Effect of TiO<sub>2</sub> and TiN on the Viscosity, Fluidity, and Crystallization of Fluorine‐Free Mold Fluxes for Casting Ti‐Bearing Steels
Wanlin Wang, Dexiang Cai, Lei Zhang, Il Sohn
Abstract
TiN inclusions are known to exacerbate slag rimming and nozzle clogging during continuous casting of Ti‐bearing steels. Herein, the effect of TiO 2 and TiN on the viscosity and fluidity of a fluorine‐free (F‐free) mold flux, as well as the corresponding precipitated crystalline phase is studied. Higher TiO 2 is found to lower the viscosity and increase the strip length of the molten slag at TiO 2 contents less than 10 wt%, whereas the viscosity increases suddenly and the strip length decreases rapidly at TiO 2 contents above 10 wt%, due to the precipitation of CaTiO 3 crystals, resulting in a solid–liquid coexisting melt. TiN has a low solubility in F‐free mold fluxes without MnO additions, and TiN is distributed in the molten slag as solid particles. TiN addition significantly increases the viscosity and shortens the strip length of the molten slag. On the other hand, F‐free mold fluxes containing MnO dissolves TiN into the molten slag through the oxidization of TiN to TiO 2 . However, beyond the solubility limit of TiN in fluorine‐free mold fluxes containing 5 wt% MnO, excess TiN is not completely dissolved. Then, the precipitation of Ca 2 Ti 2 O 6 crystals is promoted.