Lattice Boltzmann simulation of single particle melting and solidification in a selective laser melting process: Effects of wettability, supercooling, and heating duration on the balling phenomenon

Selective laser melting (SLM) is one of the most widely used additive manufacturing technologies for producing complex metallic components. It has gained significant attention in the field of industrial manufacturing. Balling is a distinct defect phenomenon in SLM that disrupts the formation of uniform melt lines, resulting in rough, discontinuous surface morphologies. However, the factors that affect the formation of balling are unclear. This study presents a three-dimensional multiphase multicomponent lattice Boltzmann method coupled with a liquid-solid phase change model to simulate the spreading and solidification behavior of molten droplets on cold substrates, following particle melting in the selective laser melting process to study the balling phenomenon. The effects of key process parameters, including substrate temperature, surface wettability, and heating duration, are systematically investigated to reveal their impacts in controlling the molten droplet behavior and mitigating the balling phenomenon commonly observed in SLM. Graphics processing unit based parallel computation is employed to enhance simulation efficiency. The results indicate that a higher substrate temperature and increased surface hydrophilicity, combined with appropriate control of the heating duration, can effectively suppress the occurrence of the balling phenomenon. This study provides new insight into controlling droplet dynamics to improve the quality and reliability of the SLM process.