The influence of surface morphology of the as-fabricated layer on the molten pool flow behavior during the forming process of the next layer for laser powder bed fusion

Abstract

The surface morphology is essential for the fabricated quality of Laser powder bed fusion (LPBF) additive manufacturing. There is a trend that more and more researchers are an attempt to improve surface quality unlimited. However, besides the final layer for the fabricated products, which directly affects the performance and user experience, does the surface morphology of the as-fabricated layer have an altogether positive effect on the forming process of the next layer? Furthermore, does it need to improve the surface quality unlimited? In this research, three kinds of typical surface morphology, flat surface, balling surface, and periodic rough surface, were analyzed and simplified. Then a fluid-heat coupling numerical model was built considering the surface morphology of the as-fabricated layer. The flow behavior of the molten pool during the forming process of the next layer under different kinds of surface morphology of the as-fabricated layer was investigated. The results indicate that achieving an excessively high-quality surface morphology is needless, and an appropriate periodic rough surface is beneficial to improve the forming quality.