Porosity defect of bucket teeth

One of the most common casting defects is porosity. It is classified into three categories based on the different mechanisms of formation.

Invasive porosity casting defect: a porosity casting defect caused by gas invading the liquid metal from the outside that cannot be removed. The gas comes from the molding sand, the mold cavity, and the cold iron, and it may also be involved in the gas during the pouring process. It frequently appears in bucket teeth casting parts, on the surface of bucket teeth castings, or inside castings. The majority of porosity casting defects are round or oval, trumpet shaped, and the root frequently refers to the point where gas enters. The majority of gases are steam, CO2, or carbon compounds.

The porosity of precipitation casting flaw: the gas dissolved into the metal during melting. Due to the decrease in solubility, it precipitates from the metal as it cools and solidifies. The majority of the gas is hydrogen and nitrogen, with scattered pitted small round holes, a bright surface, and often covered by the entire casting section.

Reactive porosity is a casting defect caused by a chemical reaction between the mold and the metal, the metal and the slag, or some metal components. CO and hydrogen are the most common gases found in cast iron and steel castings. Subcutaneous pores, surface pores, and internal pores are the three types of reaction pores.