Lost Foam Casting (LFC or EPC) is a new technology which subverts the traditional casting technology. It is known as “the new casting technology in the 21st century” and “green engineering of casting” at home and abroad for its flexible process design, high precision of casting size, soft process softening and easy to clean production.
The basic principle ofis to use foam model or model cluster that is similar to the shape and size of the casting, brush the refractory coating and dry it, then vibrate it in dry sand, and pour it under negative pressure, so that the foam model is vaporized, the liquid metal occupies the model position, and the cold casting is formed after solidification. Lost Foam Casting (EPC) was first used in the 1960s, and has been developed successively by clay sand solid mold casting (soft weighing F method), magnetic mold casting (soft weighing m method) and vacuum film sealing molding (soft weighing V method). It was not until 1980s that the combination of F process and V process was developed into the third generation EPC method of dry sand molding and negative pressure casting.
After more than 60 years of development, the technology of EPC for cast iron, cast steel and cast aluminum in developed countries has been basically mature. In recent decades, lost foam casting technology in China has also been rapid development, mainly used in cast iron and cast steel, aluminum alloy lost foam casting successful application of enterprises less. Among them, lost foam casting steel is mainly used in metallurgy industry, mining machinery and heat treatment of various wear-resistant steel, heat-resistant steel and corrosion-resistant steel. The dimensional accuracy of this kind of special steel castings is generally not high and does not need to be processed. However, it has not been widely applied in the field of medium and low carbon steel with strict quality requirements.
The fundamental reason for the slow development of EPC in the field of medium and low carbon steel is the carburization defect. The carbonization defect is caused by the pyrolysis of the polystyrene foam (EPS) at high temperature when molten metal is poured, resulting in a large amount of free carbon, which is caused by complex physical and chemical reactions with molten steel. There are four main forms: surface carburization, volume carburization, local carburization and surface decarburization. The carburization defect of medium and low carbon steel is a worldwide problem in the field of EPC, which has not been solved fundamentally, resulting in the low and medium carbon steel in LFC has not been industrialized and applied at home and abroad.