Casting powder for medium carbon peritectic steel continuous casting crystallizer

Abstract

The invention belongs to the technical field of steel melting continuous casting production, and particularly relates to casting powder for a medium carbon peritectic steel continuous casting crystallizer sensitive to cracks. The casting powder comprises the following components by weight percentage: 40 to 50 percent of CaO, 40 to 50 percent of SiO2, 1 to 6 percent of B2O, 1 to 4 percent of Li2O, 1 to 5 percent of Al2O3, 1 to 6 percent of BN1 and 1 to 2 percent of inevitable impurities, wherein the impurities comprise 0.03 percent of S and 0.03 percent of P. The preparation method comprises the steps of: fully drying and dehydrating raw materials, weighing and mixing according to weight parts, grinding and uniformly mixing, pre-melting, cooling, powdering, and adopting the conventional casting powder preparing and molding process to obtain granular finished casting powder. The casting powder has relatively low melting temperature and relatively high crystallization temperature, particularly has the advantages of good lubrication and anti-oxidization effects of glass powder and high impurity absorption capacity and the advantages of high heat preservation performance of the powder with the high crystallization temperature and casting blank crack control, and is suitable for pouring medium carbon peritectic steel sensitive to the cracks.

Description

technical field [0001] The invention belongs to the technical field of iron and steel smelting and continuous casting production, and in particular relates to a mold slag for crack-sensitive medium-carbon sub-peritectic steel continuous casting crystallizers. Background technique [0002] The continuous casting technology has been highly valued by the metallurgical industry for its advantages of high efficiency, energy saving, high quality, easy automation and intelligence, etc., and the matching continuous casting mold powder has also been developed accordingly, and has become an indispensable Metallurgical auxiliary materials; the existing continuous casting mold flux mainly uses SiO 2 -Al 2 o 3 -CaO slag system, on this basis, add a small amount of flux (alkali metal or alkaline earth metal oxide, fluoride, boride, etc.) and carbonaceous materials (carbon black, graphite, coke, etc.) Slag has a lower melting point and viscosity, and has the advantages of glass slag lu...

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Problems solved by technology

[0002] Continuous casting technology has been highly valued by the metallurgical industry for its high efficiency, energy saving, high quality, easy automation and intelligence, and many other advantages. Mold slag has also been developed accordingly and has become an indispensable metallurgical auxiliary material; the existing continuous casting mold slag mainly uses SiO2-Al2O3-CaO slag system, on this basis, add a small amount of flux (alkali metal or alkaline earth metal oxide, fluoride, boride, etc.) and carbonaceous materials (carbon black, graphite and coke, etc.), this type of mold flux has a lower melting point and viscosity, and has the advantages of glass slag lubricating effect and good effect of absorbing inclusions, but the current SiO2-Al2O3-CaO-based mold flux needs a higher content of Al2O3 in order to ensure a low melting temperature, which limits It improves the ability of slag to absorb Al2O3 inclusions, especially for the existing mold slag, in order to ensure a low melting temperature, the basicity of the slag is in the range of 0.9-1.1 The slag has obvious characteristics of low-melting glass slag, and the mold flux is not suitable for crack-sensitive sub-peritectic steel casting; for medium-carbon sub-peritectic steel, it is characterized by cracks on the surface, so continuous casting The mold flux should have two typical characteristics: First, the mold flux should have a low melting point and viscosity to ensure the fluidity and spreadability of the mold flux in the high-temperature area of ​​the mold. This is why the mold flux can lubricate and prevent oxidation The premise of metallurgical functions such as absorption and inclusion, which requires the mold flux to have the characteristics of glass slag in the high temperature zone; second, the mold flux must have strong crystallization ability, that is, high crystallization temperature, small particle size and fast crystallization speed. In this way, the mold slag forms a solid slag film in the low temperature area of ​​the mold, which increases the thermal resistance of the mold slag, slows down the heat transfer of the steel in the mold, reduces the temperature gradient of the billet, and avoids the generation of cracks on the surface of the sub-peritectic steel; therefore, for Crack-sensitive hypoperitectic steel continuous casting mold flux needs to have the characteristics of "low melting temperature and high crystallization temperature", that is, it has the advantages of good lubrication and anti-oxidation effect of glass slag, strong absorption of inclusions and high heat preservation of high crystallization temperature slag. Good performance, the advantages of controlling the cracks of the slab; In addition, the mold slag of the prior art generally uses carbonaceous materials as additives for melting speed and oxidation resistance of the slag. Therefore, the existing technology of mold flux needs to be further optimized in terms of composition selection and content range to solve the problem that the performance of the mold flux used in the current crack-sensitive sub-peritectic steel continuous casting cannot meet the requirements

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