Modified Cellular Automaton Simulation of Metal Additive Manufacturing

Abstract

Metal additive manufacturing (AM) technologies are attracting attentions not only as a fabrication process of complicated threedimensional parts but also as microstructure controlling processes. In powder bed fusion (PBF)-type AM, crystallographic texture can be controlled by scanning strategies of energy beam. To optimize microstructures, computer simulations for predicting microstructures play very important roles. In this work, we have developed simulation programs to explain the mechanism of the crystal orientation control. First, we simulated the shape of melt pool by analyzing the heat transfer using apparent heat conductivity when the penetration of laser beam through keyholes was taken into consideration because of the evaporation and accompanying convections. It was assumed that the primary crystal growth direction can be determined by the temperature gradient, and the crystals grow keeping the growth direction as generally recognized. The shapes of simulated melt pools agree well with experimental observations. The modified cellular automaton simulations successfully reproduced two typical textures with different preferential orientations along the building directions of ©100ª and ©110ª when the bidirectional scanning with and without a rotation of 90°, respectively, was accomplished between the layers.

Digital Twin Science of Metal Powder Bed Fusion Additive Manufacturing: A Selective Review of Simulations for Integrated Computational Materials Engineering and Science

“…(Online version in color.). (86) , reproduced under the CC-BY license), lower side: after Kubo et al (29) , reproduced with permission from Japan Institute of Metal and Materials)). (Online version in color.…”

“…Nevertheless, it is anticipated that the data acquisition of the microstructure formation through computer simulation is becoming practical as well. The latter can be performed using techniques such as cellular automaton (CA) (28,29,102) and phase-field (PF) methods (46,103,104) . According to the author's best knowledge, Gong et al (46) performed PF simulations of microstructure formation for solidification in AM process for the first time.…”

“…Recently, Kubo et al (29) reproduced the crystal orientation textures in SLMed β-titanium with body-centered cubic (BCC) structure by their modified CA method, as shown in Fig. 16.…”

“…The cellular automaton (CA) method can also be used for simulating microstructure. CA is more suitable for simulating microstructure formation with a relatively large length scale, such as grain structures for the whole area of a melt-pool (28) and grain structures generated by superposition of melt region for multiple melt tracks (29) . The results of these simulations are compared with the experimental data.…”

“…Figure 16. Comparison of analysis results (lower side) with experimental results (upper side: after Ishimoto et al(86) , reproduced under the CC-BY license), lower side: after Kubo et al(29) , reproduced with permission from Japan Institute of Metal and Materials)). (Online version in color.…”