Effect of TiO2 on the viscosity and structure of low-fluoride slag used for electroslag remelting of Ti-containing steels

The viscosity of CaF2–CaO–Al2O3–MgO–(TiO2) slag was measured using a rotating crucible viscometer. Raman spectroscopy analysis was performed to correlate the viscosity to slag structure. The viscosity of the slag was found to decrease with increasing TiO2content in the slag from 0 to 9.73wt%. The activation energy decreased from 95.16 kJ /mol to 79.40 kJ /mol with increasing TiO2content in the slag. The introduction of TiO2into the slag played a destructive role in Al–O–Al structural units and Q4units by forming simpler structural units of Q2and Ti2O64-chain. The amount of Al–O–Al significantly decreased with increasing TiO2content. The relative fraction of Q4units in the [AlO4]5--tetrahedral units shows a decreasing trend, whereas the relative fraction of Q2units and Ti2O64-chain increases with increasing TiO2content accordingly. Consequently, the polymerization degree of the slag decreases with increasing TiO2content. The variation in slag structure is consistent with the change in measured viscosity.