Study of a Single-Power Two-Circuit ESR Process with Current-Carrying Mold: Mathematical Simulation of the Process and E
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T-CARRYING mold was created after the development of electroslag remelting (ESR) and has subsequently been used in the ESR processes.[1] Many experiments have been conducted using current-carrying mold. Medovar and Tskulenko et al.[2,3] found that an ingot, with a very smooth surface and no surface defects, is obtained, even at very low melting rates, using currentcarrying molds. Holzgruber et al.[4] performed an experiment using a double-power two-circuit ESR system; the principle is shown in Figure 1(right). A shallower, molten steel pool and an ingot, with lower element segregation compared to conventional ESR, are achieved in their work. Dong et al.[5,6] found that current-carrying mold can also replace conventional consumable electrodes that constitute a part of the circuit when ingot is manufactured by current-carrying mold with liquid metal. Liu et al.[7] melted hollow ingots into a T-shape current-carrying YANWU DONG, ZHIWEN HOU, ZHOUHUA JIANG, HAIBO CAO, QIANLONG FENG, and YULONG CAO are with the School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, P.R. China. Contact e-mail: [email protected] and [email protected] Manuscript submitted June 25, 2016. Article published online December 13, 2017. METALLURGICAL AND MATERIALS TRANSACTIONS B
mold and found the highest temperature of the slag pool was higher than a conventional ESR process. Annular multi-electrodes between internal and external molds are adopted, but this results in operational trouble due to the narrow gap between the electrode and mold. Moreover, there is some interference between the two power supplies and the two circuits. The remelting process[8] has been simulated using current-carrying mold, but the current distribution ratio of the two circuits is not clear. Although the abovementioned experiments applied current-carrying molds, related data are still scarce, especially regarding the difference between the singlepower two-circuit ESR with current-carrying mold (ESR-STCCM) and the conventional ESR process. In this paper, we focus on the ESR-STCCM process, as shown in Figure 1(left). The current has two circuits throughout the system, but only a single-power supply. On the one hand, the current path is as follows: transformer consumable electrode slag pool ingot base plate transformer; and on the other hand, electric current flows from transformer current conductive part of mold (conductor) slag pool ingot base plate transformer. ESR is a very complex process that considers the electromagnetic force, gravity, buoyancy, fluid flow, heat transfer, and so on. It becomes even more complex in the ESR-STCCM process. Relevant mathematical models that VOLUME 49B, FEBRUARY 2018—349
Fig. 1—Schematic diagram of single power or double power of two-circuit ESR.
describe the process are established in this paper. To simplify the model, several assumptions are proposed[9] as follows: (1) The process is considered as a quasi-steady state; (2) The interface between the slag and metal pool is a horizontal surface; (3) The consumable ele
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