nodulizer for ductile iron
Nodulizing can convert graphite in spheroidal graphite cast into a spherical shape, improve the strength of cast iron, and have good plasticity and toughness. The comprehensive mechanical properties of ductile iron are similar to those of steel. Ductile iron has good casting performance, low cost and easy production, and has been widely used in the metallurgical industry. However, spherical graphite in ductile iron can increase the tendency of white mouth during welding, so the ductility of ductile iron is lower than that of gray cast iron. In the casting process, a small amount of spherical cast iron can be obtained by adding a certain amount of nodulizer to the molten iron.
Nodulizer generally refers to some metal or alloy additives added to molten iron to obtain spheroidal graphite cast iron. Elements such as Mg, Ce, and Ca can be used as the main components of the spheroidizing agent. Ce element is the earliest nodulizer agent, but the production of Ce element is insufficient, and the demand for molten iron is harsh and cannot be used for industrial production. The qualified Nodulizer type must meet the following conditions: strong spheroidizing ability; low resource and low price; easy to mass production; strong adaptability to molten iron composition and temperature; Nodulizing reaction process is stable, and reaction products are easy to discharge. In general, magnesium-based ferroalloys are most suitable as nodulizers. Although rare earths have spheroidization, they are too expensive and have other disadvantages, so they are 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 molten iron temperature is required to be high, and the waste residue after nodulizing treatment is too much. Therefore, common rare earth silicon magnesium iron alloys, as well as silicon magnesium iron alloys.