@Article{cmes.2020.09934,
AUTHOR = {Zhiqiang Wang, Xuede Wang, Xin Zhou, Guangzhao Ye, Xing Cheng, Peiyu Zhang},
TITLE = {Investigation into Spatter Particles and Their Effect on the Formation Quality During Selective Laser Melting Processes},
JOURNAL = {Computer Modeling in Engineering \& Sciences},
VOLUME = {124},
YEAR = {2020},
NUMBER = {1},
PAGES = {243--263},
URL = {http://www.techscience.com/CMES/v124n1/39390},
ISSN = {1526-1506},
ABSTRACT = {During the selective laser melting process, a high-energy laser beam acts on
the powder, a molten pool is rapidly generated and the characteristic parameters are
constantly changing. Among them, temperature is one of the important parameters
in the forming process. Due to the generation of splash particles, there will be defects
in the microstructure, which will seriously affect the formation quality of the prepared
parts. Therefore, it is necessary to study the relationships between the splash behavior,
molten pool characteristics and product quality. The finite element simulation of the
transient temperature field was performed by ANSYS software. Time-series images
at different frame rates were obtained with a high-speed camera, and the dynamic process of splashing was observed. Using IN718 alloy powder, the influence of the laser
energy density on the light intensity of the molten pool was studied. The appearance of
splash particles and the deviation of the powder chemical elements caused by the
splash were analyzed. The results show that the transient temperature field with drastic
change is easy to cause spatter, which is consistent with the experimental results. There
are large differences in the splash at different shooting frame rates. Increasing the frame
rate can allow the observation of details such as the shape, size and number of splash
particles, which is beneficial for studying the process of splash formation. At the
moment when the splash occurs, the light intensity of the molten pool always first
increases and then decreases, depending on the energy input. The higher the energy
input is, the more intense the light intensity of the molten pool and the higher the peak
interval distribution. Compared with fresh powder, the contents of Al and Ti in powder
reused 5 times were reduced by 0.15% and 0.02%, respectively. The increases of these
two elements in the splash were 16.18% and 29.62%, respectively, and the content of
Nb even exceeded the standard range. When the energy density decreased from 229.17
J/mm3 to 130.95 J/mm3
, the relative density of the part increased from 91.82% to
99.83%. This shows that reducing the energy input can reduce the splash to suppress
the generation of defects, along with the weakening of the overall light intensity of the
molten pool. These results can provide a basis for feature extraction of the molten pool,
which is of great significance for real-time monitoring and online control in manufacturing processes and ensuring product quality.},
DOI = {10.32604/cmes.2020.09934}
}