Change in mould slag composition during casting of medium alloy steel is caused by the redox
reaction between molten steel and mould flux. Mould flux generally contains a certain amount of
SiO2, but elements such as Al, Mn and Ti in high/medium alloy steels reduce SiO2 in the mould flux,
causing remarkable changes in the composition of the mould slag. As a result, the properties of the
mould slag change greatly as continuous casting proceeds. This causes casting instability, process
abnormality and casting defects. Effect of Ti as an alloying element in steel on mould slag is studied
extensively through high temperature laboratory measurements and plant measurements. TiO2 gets
picked up by the mould slag up to 3 per cent during casting a steel grade containing 0.1 per cent Ti.
This changes the mould slag composition and results in decreasing the slag viscosity by up to
10 per cent and decreases slag break temperature by 30–40°C.