Pingmei Tang, Sen Wang, Huamei Duan, Mujun Long, Yandong Li, Shuqian Fan, Dengfu Chen
||JOM, 2020, Vol.72 (3), pp.1128-1137
Humps and ripples are typical surface morphologies obtained in the selective laser melting processes and have an important influence on the surface quality of the fabricated parts. In this study, a three-dimensional powder-scale model is presented to investigate the molten behavior and the resulting hump and ripple formation processes. The results showed that a periodic separation of the molten pool and the associated solidification shrinkage of the molten liquid owing to the surface tension caused the periodic humps on the scan track at a low input energy density. Obtaining a continuous molten pool with an extended duration of the liquidus molten pool and a large flow intensity was conducive to alleviating the humps. Additionally, the molten pool had periodic oscillations due to the... recoil pressure that occurred at high input energy densities. The periodic oscillation behavior was responsible for the periodic change of the flow direction of molten liquids at the rear of the molten pool, which caused the periodic formation of ripples during the printing process. Moreover, the surface morphology of the scan track and the dimensions of the molten pool were obtained experimentally. The results were in accordance with the calculated results, which verified the reliability of the model.