Fluoride-free mold powder for low-carbon steel

Abstract

The invention provides a fluoride-free mold powder for low-carbon steel. The fluoride-free mold powder comprises the following materials by weight percent: 5-10 percent of Na2O, 3-10 percent of MgO, 3-10 percent of MnO, 3-10 percent of B2O3, 6 or less percent of AL2O3, less than 3 percent of Li2O, 1-3 percent of C and the balance of CaO and SiO2, as well as inevitable impurities, wherein the CaO / SiO2 is 0.8-1.3. The fluoride-free mold powder has the melting point of 950 DEG C-1150 DEG C and has the viscosity of 0.1-0.3 Pa*s at 1300 DEG C, and the crystallization rate measured by adopting the crystallizability detection method in the specification ranges from 10 percent to 50 percent. The fluoride-free mold powder can eliminate the adverse effect that the heat-transfer property of boron-containing residues in the using process is remarkably higher than that of traditional fluoride-containing residues, has very good environment protection and equipment corrosion reduction values, and can achieve industrial application in batch on the low-carbon steel slab continuous casting process, and the metallurgical effect completely reaches the standard of traditional fluoride-containing residues.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, specifically relates to an auxiliary material used in a continuous casting process, and more particularly relates to a fluorine-free continuous casting mold slag used in a low-carbon steel continuous casting process. Background technique [0002] Continuous casting mold flux is a powdery or small granular steelmaking auxiliary material used to cover the surface of molten steel in the mold of a continuous casting machine. Under the high temperature of molten steel, the mold slag is in two layers of solid and liquid, and the molten layer is next to the molten steel. The mold slag above the molten layer remains in the original particle or powder state, so as to play a good role in heat insulation and prevent the surface of molten steel from solidifying. . Under the action of the periodic vibration of the mold, the molten layer will continuously flow into the gap between the copper plate of the m...

AI Technical Summary

Problems solved by technology

The increase of fluoride ion concentration and pH value in the secondary cooling water greatly accelerates the corrosion rate of continuous casting equipment and increases equipment maintenance costs; at the same time, it increases the difficulty of circulating water treatment and the cost of neutralizers; in addition, it also increases the cost of sewage discharge burden

The mold slag disclosed in Chinese patent application CN200810233072.5 has too strong crystallization and is suitable for crack-sensitive steels such as peritectic steel

Chinese patent CN03117824.3 proposes to use perovskite (CaO·TiO 2 ) as a crystallization object, but the melting point of perovskite exceeds 1700 ° C, which is not conducive to lubrication, so the application prospect is not great

The mold flux designed by Chinese patent application CN201010110275.2 uses wollastonite and sorghumite as the composite crystal phase, but the viscosity is relatively high, which is more suitable for billet continuous casting process

Currently with B 2 o 3 Replacing F is the most economical and feasible technical idea, but the biggest disadvantage of boron-containing slag is that the vitrification effect is obvious, and the solid phase softening point becomes lower, which leads to low thermal resistance and continuous casting crystallization of boron-containing fluorine-free slag during use. The heat transfer of the device is too large, which is not conducive to the improvement of the casting speed of the continuous casting machine and inhibits the output of the steelmaking plant

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