Papers by Keyword: Mold Fluxes

Abstract: The effect of shear stress on the viscosity and crystallization behavior of CaO-SiO₂-Al₂O₃ based mold fluxes were investigated, and the structure evolution of molten slag under shear stress were characterized by magic-angle spinning nuclear magnetic resonance technology (MAS-NMR). The results showed that with an increase of shear stress, the shear-thinning behavior of molten slag was found, and the strongest shear-thinning behavior was formed with an addition of 15% Al₂O₃. Correspondingly, the decrement of Q³(1Al) and Q²(1Al) species in molten slag were the largest from MAS-NMR results. In addition, under agitation, the crystallization fraction of sample increased from 71% to 88%, and the average grain size was reduced 23%. However, the shear stress has no influence on the crystal phase.

Abstract: The samples of cold-rolled sheets, hot-rolled plates and continuously cast slabs have been analyzed with the condition of faint-sliver defects appeared in IF steel of Pangang, and it was shown that faint-sliver defects in cold-rolled steel sheet were mainly caused by micro-cracks in the surface of strands, slag entrapment in mold during casting and inclusions in sub-surface of strand. Faint-sliver defects were controlled effectively with the technical measures, which were decreasing oxidation of ladle slag, controlling the ratio of CaO/Al2O3 in slag, extending circulation time of deoxidization and alloying in RH process, controlling the casting speed and increasing the viscosity of mold fluxes. Therefore, the ratio of downgrade induced by faint-sliver defects reduced from 10.97% to 1.0%.

Abstract: Effects of TiO₂ on crystalline phase of mold fluxes were studied by the mineral phase microscope and the XRD. The results showed that on the experimental condition, the main crystalline phase of mold fluxes were cuspidine, wollastonite and melilite. When TiO₂ added into the mold fluxes, perovskite would be found. TiO₂ promoted Perovskite to crystallization and limited Cuspidine to growth. The morphologies and content of wollastonite and melilite were greatly affected by TiO₂ adding, especially, as 20% TiO₂ added into the mold fluxes.

Abstract: Under the experimental condition,the crystal phases of mold fluxes contained cuspidine, wollastonite and melilite. The addition of TiO2 could stimulate Perovskite to be precipitated in mold fluxes whilst the growth of cuspidine and wollastonite were inhibited. At 1300°C mold fluxes existed mainly in glass phase, with few melilite phases existed in several sections while after TiO2 was added, perovskite was precipitated and melilite was dissolved.