TY - JOUR
T1 - Simulations of microstructure coupling with moving molten pool by selective laser melting using a cellular automaton
AU - Ao, Xiaohui
AU - Xia, Huanxiong
AU - Liu, Jianhua
AU - He, Qiyang
N1 - Publisher Copyright:
© 2019 The Authors
PY - 2020/1/5
Y1 - 2020/1/5
N2 - Alloys produced by the selective-laser-melting process have excellent mechanical properties and their microstructures are significantly different from conventional cast alloys. In this paper, a model for predicting alloy microstructure coupling with heat transfer and a moving molten pool was developed using a cellular automata method, and the microstructure morphology and formation mechanism were numerically investigated. The growth kinetics of the solid/liquid interface is driven by the thermodynamic, composition and curvature undercooling, and the growth rate is computed by the Kurz-Giovanola-Trivedi model. The thermal history, cooling rate, molten pool, solidified track, grain growth, and undercooling were qualitatively analyzed by using the developed model. A complex dendritic growth mechanism including homogeneous and heterogeneous nucleations, competitive growth, and epitaxial growth was presented, and the effects of scanning speed, scanning spacing, and pre-heating temperature on the microstructure were examined. The results indicate that the cooling rate is approximately 105–106 K/s during the solidification, the equiaxed crystals increase with either increasing the pre-heating temperature or reducing the scanning speed. The epitaxial columnar grains become longer and narrower with increasing scanning spacing.
AB - Alloys produced by the selective-laser-melting process have excellent mechanical properties and their microstructures are significantly different from conventional cast alloys. In this paper, a model for predicting alloy microstructure coupling with heat transfer and a moving molten pool was developed using a cellular automata method, and the microstructure morphology and formation mechanism were numerically investigated. The growth kinetics of the solid/liquid interface is driven by the thermodynamic, composition and curvature undercooling, and the growth rate is computed by the Kurz-Giovanola-Trivedi model. The thermal history, cooling rate, molten pool, solidified track, grain growth, and undercooling were qualitatively analyzed by using the developed model. A complex dendritic growth mechanism including homogeneous and heterogeneous nucleations, competitive growth, and epitaxial growth was presented, and the effects of scanning speed, scanning spacing, and pre-heating temperature on the microstructure were examined. The results indicate that the cooling rate is approximately 105–106 K/s during the solidification, the equiaxed crystals increase with either increasing the pre-heating temperature or reducing the scanning speed. The epitaxial columnar grains become longer and narrower with increasing scanning spacing.
KW - Dendritic solidification
KW - Microstructure
KW - Selective laser melting
KW - Simulation
UR - http://www.scopus.com/inward/record.url?scp=85073053084&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2019.108230
DO - 10.1016/j.matdes.2019.108230
M3 - Article
AN - SCOPUS:85073053084
SN - 0264-1275
VL - 185
JO - Materials and Design
JF - Materials and Design
M1 - 108230
ER -
