摘要 :
In this paper, titanium-bearing blast furnace slags (CaO-SiO_2-TiO_2) produced at Panzhihua Iron and Steel Company (P. R. China) is used as the base material to develop fluoride-free (F-free) mold powders to improve the heat trans...
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In this paper, titanium-bearing blast furnace slags (CaO-SiO_2-TiO_2) produced at Panzhihua Iron and Steel Company (P. R. China) is used as the base material to develop fluoride-free (F-free) mold powders to improve the heat transfer between the mold and the strand. Effects of the binary basicity (CaO/SiO_2), TiO_2, Na_2O, Li_2O, MgO, MnO and B_2O_3 on the melting temperature, viscosity and heat flux of F-free mold powders are investigated. The laboratory results indicate that 1) the melting temperature and the viscosity of the F-free powder decrease, as expected, with increasing the content of Li_2O, B_2O_3 and Na_2O respectively, but the lowest viscosity is achieved with 6.0 mass% TiO_2; 2) the heat flux of the F-free slag film with 1.0-6.0 mass% TiO_2 is close to that of a conventional mold slag film with 2.0-10.0 mass% F; 3) the effect of basicity of the F-free powder on the heat flux is the same as the powder bearing fluoride; 4) the heat flux changes significantly with more than 8.0 mass% Na_2O and about 4.0 mass% MnO, whereas the effects of Li_2O and B_2O_3 in the F-free powder on heat flux are not significant. The suitable range of main components of the F-free powder with TiO_2 is proposed for casting peritectic-grade-steel slabs. The industrial trials of peritectic steel casting, using the proposed F-free flux, reveals a good surface quality of the slab, and well-controlled heat transfer at the continuous casting mold by the F-free powder with the precipitated crystalline phase being perovskite (CaTiO_3) instead of cuspidine in the conventional mold slags that contain fluoride.
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