Research on the structure evolution of ingots under electromagnetic feeding – cold core compositing casting

• A novel Electromagnetic Feeding−Cold Core Compositing Casting method improves ingot solidification quality. • The Joule heat generated by the electromagnetic shrinkage feeder reduces the depth of the shrinkage cavity by 68%. • The cold core has achieved directional solidification of the ingot. • Results provide guidance for designing special composite ingots. The solidification defects in mold casting include severe shrinkage and porosity due to the higher thermal resistance in the solidification direction and difficulty in feeding. To inhibit these defects in as-cast steel products, a composite casting method using an electromagnetic field and cold core is investigated in this paper. The cold core was inserted in the center of the molten steel, and an electromagnetic field was applied around the riser shell. The grain distribution of composite ingot was investigated by utilizing the optical microscope (OM). Additionally, ProCAST was utilized to study the grain characteristics under different cold core temperatures and superheating conditions The preheating temperature of the cold core and the superheating effect grain microstructure and size are exhibited in the simulation results. The results indicated that not only a reduction in the depth of shrinkage by 68% but also an improvement in the solidification quality in the center of the ingot. The effect of feeding is improved by the electromagnetic heat in the riser, and effective metallurgical bonding is shown between the cold core and molten steel. Notably, four distinct microstructural regions were identified, attributed to the impact of the cold core.