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建立了宽弦叶片定向凝固过程的宏微观数理模型,计算结果与实验结果吻合,铸件表面大部分晶粒的位置和形状一一对应.通过数值模拟预测了不同引晶方式和拉速下温度场和晶粒组织的演变过程,研究了2种因素的影响规律.通过建立糊状区形态和晶粒数的数学判据,实现了温度场和微观组织优劣的定量评价,基于判据揭示了工艺参数对糊状区和晶粒的影响机理,从而对工艺进行了定量的优化.研究表明,采用叶身正下方的引晶方式,有利于增加柱状晶数目,提高晶粒平行度,防止横向晶界生成,同时还可以在糊状区形状保持平直的前提下使用较高拉速,从而避免晶粒粗化,并提高生产率.
The macroscopical and microscopic mathematical model of the directional chilling process of wide chordal vane is established. The calculation results agree well with the experimental results, and the positions and shapes of most of the grains on the casting surface correspond one by one.The numerical simulation predicts the temperature field And the evolution of the grain structure, the influence law of the two factors was studied.The quantitative evaluation of the temperature field and the microstructure was realized by establishing the mathematical criterion of the shape and grain number of the mushy zone, based on the criterion Process parameters on the mushy zone and the grain of the mechanism, and thus the process of quantitative optimization.Research shows that the use of seeding directly below the blade body is conducive to increasing the number of columnar crystals to improve grain parallelism, to prevent horizontal Grain boundaries, but also can be used in the mushy zone under the premise of maintaining a straight shape under the higher pulling speed, so as to avoid grain coarsening and improve productivity.