Because calcium has a strong affinity for oxygen, sulfur, hydrogen, nitrogen, and carbon in molten steel, silicon-calcium alloys are mainly used for deoxidation, degassing, and sulfur fixation in molten steel. The addition of silicon-calcium to molten steel produces a strong exothermic effect. Calcium turns into calcium vapor in the molten steel, creating a stirring effect and promoting the flotation of non-metallic inclusions. After deoxidation, silicon-calcium alloys produce larger, more easily floating non-metallic inclusions, while also altering the shape and properties of these inclusions. Therefore, silicon-calcium alloys are used to produce clean steel, high-quality steel with low oxygen and sulfur content, and special-performance steel with extremely low oxygen and sulfur content. Adding silicon-calcium alloys can eliminate nodule formation at the ladle nozzle in steel using aluminum as the final deoxidizer, and address problems such as tundish nozzle blockage in continuous casting/ironmaking.
In ladle refining technology, silicon-calcium powder or core wire is used for deoxidation and desulfurization, reducing the oxygen and sulfur content in the steel to very low levels; it can also control the morphology of sulfides in the steel and improve calcium utilization. In cast iron production, in addition to deoxidation and purification, silicon-calcium alloys also play an inoculation role, which helps to form fine-grained or spherical graphite; makes the graphite distribution in gray cast iron more uniform and reduces the tendency of white cast iron; and can increase silicon, desulfurize, and improve the quality of cast iron.
