Original Article

Effect of types of calcium-containing alloy on non-metallic inclusions in high-Al steel

¹ Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China
² The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China

^* e-mail: zhuhy@wust.edu.cn

Received: 16 March 2024
Accepted: 30 July 2024

Abstract

The influence of different calcium-containing alloys on inclusions in high-Al steel is investigated in the current study. The effects of SiCa, AlCa20, AlCa75 and FeSi alloys on the modification of solid inclusions in molten steel are compared, and the mechanism of inclusion evolution is revealed based on the non-uniform distribution of elements and the lattice mismatch between the inclusion particles. The results show that the Ca yield of FeSi alloy is 26%, which is significantly higher than that of other alloys (<5%). In addition, the calcium treatment by FeSi alloy causes less aspiration of molten steel, which is conducive to avoiding the increase of AlN in high-Al steel. After calcium treatment, the primary Al₂O₃ particles in steel are transformed into CaO-Al₂O₃-CaS and CaO-Al₂O₃-MgO complex inclusions, while AlN can only be precipitated in the form of a single particle, or precipitated from the transformed CaO · 2Al₂O₃ oxide. In general, FeSi alloy has the best effect on the modification of Al₂O₃ inclusions, which can maximize the transformation of solid particles into liquid inclusions in steel liquid without introducing too much impurities.