Study of the Effect of Two Separate Tilt Angles of Laser Scanning Lines on the Microstructure and Mechanical Properties in Direct Metal Laser Sintered AlSi10Mg Alloy

Abstract

The scanning strategy has a measurable impact on the grain size and growth direction of the produced parts in powder bed fusion. Tilting of the laser scan lines by 67 degrees is a default procedure applicable to PBF machines for obtaining maximum variability in the direction of melt pools. In this work, AlSi10Mg parts were produced through direct metal laser sintering with two different scanning strategies. In the first strategy, the scanning lines were not tilted in between layers while in the second strategy, the scanning lines were tilted by 67 degrees. The microstructures of the as-deposited alloys for the two strategies were evaluated by state-of-art characterization methods like scanning electron microscopy, electron backscatter diffraction (EBSD), X-ray computed tomography (X-ray CT), and X-ray diffraction. Monotonic tensile tests were hence conducted in both categories. Greater tensile strength was demonstrated by the specimens with no tilting of the scan lines while the specimens produced with a 67 degrees tilt manifested greater elongation. Grain morphology characterized by EBSD studies suggested an inhomogeneity in grain size for the specimens with no tilting of the scan lines. This had primarily attributed to the early failure of the same. It was also found out that the preferred growth direction of grains in AlSi10Mg was hindered by tilting the scan lines by 67 degrees. X-Ray CT studies and Kocks-Mecking Analysis explained the deformation and hardening behavior of both the types in the view of porosity and structural defects.