Effects of Substituting SiO2 with Oxidisers on the Reaction Performance and Physical Properties of Mould Flux for High Ti-bearing Steel

In order to eliminate the TiN inclusion emerging from the molten steel and maintain the stable performance of mould flux during continuous casting of high Ti-bearing steel, the influence of extra oxidisers, such as Mn 2 O 3 , Mn 3 O 4 and Fe 2 O 3 substituting SiO 2 , on the reaction performance and physical properties of CaO–SiO 2 type mould flux was investigated in this study. A detailed study using thermodynamic calculation, X–ray diffraction, and thermogravimetric analysis shows that the oxidisability of oxidisers to TiN, ranging from strong to weak, is Fe 2 O 3 , Mn 2 O 3 , Mn 3 O 4 , and SiO 2 . The oxidisability of SiO 2 in the mould flux is much weaker than that of Mn 2 O 3 and Fe 2 O 3 . Results show that the precipitation of solid iron after the reaction between the CaO–SiO 2 –Al 2 O 3 type or CaO–Al 2 O 3 type mould fluxes with Fe 2 O 3 and TiN worsens the liquidity of the mould flux and further deteriorate its physical properties. Mn 2 O 3 is the best option, with a sustainable change in the physical properties at less than 10 wt.%. Moreover, following the reaction with TiN, the physical properties of the CaO–SiO 2 –Al 2 O 3 type mould flux with 15 wt.% Mn 2 O 3 show an acceptable change for the application of casting.