Application of crystallization additivity principle in continuous casting mould flux

Abstract

Testing the isothermal crystallization of mould fluxes poses challenges due to their high critical cooling rates. As a result, isothermal crystallization can be estimated from non-isothermal crystallization using the principle of crystalline additivity. However, the relationship between the TTT (Temperature Time Transformation) and CCT (Continuous Cooling Transformation) curves for volatile mould fluxes remains chaotic. This research introduces precise measurements of both isothermal and non-isothermal crystallization of volatile mould fluxes under conditions that suppressed fluoride volatilization for the first time. The CCT curves derived using the additive principle closely match the experimentally observed patterns, with only minor discrepancies, thereby validating the effectiveness of the additive principle in slag studies. Mould flux BA3 displays a double C-shaped TTT curve, where the high-temperature and low-temperature C-shapes represent distinct crystalline phases. If the computed CCT curve, generated by combining the incubation times of the two C-shaped crystallizations from the TTT curve, significantly diverges from the measured value at temperatures below the partition temperature, segmenting the CCT curve calculations based on high-temperature and low-temperature C-shape data from the TTT curve leads to calculated values that align with experimental results. The study enhances understanding of mould flux crystallization kinetics, crucial for improving the surface quality of continuous casting slab.