Graphite Nodifiers, also known as rare earth magnesium silicon iron alloys, are additives that promote the crystallization of graphite into spherical shapes in nodular cast iron. Generally used in the casting of cast iron, these additives are added to the iron melt during the casting process to cause the graphite to precipitate in a spherical form. What is the specific role of the nodifiers?

Cast iron balling, degassing, and inoculant agents.

Magnesium, rare earth elements, and calcium in the balling agent all have strong desulfurization and deoxygenation effects in the molten iron.

2. Steelmaking Additives:

Light rare earth magnesium silicon iron alloys used in the production of nodularizers, degassifiers, and inoculants are also used as additives and alloying agents in the production of steel and iron. They are employed in refining, deoxidation, modification, neutralization of harmful low-melting point impurities (such as Pb, As), and solid solution alloying to form new metal compounds, thereby purifying the steel.

In ductile iron, some elements play a de-aging role, commonly referred to as deforming elements, such as sulfur and oxygen, which are prone to form compounds with the widely used spheroidizing elements.

Magnesium, rare earth elements, and calcium can all desulfurize and deoxygenate; of course, they also consume a portion of themselves in the process. When rare earth elements are present in the deoxidizer, their sulfides and oxides exhibit high stability, with fine particle sizes that are difficult to float in the iron melt. Moreover, these compounds have a minimal lattice mismatch with the graphite crystal structure, serving as heterogeneous cores for graphite precipitation.

The impact on cast iron white mouth tendency is two-edged.

Rare earth elements dissolved in the iron melt strongly promote the formation of carbides, acting as anti-graphitization elements. However, when a small amount of rare earth is added to the spheroidizing agent primarily composed of magnesium, it significantly reduces the white mouth tendency of cast iron. On the other hand, with a higher addition amount, it enhances the white mouth tendency of cast iron.