Prediction of microporosity (microshrinkage) formation in casting alloys continues to be a subject of high interest to metalcasters because failure to avoid this defect results in many instances in rejection of the casting with associated financial loss. It is a complex problem involving multiple material and process variables. Spheroidal graphite (SG) iron castings are particularly vulnerable to this type of defects because of the low mushy zone permeability associated with the late phases of solidification of this iron. A previously developed model that captures some important elements of the physics of the problem, including gas evolution in the melt with increasing fraction of solid and decreasing mushy zone permeability during solidification, was used to calculate the porosity distribution in L-shaped SG iron castings. The calculation results compared well with experimental observation on L-shaped castings. Some disagreements between calculations and experiments are attributed to gas pore migration during solidification, a phenomenon that is not included in the physics described by the model.

中文翻译：

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球墨铸铁收缩孔隙形成的计算模型：概念验证和实验验证

铸造合金中微孔率（微收缩）形成的预测仍然是金属铸造者高度关注的主题，因为未能避免这种缺陷会导致许多情况下导致铸件报废，并伴有财务损失。这是一个涉及多个材料和工艺变量的复杂问题。球形石墨（SG）铸铁特别容易受到此类缺陷的影响，因为与该铁的凝固后期有关的低糊状区渗透性。使用先前开发的模型来捕获问题的物理学的一些重要元素，包括在熔体中气体的释放，其中固体含量的增加和凝固过程中糊状区渗透性的降低，用于计算L型SG铁铸件的孔隙率分布。计算结果与L型铸件的实验观察结果相比较。计算和实验之间的某些分歧归因于凝固过程中的气孔迁移，该现象未包含在模型描述的物理学中。