SU1420030A1 - Method of alloying and modifying basic steel - Google Patents

Abstract

The invention relates to ferrous metallurgy, and more specifically to the production of high-quality vanadium-containing steels in main open-hearth furnaces for producing castings and forging blanks. When alloying steel, alloying or their mixtures are placed on the bottom of the ladle at a ratio of alkaline earth metals to vanadium equal to 0.17-0.33, and slag is released onto the metal in 3-5 minutes after the end of the release. By maintaining the specified ratio of SCHM to vanadium and the successive release of metal, and then the bat, the waste of vanadium from a legacy lean alloy is 4 times reduced, the ductility of steel increases by 10–20% for forging, 2 tab. (WITH WITH

Description

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: The invention refers 1 s to ferrous: metallurgy, and more specifically to the production of high-quality vanadium-containing steels in main open-hearth furnaces for the production of castings and forged blanks.

The purpose of the invention is to reduce vanadium carbon monoxide and to improve the ductility of steel at forging temperature.

A decrease in the alkaline earth metal oxide / metal ratio in the ligature below 0.17 due to insufficient modifying effect leads to a decrease in the degree of shear deformation by the time of destruction (which characterizes the ductility of steel at forging temperatures). Reduces high-temperature plasticity and an increase in the SCHM content in the alloy, i.e. an increase in the alkaline earth ratio / 7 7,33. In this case, increased residual concentration leads to a failure of the steel. calcium in it.

The high degree of assimilation of vanadium and the efficiency of modification are achieved by the metal release technology. As is known, open-hearth ptaks have a high oxidizing ability, therefore, in the ladle under the donkey layer there is an increased loss of alloying elements, and modifying is not effective enough. The use of a swinging open-hearth allows the release of metal without slag. Before releasing the metal from special bunkers, a new amount of ligature is loaded into the ladle, then the metal is produced and the metal is held without pshak for 3-5 minutes. A slower shutter speed is not enough to completely dissolve the ligature, and a large one leads to a supercooling of the metal. Then, slag is released into the ladle, which protects the steel from rapid cooling, and the metal is cast into molds or molds.

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Testing of the proposed method was carried out in a 45-ton swinging open-hearth furnace with a 24XM1F steel melting in comparison with a known method.

The following alloying materials are used: ferrovanadium OBg38 according to TU 14- 5-98-78, ferrosilicon FS45 according to GOST 1415-78, ferromanganese FMp70 according to GOST 4755-80, silico-manganese SMp17 according to GOST 4756-77, ferromolybdenum FMOBO according to GOST 4759-79, ligature OC40Bg by

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TU 14-142-2-84. Chemical compositions of basic alloys are given in Table. one.

According to a known method of melting are as follows.

After the metal has been melted, the oxidation period and the oxidizing slag are downloaded, the metal is preliminary deoxidized with ferromanganese, silicomanganese and ferrosilicon additives on the basis of obtaining 0.1-0.15% silicon and 0.20-0.30% manganese. Ferromolybdenum is set in the furnace during the melting of the charge, ferrochrome - no later than 30-45 minutes before the release.

Ferrosilicon FS45, ferrovanadium ФBg38 and aluminum are applied to the ladle at the rate of 0.17-0.37% silicon in metal, 0.12-0.20% vanadium, not more than 0.045% aluminum.

The furnace is tilted and the metal and slag are released, and then cast. The chemical composition of the furnace slag is as follows,%: CaO 38.5; MgO 16.0; A1gOe 9.6; SiO 18.8; FeO 16.4; 0.7.

A slag sample is taken from the ladle before casting.

According to the proposed method of melting lead. So.

The melting of the metal, the oxidation period, the preliminary deoxidation and alloying of the metal are carried out in the same way as in the known method.

At the bottom of the bucket, a ligature of the type FS40Bg is introduced, which has the most appropriate SCHZM / V ratio, in an amount calculated for vanadium and 350-500 g / ton of aluminum.

The furnace is tilted and the metal is released, as well. the slag is left in the furnace. Maintain the metal in the ladle without oxidizing slag for 3-5 minutes, at the same time there is a complete dissolution of the ligature with minimal waste of vanadium. The presence of SHZM in the specified ratio with vanadium allows for an optimal modifying treatment of the metal with a chain to improve the shape of non-metallic inclusions. Modifying is almost impossible under a slag layer with a high content of iron oxides.

After the metal content of the furnace, the furnace is again tilted and the slag is fed into the ladle to prevent the metal from rapidly cooling. The metal is released under a layer of slag and cast.

The average chemical composition of the slag, taken from the ladle before casting, is the following,%: CaO 39.4; MgO 15.7; A1gOz 10.1; SiOj 18.9; FeO 15.7;

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Vanadium carbon in an average of ten heats in a known method reaches 19.0%, Lr at 1000 ° C - 2.2, at 950 ° C - 1.3.

The use of the proposed method in comparison with the known one allows reducing vanadium carbon monoxide by 4 times; 10-20% increase the ductility of steel

 0.2.

To determine vanadium carbon monoxide, its content in the raw materials and in the finished steel, as well as the consumption of ferroalloys and the number of year-Q at the forging temperature and to reduce waste metal, are monitored.

To determine the ductility of steel

Claims (1)

At the forging temperature, a special- (Formula of the invention comb-shaped sample with teeth of 200 mm length and 30x30 mm section) is poured. Samples are rolled onto a wedge according to the UZTM KPP-162-53 technique and the value of Lp-degree of shear deformation is determined by the moment destruction characterizing plasticity 15 20 The method of alloying and modifying: the main steel, including preliminary deoxidation of the metal in a swinging furnace, the loading of deoxidizers and alloying alloys containing alkaline earth metals and vanadium, into the ladle, the metal and slag deposited on them, and the subsequent pouring of the steel, characterized in that in order to reduce vanadium burnout 25 and to improve the ductility of steel at forging temperature, alloying alloys or their mixtures are loaded at a ratio of alkaline earth metal materials to vanadium equal to 0.17–0.33, and a putty is placed on the metal 3–5 minutes after the metal is injected. steel at forging temperature. Samples are heated to t, 1280 ° C, test temperature tу is 1100 ° C and 950 ° C. The test results of the proposed method are given in table. 2 The chemical composition of the steel obtained,%: C 0,22-0,25; MP 0.245-0.60; Si 0.20-0.27; Cr 1.20-1.60; Mo 0.40-0.60; V Oh, 10-0.15, Fe the rest. Vanadium carbon in an average of ten heats in the known method reaches 19.0%, Lr at 1000 ° C - 2.2, at 950 ° C - 1.3. The use of the proposed method in comparison with the known one allows reducing vanadium carbon monoxide by 4 times; 10-20% increase the ductility of steel at the temperature of forging and reduce the marriage of forgings. (Formula of the invention The method of alloying and modifying: the main steel, including preliminary deoxidation of the metal in a swinging furnace, the loading of deoxidizers and alloying alloys containing alkaline earth metals and vanadium, into the ladle, the metal and slag deposited on them, and the subsequent pouring of the steel, characterized in that in order to reduce vanadium carbon monoxide and improve the ductility of steel at forging temperature, alloying alloys or their mixtures are loaded at a ratio of alkaline earth metal materials to vanadium equal to 0.17–0.33, and a putty is placed on the metal 3–5 minutes after the metal is injected. Table 1 table 2