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Study on Simulation of Lubrication of Mold Flux Film

Author: DuFang
Tutor: WangYu
School: Chongqing University
Course: Metallurgical Engineering
Keywords: Continuous casting mold fluxes Lubricating Slag film structure Crystalline mineral phase Flow model
CLC: TF777
Type: Master's thesis
Year: 2009
Downloads: 157
Quote: 1
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Abstract

Fluxes is to improve the continuous casting efficiency and quality of slab key functional materials, heat transfer plays a control, lubrication, assimilation inclusion, prevent secondary oxidation of the molten steel, insulation role. Wherein the lubricating effect mainly through the slag film between the slab and crystallization achieved. With the continuous improvement of continuous casting and casting speed, mold vibration frequency to accelerate certain vibration mode, will lead to reduced consumption of the protective slag, the friction between the slab and the mold increases, increases the tensile breakout hazard. It is reported that more than 65% of the breakout in continuous casting production is mainly caused due to poor lubrication. Therefore, to improve the protection of slag lubrication performance is particularly prominent. In-depth study of the structure and properties of the slag film analysis the slag film lubrication mechanism to explore the ways to improve the protection of slag lubricating properties is of great significance for optimizing the protection of slag composition and performance, the development of high-quality protective slag. Continuous casting mold powder slag film as lubrication between the slab and the mold and the regulation of the heat transfer medium, its thickness, structure, temperature distribution, flow characteristics directly affect the the protective slag efficacy play, cis to the continuous casting process row and has an important role in the quality of the slab surface. Practice shows that the liquid slag film between the slab and the mold has better lubricating properties, is one of the main ways to improve the continuous casting lubrication. Depth study of the protective slag slag film formation mechanism and the role of behavior, is a the modern protective slag research content. In this paper, based on the the fluxes basic physical and chemical properties of viscosity and melting temperature, based on the the slag film role and presence awareness, self-designed experimental device, the the protective slag slag membrane structure of different composition was simulated. Experimental simulation of the slag film structure characteristics and consistent protection the the slag slag membrane structure research methods in the new method. In this paper, software FLUENT simulation protective slag flow behavior in the mold outlet insertion depth and inclination the meniscus steel - slag interface temperature discuss slag viscosity, casting speed and the protection of the slag flows into crystalline with slab, which factors affect the inflow of fluxes for system analysis meniscus area, and provide a foundation. By the ways and means by experimental changes in the composition and content of the slag resistance, the slag film structure test, study the protective slag composition of the crystallization rate of the slag film and crystalline mineral phase; through the establishment of the conditions for the existence of the slag film crystalline friction calculation of the mathematical model, discussed the protection of slag composition, properties (viscosity and melting temperature) and the slag film structure lubrication. The research results show that the: with cooling intensity increases, the glass layer thickness of the slag film increases, the crystallization rate is reduced; slag viscosity, melting temperature, alkalinity and its components on the structure of the slag film, the thickness of the liquid slag layer has a great impact; temperature gradient is greater, the higher the rate of crystallization of the slag film; create friction model calculation, the lower the melting temperature or viscosity of the protective slag, the thicker the liquid slag film, the friction between the billet and the mold the smaller fluxes lubrication favorable; protection basicity and its components also have some impact on the slag film friction. With the increase in the frequency of mold oscillation, the protective slag on the the meniscus root of negative pressure increases, friction increases by crystallization, which will inhibit the protective slag flows downward, is not conducive to the lubrication; slag viscosity, the more , slag inflow velocity is smaller, resulting in insufficient for slag, slag formed film is too thin uneven, resulting in poor lubrication; the submerged nozzle at the same insertion depth, with the increase of the inclination angle of the outlet, Meniscus at the temperature is decreased; in the same Advantages inclination case, as the nozzle insertion depth increases, the crystallization temperature of the meniscus is also reduced, is not conducive to the uniformity of the protective slag melted and uniform slag film is formed, guarantee its good lubrication. Pulling speed increases, the reduction of slag consumption slag inflow rate decrease, such that the formation of the slag film is too thin and uneven distribution, is not conducive to the lubrication.

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