Modeling of flow and temperature distribution in electroslag remelting withdrawal process for fabricating large-scale slab ingots

Currently, the market demands for large-scale and high-quality slab ingots are increasing significantly. A novel electroslag remelting withdrawal (ESRW) process with two series-connected electrodes and a T-shaped mould was developed to produce large-scale and high-quality slab ingots. It is very difficult to obtain large slab ingots with good surface quality and high width-to-thickness ratio. And it is not efficient for improving the quality of slab ingots by using trial-and-error-based approaches because the ESRW mechanisms are very complex. Thus, a three-dimensional mathematical model was developed to determine the relationship between process parameters and physical phenomena during the ESRW process. The relationship between the temperature field of the ESRW process and the surface quality of slab ingots was established. A good agreement between the simulated and measured temperature fields of slab ingots was obtained. The results indicate that the maximum values of current density, electromagnetic force and Joule heat all occur at the electrode-slag interface between the two electrodes. It can be found that the flow is turbulent and the temperature distribution is uniform in the slag pool with the influences of buoyancy and electromagnetic force. The wrinkles in the narrow faces of slab ingots are caused by the relatively lower input power. Increasing the electrode width and reducing the curvature can significantly improve the surface quality of slab ingots.