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.
Highlights
IN713LC, a nickel alloy with a composition of Cr-Al-Mo-Ti-Nb-Zr, is known for its good fatigue resistance, excellent mechanical properties, superior oxidation resistance, and enhanced resistance to degradation under harsh operating conditions [1,2,3,4]
The below conclusions can be extracted from the results: (1) Solidification speed can be controlled by heat input
Faster cooling rate and solidification speed are obtained by decreasing the laser heat input
Summary
IN713LC, a nickel alloy with a composition of Cr-Al-Mo-Ti-Nb-Zr, is known for its good fatigue resistance, excellent mechanical properties, superior oxidation resistance, and enhanced resistance to degradation under harsh operating conditions [1,2,3,4]. The current study develops a coupled finite element (FE) and modified CA model to predict the microstructure and micro segregation behavior of IN713LC during LPBF. The model takes account of Marangoni and surface tension forces, powder volume shrinkage during the melting, melt flow, melt surface evaluation, boundary and bulk equiaxed nucleation, and grain growth. All other powder’s physical properties, ∅p, can be expressed as a function of corresponding IN713LC property, ∅, and the porosity of the powder layer, φ, as [30]:. Both Marangoni and surface tension forced are imposed as boundary conditions on melt surface as: σ. Where vsh is the powder volume shrinkage speed during the melting and can be expressed as: vsh
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