Experimental and numerical investigation of the origin of surface roughness in laser powder bed fused overhang regions

Surface roughness of laser powder bed fusion (L-PBF) printed overhang regions is a major contributor to deteriorated shape accuracy/surface quality. This study investigates the mechanisms behind evolution surface (Ra) in regions. The morphology result combination border track contour, adhesion, warp deformation, and dross formation, which strongly related angle (?). When 0° ? ? 15°, does not affect Ra significantly since only small area melt pool boundaries contacts resulting slight adhesion. 15° < 50°, adhesion enhanced by sinking increased contact between boundary bed. > large waviness clusters, severe deformation formation increase sharply.