Development of Ca‐Containing Ferrosilicon Instead of Ca Treatment in High Silicon Steels during Ladle Refining

Calcium treatment is widely used to modify Al 2 O 3 inclusions in molten steel. However, feeding Ca wire has the problems of unstable Ca treatment effect, deterioration of molten steel cleanliness, and influence of steel plant environment. Herein, the feasibility of replacing Ca treatment with Ca‐containing ferrosilicon in ladle furnace (LF) refining process is investigated by thermodynamic calculation and industrial trials. The result of thermodynamic calculations shows that the evolution of inclusions type is similar when pure Ca wire and Ca‐containing ferrosilicon are fed, and Al 2 O 3 inclusions are also modified by ferrosilicon. The industrial trials of different addition methods of Ca‐containing ferrosilicon shown that the molten steel had high cleanliness and well inclusions control effect with the process of one‐time addition of ferrosilicon without Ca treatment (OTAF). The Ca treatment of feeding 130 m Ca wire is canceled by postponing the time of adding ferrosilicon. The fitting relationship between the addition of ferrosilicon and the increasing of Ca content in molten steel or the yield of Ca is obtained. In addition, an on‐line control software for Ca increase by adding ferrosilicon is developed to predict the Si and Ca content in the LF refining process in real time.