SU768821A1 - Method of smelting alloyed steels and alloys - Google Patents

Description

The period of time is irrized to increase the content of gases and inclusions in the cast metal, in terms of equilibrium with the usual content. The observed phenomenon was caused by the fact that the diffusion of atoms is rare with an increase in temineurura and, hence, the temperature of the radiation is considerably reduced. At the same time, due to an increase in the viscosity of the temperature due to an increase in the viscosity of the metal and the top-wind energy, the rate of emergence and the processes of increasing non-metallic inclusions (coagulation, adhesion, coalescence) are slowed down. Therefore, for more complete gas and metallic inclusions, the necessary melt aging is required at lower temperatures. The harmful effects of oxygen and oxygen content in steel are known: the plastic properties of the steel deteriorate during the rolling process: and forging, flaws are formed, the harmful effects of sulfur increase due to the formation of oxysulfide inclusions, high contents of oxide metallic impurities have a negative effect on almost all properties of steel and alloys. The closest to the proposed technical solution is the method of smelting steel and alloys, the drying of which is as follows: heating the melt in the furnace at 300-400 ° C above the liquidus temperature (or about 0.2-0.35) T .; K-i), holding at this level for 30 minutes, accelerated (within 10–15 missions using special techniques) cooling of the metal to the temperature of release and aging with it also 10–15 mice. Steel is broken at temperatures “and 30–80 ° C below normal 3. Such smelting technologies for steels and alloys make it possible to significantly improve the quality of the metal and increase the yield by 5–6%. However, this method retains the negative effect of exposure at high temperatures and the content of gases and non-metallic inclusions in the ra-alloy. Accelerated cooling of the melt after exposure to the release temperature (for the reasons given above) leads to an increase in their content in the metal after cooling. Therefore, an additional 10–15 min exposure at this temperature is, in a number of cases, insufficient for refining the melt from excessive amounts of gases and non-metallic inclusions. At the same time, the long-term exposure of the metal and the temperatures, which are much higher, their establishment in the metallurgical industry, reduces the durability of the lining of steel-smelting furnaces and reduces their productivity. It is known that short-term heating of the rasilawa to temperatures significantly exceeding the melting temperature provides a high rate of mass transfer of phosphorus and sulfur from the volume of vanilla to the metal-slag interface, which helps remove the latter from wahii, ensures the intensity of boiling of the bath of coil to low carbon carbon concentrates and increases the mechanical metal properties. At the same time, sufficiently rapid cooling of the melt from high temperatures allows the high-temperature structure of the melt to be maintained up to crystallization temperatures, which is significantly reflected in the structure and properties of the melts. Thus, the existing methods of casting of steels and snlavs, increasing the curvature, strength and quality of the cast and deformed metal, do not adequately remove non-metallic inclusions and gases from it, especially for alloyed steels, which reduces the effect of high-temperature treatment of rasil. Exposure of Rasilav at temperatures of 250-500 ° C above the liquidus temperature reduces the productivity of steel-smelting furnaces. It is known that in order to stabilize and enhance the strength of the strengths of rasilav at low temperatures, in this case, it can many times exceed the usual smelting time in practice. Therefore, the high temperature heating of the rasilaw, accelerated cooling to outlet temperatures and exposure to these temperatures can be sufficient to improve the quality and properties of the metal. The aim of the invention is to improve the quality and properties of the metal by further removing gases and non-metallic inclusions. The goal is achieved by the fact that after loading and melting of the charge, the melt is heated at (0.2-0.35) T., kv above the melting temperature, rapidly cooled to 50-150 ° C above the liquidus temperature, held in the furnace at these temperatures for 20-60 minutes, and then release the metal from the furnace. This reduces the solubility of gases in the metal, increases the degree of their removal from the liquid metal, increases the rate of emergence of non-metallic inclusions, increases the durability of the lining of steelmaking furnaces. For each co-brand steel or alloy, the heating temperature of the metal is set after determining the liquidus temperature. The proposed temperature range for vyrezhki metals neredom OVOM from the furnace (50-150 ° C above the liquidus temperature) is made on the basis of the experiments performed and is optimal for smelting alloyed steels and alloys (and the interval

temperatures 50-SOC above liquidus temperature), recommended for steels and alloys with a carbon content of 0.4%, for other grades of steels and alloys a temperature range of 80-150 ° C is recommended.

The proposed exposure of the melt in the furnace before the release of 20-60 minutes is also set on the basis of experiments. Exposure of the melt to less than 20 minutes is not effective from the point of view of the removal of gases and non-metallic inclusions, while holding the melt for more than 60 minutes there is no further decrease in the content of gases and non-metallic inclusions. The optimal exposure time for the studied steels and alloys (X12, EI417, R6M5, EI992, X20H80) is 20-40 min.

Accelerated cooling of the melt is provided in the industrial production of steel and steel from the introduction of 200-250 kg / ton into the melt, ferroalloys, and short-term immersion of metal rods.

The proposed method can be used for smelting alloyed constructional (EI992, EI417, X18P10T, EI448, etc.) and tool (X12, X12M, X12I, R6M5, R18, R6M5K5, etc.) steels and alloys (X20H80, EI929, EP220, EI, etc.) of steels and alloys (X20H80, EI929, EP220, EI, etc.) of steels and alloys (X20H80, EI929, EP220, EI, etc.) of steels and alloys (X20H80, EI929, EP220, EI4, EI9, etc. and etc.).

An example of a specific drying process: smelting (steel production of grades X12 and EI992 in open induction 1 t furnaces) - Shikhtovka, preparation of materials, filling and melting. Content of non-metallic inclusions and gases in steel

The metal was produced according to the operation1; After awards of the refining slag, its deoxidation with 75% ferrosilicon powder in the amount of 0.25 kg / ton was produced. The metal was heated to 1660 ° C (steel XI2) and 1720 ° C (steel EI992). At these temneterurus the metal was liquefied by lumpy aluminum in the amount of 0.5 kg / t, the slag was liquefied by ioroshk

75% ferrosilicon in the amount of 0.25 kg / t, after which the metal was cooled to a temperature of 1470 ° C for steel X12 (T, „in 1320 ° C) and to 1490 ° C for steel EI992 (T ,, KB 1400 ° C) . The cooling of the metal was carried out by repeated immersion in it for 5-10 from metal rods with a diameter of 150-200 mm. The cooling rate was 10-20 ° C. After obtaining the required temperature, the metal

0 kept before release for 20-30 minutes, then released into the ladle and poured from above into a mold circle 310 mm with an ingot mass of 0.5 tons. Lubrication of the molds - Kuzbass varnish. Backfill of the profitable part of the ingots - lunker of mark L28 in the amount of 2 kg / t of steel.

The results of the study of the metal smelted by the proposed technology are given in Table. 1-3.

0 Analysis of the research results shows the advantages of the proposed technology for smelting alloyed steels in comparison with the existing prototype: the content of gases and non-metallic inclusions in the finished metal is reduced.

Table I

Table 2 Properties of steels in the cast state

Mark

Properties, indicator

Steel size

The average density of metal1-2 la at 20 ° С, g / cm

7,680 Fatal limit, kgf / mm

t Relative .1 elongation

%

38

Relative narrowing,% 59

Average metal density

I992

at 20 ° C, g / cm

7.69 P

Strength, kgf / mm

Relative extension,

30 58

%

Relative narrowing,%

Note. The mechanical properties of the steels are given when the temperature of the end of hot deformation of the metal is 900 ° C.

Table 3 Evaluation of the microstructure of the metal

its density and mechanical properties are increased, the macrostructure is improved.

Claims (3)

The application of the proposed method will reduce the marriage in the conversion workshops on average by 25-30%. For example, during the smelting of 15 tons of steel grade X) 2 according to the proposed technology, the scrap on the redistribution of raw materials decreased from 8% to 2%. With an average etoimeti 1 t etnn 140 rubles. Expected economic efficiency of 0.3 rubles / ton of cast steel. The invention method of smelting alloyed steels and alloys, including loading, melting the mixture, heating the melt above the melting temperature by 0.2-0.35 liquidus temperature, accelerated cooling, followed by exposure, , in order to improve the quality of the metal 10 15, the melt is cooled to a temperature of 50-150 ° C above the liquidus temperature and maintained at these temperatures for 20-60 minutes, then released from the furnace .: Information sources, . accepted in the attendee at the examination 1.Za vka UK No. 1380557, cl. C 21 S 7/00, 1975. 2. Certificate of author No. 621735, cl. C 21 C 5/52, 1978. 3. Khasin, A. A., et al. The effect of temperature-time smelting on quality. Steel, M. Metallurgi, No. 9, 1978, p. 814-817.