PhD abstract
The laser powder bed fusion (PBF-LB) use is increasing in the industry, but a lack of understanding remain on some aspects, which limits its development. This is the case for the dimensional and geometric properties of the parts produced by this process, which can display significant deviations from the numerical model. Thus, the aim of this work is to improve the understanding of the mechanisms behind dimensional and geometric deviations. Following a literature review which identified the main causes of these deviations and the most influential process parameters, it was decided to study the dimensional and geometric aspects at different scales. An initial study was carried out on the scale of the melt bead, which enabled us to gain a better understanding of the ranges of parameters that allow for healthy construction. This study also enabled the determination of the variations in bead morphology as a function of the process parameters used. The second study at part scale illustrated the impact of bead geometry and surface roughness on dimensional deviations. The geometric deviations are influenced by the surface roughness, and by the distortions due to residual stresses, which were specifically studied afterwards. The role of the process parameters laser power and scanning speed was also assessed, revealing a less significant influence than expected compared to the influence of the chosen geometry. Finally, attention was paid to lattice structures, the study of which revealed the importance of orientation as well as the difficulty of evaluating the geometry.
Key words
metrology, additive manufacturing, dimensional, powder bed fusion, metal, geometry
PhD Thesis
Full document (FR) : HAL-04271836