RU2310006C2 - Ferroaluminum alloy for deoxidation of the lump-type steel - Google Patents

Abstract

FIELD: ferrous metallurgy; production of the ferroaluminum alloy used for deoxidation of the lump-type steel.

SUBSTANCE: the invention is pertaining to the ferrous metallurgy and may be used for production of the ferroaluminum alloy used for oxidation of the steel present in the form of the lumps with the dimension of 40-80 mm and the density of 5.0-7.0 g/cm³. The alloy contains ingredients at the following ratio(in mass %): aluminum - 28-32, silicon - 0.5-5.0, manganese - 5.01-8.0, carbon - 0.1-0.9, copper - 0.2-2.0, phosphorus - 0.02-0.1, sulfur 0.02-0.1, iron - the rest. The invention allows to improve the operational characteristics of the alloy, namely - the density, the crushability and the mechanical strength for the long time with the maximum assimilation of ingredients at the expense of the optimal composition.

EFFECT: the invention ensures the improved operational characteristics of the alloy, namely - the density, the crushability and the mechanical strength for the long time with the maximum assimilation of ingredients at the expense of the optimal composition.

1 ex, 1 tbl

Description

The invention relates to ferrous metallurgy and can be used to obtain ferroaluminum for deoxidation of steel in the form of pieces with a size of 40-80 mm and a density of 5.0-7.0 g / cm ³ .

Known alloys FA10-FA23 for deoxidation and alloying of steel (ChMTU 5-37-71. M.I. Gasik, B. I. Emlin. Electrometallurgy of ferroalloys. Kiev: Higher school, 1983 - 376 S.), containing, wt.% :

Aluminum 8.0-24 Silicon Up to 4 Carbon Up to 4 Phosphorus Up to 0.06 Sulfur Up to 0.06 Iron Rest

The main disadvantage of these alloys is the low aluminum content, which reduces their scope and complicates the production process, as well as the limitation on the silicon content, which does not allow the use of numerous cheap charge materials used in the smelting of aluminum alloys.

The closest to the proposed technical essence and the achieved result is an alloy (RF Patent No. 2214473, IPC 7 C22C 35/00. Alloy for deoxidation of steel / Kostarev VG, Pochivalov OV, Telyashov NV, Sheshukov O .YU. // Inventions. 2003. No. 29 (II hour). S.370) for steel, containing, wt.%:

Aluminum 20-40 Silicon 0.5-20 Manganese 0.5-5 Carbon 0.1-0.9 Copper 0.2-2.0 Phosphorus 0.02-0.1 Sulfur 0.02-0.1 Iron Rest

The main disadvantage of these alloys is the wide limits of the aluminum content, which is not justified both from the standpoint of production and from the standpoint of storage and transportation of the resulting alloys. On the other hand, wide limits on the silicon content and especially high silicon content (up to 20%) make it more expensive to obtain the indicated alloy (it is impossible to obtain an alloy of the specified composition without additional introduction of ferroalloys such as ferrosilicon) and limits its scope (it is impossible to use in the preparation of silicon-free steel grades )

The technical result of the claimed invention is to improve the service characteristics of the obtained alloy (density, crushability and mechanical strength for a long time) with maximum assimilation of elements due to the optimal composition of ferroaluminium obtained in the form of pieces with a size of 40-80 mm and a density of 5.0-7.0 g / cm ³ .

Said technical result is achieved in that for deoxidizing steel ferroaluminum in lumps the size of 40-80 mm and a density of 5.0-7.0 g / cm ³ containing aluminum, silicon, manganese, carbon, copper, phosphorus, sulfur and iron, in the following ratio of components, wt.%:

Aluminum 28-32 Silicon 0.5-5.0 Manganese 5.01-8.0 Carbon 0.1-0.9 Copper 0.2-2.0 Phosphorus 0.02-0.1 Sulfur 0.02-0.1 Iron Rest

The proposed complex alloy has optimal aluminum content limits. Firstly, the claimed limits of the aluminum content determine the optimal density of the alloy, which is recommended in the range of 5.0-7.0 g / cm ³ , providing immersion and soaring of the alloy in liquid steel with maximum assimilation of elements; secondly, an alloy containing less than 28% aluminum will have increased mechanical strength, which makes it difficult to obtain pieces in the range of 40-80 mm, which is required for the efficient deoxidation process; thirdly, an alloy containing more than 32% aluminum will have an increased tendency to self-scattering, which makes it difficult to transport and use it for processing steel.

A content of less than 0.5% silicon in the alloy is impossible, since during the smelting process it passes into the alloy from both recoverable raw materials and metal additives. The concentration of silicon in the alloy up to 5% practically does not affect the physical properties of the alloy and the process of steel deoxidation, and in the case of an increase in the silicon content above 5%, a decrease in the density of the alloy below the recommended limit of 5.0 g / cm ³ is observed, i.e. reduced performance characteristics of the resulting alloy. In addition, a higher silicon content in the alloy (more than 5.0%) significantly complicates the production technology and increases the cost of the alloy by increasing the cost of raw materials (in this case, silicon ferroalloys such as ferrosilicon must be used in a charge).

The content in the alloy of manganese in the range of 5.01-8.0% improves the performance characteristics of the resulting alloy. The specified manganese content is obtained through the use of manganese-containing steel scrap, which ensures the mechanical strength of the resulting alloy for a long time, which was not achieved in the prototype.

The carbon content in the alloy from 0.1 to 0.9% depends on its concentration in the source ores, metal additives, reducing agents and the degree of transition to the alloy. The lower and upper limits of the content of this element are associated with the type of charge materials and do not require additional input materials. Moreover, carbon within the claimed limits either does not affect the process of deoxidation and properties of steel, or has a positive effect on the process of deoxidation and removal of deoxidation products. A carbon content of more than 0.9% will require additional costs for producing ferroaluminium, and an even higher carbon content may cause an undesirable increase in its content in steel.

The presence of sulfur and phosphorus in steel is inevitable due to their presence in any ore and steel scrap, and copper in the aluminum-containing scrap used in the production of ferroaluminium by fusion. The lower limit of the content of copper (0.2%), sulfur and phosphorus (0.02%) is due to the content of these elements in the feed and the degree of their transition to alloy, and the upper limit is limited by the harmful effects of these elements on steel and their permissible concentrations according to technical conditions . If the content of sulfur, phosphorus and copper in the alloy is above the upper limit, they will be introduced into the steel (with a maximum consumption of the alloy of 1.5 kg / t) of these elements, respectively, 0.00015; 0.00015 and 0.003%, which cannot but affect its composition and quality.

The use of ferroaluminium for the deoxidation of steel makes it possible to simplify the introduction of aluminum into molten steel and reduce the costs of deoxidation by increasing the useful use of aluminum (silicon) up to 60-90% with the usual input of alloy from hoppers into the ladle. However, non-compliance with the recommended aluminum and silicon content limits when producing ferroaluminium leads to a deterioration in the service characteristics of the obtained alloy and, as a result, to unstable results during steel deoxidation. Thus, the use of ferroaluminium for steel deoxidation, containing the main components within the claimed limits, will stabilize the deoxidation results.

The invention is illustrated by the following examples.

At Kurganmashzavod OJSC, three companies were smelted of the inventive alloy from steel and aluminum metal wastes in the IChT-2.0 induction furnace.

As scrap steel, trimmings of shaped castings from steel of the St3 grade were used (with an average content,%: 0.2 C; 0.6 Mn; 0.27 Si, up to 0.04 P and up to 0.05 S) and steel of the 110G13L grade (with an average content,%: 1.1 C; 13 Mn; 0.27 Si, up to 0.04 P and up to 0.05 S). Aluminum was used in the form of briquettes and shavings containing,%: not less than 85 Al; 0.5 Mn; 1.5-8.0 Si.

The mixed metal charge was loaded into an induction furnace until it was completely filled and then in portions as it was melted. Melting was carried out under the slag resulting from the oxidation of impurities. Metal was cast from a ladle into cast-iron molds to obtain ingots of equal weight. The temperature of the metal at the outlet was 1320-1350 ° C.

In total, 20 experimental swimming trunks were conducted.

The composition of the obtained metal was in the following ranges,%: 22.7-34.8 Al; 0.5-5.2 Si; 0.5-8.1 Mn; 0.03-0.08 C; the copper content did not exceed 0.2.

The table shows several compositions of the obtained alloys (numbers 1-9) and, for comparison, the alloy compositions of the prototype.

Under the conditions of the foundry of OJSC Kurganmashzavod, experimental melting of steel St40 was carried out with its deoxidation by the alloys shown in the table. Steel was smelted in DSV-6 furnaces, and ferroaluminium of various compositions was introduced into the ladle for a stream of metal at the rate of obtaining residual aluminum content in steel of at least 0.02%. The results on the technological properties of ferroaluminium and the beneficial use of aluminum are given in the table.

The evaluation of technological properties showed that the aluminum content in the alloy should be in the range of 28-32%, silicon from 0.5 to 5%, and manganese 0.5-8.0%. Alloys containing aluminum below the specified limits had an increased density and hardness, which made them difficult to use as a deoxidizing agent and did not allow to obtain stable results. Alloys containing aluminum above the specified limits, although they met the requirements for density and melting point, were subject to self-scattering.

Experiments on the deoxidation of steel showed that the alloy containing the leading elements in accordance with the prototype lower technological performance and, accordingly, the useful use of aluminum. Most suitable for processing steel is an alloy containing components within the scope of the claimed invention.

Practical results have shown the fundamental possibility of producing ferroaluminium with an aluminum content of 30% on average from metal waste in an induction furnace, the possibility of using it for the effective deoxidation of steel with an increased efficiency of aluminum and silicon of the proposed alloy.

Table The composition of complex ferroaluminium and its useful use in the deoxidation of steel Alloy number Chemical composition, wt.% Density, g / m ³ Crushability Spill time Useful use of aluminum,% Al Si Mn FROM R S Fe one 28.0 4.2 0.8 0.06 0,026 0.010 rest 5.31 sat. not less than 3 months 83,2 2 27.9 1.80 0.5 0,07 0.009 0.009 rest 5.56 bad not less than 3 months 82.6 3 30.1 0.6 0.7 0.04 0.010 0.010 rest 5.54 sat. not less than 3 months 87.3 four 32,0 0.5 0.7 0.04 0.010 0.010 rest 5.30 good not less than 3 months 86.5 5 32.6 0.5 0.5 0,03 0.010 0.010 rest 5.42 good 1 month 86.2 6 34.8 0.92 0.5 0,03 0.012 0.005 rest 5.37 good 2 weeks 84.5 7 22.7 5,0 0.6 0.08 0.011 0.006 rest 5.77 not crushed not less than 3 months 74.7 8 28.7 0.8 8.0 0.65 0.010 0.007 rest 6.01 good not less than 3 months 84.7 9 29.6 5.2 0.8 0.06 0.012 0.010 rest 4.86 good not less than 3 months 76,4 Prototype 20,2 1,0 0.7 0.14 0,03 0.06 rest 6.12 not crushed not less than 3 months 70.8 39,4 0.84 0.5 0.8 0.05 0.04 rest 4,53 good 1 Week 64.3 30,2 15.4 0.5 0.6 0.05 0.06 rest 4.66 good not less than 3 months 67.9

Claims (1)

Ferroaluminium for deoxidation of steel in the form of pieces of size 40-80 mm and a density of 5.0-7.0 g / cm ³ containing aluminum, silicon, manganese, carbon, copper, phosphorus, sulfur and iron, in the following ratio, wt. %: Aluminum 28.0-32.0 Silicon 0.5-5.0 Manganese 5.01-8.0 Carbon 0.1-0.9 Copper 0.2-2.0 Phosphorus 0.02-0.1 Sulfur 0.02-0.1 Iron Rest