The solidification process of the investment casting of the turbine guide is shown in Figure (a). The melt begins to solidify 8.5 s after pouring. When the pouring time reaches 148 s, the solid fraction at the intersection of the investment casting of the turbine guide and the inner runner increases, which is the first to solidify than the liquid metal of the investment casting of the turbine guide. This indicates that the channel filling the cavity in the inner runner has been broken, and the liquid metal of the inner runner cannot fill the cavity, as shown in Figure (b), so there is shrinkage defect at the top of the inner and outer rings of the investment casting of the turbine guide. Shrinkage casting defect in turbine guide.
As shown in Figure (c), the boundary value is set to 0.01, and the shrinkage porosity of the presented parts is more than 1%. This is probably due to the fact that the intersection of the investment casting of the turbine guide and the runner is solidified first during the solidification process, resulting in the inability of liquid metal to effectively fill the cavity.