Casting Defects of Metal Materials, part 2

The main defects of casting products are segregation, pores, shrinkage and shrinkage, inclusions, cracks, cold shut and other defects.

Pores

During the solidification process of metal, the solubility of gas decreases sharply. It is difficult for gas to escape from the solid metal with high density and is retained in the melt to form pores.

Different from shrinkage cavities and shrinkage porosity, pores are generally round, oval or long strips, distributed individually or in strings, with smooth inner walls.

Common gases in the pores are H2, CO, H2O, CO2, etc. According to the location of pores in the ingot, they are divided into internal pores, subcutaneous pores and surface pores.

The existence of pores reduces the effective volume and density of the ingot. Although it can be compressed and deformed after processing, it is difficult to weld, resulting in defects such as peeling, blistering, pinholes, and cracks in the product.