Microstructure and Elements Concentration of Inconel 713LC during Laser Powder Bed Fusion through a Modified Cellular Automaton Model

Abstract

In this study, a hybrid finite element (FE) and cellular automaton (CA) model is developed to explore crystallization behavior and alloying of Inconel713LC during Laser powder bed fusion. A cellular automaton model is considering the surface nucleation, equiaxed bulk nucleation, and grain growth kinetics. In addition, the equation for solute diffusion is coupled with a cellular automaton model to simulate the IN713LC elements segregation. During the phase change, the non-equilibrium segregation model is applied to insert the effect of ultra-fast solidification happening during LPBF. It is found that, during LPBF processing of IN713LC, the micro segregation of Nb, Ti, and C is accrued at the grain boundaries. It is further shown that the micro segregation intensity depends on the solidification speed, which is determined in turn by the laser heat input. In particular, a lower laser heat input increases the solidification speed and results in a more uniform solid phase, thereby reducing the risk of crack formation. Finally, using a comparison between simulation results and experimental observation, it was shown that the proposed model successfully predicts the bulk element concentration of IN713LC after laser melting.

3D Multi-Track and Multi-Layer Epitaxy Grain Growth Simulations of Selective Laser Melting

“…By solving Equations (3)–(5), the growth velocity was obtained as [ 15 , 26 ] where Γ is the Gibbs–Thomson coefficient.…”

“…Moreover, the SLM parameters exert both individual and interactive effects on the SLM outcome, and thus, experimental trial-and-error methods offer no guarantee of success in obtaining the optimal solution. As a result, the use of simulation modeling techniques to predict the microstructures of SLM components as a function of the processing conditions has attracted increasing interest in recent years [ 15 , 16 ].…”

“…The CA method, originally proposed by Gandin and Rappaz [ 20 , 21 ], takes into account all aspects of the solidification kinetics in SLM processing, including heterogeneous nucleation, the growth kinetics of the crystal structure, the preferred grain growth direction, and so on. Zinoviev et al [ 15 ] used a two-dimensional (2D) CA model to evaluate the grain structure during the SLM processing. However, although the model successfully reproduced the columnar growth behavior of the grains during the build process, the final grain structure morphology was different from that observed experimentally due to the 2D nature of the simulation model.…”