Optimization of LF refining process and slag for low carbon aluminum containing steel

Ladle furnace (LF) refining slag plays an important role in desulfurizing and inclusion removal from steel. According to the highO content and lowC in the initial liquid steel from BOF (basic oxygen fur-nace) furnace, the CaO-Al₂O₃ slag system was suggested to use in the LF refining of low carbon aluminum con-taining steel. To enhance the desulfurizing and inclusion absorption for the liquid steel, the compositions of the final refining slag in LF can be chosen as:CaO=55%-60%, SiO₂=4%-7%, Al₂O₃=28%-32%, MgO=4%-8% (mass fraction), and CaO/Al₂O₃=1.7-1.9. During the tapping, most of the refining slag was added into the ladle to real-ize slag filtration. The oxidizing slag tapped into the ladle from BOF was reduced in the end of tapping. And enough time was kept to killing the liquid steel with Ar soft blowing. By all of above methods, the steel grade of 16MnR was refined with a better result as:the desulfurizing ratio was 61.8%, the total oxygen content TO in slab decreased to 22×10_-6, and the macro inclusions (≥ 50 μm) in slab also dropped down to 15.68 mg/10 kg steel.