4. Analysis cases

In order to show the capability of the coupled model, a sequence of tundish filling and continuous casting of a Fe-C-Mn thin slab (125 mm) of 1200 mm width is presented. The tundish has 60 ton capacity, and the basic properties of the steel are presented in Table 1.


Table 1. Basic thermophysical properties of SAE 1018 (Fe-C-Mn) with simulation data.

The initial step of the tundish feeling presents strong turbulence features and plays important role on the stable flowing development and security of the whole operation. Figure 7 shows the flowing pattern (t= 3 s) for a thin slab operation while the slab extraction is off. As can be observed, the inhibitor apparatus is important to avoid splashing and protect the refractories. Figure 8 shows the conditions where the stable flow rates are achieved with the liquid level of the tundish nearly constant. The flow pattern indicates that a complex turbulent flow is observed and the liquid flow promotes strong mixing.

over a typical control volume. The final product of this operation is a set of algebraic equations. Coefficients are obtained by the so-called power law scheme, according to Patankar [26]. The SIMPLE algorithm is used to iteratively determine the velocity components and pressure linked equations. The numerical solution of the set of algebraic equations demands large computational effort. A line-by-line solver based on the tridiagonal matrix algorithm (TDMA) was used to solve the system of algebraic equations. The Alternate Direction Implicit (ADI) iterative procedure was applied within a common solver for all discretized equations. The iterative solution was obtained for each time step in a fully implicit scheme [25, 26]. The convergence criteria were used for all variables admitting a maximum local error less than 1%

In order to show the capability of the coupled model, a sequence of tundish filling and continuous casting of a Fe-C-Mn thin slab (125 mm) of 1200 mm width is presented. The tundish has 60 ton capacity, and the basic properties of the steel are presented in Table 1.

Properties Units C-Mn SAE 1018 steel

Slab material SAE 1018 steel

.K<sup>1</sup> 25.400

.K<sup>1</sup> 29.700

.K<sup>1</sup> 783.400

.K<sup>1</sup> 647.500

.K<sup>1</sup> 803.200

Emissivity 0.600

Density of solid phase BCC 300–838C kg.m<sup>3</sup> 7.830 Density of solid phase FCC 838–1416C kg.m<sup>3</sup> 7.305 Density of liquid at 1522C kg.m<sup>3</sup> 7.034 Latent heat of solidification, ΔH J.kg<sup>1</sup> 231.900

Table 1. Basic thermophysical properties of SAE 1018 (Fe-C-Mn) with simulation data.

Thermal conductivity in liquid phase W.m<sup>1</sup>

Thermal conductivity in solid phase W.m<sup>1</sup>

Specific heat in BCC phase at 30–838C J.kg<sup>1</sup>

Specific heat in FCC phase at 838–1416C J.kg<sup>1</sup>

Specific heat in liquid phase 1416–1519C J.kg<sup>1</sup>

Slab width m 1.600 Slab depth m 0.255 Casting temperature C 1.574 Casting speed m.min<sup>1</sup> 0.810 Cooling water temperature C 30 Environment temperature C 40 Liquidus temperature C 1.519 End of solidification temperature C 1.410

for all variables simultaneously.

298 Numerical Simulations in Engineering and Science

4. Analysis cases

In order to assure the coupled model formulation and the simultaneous solution in the parallel platform simulation, a confrontation with measured temperature profile measured in the industrial machine was performed. Figure 9 showed a comparison of the model predictions for the serial, parallel and the pyrometer measurement at the industrial machine.

As can be observed, a close agreement with the industrial operation measurements for the temperature is reached. The measurements and calculations were compared for the stable casting operation, and the measured values were obtained using infrared pyrometer, and the plotted values are the average of five runs with intervals of 5 min.

As can be observed also, the values obtained with the serial and parallel versions are virtually the same. A complete view of the solid portion of the continuous casting domain is shown in Figure 10 for stable flowing state. A thin skin formed in the oscillating mould region and continuous growing along the bending and cooling zones is observed. A recalescence and final cooling regions are observed. These regions are critical for the process due to the possibility of crack and defect susceptibility depending on the cooling rates and inclusions dragged and formed during the casting development [22–24].

Figure 7. Fluid flow pattern during initial stage of the tundish feeling period.

Figure 8. Fluid flow pattern obtained with the solutions of the model equations with parallel code version.

5. Conclusions

of steel slab.

Acknowledgements

A unified formulation for the liquid metal flows and heat transfer within the tundish and continuous casting was presented and applied for actual industrial practices. New operational conditions for the metal flows aiming to allow the inclusion flotation and slag capture are suggested. The prediction of actual continuous casting practice is compared with industrial data. Thus, the simulation platform can be used for designing new thin slab continuous casting process, which could decrease the subsequent steps of hot rolling for thickness reduction.

Figure 10. Full domain temperature distribution pattern and the solid skin formed during the continuous casting process

Numerical Study of Turbulent Flows and Heat Transfer in Coupled Industrial-Scale Tundish of a Continuous…

http://dx.doi.org/10.5772/intechopen.75935

301

Authors acknowledge financial support provided by FAPERJ (Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro), CAPES (Coordenação de Aperfeiçoamento de Pessoal

de Ensino superior) and CNPq (Conselho Nacional de Pesquisa)

Figure 9. Model validation with industrial data acquisition along the steel slab and comparison with the solutions obtained with the serial and parallel code versions.

Numerical Study of Turbulent Flows and Heat Transfer in Coupled Industrial-Scale Tundish of a Continuous… http://dx.doi.org/10.5772/intechopen.75935 301

Figure 10. Full domain temperature distribution pattern and the solid skin formed during the continuous casting process of steel slab.
