AlSi10Mg cubes were fabricated with the laser powder bed fusion (LPBF) process, using different exposure times and scan strategies to gain insight into the effect of energy density and part orientation on surface roughness. The results showed that, with increasing energy density, the five-face roughness first decreased and then increased, whereas the top roughness increased slightly. Moreover, considerable differences in roughness appeared for the different faces. A good surface quality was obtained at 175 J/mm³ and 200 J/mm³ when the rotation start angle and rotation increment angle were set as 0 in meander scan mode. The roughness variation was caused by the scan direction, gas flow direction, and wiper movement direction. The scan strategies with rotation increments of 90° effectively narrowed the variation. These results support direct part orientation and placement and can guide users to further reduce roughness through process optimisation or simplification of post-processing procedures.

A 3D Finite Element (FE) model was developed to investigate the thermal behaviour within the melt pool during point exposure to Selective Laser Melting (SLM) processed AlSi10Mg powder. The powder–solid transition, temperature-dependent thermal properties, melt pool convection, and recoating phase were taken into account. The effects of Exposure Time (ET) and Point Distance (PD) on SLM thermal behaviour were also investigated and showed that the short liquid phase time and high cooling rate of the melt pool reduced the viscosity of the melt pool at a lower ET or a higher PD. This resulted in poor wettability and the occurrence of balling and micropores. At a higher ET or lower PD the melt pool became unstable and allowed for easy formation of the self-balling phenomenon, as well as further partial remelting in the depth direction resulting in the creation of larger pores. The proper melt pool width (119.8 μm) and depth (48.65 μm) were obtained for a successful SLM process using an ET of 140 μs and a PD of 80 μm. The surface morphologies and microstructures were experimentally obtained using the corresponding processing conditions, and the results aligned with those predicted in the simulation.