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使用有限元数值模拟和实验方法对DD6合金选晶器定向凝固过程的温度影响、晶粒组织以及晶粒生长进行了研究。结果表明,温度场模拟与选晶器定向凝固过程的温度变化基本相符,晶粒组织生长的模拟能够反映晶粒竞争生长的实际情况,与实验试样基本一致。由于取向与温度梯度不一致晶粒的位置被取代,使得引晶段中的晶粒平均半径随着高度增加而增大,晶粒密度不断减小,两者有负指数关系。对比了螺旋段不同高度截面EBSD晶粒取向实验成像与晶粒模拟结果,组织模拟与实验结果较为吻合。通过分析螺旋通道中的晶粒竞争生长关系,位于螺旋通道内侧和上部的晶粒更具有位置优势,容易被选晶器选出。
The influence of temperature, grain structure and grain growth on the direction solidification process of DD6 alloy selectors were studied by finite element method and numerical simulation. The results show that the temperature field simulation basically coincides with the temperature change during the directional solidification of grain-selecting device. The simulation of grain-growth can reflect the actual situation of grain-growth competition, which is basically consistent with the experimental specimen. Due to the mismatch between the orientation and the temperature gradient, the grains’ position is replaced, the average radius of the grains in the seeding section increases with the increase of height, and the grain densities decrease with the exponential relationship between the two. Comparing the EBSD grain orientation experiment images and grain simulation results at different heights of spiral section, the simulation results are in good agreement with the experimental results. By analyzing the competition for growth of the grains in the spiral channel, the grains located inside and above the spiral channel are more positionally located and are easily selected by the crystal selector.