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The characteristics of carbides, such as type, size, and distribution, are important factors that affect the quality of high‐speed steel. To improve the characteristics of carbides produced by the electroslag remelting (ESR) process, an innovative process of electroslag remelting withdrawal with secondary aerosol cooling (ESRW–SAC) is proposed. The structure of the molten bath is obtained using tungsten powder detection, and the characteristics of carbides are statistically quantified by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and the Image‐Pro Plus quantitative analysis software. The 3D carbide morphologies and carbides types are determined by an electrolysis device and SEM–energy‐dispersive spectroscopy (EDS). The results show that, compared with the traditional process, without SAC, the structure of the molten metal bath becomes shallower and flatter with the ESRW–SAC process. Under the influence of SAC, the network spacing and lamellar thickness of carbides considerably decrease, the phase area of carbides increases, and the distribution of carbides becomes more uniform. After the ESRW–SAC process, M2C and M6C carbides are still dominant; however, the morphology of M2C carbides changes from a lamellar to a curved short‐rod form.

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.

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A comprehensive mathematical model of electroslag remelting with two series-connected electrodes (TSCE-ESR) was constructed based on sequential coupling method. The influence of droplet effect on electroslag remelting process (ESR) was considered in this model. Compared with one-electrode electroslag remelting (OE-ESR), the multi-physics field, droplet formation and dripping behavior, and molten metal pool structure of TSCE-ESR process were studied. The results show that during the process of TSCE-ESR, the proximity effect of the electrodes suppresses the skin effect, and Joule heat is concentrated in the area between the two electrodes of slag pool, making the temperature distribution of the slag pool more uniform. The heat used to melt the electrode in the process of TSCE-ESR accounts for about 34% of the total Joule heat, which is lower than the OE-ESR (17%). Therefore, it makes a higher melting rate and a smaller droplet size in the process of TSCE-ESR. Compared with OE-ESR, TSCE-ESR process can realize the unification of higher melting rate and shallow flat molten metal pool. Compared with the results without droplet effect, it is found that in the simulation results with droplet effect, the depth and the cylindrical section of molten metal pool increased, and the width of the mushy zone is significantly reduced, which is more consistent with the actual electroslag remelting process.