MODELLING THE THERMO-SOLUTAL CONVECTION, SHRINKAGE FLOW AND GRAIN MOVEMENT DURING GLOBULAR EQUIAXED SOLIDIFICATION IN A MULTI-PHASE SYSTEM II. MODEL APPLICATION
等轴球晶凝固多相体系内热溶质对流、补缩流及晶粒运动的数值模拟Ⅱ.模型的应用

The developed three-phase model of globular equiaxed grain solidification has been applied to the cooling channel process of semi-solid slurry of A356 aluminum alloy. The effects of the processing parameters on the grain density, size and solid fraction have been studied. The results show that, grain density has its maximum at the pouring position of the cooling channel, the grain size and solid fraction have their maximum at the end of the cooling channel. Their distributions are almost uniform in the mold after rheocasting process. Decreasing proper pouring temperature is helpful to increase the grain density and solid fraction, and to decrease the grain size. In addition, the flow pattern of Al-4%Cu (mass fraction) solidification has been numerically investigated, showing that the thermal convection and feeding flow dominate the flow pattern at the beginning of solidification and the thermo solutal convection dominates the middle and the feeding flow controls the end. Additionally, the effects of grain movement and feeding flow on the formation of free surface and macrosegregation have been studied. The results show that the obstacle of grain movement directly affects the shape of free surface, and completely different macrosegregation maps are obtained with considering feeding flow and without. The developed model has been validated by comparing the grain size between the measurement and simulation.