Investigation of Local Cooling Rate and Microsegregation Behavior in Low‐Carbon Steel During Thin Slabs Continuous Casting Process

High‐speed thin slab casting is challenging for peritectic steel production due to increased crack sensitivity at higher casting speeds. During the solidification process of peritectic steel, the peritectic reaction involving liquid, δ‐ferrite, and γ‐ferrite phases occurs and is influenced by cooling rate. The cooling rate affects dendritic formation, micro‐segregation, and solidification shrinkage, making obtaining the actual cooling rate crucial for controlling the formation of cracks. This study investigates the cooling rate differences between the edge and internal regions of 1250 mm × 115 mm thin slabs of Fe–0.185C–0.2Mn–0.12Si peritectic steel. Using industrial sampling, directional solidification experiments, electron probe microanalysis (EPMA), and optical microscopy (OM), the study investigates microsegregation and microstructure evolution. A novel predictive model (λ 2 = 83.41 C R −0.319 ) for local cooling rate is established through thermodynamic calculations. Results show the average cooling rate at the edge is 1.80°C/s, while the internal rate is 0.36°C/s. The microsegregation of carbon and manganese is validated by the Voller and Beckermann model. This work establishes a predictive model for local cooling rate, analyzes the differences in element microsegregation and cooling rate between the edge and internal regions of thin slab, and provides a foundation for designing cooling strategies to improve the quality of thin slab .