O-LHAM samples was refined from 22–32 μm to 18–20 μm at 300 Hz, while the percentage of Al₈Mn₅ and Mg₁₇Al₁₂ precipitation increased from 1.42–1.61% to 2.55–3.32%. For this reason, a stirring laminar flow was induced using the oscillating laser in the melt pool, with the ability to disrupt the grain structure and provide more nucleation sites, which is beneficial in reducing the average grain size and promoting the precipitation of the precipitated phase. Meanwhile, for the component without pores, the ultimate tensile strength is 205 MPa, slightly less than the base, but the elongation is 20.7%, twice that of the base. The tensile fracture is characterized by a large number of dimples and some ductile tearing ridges, demonstrating good ductility, which is associated with the grain refinement and precipitation strengthening induced using the oscillating laser. The results indicated that O-LHAM would be an effective method for manufacturing Mg alloy fast and well.

Hybrid wire arc additive-milling subtractive manufacturing (HWMM) is an effective way to improve the quality of complex metal components, but the difference in the properties of the aluminum alloy and magnesium alloy fabricated by HWMM has been not addressed. In the paper, the differences in deposition accuracy and tensile anisotropy between the Al5Si Al and AZ31B Mg alloys were studied by using the HWMM method. Under the optimal parameters, the minimum surface roughness of the AZ31B sample was 146.1 μm, which was 90% higher than for the Al5Si sample. The differences in the tensile strength and elongation of the AZ31B sample were 32% and 56%, respectively, being 6 and 3.3 times higher than those of the Al5Si samples. According to the fracture behavior of the samples, the tensile anisotropy of both alloys was mainly attributed to defects such as incomplete fusion and porosity in the fusion line. However, there was obvious structural inhomogeneity in AZ31B samples, where the grain size difference between adjacent areas reached 40%. This led to the easier fracture of AZ31B samples. These results contribute to our understanding of the HWMM of light alloys.

Hybrid wire arc additive-milling subtractive manufacturing (HWMM) represents an innovative digital direct manufacturing approach for crafting intricate and low-volume structural components by using the two processes alternately. In order to solve the question that the chatter easily occurs and results in the instability of the milling due to the dynamic deposition of the HWMM, a modelling of HWMM was developed by the finite element modal analysis in this paper. Then, a stability region dynamic lobe diagram was drawn according to the dynamic model of robotic milling system "rigid tool-flexible workpiece", which can predict the optimal parameters. Within this parameter optimization range, milling tests demonstrated an absence of chatter. Furthermore, the prediction results of randomly selected parameters within the stable region are in good agreement with the experimental data. Notably, the milling vibration mean and Ra values for the externally chattered sample were 10.5 times and 4.1 times higher, respectively, than those of the stable milling sample devoid of chatter in the same region. In addressing the challenge of diminishing optimization window width with increasing deposition height, and to enhance stability, the impact of stiffeners on natural frequency was investigated. The study revealed that the T-shaped and J-shaped stiffeners induced the most substantial increase in natural frequency, presenting a promising avenue for expanding the process window. A simultaneous dynamic milling strategy of HWMM is proposed based on the stability region simulation and stiffeners assistance, which can determine quickly, and broaden the milling window, and improve the accuracy and efficiency.