Knowledge

The specific ways in which spheroidizing agents improve the performance of cast iron mainly include the following points:

 

Promoting graphite spheroidization: Spheroidizing agents can introduce stable elements (such as magnesium, rare earths, etc.) into liquid iron. These elements combine with carbon in the iron to form spherical graphite. Compared with flake graphite, spherical graphite has a reduced tendency to fracture the matrix, thereby enhancing the strength, plasticity and toughness of cast iron.

 

Improving the solidification structure of molten iron: Spheroidizing agents can optimize the solidification process of molten iron, making it more uniform and stable. This helps to reduce shrinkage cavities and segregation inside the castings, and enhances the overall performance of the castings.

 

Improving mechanical properties: After spheroidizing, the tensile strength, yield strength and other mechanical properties of cast iron are significantly enhanced, while its brittleness is reduced, making it more capable of withstanding tensile and impact loads.

 

Improving surface quality: Spheroidizing agents cause inclusions in molten iron to form spherical shapes rather than flaky ones, reducing surface roughness and porosity defects in castings and enhancing the surface quality of castings.

 

Enhanced wear resistance and vibration resistance: After spheroidizing, the graphite in cast iron is distributed in a spherical form, reducing the material's crack sensitivity and thereby improving the wear resistance and vibration resistance of the cast iron.

 

Improving processing performance: Spheroidizing agents can also reduce the gas content and oxide layer thickness in cast iron, thereby enhancing its processing performance.

 

The influence of spheroidizing agents on the morphology of graphite is mainly reflected in the following aspects:

 

Promoting Graphite Spheroidization: The magnesium, rare earth and other elements in the spheroidizing agent can react with sulfur, oxygen and other elements in the molten iron to form sulfides, oxides and other compounds. These compounds act as the core for graphite nucleation, promoting the aggregation of carbon atoms around them to form spherical graphite. By consuming harmful elements and providing nucleation cores, the spheroidizing agent effectively promotes the spheroidization of graphite.

 

Reducing graphite defects: The use of spheroidizing agents can reduce the defects of graphite, such as flake, vermicular, and tadpole-shaped non-spherical graphite. Spheroidizing agents can stabilize the graphite morphology in the molten iron, making the graphite more evenly and regularly distributed, thereby improving the mechanical properties and machinability of cast iron.

 

Optimizing solidification structure: Spheroidizing agents can also improve the solidification structure of molten iron, reducing defects such as shrinkage cavities and segregation. By optimizing solidification conditions, spheroidizing agents help to achieve a denser and more uniform casting structure, further enhancing the performance of cast iron.

 

Controlling the spheroidization effect: The amount, type and addition method of spheroidizing agent, among other factors, all influence the spheroidization effect. Reasonable selection of spheroidizing agent and process control are the keys to achieving a good graphite morphology.

 

Spheroidizing agents influence the morphology of graphite by promoting the spheroidization of graphite, reducing graphite defects, optimizing the solidification structure and controlling the spheroidization effect, thereby enhancing the mechanical and processing properties of cast iron.

 

Vigor has more than 18 years experience on ductile iron castings. If you have any question and demand of products development or improve your supply chain, please feel free to contact us at info@castings-forging.com