SU1643618A1 - Method of production of chromium containing fused flux - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular, to the production of fluoride-oxide fluxes for electroslag remelting and welding mainly low- and medium-alloyed steels. The chain of the invention is to reduce the sulfur content and obtain the desired bulk density. As a component containing oxides of aluminum and chromium, alumina-chrome raw materials of petrochemical production are used with an A12Oe: Cr2Oe ratio of 3.5-8.0, and in the period of refining, aluminum powder in the amount of 0.2-0.75% is loaded onto the melt surface by weight of the melt in a mixture with fluorite concentrate with the ratio Al: CaF2 (0.15-0.30) :. By using a less expensive complex raw material with a reduced sulfur content and additional deoxidation of the flux, regulation of the bulk density at given values and the sulfur content of the flux less than 0.08% are achieved. 1 tab. in $

Description

The invention relates to ferrous metallurgy, in particular to the production of fluoride-oxide fluxes for electroslag remelting and welding, mainly for low- and medium-alloyed steels.

The aim of the invention is to reduce the sulfur content and obtain the desired bulk density.

As a component of the mixture containing oxides of aluminum and chromium, use alumina-chrome raw materials of petrochemical production with the ratio in it and СG03 equal to

3.5-8.0, and the period of finishing on the surface of the melt serves aluminum powder in an amount of 0.2-0.75% by weight of the melt in a mixture with fluorite concentrate with a ratio of A1 and CaFgj equal to (0.15-0.30) :.

The introduction of a complex alumina-chromium raw material of a petrochemical production (15-20% Crz03, 01% and the rest), having an AZ-SrS value of 3.5-8.0, allows to obtain a flux with a sulfur content of claim 0 , 01% and bulk density in the range of 1.0-1.5 t / me. Everything

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This makes it possible to obtain high quality metal.

The determination of the ratio of A1 and CaF as well as the amount of aluminum powder introduced was made possible due to the dependence found by the applicant between the flux bulk density and the input during the period of finishing these additives.

The introduction of alumina-chromium raw materials into the flux, having compounds with the ratio of Al2O3 and 8, does not contribute to the creation of an oxidizing potential, which does not allow obtaining a flux with a sulfur content of less than 0.01%. In addition, when flux is melted, fluorine-containing compounds of the AlFa type are formed, which is associated with an increase in the activity of A1203. The latter leads to additional consumption of fluorite, which worsens the technical and economic indicators of flux smelting.

The use of raw materials having compounds with a ratio of 3 and

  3.5, leads to an increase in activity in the flux. The latter leads to the oxidation of highly active alloying elements during ESR and welding, which degrades the quality and

mechanical properties of the metal.

The loading of aluminum powder in the period of fine-tuning to the surface of the melt in an amount of less than 0.2% by weight of the melt of the flux does not allow to obtain a flux with the required bulk density (1.0-1.5 t / m). The consumption of aluminum powder in an amount of more than 0.75% by weight of the melt flux causes a sharp increase in the temperature of the melt, this leads to an increased loss of calcium fluoride and a low bulk density (less than 1.0 t / m3).

When a mixture is introduced into the furnace1 with an Al: CaF ratio of 0.15; 1 does not achieve a decrease in the melt density of the flux, which leads to a high bulk density of the finished flux. If the mixture is used with the A1: CaP ratio of 0.30: 1, then, apart from intensive evaporation of fluorides from the melt, liquid flux from the furnace can be released, which is unsafe for the operating personnel.

Under identical laboratory conditions, a comparative analysis was made of the quality and bulk density of the flux type FTs-17, produced according to the proposed rt known methods.

Sand (30.6 kg), fluorite concentrate (15.2 kg), and alumina-chrome feedstock (in the amount of 25.7; 25.7; 24; 22.5; 22.5 kg with a ratio equal to 2.8 3.5; 5.75; 8; 10 respectively); magnesite (30 kg); sodium carbonate (6.7 kg) and potash (3.3 kg). After melting in the period of finishing on the surface of the melt, aluminum powder is set in an amount of 0.1; 0.2; 0.475; 0.75; 0.9 kg, which corresponds to 0.1; 0.2; 0.475; 0.75; 0.9% by weight of the flux with fluorite concentrate in the ratio Al: CaF2, equal to 0.13: 1; 0.15: 1; 0.225: 1; 0.30: 1; 0.35: 1 (0.77; 1.3; 2.1; 2.5; 2.57 kg of fluorite. The finished flux is poured into molds and punched. Flux samples of FC-17 type are subjected to chemical analysis for sulfur content and determined bulk mass.

When smelting flux by a known method in the fluxing furnace load, kg: sand 30,6; alumina 18.4; magnesite 30; fluorite concentrate 15.2; sodium carbonate 6.7; potash 3.3; chromium oxide 4.0. Melting is carried out in a 25 kg fluxing furnace with electric mode: current 2.5-3.5 kA, voltage 30-40 V.

The consumption of charge materials and the quality of melted fluxes are given in the table.

The fluxes obtained by the variants satisfy all the requirements for chromium-containing fluxes used in welding and ESR. They have a low sulfur content (0.005-0.008%), the required bulk density (0.1-1.2 t / m). The best results are flux, smelted for option 3.

The fluxes obtained with options 1, 5 and 6 do not satisfy the increased requirements for chromium-containing fluxes. They have a high content of szry 0,012-0,018%. In addition, the fluxes obtained for options I and 6, have an increased (1.59 and 1.65 t / m, and for option 5 - a reduced (0.9 t / m3) bulk density, which leads to disruption of the electric mode and excessive consumption flux when using them at ESR and welding.

Thus, the results of payments for flux type FTs-16 showed that

using the proposed method allows to obtain fluxes with a reduced sulfur content, the required bulk density. In addition, the use of petrochemical alumina-chromium feedstock allows to completely replace the scarce and expensive alumina and chromium oxide.

Claims (1)

Invention Formula The method of obtaining chromium-containing fused fluxes, including the loading into the furnace of a mixture containing sand, magnesite, sodium carbonate, potash, and materials having 436186 oxides of aluminum and chromium, subsequent melting of the charge, fine-tuning of the melt and discharge of the flux from the furnace, characterized in that, in order to reduce the sulfur content and obtain the required bulk mass, alumina-10 chrome raw materials of petrochemical were used as materials containing aluminum oxides and chromium about 15 production with an Al2O3: rCtgOg ratio of 3.5–8.0, and during the finishing period, aluminum powder is introduced on the surface of the melt in an amount of 0.2-0.25% by weight of the melt mixed with fluorite concentrate at a ratio of A1: CaP2 "(0.15-0.30):