The nodulizer can transform the graphite in the ductile iron into spherical shape, which can make the cast iron have good plasticity and toughness, and improve its strength. In the casting process, a small amount of spheroidal cast iron can be obtained by adding a certain amount of nodularizing agent to the molten iron.
The comprehensive mechanical properties of ductile iron are similar to those of steel. Ductile iron has the advantages of good casting performance, low cost and easy production, and has been widely used in the metallurgical industry. However, the spheroidal graphite in ductile iron increases the tendency to appear white when welded, so ductile iron is less ductile than grey cast iron.
Nodulizer generally refers to adding some metal or alloy additives to molten iron to obtain ductile iron. Qualified spheroidizing agent types must meet the following conditions: strong spheroidizing ability; few resources and low price; easy mass production; strong adaptability to molten iron composition and temperature; stable spheroidizing reaction process and easy discharge of reaction products.
In general, magnesium-based iron alloys are most suitable as nodularizers. Although rare earth has a spheroidizing effect, it is too expensive and has other disadvantages, so it is generally used in combination with silicon. There is also a calcium-based nodulizer, which is generally more common in Japan. The calcium content is 20-30%. The disadvantage is that the temperature of molten iron is required to be high, and the waste residue after spheroidizing treatment is too much.
Therefore, common rare earth silicon magnesium iron alloys, as well as silicon magnesium iron alloys. As the main component of the spheroidizing agent, elements such as Mg, Ce, and Ca can be used. Ce element is the earliest nodularizing agent, but the output of Ce element is insufficient and the demand for molten iron is harsh, so it cannot be used in industrial production.
The thickness of each grade of rare earth magnesium ferrosilicon alloy castings is not more than 100mm. The standard particle size of rare earth magnesium ferrosilicon alloy is 5~25mm and 5~30mm. According to the application, customers can specify special particle size such as 5~15mm, 3~25mm, 8~40mm, 25~50mm, etc.