SU876270A1 - Method of casting rimming steel ingots - Google Patents

Description

(54) METHOD OF CASTING BULK STEEL INGOTS

I

The invention relates to the metallurgy of ferrous metals, more specifically to the doping of boiling steel with boron during its casting and crystallization.

The closest in technical essence to the present invention is a method that provides more intensive boiling of steel in a mold, some reduction in the content of non-metallic inclusions in it, and also causes a certain possibility of reducing the tendency to aging 1.

The disadvantage of this method is that it is impossible to provide intensive boiling of steel and uniform boron recovery over the entire height and section of the ingot. Entering the entire slag-forming mixture to the bottom of the mold, followed by pouring the stele from the top, leads to uneven restoration of boron in ingot height, a decrease in the amount of oxygen absorbed from the atmosphere, due to a significant coating of the upper layer of meltean molten slag, to a deterioration in the steel boiling during the casting period. In addition, the accumulation of significant amounts of slag-forming steel -In the lower part

the mold slows down the process of its melting and leads to the jamming of individual particles in the metal and, therefore, reduces the purity of the metal at the lower level of the ingot.

The purpose of the invention is to reduce the content of non-metallic inclusions in the metal, reduce the chemical heterogeneity of the ingot in terms of the content of the bur due to the uniform and complete restoration of it during casting and increase the thickness of the dense, bubbly-free crust of the ingot.

The goal is achieved

15 in that the boron-containing mixture is introduced into the mold in two stages: at the bottom of the mold before the start of casting in the amount of 25-40% of the total consumption of the mixture, and the rest - when filling

20 molds for 50-80% of its height, while the total consumption of the mixture will be 0.5-1.5 kg / t of steel.

The proposed method was tested when casting steel 08 CP into ingots

25 weighing 14 tons. It was used a three-component mixture of the following composition,% g

Bura (Datolite) 57 Nepheline Con30 Cent 32

Cryolite 11

Slag mixture was prepared by mechanical mixing of the starting components, and the mixture was packaged in plastic bags in quantities corresponding to two-stage consumption. The packaged mixture was introduced to the bottom of the mold (stage 1) and then when filling the mold at 50–80% of its height (stage 11).

The results of testing the method are given in the table.

Analysis of the results of testing the proposed method shows that the content of nonmetallic inclusions in the metal decreased and amounted to 0.0046-0.0057% in the middle. The improvement of this indicator was achieved due to a two-stage input of the slag-forming mixture, which ensures its timely melting height and sections of ingot. Using this method helps reduce the degree of chemical inhomogeneity of steel (segregation for boron content of 50-72%. This result was achieved due to the rapid melting of the slag-forming mixture, timely and more complete recovery of boron from its oxides, and improved use of the physicochemical properties of the molten refining slag. In addition , casting of boiling steel ingots according to the proposed option contributes to increasing the thickness of the dense outer crust from T and II (level 50% of height) 32.5 / 67.5 40.0 / 60.0

25/75

I and Ti (level 65% Note:

21 to 25 mm. The improvement of this indicator is caused by an increase in the intensity of metal boiling, due to a significant access of oxygen to the surface of the metal mirror during casting, covered with the optimal amount of refining mixture at all horizons along the height of the ingot. The proposed method of entering the slag-forming mixture in two stages, in accordance with the specified costs and input levels (see table / is optimal, since it contributes to a more complete use of the positive physicochemical properties of the molten slag, eliminates technological and organizational delays. Thus, slag-forming mixture (stage II at the level of 45% of the height of the mold deteriorates the performance of the method (the content of non-metallic inclusions, the chemical inhomogeneity of the ingot according to the boron content, the thickness of the dense acacia rind), as well as a later entry of the mixture at the level of 85%. Entering the slag-forming mixture at stage 1 in an amount less than 25% of the total consumption, or more than 40% (respectively at stage II 75%, 60%) does not provide optimal quality indicators provided by the proposed method, as it leads to an increase in the duration of its melting, reducing the efficiency of the molten mixture.

58.00

0,0046

24 In the numerator - the mixture flow to the bottom of the mold, in the denominator - the mixture flow in accordance with the specified height of the mold 0.0048 0.0052 0.0050

Claims (1)

Invention Formula The method of casting boiling steel ingots, which includes treating it with boron-containing slag-forming mixtures in molds, characterized in that, in order to reduce the content of non-interglacial inclusions in the metal, reduce the chemical inhomogeneity of the ingot in terms of boron content due to its uniform and complete recovery during the casting process and increase the thickness of the tightly bubbly crust of the ingot, the boron-containing mixture is introduced into the mold in two stages: at the bottom of the mold before the start of casting in the amount of 25-40% of the total consumption of the mixture, and the rest - when filling the mold at 50-80% of its height, while the total Bmesi consumption is 0.5-1.5 kg / ton, become. Sources of information received by the HE attention in the examination ;, 1. Shneerov Ya.A. and others. Refining of boiling steel with boron-containing slag-forming mixtures in molds. Information Bulletin, CRIIM, 1979, 23, p. 33-34.