Effect of scanning tracks on the contour morphology and dimensional accuracy of the fine structure manufactured by laser powder bed fusion

Surface quality and dimension accuracy are severe challenges encountered by fine structures like threedimensional lattice structures manufactured by laser powder bed fusion, which seriously affect the mechanical and functional performance. Previous research paid close attention to the surface roughness but neglected the contour morphology. For the fine features with curved surfaces, scanning tracks significantly influence the contour morphology and distort the profile. Therefore, to demonstrate the influence of scanning parameters, such as hatch spacing, orthometric remelting scanning, and laser power on the contour morphology, the cross sections of vertical cylindrical struts were examined based on the image analysis technique. The effect mechanism of scanning parameters was explored experimentally and numerically. AlSi10Mg as feedstock was used in this work. The results show that scanning tracks have an important effect on the profile of the cross-section and dimension accuracy. Affected by the deflection and resolution of tracks, the geometry morphology of part will distort. When the hatch spacing increases from 100 mu m to 150 mu m, the surface quality will deteriorate, and the circularity and aspect ratio of the contour will further deviate from the designed model. Keeping the hatch spacing of 150 mu m unchanged, orthometric remelting scanning can improve the contour tolerance slightly. Among all those schemes, increasing laser power from 200W to 320 W is proved to be the most effective method to improve the contour morphology, and this scheme also contributes to the stability of print quality. However, increasing laser power will cause serious deviation of size due to bigger molten pool size, so it is recommended that larger laser power should be matched with reasonable settings of border offset.