The Grain Structure of Castings

本研究采用实验和模拟相结合的方法来研究铸件中等轴晶的形核过程。在该模型中，晶体是由枝晶碎片形核的，因此该模型比目前所采用的半经验非均相成核模型更接近实际。这项研究计划包括：(1)使用透明的含水模拟物来证实模型的基础；(2)检查实验室规模的金属铸件，以确定该模型是否可以进行合理的外推；以及(3)作为模型的最终检验，研究连续铸钢中的晶粒结构。%该程序通过开发柱状到等轴晶转变以及等轴晶尺寸和尺寸分布的改进预测模型，将基本方法与实际铸造实践联系起来。这一主题对于准确模拟铸件的晶粒结构至关重要。

This research incorporates an experimental and modeling approach to the nucleation of equiaxed crystals in a casting. In the model the crystals are assumed to nucleate from dendrite fragments, and therefore the model is considered to be more realistic than the semi-empirical heterogeneous nucleation models employed heretofore. This research plan includes: (1) the use of a transparent aqueous analogue to substantiate the basis of a model; (2) examination of laboratory scale metallic castings to see if the model can be extrapolated with justification; and (3) study of grain structures in continuously cast steel as an ultimate test of the model. %%% This program links a fundamental approach to real foundry practice by developing improved predictive modeling of the columnar to equiaxed grain transition and the equiaxed grain size and size distribution. This subject is critical to accurate modeling of the grain structure of castings.