Shear-thinning property of mold flux for thin slab continuous casting with high casting speed
YUAN Zhi-peng1,2, ZHU Li-guang3, WANG Xing-juan1,2, WANG Bo1,2, ZHANG Yan-chao1,2
1. College of Metallurgy and Energy,North China University of Science and Technology, Tangshan 063210, Hebei, China; 2. Hebei High Quality Steel Continuous Casting Technology Innovation Center, Tangshan 063009, Hebei, China; 3. School of MaterialsScience and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, Hebei, China
Abstract:To solve the problems of slag entrapment risk and frequent bond alarm in the field application of mold flux for high-speed thin slab continuous casting,the above problems can be effectively solved by making the mold flux generate non-Newtonian fluid behavior. The new mold flux has the characteristics of shear-thinning,that is,it has a higher viscosity at lower shear rates and vice versa. Based on the field data,it is calculated that the shear rate of the steel surface area of the thin slab mold with high casting speed is between 10-90 s-1,and the shear rate of the meniscus and below of the mold can reach 120-1 600 s-1. The effect of Al2O3 on the shear-thinning property of mold flux was studied by rotating cylinder method. The shear-thinning behavior is quantitatively analyzed by Oswald-De Waele power law model. It was found that with an increase in the Al2O3 content,the shear-thinning behavior of the mold flux first increased and then decreased. The sample with 8.61% Al2O3 content had the strongest shear-thinning property and the lowest fluidity index, which reached 0.764 4. It is found that the shear-thinning property of non-Newtonian fluid mold flux can meet the requirements of mold flux viscosity in the surface area of the mold steel level and the meniscus and below. Based on the specific process parameters of thin slab continuous casting with high casting speed,a multiphase coupling model in the mold is established. Through model calculation, it is found that the enhanced shear-thinning property of mold flux will not only significantly reduce the risk of shear slag curling and improve the uniformity of liquid slag inflow in the meniscus area of the mold,but also have a thicker liquid slag film in the meniscus and below of the mold,which makes it easier to realize full range liquid lubrication. At the same time,the slag consumption is increased,and the effect of shear-thinning property of mold flux is further analyzed. This research provides a theoretical basis for the development of non-Newtonian fluid high casting speed thin slab continuous casting mold flux.
袁志鹏, 朱立光, 王杏娟, 王博, 张燕超. 高拉速薄板坯连铸保护渣剪切变稀性质[J]. 钢铁, 2022, 57(12): 97-108.
YUAN Zhi-peng, ZHU Li-guang, WANG Xing-juan, WANG Bo, ZHANG Yan-chao. Shear-thinning property of mold flux for thin slab continuous casting with high casting speed[J]. Iron and Steel, 2022, 57(12): 97-108.
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