Search

• A finite element model used to study the influence of the block support structures on the starting layer is established. • The thermal behavior of the melt pool in the starting layer is numerically investigated. • The average dimension of the melt pool in the starting layer is related to the thickness of porous defect area. • The results of simulation and experiment are used to obtain the optimal dimension parameters of block support structure. Support structures are necessary for laser powder bed fusion (LPBF) especially when overhanging structures are fabricated. In this study, in order to understand the heat dissipation effect of the block support structures on the overhanging structures, a three-dimensional finite element model including the starting layer of the overhanging structure and the block support structures with different dimension parameters was established to numerically investigate the thermal behavior during the LPBF process. The results revealed that the support structures could dissipate the excessive heat of the melt pool in the starting layer, thus formed smaller melt pool and denser area. Different morphological characteristics of melt pool were observed at different positions above the support structures. Compared with increasing the thickness of the support structures, decreasing the distance of the support structures caused the obvious reduction of the average dimension of the melt pool. Samples and the block support structures with different dimension parameters fabricated by AlSi10Mg powder were also experimentally performed and the microstructures of the bottom section of the sample with starting and subsequent layers were investigated to verify the reliability of the numerical model. The minimum porous defect area was achieved at the optimal dimension parameters of the block support structures with 1.0 mm distance and 0.15 mm thickness. [ABSTRACT FROM AUTHOR]