| The slag film between the crystallizer and the slab deeply affect the lubrication and heat conductivity in continuous casting, the mineralogical structure of the slag film can reflect the slab surface quality and have an important influence on rolling yield. In light of the slab cracks caused by the mold slag which can not completely coordinated the lubrication and heat transfer function, the process mineralogy structure of the industrial slag films in Tangshan Plate Co. and Handan Plate Co., Ltd., were studied and the reasonable mineralogical structure was found. Based on the previous research, the influence of mineral composition on the physicochemical properties and mineral structure has been studied through orthogonality experiment.The thickness of the flux films for Q345 B steel and X70 steel ranges from 0.877 mm to1.687 mm. The mineralogical composition of the films for Q345 B steel is melilite, cuspidine and wollastonite. The mineralogical composition of the films for X70 steel is cuspidine and some wollastonite. In general, the crystallization ratio of the normal films ranges from 35% to 65%. However, the accdient films has a high crystallization ratio which reached to 90% and it will generate excess cupidine or melilite.The physicochemical properties of crystallization temperature, viscosity, heat flux and melting temperature have been studied through hot wire method, heat flux of flux film simulation method, hemisphere method. The mineralogical compositions, the crystallization ratio and the microstructure of laboratory prepared slag have been studied by light microscope. With the increasing mineral content of quartz, wollastonite, soda ash, the crystallization temperature decreases, the influence of fluorite is opposite. With the increasing mineral content of fluorite and soda ash, the viscosity decreases, the influence of quartz and wollastonite is opposite. With the increasing mineral content of fluorite and soda ash, the melting temperature decreases, the influence of quartz and wollastonite is opposite. The mineralogical composition of the laboratory films was cuspidine and wollastonite. With the increasing mineral content of quartz, wollastonite and soda ash, the melting temperature decreases, the influence of fluorite was opposite.The industrial mold fluxes and slag films from for low-alloy slab casting Tangshan Plate Co. and Handan Plate Co., Ltd., have been studied to find out the resonable process mineralogy feactures. And then, the optimum mineral compositions suitable for low-alloy steel have been elected. The results can provide a theoretical basis for reasonable material choice to develop high-quality powders. |
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