Comprehensive Mathematical Model for Simulating Electroslag Remelting

Abstract

Droplet formation and departure from an electrode tip affect the temperature distribution in liquid slag and a molten steel pool, as well as the removal of nonmetallic inclusions in the electroslag remelting process. In this article, magneto-hydrodynamics modules coupled with a volume of fluid (VOF) model (as described in VOF model theory) for tracking phase distribution have been employed to develop the electrode fusion model and to investigate formation and departure of a droplet from the electrode tip. Subsequently, the remelting rate and molten steel pool have been achieved based on the electrode fusion model. Results indicate that a droplet can increase the flow rate of liquid slag, especially the region of droplet fall through the slag pool; yet it has little impact on the flow distribution. Asymmetric flow can take place in a slag pool due to the action of the droplet. The depth of the molten steel pool increases in the presence of droplets, but the width of the mushy zone decreases. In addition, the shape of the electrode tip is not constant but changes with its fusion. The remelting rate is calculated instead of being imposed in this work. The development of the model supports further understanding of the process and the ability to set the appropriate operating parameters, especially for expensive and easy segregation materials.

Effect of Slag Composition on the Oxidation Kinetics of Alloying Elements during Electroslag Remelting of Stainless Steel: Part-1 Mass-transfer Model

“…According to the references 3,8,14) and the liquidus temperature of 1Cr21Ni5Ti (1 730 K, 1 457°C) calculated by Thermo-calc, the interface temperature at the tip of consumable electrode is considered to be 1 750 K (1 477°C), with a 20 K (20°C) superheat. The temperature at the metal pool/ slag interface has been determined according to the reference 14) under similar condition and considered to be 1 950 K (1 677°C) in remelting with 1Cr21Ni5Ti stainless steel.…”

“…The temperature at the metal pool/ slag interface has been determined according to the reference 14) under similar condition and considered to be 1 950 K (1 677°C) in remelting with 1Cr21Ni5Ti stainless steel. The falling droplets are assumed to equilibrate quickly with the slag in terms of temperature, and an average droplet/slag interface temperature is used, equal to the metal pool/slag temperature.…”

“…On the basis of the penetration theory, the metal and slag at the slag-metal interface can be considered as large numbers of fluid tiny particles, and then the τ in Eqs. (24) and (25) can be replaced with the time of every fluid tiny particles transporting through the AB distance at the speed of v (the velocity of slag at the electrode tip, 10 cm/s according to the reported reference 14) ), as shown in Fig. 4(b).…”

“…Volume at the Droplet/slag Interface As the description of reference, 14,28) the reaction time t d can be estimated as 0.19 second, and the velocity of the drop can be estimated to be 31 cm/s. The velocity of the molten slag at the droplet is taken as 10 cm/s.…”

“…In addition, the area and volume of the droplet has been measured as 8.38 cm 2 and 0.35 cm 3 in the M.E. Fraser report, 3,14) respectively.…”