The casting simulation of four branch cast steel joints is carried out by using ProCAST casting simulation software to explore the causes of defects. The casting process and parameters are selected according to the actual casting conditions to simulate the metal flow and solidification process in the process of sand mold casting, then predict the location of sand mold casting defects, reveal the formation mechanism of shrinkage defects and crack defects, and make a comparative analysis with the results of slice test in Chapter 3. On the basis of verifying the accuracy of the casting model, the influence of the casting process on the defect distribution of sand mold casting is obtained by adjusting the casting process.
(1) The casting simulation of four branch cast steel joints made of gs20mn5 is carried out by using ProCAST software. The casting simulation results show that the defects are concentrated near the riser, the stiffener and the R area, which is consistent with the defect concentration area found in the slice test in Chapter 3. The casting simulation results explain the causes of shrinkage near the riser, crack in the intersection area, shrinkage of stiffener and shrinkage of branch pipe root.
(2) The effects of different riser height on the defect distribution of cast steel joints are compared. It is found that changing riser height has a significant effect on shrinkage and porosity defects; The effects of layered casting and bottom injection casting on the defect distribution of cast steel joints are compared. It is found that the two casting modes have little effect on the defect distribution; The effect of cold iron on the defect distribution of cast steel joints is studied. It is found that the use of cold iron makes the liquid steel near the gate and at the bottom of sand casting cool rapidly, which can give better play to the feeding role of riser, but cold iron will transfer the defects.