A Comprehensive 3D Mathematical Model of the Electroslag Remelting Process
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remelting (ESR) process is an advanced metallurgical technology with functions of secondary refining and directional solidification and thus widely used for producing high quality steels and super alloys with high purity and fine grain.[1,2] The ESR process is schematically shown in Figure 1. An alternating current (AC) or a direct current (DC) flows from the electrode, through the slag pool to the ingot. The thermal energy of ESR process, which is primarily supplied by the Joule heating of slag, provides the necessary energy for melting the consumable electrode. The molten metal in the form of droplets or the continuous stream (depending on the melt rate) falls through the slag pool into the metal pool. During the formation and falling period of metal droplets, the harmful elements and inclusions of molten metal are XIAOHUA WANG, Ph.D. Candidate, and YING LI, Professor, are with the School of Materials & Metallurgy, Northeastern University, Shenyang 110819, P.R. China. Contact e-mail: liying@ mail.neu.edu.cn Manuscript submitted August 2, 2014. Article published online May 19, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
removed by slag/metal reaction in the slag pool, and finally the refined molten metal is directionally solidified in the water-cooled copper mold. Consequently, ESR makes great improvements in the final ingot quality, such as a fine solidification structure, less solidification defects, homogenous composition distribution, and low level of inclusion. The ESR process is a complicated metallurgy process with a series of physical and chemical phenomena, and involves complex interactions of the electromagnetic, the flow and the heat transfer. Owing to the presence of high temperature and opaque materials, it is impossible to in situ observe the melting and solidification process during the ESR process. And also trial and error method is very expensive and not well suitable for systematic studies. Therefore, a numerical model, as an alternative method, can be an effective tool to fundamentally understand the ESR process and investigate the effects of the operational parameters on the final ingot quality. Thus modelling has attracted more and more attentions in recent years. In the past decades, many numerical works have been carried out to explain the electromagnetic field, the flow field, and the temperature field of the ESR system. Hernandez-Morales and Mitchell[1,2] gave a detailed VOLUME 46B, AUGUST 2015—1837
Fig. 1—Schematic diagram of ESR process.
review of the development of numerical model of ESR process in the 20th century and pointed out that more efforts were required before the model could be used to provide fundamental understanding of the physical phenomena and quantitative information about the effects of operational parameters. Here, a brief summary of the development of numerical model of the ESR process was given. In 1970s, Dilawari and Szekely[3,4] originally developed a mathematical formulation to represent the electromagnetic force field, the flow field, and the temperature field of the ESR system ba
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