Designing mould fluxes to prevent longitudinal cracking for peritectic steel slab casting

During continuous casting of hypo-peritectic steel slabs, control of horizontal heat transfer rate in mould is important to avoid longitudinal cracks. This rate can be manipulated by mould slag crystallization. From an industrial situation where the longitudinal cracking index was too high, a new mould flux was designed with appropriate crystallization kinetics. The mould flux crystallization process was analysed in laboratory through differential scanning calorimetry. The Friedman isoconversional method was applied to determine the activation energy of crystallization from melt. Besides, a new quick test was developed to evaluate crystallization kinetics. The industrial tests have shown that the new mould flux decreases the longitudinal cracking index, and this is related to the decrease of horizontal heat transfer rate during the continuous casting process, which in turn is related to crystallization from mould slag.