Journal
INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE
Volume 137, Issue -, Pages 67-78Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.ijmachtools.2018.10.006
Keywords
Selective laser melting; Discrete element method; Powder flow-ability; Laser processability; Mesoscopic simulation
Funding
- National Natural Science Foundation of China [51735005]
- Priority Academic Program Development of Jiangsu Higher Education Institutions
- Funding of Jiangsu Innovation Program for Graduate Education [KYLX16_0345]
Ask authors/readers for more resources
A deep understanding of the underlying relation of powder paving and subsequent melting/solidification behavior is critical in predicting and tailoring the processing quality of components fabricated by selective laser melting (SLM) additive manufacturing technology based on the mesoscopic scale. Combining discrete element method (DEM) and finite volume method (FVM), the present work proposed a newly developed three-dimensional DEM physical model coupling with mesoscopic FVM model to give a unique insight into the influence of powder particle size on the flow behavior of powder and resultant melting/solidification characteristics of SLM-processed WC/Inconel 718 composites. The contacting force among powder particles, transition of solid/liquid, and surface tension of melt were considered in the model. By characterizing the packing profiles, velocity vectors and packed state of particles, the simulation results and corresponding experimental validations generally revealed that the powder possessed an elevated flow-ability as increasing the average diameter of powder below 25 mu m, due to the alleviation of the domination of adhesive force among neighboring particles. The considerably high-quality SLM-processed surface without apparent laser-induced defects was obtained with a significantly low surface roughness of 2.2 mu m, attributing to the formation of a denser and more homogeneous powder-bed during SLM. However, when the average diameter of powder particles was elevated over 25 mu m, the combined influence of the elevated gravity of large-scaled powder and the considerable space between neighboring powder particles worsened the flow-ability of powder. The discontinuous and loose powder-bed with a low packing density of particles had a high tendency to produce the top surface with a higher surface roughness, resulting in the formation of a number of defects in SLM-processed parts such as cave-like porosities, balling and discontinuous laser-melted tracks.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available