Effect of Calcium Treatment on Non-metallic Inclusions in Steel During Refining Process

Different amounts of calcium wire were added to the molten steel during the refining process in industrial trials to study the effect of calcium contents on the size distribution, content, and morphology of inclusions. Thermodynamic calculations were also conducted to study the effect of calcium contents on inclusions. It was found that with the increase of calcium content in steel, Al2O3 content in inclusions decreased while CaS content increased. However, when calcium content was bigger than 30 ppm, the CaO content decreased slightly and the CaS content increased more. As the calcium content in steel increased, the average size and area fraction of inclusions decreased, which means that appropriate calcium treatment technology will not reduce the cleanliness of molten steel as well as will not increase the proportion of large-sized inclusions in the steel.