SU833366A1 - Slag forming mixture - Google Patents

Description

(54) SLAG FORMING MIXTURE

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The invention relates to ferrous metallurgy, in particular to mixtures for casting steel into ingots in continuous casting plants.

Synthetic slag for steel casting of the following composition is known, wt%: fluorspar 15-35; silyg katna lump 15-35; aluminum 10-23; silicocalcium 5-15; sodium nitrate 5-20; graphite 1-5.

The disadvantage of this slag is the high content of pure aluminum (10-25 wt.%), The oxides of which dramatically increase the viscosity of the slag at a temperature below. During the casting process, the chemical and mineralogical compositions of the synthetic slag change, the content of refractory oxides increases. This leads to a deterioration of its adsorption properties and increases the wear of the lining of the mold.

Closest to the proposed is slag-forming mixture 21, containing, wt.%:

Fluorspar5-25

PyrocarbonErest

However, the known mixture causes the formation in the metal of an increasing amount of non-metallic inclusions of an unfavorable form due to the presence of 8–14% calcium oxide and 12–18% iron oxide in the pyrocarbon. The mechanical properties of the metal deteriorate.

The purpose of the invention is to reduce non-metallic inclusions in steel and increase the plastic properties of the deformed metal.

This goal is achieved in that the mixture, which includes fluorspar, additionally contains shungite in the following ratio of components, wt.%:

Fluorspar5-25

ShungiteExtra schungite is a natural mineral mined by the open method. In my proposed mixture, shungite is used, having the following chemical composition:%: Silica 20-65 Alumina 3-5 Iron oxide 1.6-2.0 Magnesium oxide, 0.50-0.95 Titanium dioxide 0.17-0.25 Carbon Else Except Moreover, shungite contains insignificant amounts of impurity oxides, such as, for example, calcium oxides up to 0.14%, manganese oxides up to 0.1%, vanadium oxides up to 0.15%. The mixture of low-melting point, well assimilates pop-up non-metallic inclusions, and the remaining inclusions in steel, due to the insignificant amount of calcium oxide, are transformed into the most favorable form — globules enriched in silica. The assortment of non-metallic inclusions occurs successfully due to the fact that in every smallest particle of shungite all its components are contained. The process of its interaction with the metal, consisting in the capture of non-metallic inclusions and the enveloping of their slag, takes place simultaneously. Shpak with an acid base, flowing between the ingot and the mold, provides a clean And smooth surface of the workpiece. The presence of such impurities in the shungite, ka vanadium, improves the properties of steel. As a result, the quality of the workpiece and the plastic properties of the rolled products are improved. An increase in the mixture content of fluorspar more than 25 wt.% Leads to a sharp increase in the fluidity of the slag and, consequently, to an increase in its gas permeability and increased 0060 28.0 72.0

95 80 75 97 70

20 25 3

30 8

5.9 6 the content of gases in steel. A decrease in the content of fluorspar less than 5 wt.% Leads to a higher viscosity, thickening of the slag mixture and a decrease in its adsorption capacity with respect to non-metallic inclusions m. The compositions of the proposed mixture and the results of the study are shown in the table. Along with compounds 1-3, compounds 4 and 5 are tested, in which the content of fluorspar is less than 5 wt.% And more than 30 wt.%. Experimental casting of St 45 steel smelted in a 500-pound induction furnace was carried out into ingots weighing 100-250 kg. Mirror metal protect mixture. The mixture consumption is 300-400 g / t steel. The cast metal determines the content of non-metallic inclusions. Ingots are forged on rods with a cross section of 16 mm, from which samples are made to determine the mechanical properties. When using a known mixture with pyrocarbon, steel contains 0.0075% non-metallic inclusions, including 55% silicates and 45% corundum, and the impact strength of the steel at + is 4.5 kgf m / cm. The use of the proposed mixture ensures a reduction in the steel content of nonmetallic inclusions (0.0055-0.0060%) and conversion of the remaining inclusions into a favorable globular shape, as well as increases the steel toughness (5.8-6.0 kgf m / cm X The expected economic effect is 2.40 p / t of steel.

Claims (2)

1. USSR author's certificate number 529900, cl. On 22D 27/00, 1975. 2. USSR author's certificate number 623641, cl. On 22 D 27/00, 1977.