Shrinkage cavity and porosity casting defect is a hole that occurs when the temperature of molten metal decreases during solidification and the volume shrinkage of molten metal cannot be compensated. The critical solid ratio method is the main prediction method of shrinkage cavity and shrinkage porosity casting defects.
Critical solid rate method means that when the liquid metal is cooled and solidified, when the solid fraction of the tissue reaches the critical value, it will stop flowing and lose the ability to feed other areas. This characteristic is often used to study shrinkage porosity and shrinkage cavity casting defects. Observation method in numerical simulation – when the contour line of critical solid rate of liquid metal forms a closed region, defects will appear in the closed region. This method is simple and intuitive to judge defects, but it is often difficult to supplement when the critical solid rate curve is in the shape of ‘U’ and has not been closed, because the judgment accuracy of this method is not enough.