Abstract
In order to meet the requirement of high-quality ingots, the vibrating electrode technique in the electroslag remelting (ESR) process has been proposed. Non-metallic inclusions in ingots may cause serious defects and deteriorate mechanical properties of final products. Moreover, the dimension, number and distribution of non-metallic inclusions should be strictly controlled during the ESR process in order to produce high-quality ingots. A transient 2-D coupled model is established to analyze the motion behavior of inclusions in the lab-scale ESR process with a vibrating electrode, especially under the influence of the vibration frequency, current, slag layer thickness, and filling ratio, as well as type and diameter of inclusions. Simulation model of inclusions motion behavior is established based on the Euler-Lagrange approach. The continuous phase including metal and slag, is calculated based on the volume of fluid (VOF) method, and the trajectory of inclusions is tracked with the discrete phase model (DPM). The vibrating electrode is simulated by the user-defined function and dynamic mesh. The results show that when the electrode vibration frequency is 0.25 Hz or 1 Hz, the inclusions will gather on one side of the slag layer. When it increases from 0.25 Hz to 1 Hz, the removal ratio of 10 μm and 50 μm inclusions increases by 5% and 4.1%, respectively. When the current increases from 1200 A to 1800 A, the flow following property of inclusions in the slag layer becomes worse. The removal ratio of inclusions reaches the maximum value of 92% with the current of 1500 A. The thickness of slag layer mainly affects the position of inclusions entering the liquid-metal pool. As the slag layer thickens, the inclusions removal ratio increases gradually from 82.73% to 85.91%. As the filling ratio increases, the flow following property of inclusions in the slag layer is enhanced. The removal ratio of 10 μm inclusions increases from 94.82% to 97%. However, for inclusions with a diameter of 50 μm, the maximum removal ratio is 96.04% with a filling ratio of 0.46. The distribution of 50 μm inclusions is significantly different, while the distribution of 10 μm inclusions is almost similar. Because of the influence of a vibrating electrode, 10 μm Al2O3 and MnO have a similar removal ratios of 81.33% and 82.81%, respectively.
Highlights
Introduction distributed under the terms andThe electroslag remelting (ESR) process is widely used in the production of high quality special steels and alloys as a secondary refining technology [1]
The temperature-field distribution in the ESR process with a vibrating electrode and a conventional electrode is demonstrated in Figure 2a,b respectively
The temperature field distribution in the liquid-metal pool is more uniform with a vibrating electrode, and the average temperature is higher than that with a conventional electrode
Summary
The electroslag remelting (ESR) process is widely used in the production of high quality special steels and alloys as a secondary refining technology [1]. In the ESR process, the consumable electrode and water-cooled baseplate are fed with AC (Alternating Current) or DC (Direct Current) power. Of a consumable electrode, slag layer, liquid-metal pool, transformer, and water-cooled baseplate. There is a high temperature in the slag layer due to high thermal resistance. The tip of consumable electrodes submerged in the slag layer will be heated and gradually melted to form metal droplets. The metal droplets fall off under the force of gravity, pass through the slag layer, and go into the liquid-metal pool. The molten metal is gradually solidified due to water-cooled mold, forming an ingot
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