The hot cracking of lost foam cast iron is a com […]
The hot cracking of lost foam cast iron is a common casting defect, so what can we do to avoid the phenomenon of preventing this kind of thing?
The defects of the lost foam cast iron are mainly due to the partial thermal decomposition products discharged through the coating during the casting process, and other thermal decomposition products gradually move upward as the molten iron fills upward. When the section of the casting suddenly becomes thinner, the iron-filled turbulence is severe, the thermal decomposition products in the molten iron increase, and there is no riser at the top. Hot metal contaminated by thermal decomposition products cannot be excluded from castings.
The riser molten iron is seriously carbonized. As the carbon content of molten iron increases, the linear shrinkage coefficient of cast iron increases, and the internal stress gradually increases. After pouring, the vacuum degree is high and the molding sand strength is high, which seriously hinders the shrinkage of the casting. Under the action of the ribs, cracks appeared on the plane of the connecting plate.