Study On Simulation Of Lubrication Of Mold Flux Film

Mold flux is a key material to enhance continuous casting efficiency and improve slab quality. Its main functions are controlling heat transfer, lubrication slab, absorbing inclusion of molten steel, avoiding second oxidization of molten steel and heat preservation etc. The lubrication of mold flux is achieved through mold flux film between slab and mold. With continuously advance of casting speed, the oscillation frequency of the mold expedites. When the mode of oscillation is stated, the consumption of mold flux decreases and the friction between slab and mold increases,which increases the possibility of tension fracture and breakout. As it is reported, the breakout of above 65% is part of close-burning breakout, moreover, it is aroused by the ill lubrication.Therefore, it is very important to improve the lubrication of mold flux. Studying film structure, properties of the mold flux film, the lubrication mechanism of flux film and discussing the approach of improving its lubrication, has important significance on optimizing the composition and properties of the mold flux and desinging high quality mold flux.Continuous casting mold flux film is a medium for mold lubrication and heat transfer control, its thickness, structure, temperature distribution and flow characteristics have a direct impact on the effectiveness exertion of the flux function, an important influence on the continuous casting process and the slab surface quality. Practice shows that the liquid slag lubrication film between slab and mold has a good lubrication performance, which is one of the main methods to improve the lubrication of continuous casting. It is important content to study forming mechanism and function of slag in-depth.In this paper, first, we studied basic physical chemistry property of slag. Based on the function and distribution of slag film, we designed a equipment by ourselves to simulate slag film and study their structure under different conditions. The structure of mold flux film by this device is the same with the plant's film structure. It is the new method for studying film structure.This paper uses the software FLUENT to simulate the mold slag flowing in the meniscus field, to study the influence of depth of immersion and obliquity of SEN on temperature in the steel-slag interface and the effect of viscosity and casting speed on flow rate of flux in mold meniscus. It provide theoretic base for the systematically analysis of the factor which influence the slag flowing behavior in the meniscus field. Used the method mentioned above, by the test of the slag property and flux structure with different composition content. By the friction model of slag film, the paper discusses the effect of slag composition, physical chemistry property(viscosity and fusion temperature), the structure of slag on lubrication.The results show: With the cooling intensity's increace, the glass layer thicken, the ratio of crystallization reduces; Viscosity, fusion temperature, basicity and the content of the flux have an important impact on the slag film structure and liquid slag layer. The bigger of temperature gradient, the higher of crystallization ratio of flux; the smaller of viscosity or fusion temperature, the thicker of liquid slag film, the smaller of friction force between slab and mold, it is good for lubrication. Accoding to the simulation model,when viscosity and fusion temperature decrease, liquid slag film increases, and the friction force falls, it is good for lubrication. Basicity and its component also have influence on friction.With the increace of mold oscillation frequency, the negative pressure of the root of meniscus field increases, the friction force of the mould also increases, which will restrain inflow of flux and be bad for lubrication. The bigger of viscosity, the smaller of the fulx flowing rate, it results in supplying slag deficiency and thin slag film, which is bad for lubrication. When SEN is in the same depth, with obliquity of SEN increasing, the temperature decreases in the mould meniscus. If the obliquity is the same, the temperature also decreases in the mould meniscus with the depth deepening. It is bad for equality melting of slag, forming equality slag film. It can not assure its lubrication property. When casting speed increases, the wastage of flux falls, the flow rate of flux decreases,result in sparse slag film and not homogeneous distributing, which will go ill with lubrication.