Evolution and control of inclusions of Ti-bearing ultra-low carbon steel during the steelmaking process

This article investigates the evolution and control of inclusions in the smelting process of titanium containing ultra-low carbon steel. Through industrial experiments, the influence of oxygen content before aluminum addition on inclusions in ultra-low carbon IF steel was explored, and the evolution process of inclusions was studied. The microstructure of different types of inclusions was observed using three-dimensional analysis techniques. Research has found that the oxygen content before aluminum addition has no significant effect on the final oxygen content. However, under low aluminum and low oxygen conditions, the size of inclusions formed is small and difficult to float and remove. Even if the cycle time is extended, the AF index of inclusions remains at a high level. Through three-dimensional morphology analysis of inclusions, it was found that alumina formed under high aluminum and high oxygen conditions is very dense, while inclusions are relatively loose under low aluminum and low oxygen conditions. In addition, through the analysis of aluminum oxygen supersaturation before the formation of aluminum oxide inclusions, it was found that due to the low oxygen content, the nucleation rate of aluminum oxide in the early stage of inclusion formation is relatively low, and the inclusions grow along the trajectory of oxygen, ultimately forming polycrystalline aluminum oxide inclusions. This article also observed for the first time the initial three-dimensional morphology of Al Ti inclusions, providing a theoretical basis for further optimizing smelting processes and controlling inclusions.