Effect of Melting Rate on Macrosegregation Behavior in the Electroslag Remelting Process of 06Cr18Ni11Ti

A transient two-phase coupled model for macrosegregation behavior was developed to investigate the coupled electromagnetic, fluid flow, heat transfer, solidification, and solute transport during the electroslag remelting (ESR) process of 06Cr18Ni11Ti steel. This model enabled a systematic analysis of how melting rate affects macrosegregation and multi-physics interactions, optimizing process parameters to reduce segregation. Results show that an increase in melting rate enhances electromagnetic stirring and thermal buoyancy, leading to higher slag pool temperatures, increased turbulent kinetic energy, and greater metal pool depth and cylindrical section height. Solute elements are expelled into the mushy zone during solidification and redistributed within the metal pool, forming an Omega-shaped contour. Under gravity, Lorentz force, and thermal buoyancy, elements accumulate at the bottom of metal pool, with concentration increasing over time. Positive segregation is observed at the center of the ingot, while negative segregation occurs at the bottom and edges. Both lower and higher melting rates lead to an increased segregation index. Lower melting rates result in a smaller metal pool with higher solute concentration and insufficient diffusion, while higher melting rates promote solute accumulation at the bottom, exacerbating segregation. In this study, an optimal melting rate of around 5.5 kg/min minimizes macrosegregation in the ESR ingot.