Heat Transfer and Flow of Molten Pool in Single Track Multi-Layer Aluminum Alloy Laser Wire Additive Manufacturing

Abstract

In the process of single track multi-layer aluminum alloy laser wire additive manufacturing, there is a lack of in-depth understanding of the heat transfer and dynamics within the melt pool, and it is difficult to characterize the flow behavior inside the melt pool. This paper introduces the numerical simulation of single-track multi-layer aluminum alloy laser wire additive manufacturing. Through numerical simulation methods, the continuous feeding of the wire is realized in the form of mass source terms. Using the user programming interface provided by FLUENT, secondary development is carried out, and programs for laser beam movement and metal wire feeding are written. The results show that as the specific energy K increases, the length and depth of the molten pool gradually increase, the Marangoni force and thermal buoyancy are enhanced, and the flow speed of the molten pool gradually increases. As the number of layers increases, the heat accumulation between layers increases linearly. By adopting a laser attenuation strategy, the overall temperature of the deposition layer was significantly reduced. The flow within the melt pool changed from non-rotational to rotational. Under the rotational flow mode, the flow speed of the melt pool was significantly reduced, achieving a stable temperature distribution, orderly flow of the melt pool, and a deposition layer with good geometric morphology.

Keywords: Additive manufacturing, Laser wire, Numerical Simulation, thermal behavior, Weld pool behavior