Effects of linear energy density on melt pool and microstructure of selective laser melted AlSi10Mg: An experimental and numerical study

Precise quality control in selective laser melting (SLM) remains challenging due to the numerous process parameters involved. Single-track laser scanning is fundamental to the process, influencing final part quality. This study examines the effect of laser linear energy density (LED) on the morphology and microstructure of singletrack melt pools in AlSi10Mg. Experimental results demonstrate a linear increase in both the width and depth of the melt pool as LED increases from 0.30 J/mm to 0.50 J/mm. The melt track remains consistent in width, with no observable defects. Moreover, the increase in LED correlates with an increase in the area fraction of the Al-Si eutectic and grain size within the melt pool. To investigate the microstructure evolution mechanisms, a singletrack SLM model was established using FLOW-3D to study LED's effect on the thermal history of the melt pool. The results show that as LED increases from 0.26 J/mm to 0.57 J/mm, the peak temperature in the melt pool increases from 2304.05 K to 2830.25 K, while the peak cooling rate decreases from 1.423 x 107 K/s to 8.86 x 106 K/s. A correlation between LED, melt pool dimensions, cooling rate, and microstructural characteristics was established. Furthermore, strategies for suppressing porosity defects and methods for regulating cellular structures and grain size within the melt pool are also discussed.