The Role Of SiC Inoculant in Cast Iron

The role of SiC inoculant in cast iron

(1). (Si) in SiC enters molten iron, (C) a small part is oxidized by oxygen in the air, and other SiC particles enter the casting.

(2). The SiC microparticles enter the molten iron and play the role of core substrate when solidified. The finer and more SiC, the stronger the nucleation ability. Observation under TEM shows that the interface between SiC particles and the matrix is well combined, and there are high-density dislocations around the particles, which leads to grain refinement, and changes in the shape of graphite.

The length of graphite is shortened, the A-type graphite is increased, the D-type graphite is decreased, and the number of eutectic groups and pearlite is significantly improved. As we all know, when it reaches 300 pieces/mm2, the casting has shrinkage cavities, while after SiC is used, it is 130~250 pieces/mm2, so the mechanical properties are improved without leakage.

(3). Si in SiC can reduce gas and slag inclusion when molten iron is processed in the ladle before the furnace.

(4). C-increasing SiC inoculants are divided into low-carbon and high-carbon. Low carbon type (C<10%) will not increase C in castings; high carbon type (C≥23%) can increase C in castings, and the carbon equivalent is easy to grasp, so that more scrap steel can be added, and castings with good performance can be easily obtained.

(5). Silicon carbide inoculant is added before pouring. Its function is to increase both C and Si (Φ2-3mm can be used before the furnace, and 20-30mm after the furnace).