SU969752A1 - Method for producing steel for casting in sand molds - Google Patents

Description

This invention relates to metallurgy, in particular to the deoxidation of steel smelted in an open-hearth furnace.

A known method for producing steel in the main open-hearth furnace involves obtaining molten metal in the main open-hearth furnace by deoxidizing it in a furnace with silicomanganese based on 0.100 metal added to the metal, 20% silicon, metal production into the ladle, an additive during metal production 1 / 4-2 / 3 deoxidizing agents ferrosilicon, ferromanganese and aluminum. tl.

The disadvantage of the method is that at the beginning of production the metal in the ladle does not deoxidize, as a result of which the oxidation of the steel increases, the waste of the deoxidizing agents increases and the stable quality characteristics of the steel are not obtained. Unfavorable non-metallic inclusions are formed in the metal, the properties of the steel deteriorate.

The closest to the proposed technical essence and the achieved result is the method of | Beaming steel for sand casting, including the production of met-alla in the main open-hearth furnace, its deoxidation. silico-manganese in the furnace in the amount of 9-14 kg / t, the release of metal into the ladle with ferrosilicon loaded into it, the introduction of chili1 ali, ferromanganese with the release of 1 / 5-1 / 2 of metal 2.

The disadvantage of this method is that when it is realized, there is an increased waste of manganese, as a result of which an increased amount of manganese alloys is required to produce steel of the required composition. Increased consumption

15 deoxidizing agents leads to a significant re-phosphorization and an increase in the phosphorus content in the finished steel, a decrease in the yield of castings due to a decrease in crack resistance

20 steel, reducing its mechanical properties.

The purpose of the invention is to increase the crack resistance and yield of castings, reduce the consumption of thinning helium, increase the mechanical properties of steel, decrease the degree of re-phosphorization and decrease the phosphorus content in the finished steel.

The goal is achieved by that;

30 that according to the method of producing starI for casting into sandy forms, including the production of metal in the main open-hearth furnace, its deoxidation in the furnace with silicomanganese in the amount of 9-14 kg / t, the release of metal into the ladle loaded with ferrosilicon, the introduction of aluminum, ferromanganese at Release 1 / 5-1 / 2. Metal, ferrosilicon is introduced in a mixture with aluminum at an aluminum: silicon ratio of 1: 9-15; after releasing 15-20% of the metal, a second batch of aluminum in the amount of 0.8 is introduced just before the addition of ferromanganese. -0.9 from the mixture with ferrosilicon, and in the process of producing 40-50% of the metal after the addition of ferromanganese, a third portion of aluminum is introduced in an amount of 0.3-0.4 kg / ton. After the metal is deoxidized in a furnace with silicomanganese, a metal with moderate oxidation gets into the ladle, but with enough oxygen to form complex aluminomanganese silicate inclusions when the melt interacts with silicon and aluminum that are in the ladle. The relationship between aluminum and silicon is important. When aluminum is related to silicon less than 1:15, the amount of aluminum is insufficient to prevent silicate inclusions from being wetted with metal and relatively slowly removing hydrogen from it. It is characteristic that after three subsequent aluminum deoxidation, these silicate inclusions are partially reduced to lower silicon oxides, which significantly impair both the casting and mechanical properties of the steel. When the ratio of aluminum to silicon is more than 1: 9, dispersed inclusions of corundum are formed in the steel, which have a low rate of emergence. A significant proportion of these inclusions remain in the steel and degrade its mechanical properties, especially plasticity and impact strength. The optimum ratio between aluminum and silicon introduced into the bottom of the ladle before the melting is released is 1: 9-15. In this case, satisfactory deoxidation of the steel is ensured with the formation of a nonmetallic aluminum-manganese-silicate phase which is easily removed from the molten steel. In the process of metal production, aluminum introduced at the bottom of the ladle is relatively quickly consumed for steel deoxidation and after the release of 15–20% metal aluminum, loaded with the first portion, deoxidation and the formation of non-metallic inclusions are consumed by 80–90%. At this moment, the oxidation of the metal sharply increases, and the deoxidation of the metal with silicon develops with the formation of silica inclusions, which deteriorate the properties of the steel. In addition, the introduction of manganese at this point is accompanied by its considerable frenzy. To prevent the formation of silica inclusions during this period of release, a portion of aluminum is introduced into the metal and immediately after the addition of aluminum — ferromanganese. The amount of aluminum introduced before the addition of ferromanganese is 0.8-0.9 of its amount introduced to the bottom of the ladle mixed with ferrosilicon, and corresponds to the aluminum frit from the first batch, which is observed by this time. As a result, conditions favorable for the formation of aluminum-manganese silicate inclusions, relatively easily removed from the melt, are maintained in the metal. By the time of release, 40-50% of the metal is significant, and a part of the introduced aluminum is spent on steel deoxidation. At this point, the last aluminum additive is produced. Its role is to partially deoxidize and alloy the metal; with the last portion, aluminum is introduced in the metal to 0.3-0.4 kg / ton. With the introduction of aluminum less than about 3 kg / t, its increased frenzy and a decrease in the mechanical properties of steel are observed. With the introduction of aluminum more than O, 4 kg / t in the amount of dispersed inclusions of corundum in steel increases. In addition, after sand casting, the metal is rich in saturated lower silicon oxides due to the reduction of silica from the mold to lower silicon oxides contained in the aluminum. Casting properties are deteriorating. PRI me R. In a 60-tonne main open-hearth furnace, steel is produced containing,%: carbon 0.150, 25; manganese 1-1 / 5; silicon 0.20 / b; iron - the rest and impurities. The main slag containing 6-10% manganese oxide is induced in the furnace. The metal is heated to 1640-1650 ° C and deoxidized with silico-manganese in the amount of 9-14 kg / ton. Before the start of the release, the mixture of ferrosilicon is loaded into the ladle at a ratio of aluminum to silicon of 1: 9-15. The ladle with the mixture is heated by a gas burner for 30-60 minutes. In the process of releasing 15–20% of metal (marking by rows of refractory lining), aluminum in the amount of 0, 80, 9 of the amount of aluminum introduced in a mixture with ferrosilicon is introduced under the stream of metal, and then immediately after the addition of aluminum — ferromanganese. The addition of ferrymanganese is completed by the time of release of 40% of the metal. In the process of producing 40-50% of metal, the third portion of aluminum is added to the ladle in the amount of 0.3-0.4 kg / ton.

After melting, the metal is held for 15–20 min and sent for casting.

Specific technological parameters carried out on swimming trunks 1-3 are given in Table. 1, the qualitative characteristics of the metal - in table. 2

Melting 4-5 table. 1, in which the methods of introducing deoxidizing agents and doping agents: correspond to those proposed, but the amount and correlation of their expenses deviate from the proposed oh. As you can see, the deviation of technological

the modes from the proposed ones give the worst results on the phosphorus content, the consumption of ferroalloys and aluminum, the yield of suitable castings and the toughness of steel (Table 2).

As can be seen from the results given in Table 2, the proposed method provides a reduction in the degree of re-phosphorus and a decrease in the phosphorus content of steel by .0.002-0.003%, an increase in the degree of manganese absorption by 15% and, accordingly, a decrease in the consumption of manganese alloys, a decrease in the consumption of aluminum , an increase in the yield of suitable castings due to a decrease in the rejects for hot 1M cracks by 1.9–2.3% and an increase in toughness at 1.5–2 kg / M.

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Claims (2)

ve 1196975 Claim method A method of producing steel for casting into sand forg "l", including the production of metal in the main open-hearth. What is the furnace, its deoxidation in the furnace with silicomanganese in the amount of 9-14 kg / t, the release of metal into the ladle loaded with ferrosilicon, the introduction of aluminum, ferromanganese at the release of 1/51/2 metal, characterized in that crack resistivity and yield, reduction of deoxidizing agent consumption, increase of mechanical properties of steel, reduction of the degree of refosphoria and reduction of phosphorus content in finished steel, introduction of ferrosilicon. 212 dt mixed with aluminum with an aluminum: silicon ratio of 1: 9–15, after the release of 15–20% of the metal, just before the addition of ferromanganese, aluminum is added in the amount of 0.80, 9 from the mixture added with ferrosilicon, and during the release 40-50% of the metal after the addition of ferromanganese is introduced aluminum in the amount of 0.30, 4 kg / t. Sources of information taken into account during the examination 1. Technological instructions for the MMC USSR TTI-54-15-08-77, Dnepropetrovsk. 2. Technological instructions of the Wezhitsky Steel Plant 09.25000.00001. Br nsk, 1978.