In the casting production of steel castings, the most common defect is shrinkage cavity and porosity casting defect, and the main purpose of numerical simulation of the solidification process of castings is to predict the casting defects formed in the solidification process of these steel castings, so that the ultimate purpose of controlling the internal quality of steel castings can be achieved through analysis and research. We know that in the forming process of steel castings, the molten metal will undergo a series of changes, including the cooling process of molten metal, the transformation process of solid and liquid, and the continuous cooling process of steel castings after solidification. In the process of these changes, steel castings will have relatively large shrinkage, and if in the process of shrinkage, it can not be effectively fed, or the feeding is unreasonable, then shrinkage cavity casting defects may occur in steel castings. Generally, according to the different formation mechanism of shrinkage casting defects, shrinkage can be divided into micro shrinkage and macro shrinkage casting defects.
In the early research, the same criterion is generally used to predict the shrinkage cavity and shrinkage porosity that may occur in the casting process of steel castings, and these criterion methods can only predict the location of shrinkage cavity and shrinkage porosity casting defects, but can not predict their size. After long-term and unremitting efforts, the later casting researchers collectively referred to shrinkage cavity and macro shrinkage porosity as shrinkage cavity casting defects, and found a new method to predict the location and size of shrinkage cavity and shrinkage porosity casting defects. For example, the equivalent liquid level shrinkage method proposed by Li Wenzhen, Kang Jinwu, Jia Baoqian and other similar shrinkage methods can well predict the shrinkage cavity. As for the micro shrinkage casting defects, niyama criterion and other methods can be used for prediction.