Thermodynamic calculation of activity for CaO-CaF2-SiO2-Al2O3 quaternary slag system in crankshaft steel
ZHAO Bo1, QIAO Tong2, WU Wei1, ZHI Jian-guo3,4
1. Metallurgical Technology Institute, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, China; 2.State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China; 3. Technical Center, Inner Mongolia Baotou Steel Union Co., Ltd., Baotou 014010, Nei Mongol, China; 4. Inner Mongolia Enterprise Key Laboratory of Rare Earth Steel Products Research and Development, Baotou 014010, Nei Mongol, China
Abstract：ANF-8 slag system is commonly used in the electroslag remelting process of crankshaft steel, which has strong desulfurization, dephosphorization and removal of non-metallic inclusions. However, the slag system has high alkalinity, and the molten steel is prone to hydrogen absorption and oxygen increase, thereby reducing the comprehensive performance of steel. Appropriate addition of SiO2 can reduce the occurrence of such problems. In view of the influence of SiO2 mass fraction on the performance of ANF-8 slag system, based on the ANF-8 slag system, the activity of slag components at different temperatures and different SiO2 mass fractions was calculated by the coexistence theory, and the activity variation of slag components was quantitatively analyzed, so as to optimize the thermodynamic performance of slag system at high temperature. The results show that the addition of SiO2 has a great influence on the activity of slag components, the activity of CaO in slag decreases, and the activity of CaF2, SiO2 and Al2O3 increases. Temperature change has little effect on the activity of each component. The SiF4 equilibrium partial pressure of slag system scheme, melting point, viscosity, surface tension and inclusion type of slag were statistically analyzed. It is concluded that 6%SiO2 content can improve the overall performance of slag.
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2022, Vol. 32 
