Research On Mineralogical Composition And Microstructure Of Mold Powder And Film For Continuous Casting

Lubrication and heat conductivity are very important factors to control slab surface quality in continuous casting mold and to affect continuous casting production. The effect of mineralogical structure of film on heat resistance to control heat conductivity and lubrication is very important. Moreover, mineralogical compositions of powder influence mineralogical structure of film directly. Therefore, it is important significance for slab quality improvement by analyzing mineralogical compositions and microstructure of powder and film.The mineralogical compositions and microstructure of powder and film are studied by means of chemical element analysis, light microscope observation and X-ray diffraction. F-in powder mainly in fluorspar, Na2O mainly in feldspar, MgO mainly in augite and periclase are discovered. Mineralogical compositions are very complicated, and they affect mineralogical structure of film. While the content of glass phase in powder exceeds 35%, vitrification of film is promoted. While the content of quartz in powder reaches 10%～20%, vitrification of film is promoted. While the content of melilite in powder reaches 15%～40%, formation of melilite in film is promoted. While the content of Wollastonite in powder reached 35%～45%, crystallization rate of film is increased, and formation of melilite in film is promoted. While the content of augite in powder is 15%～25%, crystallization rate of film is restrained. Fluorspar in powder promotes formation of cuspidine in film. Limonite and other metallic mineral promote crystallization of film.Different mineralogical structure of film fit different steel grade is discovered by studying effect of mineralogical structure of film on slab quality. The film, in which vitrification rate is high, is fit in with low-carbon steel; the film, in which crystallization rate is moderate and without bigger friction minerals, is fit in with medium carbon steel.The mineralogical compositions and microstructure of laboratory prepared slag are studied, and the compositions of powder for differ steel are discovered by combining physical-chemistry properties. The powder, in which content of glass exceeds 40% with more augite and less quartz, fluorspar, is fit in with low carbon steel; The powder, in which content of melilite exceeds 15%, glass phase reaches 30%～50%, with a lot of wollastonite, augite, and less plagioclase, quartz and fluorspar, is fit in with medium carbon steel.