Influence of Mold Geometry on Solidification Behavior and Solute Segregation in Low‐Alloy Steel Ingots

This study investigates the effect of mold geometry on carbon segregation in 20‐ton low‐alloy steel ingots by combining industrial experiments with numerical simulations. Polygonal and rectangular ingots were compared to clarify how geometry‐dependent heat transfer, melt flow, and grain evolution affect macrosegregation. The industrial results show that the rectangular ingot has a markedly smaller carbon segregation range, with a maximum Δ C of 0.27, compared with 0.53 in the polygonal ingot. The polygonal ingot exhibits more severe positive segregation at the head, with a maximum carbon content of 1.00 wt%, and stronger negative segregation at the tail, with a minimum carbon content of 0.409 wt%. In contrast, the rectangular ingot shows milder segregation and a smaller affected region. Numerical simulations indicate that these differences are associated with variations in the temperature field, melt flow pattern, solidification front morphology, and grain growth behavior. In the polygonal ingot, unstable convection, narrow remaining liquid channels, and dendrite bridging restrict solute transport and aggravate local segregation. By contrast, directional heat extraction through the broad faces of the rectangular ingot produces a wider and more regular solidification front, a more stable flow pattern, and smoother solute redistribution, thereby reducing macrosegregation.