Abstract
The element Al in molten aluminum containing steel reacts with the liquid mold flux and thus be transferred into the mold flux during the continuous casting process. Additionally, the increase in alumina in a mold flux changes its performance significantly. Thus, in this paper, the heat transfer properties of mold fluxes with the Al2O3 content ranging from 7 to 40 wt. % were studied with the Infrared Emitter Technique (IET). Results found that heat flux at the final steady state decreased from 423 kW·m−2 to 372 kW·m−2 with the increase in Al2O3 content from 7% to 30%, but it increased to 383 kW·m−2 when the Al2O3 content was further increased to 40%. Both crystalline layer thickness and crystalline fraction first increased, then decreased with the further addition of A2O3 content. Moreover, it indicated that the heat transfer process inside the mold was dominated by both a crystallization of mold flux and the resulting interfacial thermal resistance. Further, the Rint increased from 9.2 × 10−4 m2·kW−1 to 11.0 × 10−4 m2·kW−1 and then to 16.0 × 10−4 m2·kW−1 when the addition of Al2O3 content increased from 7% to 20% and then to 30%, respectively; however, it decreased to 13.6 × 10−4 m2·kW−1 when the Al2O3 content reached 40%.
Highlights
Aluminum, as an effective additive, is widely used for the new generation of automotive steels (TRIP/TWIP, etc.) development, as it can lower the weight of an automotive body for a better fuel-efficiency without losing the safety through the improvement of the mechanical properties of steels
The mold fluxes interface thermal resistances, Rint, with different amounts of Al2O3 are shown in to 11.0 × 10−4 m2∙kW−1 (Sample R0.8A20) and to 16.0 × 10−4 m2∙kW−1 (Sample R0.8A30) when the addition of Al2O3 content increased from 7% to 20% and to 30%, respectively; it
The mold fluxes interface thermal resistances, Rint, with different amounts of Al2 O3 are shown in to 11.0 ˆ 10 ́4 m2 ̈ kW1 (Sample R0.8A20) and to 16.0 ˆ 10 ́4 m2 ̈ kW1 (Sample R0.8A30) when the addition of Al2 O3 content increased from 7% to 20% and to 30%, respectively; it decreased to 13.6 ˆ 10 ́4 m2 ̈ kW1 (Sample R0.8A40) when the Al2 O3 content reached 40%
Summary
As an effective additive, is widely used for the new generation of automotive steels (TRIP/TWIP, etc.) development, as it can lower the weight of an automotive body for a better fuel-efficiency without losing the safety through the improvement of the mechanical properties of steels. The containing aluminum in steels would tend to introduce problems for continuous casting processes, as partial dissolution of aluminum in the steels would transfer into a mold flux and lead to a dramatic interaction between silica and aluminum that would deteriorate the mold flux properties such as viscosity and crystallization, which would further degenerate the quality of the shell and affect the smooth casting process. Showed that the content of alumina in the mold flux can reach more than 30% during the TRIP steel continuous casting process. Regarding the effect of Al2 O3 content on the heat transfer behavior, the related reports are relatively rare. Cho et al [9] observed a fade in mold heat transfer rate when the conventional lime-silica mold fluxes were used during casting the TRIP steel. %) on heat transfer behavior of the mold flux, and interfacial thermal resistance between the mold/slag, were studied via an advanced Infrared Emitter Technique (IET) In this study, the effect of Al2 O3 content (ranging from 7 to 40 wt. %) on heat transfer behavior of the mold flux, and interfacial thermal resistance between the mold/slag, were studied via an advanced Infrared Emitter Technique (IET)
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