Effect of combining F-EMS and MSR on the segregation and shrinkage cavity in continuously cast high-carbon steel blooms

This study established a two-dimensional mathematical model of solidification and heat transfer for a bloom with a 310 mm×360 mm cross-section using ANSYS software, which was verified by nail-shooting experiments in the narrow side of the bloom and surface temperature testing. The effect of the casting process parameters, such as superheat, casting speed, and secondary cooling intensity, on the solid fraction in the strand centerline and the solidified shell was investigated. Moreover, the optimum casting speed and the optimum solid fraction in the core of the partially solidified strand throughthe soft reduction zone were determined by the model considering the hot ductility of the high-carbon wear-resistant ball steel BU. Plant trials of BU with different casting speeds were performed to validate the theoretical model and analyze the effect of the casting speed on the segregation and shrinkage cavity of BU on a 310 mm×360 mm bloom caster equipped with final electromagnetic stirring (F-EMS) combined with mechanical soft reduction (reduction amount with 17 mm). The results show that the inner defects (e. g., center segregation, V-segregation, and shrinkage cavity) significantly improve when the casting speed is adjusted to meet the required soft reduction zone as a matter of priority; otherwise, the casting speed is only adjusted to preferentially satisfy the required F-EMS stirring region. The inner quality does not show any obvious improvement. Except for the internal cracks and the negative center segregation caused by the improper distribution of the reduction amount, the inner defects (e. g., macro segregation and shrinkage cavity) significantly improve with a casting speed of 0.52 m·min^-1 and a solid fraction in the strand centerline ranging from 0.30 and 0.75 in the soft reduction zone.