Influence of differential reduction rate in adjacent roll reduction zone on internal cracks of high carbon bloom induced by mechanical soft reduction

To comprehensively investigate and alleviate internal cracks in high carbon bloom induced by mechanical soft reduction (MSR), a 3D thermal-mechanical coupled model, containing two adjacent pairs of reduction rolls, was developed to investigate the influence of differential reduction rate on evolution of stress concentration and displacement in as-cast bloom. In order to effectively provide theoretical basis for actual production, the reduction rate was calculated according to the appropriate reduction amount of each pair of reduction rolls, which can be adopted in the MSR to determinate the appropriate roll reduction amount in adjacent roll reduction zone. With the differential reduction rate of MSR increasing from −2.67 mm/m to 5.33 mm/m, the maximum equivalent stress of cracking area in as-cast bloom significantly decreased under first roll reduction position, the maximal displacement along the bloom width direction is significantly decreased with increasing of the differential reduction rate of MSR under end roll reduction position. According to the results of industrial experiment, the internal cracks were effectively alleviated and center shrinkage cavities were nearly eliminated by optimum designed experiments.