SU1423266A1 - Slag-forming sand for casting steel - Google Patents

Abstract

This invention relates to ferrous metallurgy, specifically to casting steel from above. The purpose of the invention is to improve the quality of the metal by improving the process of slag and foaming. The essence of the invention is that sodium carbonate is used as a gassing agent, and blast furnace slag is used as a filler at the following ratio, wt.%: Blast ishak 50-60; sodium carbonate 40-50. 2 tab.

Description

 to

with y

about

O5

The invention relates to ferrous metallurgy, 5 specifically to casting, from above.

; The purpose of the invention is to increase the quality of metal by increasing the slag and foam formation.

The essence of the invention is

 that sodium carbonate is used as the gaseous agent, and

II quality filler - blast 1 torn slag in the following ratio, wt.%:

Blast furnace slag 50-60 Sodium carbonate AO-50 As slag-forming material, blast furnace slag of the following composition is used, ifac.Z:

MgO not 15.0 MpO, TiOjHe 4.0

Sodium Carbonate - Technically Pure

The improvement of the process of slag formation occurs due to the use in 11: the quality of an inert filler of only one material — blast furnace slag, which is already fused by the IOMO gene mass, having

Co low melting point 1300 ° C) and moderate basicity 1.05-1.5). One of the advantages of blast furnace slag is the low content (less than A, 0%) in it of iron oxides, which could oxidize components of the steel melt. HocTyh- in the formed liquid slag phase of sodium oxides during dissociation of sodium arboiate provides good physical properties of the slag: temperature of melting 1 250–1270 s, B s at the temperature of the metal to be cast (1550 ° С) 0.03 -0.05 Ns / m. At the same time, the use of sodium carbonate in the composition leads to the interaction of the resulting slag with sulfur, B1 blast furnace slag, and the formation of durable sodium sulfide sids () by tert Modinae (), which prevents the transfer of sulfur from the slag melt to contributes to its partial desulfurization. The use in the quality of the gas-forming agent of lightly dissociating sodium carbonate provides a satisfactory foaming ability of the slag melt and the formation of a thick layer of slag foam. Physical properties

o

five

e

0

0

five

slag, as well as the use of sodium carbonate for foaming, provide early formation and high stability of the slag foam.

All these factors contribute to a significant increase in the quality of metal by reducing the number of surface defects in the form of captivity, cracks, nonmetallic (slag) inclusions, due to the reduction of splash formation, eliminating secondary oxidation, reducing heat loss through the metal mirror, forming a more uniform slag thickness. interlayer (skull) between the body of the ingot and the mold.

The introduction of a slag-forming component in an amount less than the proposed lower limit and the sodium carbonate Bbmie of the upper limit results in a significant decrease in the melting point and viscosity of the resulting α-spac. Because of this, despite the large gassing, the foaming capacity of the slag melt deteriorates, the multiplicity and stability of the slag foam decreases, since the low viscosity slag gives low-strength films. In connection with this, a skull is formed of insufficient thickness, and the slag of metal splashes is not satisfactorily quenched. This leads to the occurrence of such defects.

5 ingot surfaces, like captives, hot cracks and cracks hanging.

Incorporation of the slag-forming components in the amount of more than the upper limit and carbonate less than the lower limit results in a high-viscosity refractory slag, while the slag formation process deteriorates and the slag crust formed is uneven.

5 thick. This leads to uneven shrinkage of the ingot and the appearance of cracks in the suspension and hot, as well as slag inclusions. Due to the lack of gas, the foaming capacity of the slag melt is deteriorated, which leads to the appearance of captivity. At the same time, conditions are created for the transfer of sulfur from slag to metal.

The mixture may be applied as

5 granules and in powder form. The consumption of the mixture is 0.001-0,, 004 kg / kg of steel, depending on the weight of the ingot and the configuration of the mold. Under the mixture can be poured steel mass through the carbon content

production from 0.1-0.7%.

Example. Blast furnace slag and sodium carbonate are dried and crushed to a fraction of 1.0-0.88 mm. Dried and ground components in the ratio:

Domain pshak 55%

Sodium carbonate 45% is thoroughly mixed, not regulating the sequence of mixing the components. Casting steel of grade 3 JV into 8.0 ts ingots using the prepared mixture is conducted at a speed of 0.035 m / s through a 60-mm-diameter beaker from a 250-ton bucket with a mixture of 2 kg / t of steel.

As a result, the slagging process is improved and high quality metal is obtained. Investigation of the ingot surface quality was carried out visually.

Table 1 shows the mixtures studied and the physical characteristics of the slags that are formed.

Table 2 shows the surface area of the ingots occupied by defects in the form of captivity, non-metallic inclusions of cracks.

Investigation of the quality of ingots (Table 2), obtained by casting metal using the developed

/ 4232664

compositions of slag mixtures (Table 1), as well as prototype mixtures (Table 2, No. 6) and without using the mixture showed

J. that the surface of ingots cast under mixtures nos. 1, 5 and 6, as well as without the use of the mixture, is affected by a significant number of flaws in the form of captivity and cracks; metal contains

10 inclusions, the source of which is a slag mixture.

When casting etali using mixtures No. 2-4, the number of surface defects in the form of captivity and cracks

15 decreases sharply, the metal does not contain inclusions, the source of which is the slag mixture.

Claims (1)

Invention Formula Slag-forming mixture for steel casting, including filler and gas-emitting agent, is characterized by the fact that, in order to improve the quality of the metal by improving slag and foaming, the mixture as a gas-emitting agent contains sodium carbonate, and as a filler - blast-furnace 30 slag with the following ratio, wt.%: Blast furnace slag 50-60 Sodium carbonate 40-50 The viscosity study of slag melts was carried out at a melt temperature of 1550 C. Table 1 14232666 Table 2 Note: Evaluation criteria for clogging ingots by captives and non-metallic inclusions served as their area. When assessing the ingot’s elimination of cracks, its four edges were taken as 100%. If the cracks were over the entire facet, the faults were estimated at 25% — every third of the faces (bottom, middle, top of the ingot) was estimated at 8.3%.