Role of Electrode Rotation on Improvement of Metal Pool Profile in Electroslag Remelting Process

Abstract

A comprehensive transient model is developed to study the effect of electrode rotation on the evolution of metal pool profiles and the solidification quality of ESR ingots. Magnetohydrodynamic flow, heat transfer, solidification, and electrode melting are considered simultaneously in the model. The growth of the ESR ingot is predicted using the dynamic layering method. The numerical results show that the productivity reaches a maximum of 15.97% at the rotating speed of 40 rpm without increasing power. With the increasing rotating speed, the maximum temperature of the melt decreases, and the temperature distribution becomes more uniform. Compared with the static one, the pool profiles are flattened by −1.19%, −8.52%, and 12.44% at the rotating speeds of 20, 40, and 60 rpm, respectively. The metal pool profile was improved remarkably, but only at the higher speed (i.e., 60 rpm). The effect of rotating speed on the metal pool profile depends on the competition between the melting rate and slag temperature. Meanwhile, the local solidification time and the secondary dendrite arm spacing are slightly improved at lower rotating speeds but are significantly worse at higher rotating speeds.

Numerical Simulations of the Molten Metal Droplet Formation in the Electroslag Remelting Process with a Rotating Electrode

“…Comparing the results of the changed flow field and temperature field against other research publications, especially those of Huang et al, which use a very similar geometry setup, the general observations regarding rotational‐induced changes to flow field and temperature distribution tend to agree. [ 23,24 ] Huang et al do not show auantitative analysis about the film thickness, but from the qualitative figures for different cases, the “ring formation” near the edge of the electrode for rotation speeds around and above 40 rpm also can be observed. Furthermore, adopting the here called CPAD routine for further simulation evaluations seems to be useful, as these data may indicate behavior that one might otherwise not notice within the large amounts of transient CFD data.…”

“…Here, the roughly estimated performance disadvantage factor per timestep is between 100 and 200. [ 22–24 ] Even if the use of a simplified MHD modeling approach, for example, using the ANSYS Fluent MHD module, does not allow the consideration of temperature‐dependent conductivities, eddy, or displacement currents (remark: to the best of our knowledge, there are no comprehensive publications on how relevant these influences can be within the wide range of different ESR processes), using simplified MHD approaches for the modeling of the rotating‐electrode ESR processes, as done by mentioned publications, obviously offers a very significant performance advantage, with comparable results in the tendency. Regarding the case of a rotating electrode simulation, this is especially caused by the fact that a 3D resolution is necessary.…”

“…Furthermore, they reported shifting of droplet detachment to the outer radius of the electrode bottom, decrement of inclusions, and the influence on the pool profiles of different rotation speeds. [ 23,24 ]…”

Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting

“…The ESR is an important refining process for producing high-quality steel, and the process always suffers from segregation defects in the ESR ingots, which are caused by a deep V-shaped metal pool profile. Huang et al [9] developed a comprehensive transient numerical model that considered the magnetohydrodynamic flow, heat transfer, solidification, and electrode melting under the effect of electrode rotation. Results show that the increase of rotating speed accompanied by a reduction of power input is an effective way to simultaneously improve metal pool profiles and reduce the local solidification time and secondary dendrite arm spacing.…”

The Microstructure Formation in Slag Solidification at Continuous Casting Mold

“…Solidification theory, diffusion-limited crystal growth, and segregation-related rheological property were implemented to understand the microstructure evolution. Improvement of the fundamental understanding of the microstructure formation in slag film is the first step to understand its microstructure evolution in more complicated situations, such as the cases when electric field and magnetic field are present in the continuous casting [13,14]. The knowledge about the microstructural control and modification in slag solidification is directly related to the quality of steels made by the continuous casting.…”