On modelling viscoplastic behavior of the solidifying shell in the funnel-type continuous casting mold

Abstract

As it is known from literature, the metals tend to follow a viscoplastic law at high temperatures. Thereby, based on the authors’ previous developments to simulate the behavior of the equiaxed crystals packed bed, a viscoplastic stress model is applied to the thin slab casting process. The model is reduced to the single phase mixture formulation for faster and robust simulations. In this idea, the solidifying shell represents a ‘creeping solid’ and the Norton-Hoff type stress model is formulated with the model parameters obtained experimentally. A coupling procedure is established to converge the non-linear terms. The influence of the stress model parameters is investigated. Next the model is applied for the simulation of the thin slab casting to improve a previously developed technique: a viscoplastic rheology is applied to calculate the motion of the solidifying melt instead of imposing the velocities of the mush. The simulation results show that the most deformations happen at the funnel part of the mold, causing highest strain rates and the significant drop of the viscoplastic ‘apparent viscosity’ according to the Norton-Hoff law. The solid shell velocities are mostly uniform at the straight parts of the strand but a slight acceleration of the shell is observed along the funnel surface. Strong compression / expansion zones are detected at the funnel part, which could lead to defects formation. The solid shell thickness was successfully predicted as well and compared to the previous work by the authors.

Important Key Process Simulations in the Field of Steel Metallurgy

“…Further details on that research field can be found in ref. [26][27][28][29][30][31][32][33][34][35].…”

Electric Current Distribution During Electromagnetic Braking in Continuous Casting

“…First, the averaged ratio between the liquid and solid electric conductivities is plotted in Figure 16(a) in the left curve, which is derived here from the extended data for different AISI steel grades, reported in 1978 by Chu and Ho. [44] The right curve in Figure 16(a) shows slab surface temperature along the mold's wide face, simulated by Vakhrushev et al [45,46] The corresponding thickness (100 pct of solid, top picture) and the conductance ratio (bottom picture) of the solid shell are plotted in Figure 16(b), which are obtained from the thin slab simulations [45,46] and calculated for the 72-mm-thick slab using Eq. [19] based on the temperature-dependent electric conductivity (see Figure 16(a)).…”

“…[Chu & Ho 1978] wide face m m Fig. 16-Solid shell conductance ratio for the thin slab casting: (a) averaged temperature-dependent ratio r sol =r liq (from Chu and Ho 1978) [44] and surface temperature T surf for the 72-mm-thin slab (Vakhrushev et al); [45,46] (b) simulated shell thickness (top); and its conductance ratio (bottom).…”

On Modelling Parasitic Solidification Due to Heat Loss at Submerged Entry Nozzle Region of Continuous Casting Mold

“…Several numerical models have been developed for the contact problem and air gap formation [20][21][22][23]. Deformation models coupled with the fluid flow, heat transfer, and solidification have been described elsewhere [24][25][26][27][28][29].…”