Numerical Simulation Of Microstructure In Solidification Of Al-7%Si Alloy

A PC-based software system for numerical simulation of microstructure in solidification of Al-7%Si alloy has been developed by using C++ language. The system consists of three main modules, namely, the pre-treatment, the microstructure simulation module and the post-treatment. In addition, it is user-friendly, easy to administrator memory capacity and transport to other machines.Based on the combination of heat-field simulation, resolution-field simulation and the nucleation and grain growth, processes of microstructure formation, such as grain nucleation, the selection of grains in the columnar zone and the CET transition, are reproduced nicely by using Cellular Automata technique which takes advantage of both probabilistic methods and deterministic approaches. On the basis of KGT model, a modified growth velocity model is presented. One undercooling criterion of equi-nucleation is derived from analysis of Gaussian distribution model of heterogeneous nucleation.A practical system for automatic finite difference mesh subdivision by ray piercing method based on STL is developed. Automatic uniform mesh generation can be realized quickly. The developed pre-treatment module laid a solid basis for further computation.In post-treatment module, directdraw technique and animated-file combination technique are used to output three dimension color graphics of dynamic solidification and color temperature field. Therefore, a simple output manner of 3D graphics is adopted to deal several graphics transformations. The results of output graphics could accurately simulate the solidification process and temperature field distribution of castings.Because the results of computer numerical simulation coincided with those of experiments, computer simulation of microstructure presents the applied prospect for the transition of macro-control of heat treatment process to the micro-control.