Abstract
The mesoscopic grain model is a multiscale model which takes into account both the dendrite growth mechanism and the vast numerical computation of the actual castings. Due to the pursuit of efficient computation, the mesoscopic grain calculation accuracy is lower than that of dendrite growth model. Improving the accuracy of mesoscopic grain model is a problem to be solved urgently. In this study, referring to the calculation method of solid fraction in microscopic dendrite growth model, a cellular automata model of 3D mesoscopic grain evolution for solid fraction calculated quantitatively at the scale of cell is developed. The developed model and algorithm validation for grain growth simulation is made by comparing the numerical results with the benchmark experimental data and the analytical predictions. The results show that the 3D grain envelopes simulated by the developed model and algorithm are coincident with the shape predicted by the analytical model to a certain extent. Then, the developed model is applied to the numerical simulation of solidification process of nickel-based superalloys, including equiaxed and columnar dendritic grain growth. Our results show good agreement with the related literature.
Highlights
Grain evolutions including nucleation and growth during solidification process have a profound effect on the material mechanical properties of alloys
The detailed model and algorithm validations are performed by comparing the numerical results with the analytical model predictions
The mesoscopic grain growth in a simple temperature field is studied in this present work, the proposed grain envelope trajectory coupled with the cell solid fraction method can be extended to complex multiscale and multiphysical field calculations
Summary
Grain evolutions including nucleation and growth during solidification process have a profound effect on the material mechanical properties of alloys. Over the past few decades, many computer models and methods have been developed to study theoretically and experimentally the grain growth in alloy solidification, such as the volume-averaged, front tracking, cellular automata (CA), and phase field models [1,2,3,4,5]. In 1993, the CA model was applied for the first time in alloy solidification by Rappaz and Gandin [12]. It mainly dealt with nucleation and growth of grains in a uniform temperature field
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