| Abstract Scope |
Laser beam shaping is the process of adjusting the intensity profile of the laser beam to generate an optimal distribution at a specific location. By carefully adjusting the laser intensity profile, peak temperature, pool geometry, solidification properties, and cooling rate, can be controlled. To provide a thorough scientific understanding of how beam shaping affects temperature fields, fusion zone geometry, cooling rates, and solidification parameters during LPBF, we have developed a 3D transient numerical heat transfer model. We have studied the effects of six beam shapes: Gaussian, elliptical Gaussian, top hat, flat top, ring-shaped, and adjustable mode beam (AMB). The model took alloy properties and process variables as inputs. The model was implemented using the ABAQUS/CAE software. The temperature variations within the powder layer are modeled using the energy conservation equation. The subroutine DFLUX is used to implement the laser's heat and control variables such as scanning speed, layer thickness, and preheat temperature. The assumption of pure heat conduction is made, ignoring the influence of Marangoni-driven molten pool convection. The experimental data for the LPBF of AlSi10Mg were then collected from the literature to validate the model. It was found that AMB lasers that combine a ring-shaped beam with a Gaussian core achieve the lowest peak temperature. The Ring-Shaped beam forms wider, shallower melt pools. The Elliptical-Gaussian and Flat Top beams generate broader, shallower pools with lower peak temperatures. AMB and Ring-Shaped lasers yield larger melt pools and slower cooling rates. The Gaussian beam’s power density decreases from its center. The Elliptical-Gaussian profile also has a central peak, with scanning along the minor axis chosen for higher heat input. The Top Hat profile, despite having the same effective area, has a lower power density. The Ring-Shaped beam’s power density increases outward, reducing heat input. |