Assessing Soft Reduction Effects on Centerline Macrosegregation in Continuous Casting Using Five Evaluation Metrics

Centerline macrosegregation remains a quality issue in continuously cast steel slabs and arises from the coupled interaction of heat transfer, solidification, fluid flow, microstructural phenomena, and mechanical deformation within the mushy zone. This study quantifies Mn macrosegregation in eight industrial Fe–Mn–C slab samples cast under varied composition and processing conditions, with emphasis on soft reduction (SR) practice. Segregation was evaluated using five complementary metrics: qualitative morphology (macroetching), 2D Mn mapping by synchrotron XRF, 1D average Mn profiles, and two scalar metrics derived from the synchrotron data, namely segregation coefficient ( S c ) and maximum segregation value ( V max ). The non‐SR reference sample exhibits the most severe segregation ( S c = 0.37, V max = 3.05), confirming the mitigating role of SR when appropriately applied near the end of solidification. Across the SR cases, segregation severity depends on the interaction of steel grade, casting speed, superheat, and the SR location, extent, and amount. Increasing total SR amount reduces macrosegregation when the mushy zone remains mechanically responsive to deformation. Lower superheat appears to reduce SR effectiveness, whereas the sample with the highest superheat exhibited the lowest segregation ( S c = 0.26 and V max = 2.84). Overall, the results demonstrate that effective segregation mitigation requires coordinated control of composition, thermal conditions, and SR practice.