Droplet Formation and Dripping Behavior during the Electroslag Remelting Process with Two Series-Connected Electrodes

Abstract

The formation and dripping behavior of droplets in the process of the electroslag remelting with two series-connected electrodes (TSCE-ESR) has an important influence on the optimization of power supply parameters and the purity of the electroslag ingot. In this article, through numerical simulation based on the VOF (volume of fluid) model, combined with the transparent experimental device for physical simulation, the mechanism of metal droplet formation and the effect of the filling rate on its droplet behavior were studied. The results showed that the proximity effect, instead of the skin effect, is a major factor influencing droplet formation in TSCE-ESR process. The proximity effect makes the region inside the two electrode tip melt first, and the molten steel converges at the electrode tips to form a droplet source. The process of droplet formation and dropping can be divided into three stages: formation of molten layer, droplet stretching and necking, and detachment. In the stage of droplet stretching and necking, the increase in the contact area between the droplet and the slag and the instantaneous increase of the current provide good thermodynamic and dynamic conditions for the removal of non-metallic inclusions. After the droplet drops into the slag pool, it promotes the flow of slag and improves the heat and mass transfer efficiency of the slag/metal interface. The relatively large filling rate can form smaller and dispersed droplets, which improves the refining effect. At the same time, the increase of the filling rate can improve the input power and the electrode remelting rate.

A Comprehensive Mathematical Model of Electroslag Remelting with Two Series-Connected Electrodes Based on Sequential Coupling Simulation Method

“…During the formation and dropping of molten droplets, the full contact and interaction between molten slag and molten steel play an important role in the removal of inclusions. In addition to the dissolution and adsorption of inclusions by liquid slag [29], the stretching stage of the molten droplets provides good kinetic and thermodynamic conditions for the removal of inclusions [30]. Compared with OE-ESR, because the heat used to melt the electrode in the TCES-ESR process is higher, the droplet dropping frequency is increased, which makes TSCE-ESR form smaller and more droplets.…”

Numerical Study on the Effect of Low‐Frequency Power Supply on Desulfurization in the Electroslag Remelting Process

“…The continuity and Navier–Stokes equations were used to calculate the two‐phase flow of the slag and the metal, with the Lorentz force added to the Navier–Stokes equations to serve as a source term. [ 26–28 ] The flow was mainly driven by thermal buoyancy and Lorentz force. [ 29 ] The maximum Reynolds number was mainly caused by liquid droplets, which are a low‐Reynolds flows, so the k‐epsilon model was used to calculate the turbulent viscosity.…”