Brief Talk about Common Defects in Castings and Causes

Pore defects in castings

When a molten metal solidifies, there is no time for gas to escape and form round holes in the metal surface or interior. There are three gas elements O, H and N in molten iron. During solidification, the solubility of these three gas elements suddenly decreases. After precipitation, gas forms pore. Another is the large amount of gas generated by sand core, which is easy to form pore when moisture returns or coating is not dry.

Sand inclusion defects in castings

Defects formed by mixing molten slag in the molten iron ladle with molten iron during casting.

Dense pore defects in castings

Pore clusters occurring during solidification as a result of metal shrinkage.

Defects of intercooling insulation in casting

The main reason is that the casting temperature is too low, the metal solution can not flow fully in the casting mould, the two melts do not melt together and the defects are formed on or near the surface of the casting. Or intermittent pouring during pouring operation, lack of full cup pouring and solidification blockage or head oxidation caused by several water-inflowing flow heads which could not be combined

Shrinkage and Porosity Defects in Castings

Defects caused by shrinkage and insufficient shrinkage during solidification of castings are shrinkage holes. The common cause is poor early solidification shrinkage due to low CE value of liquid metal. The porous structure along the center of the casting is called central looseness.

Crack Defects in Castings

Cracks due to shrinkage stress during solidification due to improper material and casting shape. Hot cracks at high temperatures and cold cracks at low temperatures.