Evolution of Inclusions in Si-Mn-Killed Steel During Ladle Furnace (LF) Refining Process

• DOI: 10.1007/s11663-021-02074-0
• Publication Date: 2021-03-05T18:03:53Z
• Authors: Zonghui Liu; Guodong Song; Zhiyin Deng; Miaoyong Zhu
• Keywords: Refining (metallurgy); Liquid steel; Ladle; Slag (welding); Refractory (planetary science); Induction furnace

To further clarify the evolution of inclusions in Si-Mn-killed steel grades, industrial samples were taken during the LF (ladle furnace) refining process, and laboratory experiments were carried out to investigate the effects of alloy additions, refining slags, and refractory materials on the evolution of inclusions. It is found that the inclusions transform along the route of “MnO-SiO2-based inclusions → CaO-MnO-SiO2-based inclusions → CaO-SiO2-based inclusions”, and a small amount of MgO and Al2O3 are contained in these inclusions. The increase of CaO content in inclusions is generally caused by the reduction of MnO and SiO2 (especially MnO) by dissolved Ca in liquid steel, while the dissolved Al and Mg in liquid steel could also increase Al2O3 and MgO in the inclusions. Both alloys and refining slag supply very limited Ca to liquid steel, which make it difficult to transform the MnO-SiO2-based inclusions into CaO-SiO2-based inclusions. The use of CaO-containing refractory is the main reason to cause the generation of CaO-MnO-SiO2-based inclusions in this study, and this kind of refractory is not recommended for tire cord and saw wire steel grades.