Regular Article

Effect of lining refractory and high-basicity slag on non-metallic inclusions in a high carbon Al-killed steel

¹ School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, PR China
² School of Mechanical and Materials Engineering, North China University of Technology, Beijing 100144, PR China
³ WISDRI Engineering Technology Co., Ltd., Wuhan, Hubei 430223, PR China
⁴ School of Mechanical Engineering, Yanshan University, Qinhuangdao, Hebei 066004, PR China

^* e-mail: zhanglifeng@ncut.edu.cn
^** e-mail: wenyang@ustb.edu.cn

Received: 25 January 2022
Accepted: 7 June 2022

Abstract

Laboratory experiments on the effect of lining refractory and high-basicity slag on non-metallic inclusions in a high carbon Al-killed steel were carried out. Alumina inclusions in the steel could hardly be affected by the Al₂O₃ refractory, however, would be transformed into MgO · Al₂O₃ when the MgO refractory was used. After the steel-slag-MgO lining-inclusion reaction, the high-basicity slag was saturated with MgO due to the dissolution of MgO from the refractory into the slag, meanwhile, original Al₂O₃ inclusions were transformed into MgO via MgO · Al₂O₃, regardless of the slag basicity. After the steel-slag-Al₂O₃ lining-inclusion reaction, the CaO/Al₂O₃ ratio of slag decreased significantly due to the dissolution of Al₂O₃ refractory into the slag, resulting in the slight increase of the magnesium content in steel and the transformation of Al₂O₃ inclusions into MgO · Al₂O₃. The reduction of the MgO in the lining refractory and top slag by the dissolved aluminum ([Al]) in molten steel occurred independently, and a higher CaO/Al₂O₃ ratio of slag would result in a higher activity of MgO, which was beneficial for the reduction of MgO. The CaO in the slag was hardly reduced by the [Al] in the molten steel, thus, it was proposed that CaO-Al₂O₃ type inclusions could hardly be generated from the steel-slag reaction during the production of high carbon Al-killed steels.