SU1715854A1 - Modifier for cast iron - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular to materials for modifying and slagging during the smelting of pig iron. The purpose of the invention is to reduce the build-up and increase the modifying efficiency. The modifier for cast iron in the form of a briquette contains, wt%: metal-silicon waste from the production of synthetic cast iron of the following composition, wt%: metallic silicon 15 20, silicon carbide silicon dioxide 1-3; carbon (free) 15–26, iron (metallic) balance, in quantity and binder in the form of a mixture of 10–20% sodium aluminate and 80–90% ground silicate alkaline glass. The use of a modifier makes it possible to increase the tensile strength in cast iron by 5–10%, the yield strength by 2–6% and increase the hardness, and cast iron 10–15%, as well as reduce the cost of modification. 2 tab.

Description

The invention relates to ferrous metallurgy, in particular to materials for modifying and slagging during the smelting of pig iron.

The composition of modifiers used in the foundry industry, based on silicon and its compounds, is known. However, they are not sufficiently effective in removing pig iron castings and are relatively expensive. . . .

The closest in technical essence and the achieved result to the proposed is modifying with ferrosilicon. However, the degree of silicon doped from ferrosilicon during smelting of cast iron does not exceed 70-75%, which is not economically feasible. Therefore use as

 modifier of expensive and scarce electric furnace ferrosilicon leads to an increase in the cost of pig iron.

The aim of the invention is to reduce the cost and increase the efficiency of the modification.

The goal is achieved

We can say that metal-silicon waste from synthetic foundry production is used in the modifier briquette.

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of pig iron and binder in the following ratio of components, wt.%: Metal-silicon waste from the production of synthetic cast iron88-95

Binding15-20

Chemical composition of metal-silicon waste: Siwer 15-20%; SiC 3-7%; SiOz 1-3%; CC606 15-20%; Femer rest. The binder contains: sodium aluminate (NaA102) 10-20%; ground silicate alkaline glass 80-91%.

Sodium aluminate (NaAlO) and ground silicate alkaline glass containing, in wt.%: SiO 71.2-72; CaO 6.8- 9.1; 13.8-15.2; MgO 3.15-4.0;

Metal-silicon waste form- 15 A1G03P, 91-1.9; Reg05 0.08-0.15, vys in the smelting of synthetic casting iron due to the difference in the specific weights of lump ferrosilicon (when it is added to the ditch) and liquid iron. At the same time, the low specific surface of pieces of ferrosilicon leads to an elongation of the process of its dissolution and reduces the efficiency of its use despite the use of such complex mechanical means as agitators, partition walls and other

When applying ferrosilicon to a ditch in a cast-iron ladle on the surface. molten iron, a refractory crust is formed, consisting of entangled iron, undissolved ferrosilicon, graphite, etc., which is metallocryous waste from the production of synthetic cast iron, which is proposed to be used. , -2.0% of the weight of smelted synthetic cast iron. Further, the metal-silt waste is sent to the slag heap and is not used anywhere else.

- The use of metal-silicon waste in the composition of a briquette with a slag-forming modifying mixture makes it possible to expand the metallurgical capabilities of smelting iron due to the presence of carbon and silicon compounds in the form of silicon carbide. The positive effect is achieved by the fact that silicon and its compounds in the composition of metal-silicon waste affect not only the crystallization kinetics of graphite, but also primary austenite, and also contribute to the formation of thin and disconnected austenite dendrites. Silicon carbide readily decomposes during and after hardening. 71585 1

devani (so-called self-annealing), which can lead to the formation of nodular graphite.

The carbon dioxide (free) in the metal-silicon waste also contributes to the formation of the microstructure of cast iron and can help to eliminate chill off without much influence on the mechanical properties of cast iron,

Sodium aluminate (NaAlO) and ground silicate alkaline glass containing, in wt.%: SiO 71,2-72; CaO 6.8- 9.1; 13.8-15.2; MgO 3.15-4.0;

- 15 A1G03P, 91-1.9; Reg05 0.08-0.15, you 0

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five

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five

Complete binder function. In addition, silicon dioxide contained in silicate alkaline glass, as additional centers of crystallization, contributes to the refinement of the cast iron structure, and the oxides of alkali and alkaline earth metals contribute to a significant liquefaction of slag.

The number of components of the modifier (metal-silicon waste material, waste) is taken in such a way that not only good mechanical properties of produced iron are obtained, but also sufficient strength of the modifying briquettes. When the amount of binder is reduced to less than 15%, the strength of the briquette decreases sharply, the modifying effect and, consequently, the mechanical properties of cast iron deteriorate. As the amount of binder increases by more than 20%, the strength of the briquette remains the same, but the modifying effect and, consequently, the mechanical properties of the cast iron deteriorate.

In turn, the binder containing less than 15% and more than 90% of ground silicate alkaline glass does not perform its basic functions — the strength of the modifier briquettes decreases.

The rational temperatures at which the modifier should be introduced are determined by the equilibrium temperature of the carbon reduction reaction of silicon. The proposed briquette is introduced at temperatures lower than the equilibrium temperature for a given iron. At the same time, silicon modifier is actively oxidized, whose oxides are additional centers of graphitization, along with the existing silica modifier.

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Yulia iron has the following chemicals: C 2,910.2%; Si 1.75 Mn 0.6 + 0.08%; P 0.07 + 0.0 10.006%. Once manufactured, they were subjected to a compression test. Strength on luy by quantity sbras cell. m on the cast iron plate or briquette

The briquettes and FS-75 were filled in with metal 1 at C. The effect of modif was evaluated by the size of the novoid sample of size (poured into a mold from a mixture of metal

In order to determine the liquid iron, it is poured by spiraling 6x6 mm into the mold from the mixture. Volumetric shrinkage of the conical sample and the calculation of the mule:

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The consumption of briquettes is determined based on a given increase in the silicon content in the iron in an amount of 0.8-2.0% of the weight of the charge loaded. When the modifier is supplied less than 0.8% of the weight of the charge, an uneven distribution of silicon and its compound occurs; In pig iron due to the small amount of modified briquette, an increase in briquette consumption of more than 2.0% of the weight of the charge is impractical because it leads to an increase in the carbon content in the iron.

Castings modified with briquette-J5, have a fine-grained fracture, uniform and uniform throughout the section.

In contrast to modifying pig iron with ferrosilicon, where the amount of 20 ferrite in a metal matrix is 5-10% - modifying the proposed modifier reduces the amount of ferrite to 3-6% while increasing the dispersion of perlite.

The absorption of silicon by melt using the proposed briquettes is: when smelted in a cupola when smelted into an induction shell, the C-A-PE chita is shown in Table 1, ch5-60%; when added to the variety

military bucket

Briquette is made as follows.

The metal-silicon waste was crushed to a fraction of less than 5 mm and cleaned from graphite sang by air separation or another method. A binder is prepared, for which alkali silicate glass is crushed to a specific surface of 3000-5000 cm2 / g, dissolved in an aqueous solution of sodium aluminate. The binder is mixed thoroughly with crushed metal-silicon waste. Then, the mixture prepared in this way is used to form articles and heat treat them in an autoclave at a pressure of Qtk 1.6 MPa at 2 + 6 + 3 hours. Briquettes are made with a diameter of 100 mm and a height of 50 mm.

Studies on the modification of cast iron with briquettes of slag-forming modifying mixtures have shown that they are able to prevent churning and ensure uniformity of the structure and properties of cast iron.

PRI me R. In an induction crucible furnace of type IST-0, About melted Composition, mechanical

35

40

45

50

55

As can be seen from table 1, the properties have brik which have a large pr

The effect of modifying is determined by the strength and hardness of the cast iron, the rolling distribution of the casting, and the samples are cast in steps of thickness kO, 60 mm. Fluid and shrinkage (VOTH) are also determined for the smelted.

, Chemical composition, fur properties, fluidity of melted pig iron in the table ...

As can be seen from Table 2, the properties obtained using 3, b, 5 also possess properties. These cast irons, modified with cast irons, possess insignificant shrinkage with the best m properties (greater tensile strength, great hardness throughout of the sample), a larger flowable less content harmful.

There are cast iron of the following chemical composition: C 2,910.2%; Si 1,; 1%; Mn 0.6 + 0.08%; P 0.07 + 0.005%; S 0.041 / 10.006%. After making the briquettes, they were subjected to impact and compression tests. Shock resistance is determined by the number of drops from a height. m on the cast-iron plate to the destruction of the briquette.

Briquettes and FS-75 are introduced into the bucket after filling 1/5 of their volume with metal at C. The effect of modification is assessed by chipping off a wedge-shaped sample of 110x50x20 mm (cast into a mold from a core mixture with a metal plate).

To determine the fluidity of the cast iron, a spiral sample with a cross section of 6x6 mm is poured into the core mixture. Volumetric shrinkage is estimated by the conical sample and calculated by the formula:

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The composition, mechanical properties of briCheta keta are given in Table 1, d

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40

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As can be seen from table 1, the best, properties have briquettes 3,, 5, which have greater strength.

The effect of the modification is further determined by the tensile strength and hardness of the iron. For control distribution of hardness over the cross section of the casting, step samples with steps of 10, 20, kO, 60 mm thick are poured. For molten iron, the fluidity () and shrinkage (VOTH) are also determined.

The chemical composition, mechanical properties, fluidity and shrinkage of melted iron are given in Table ...

As can be seen from Table 2, cast iron obtained using briquettes 3, b, 5 also possess the best properties. These cast iron, compared to cast iron, modified with PS-75, with slightly greater volumetric shrinkage, have better mechanical properties (high tensile strength, more uniform hardness over the entire cross section of the sample), greater fluidity and a lower content of harmful phosphorus.

The technical and economic effect of using the proposed invention is to replace expensive and scarce modifiers with a cheaper briquette of a slag-forming modifying mixture, to improve the modifying effect and will be from 4 to 6 rubles. per 1 ton of pig iron produced.

Formula. And gain

Modifier for cast iron, containing metal-silicon waste from the production of synthetic cast iron of the following composition, wt.%: SiweT 15-20, SiC

3-7, SiC 1-3, Cteo6 15-26, Pe, the rest, characterized in that, in order to reduce the cost and increase the efficiency of the modification, it additionally contains a binder in the form of a mixture of 10-20% sodium aluminate and 80 -90% ground silicate alkaline glass in the following ratio of components, wt.%: Metal-silicon waste from the production of synthetic iron 80-85 Binding 15-20

Table z

Claims (2)

Claim Modifier for cast iron containing metal-silicon waste from the production of synthetic cast iron of the following composition, wt.%: Si _weT 15-20, SiC 3 7, SiO ^ 1 3, C _teo6 15 26, Fe else, characterized in that, in order to reduce the cost of ₅ and increase the efficiency of the modification, it additionally contains a binder in the form of a mixture of 10-20% sodium aluminate and 80-90 % of ground silicate alkaline glass with the following ratio of components, wt.%: Silicon-metal waste from the production of synthetic 5 cast iron 80-85 Binder 15-20 Table! Briquette The composition of the briquette, wt.% Briquette strength Siliceous waste Acting per stroke, number of drops to failure compression MPa sodium aluminate silicate alkaline glass All- go FS-75 - - - - - - 1 79 fifteen 85 21 4 21, 5 2 80 9 91 20 3 13.7 3 ‘80 10 90 20 4 20,4 4 82 fifteen 85 18 5 24.9 5 85 20 80 fifteen 4 21.9 6 85 21 79 fifteen 3 15.9 7 86 fifteen 85 14 2 9.3 table 2 Cast iron .......... The chemical composition, wt.% | Mechanical properties Fluid Flow (¾). many Shrinkage FROM Si Mp R S Strength, MPa HB. units 10 | 20 | 40 | 60 The original unmodified ny 2.9 1.75 0.6 0,065 0.04 Modifi- cited shaved ketos ♦ S-75 2.95 1.80 0.6 0,065 0.04 1 2.95 1.82 0.6 0,069 0.04 2 2.95 1.81 0.6 0,070 0.04 3 2.95 1.82 0.6 0,064 0.04 4 2.96 1, 82 0.6 oh review 0.04 5 2.96 1.82 0.6 0,063 0.04 6 2.94 1.80 0.6 0, Ob7 0.04 7 2.93 1.78 0.6 0,068 0.04 205 364 286 241 187 600 235 305 266 228 207 600 5.7 230 318 281 235 220 605 5.9 220 309 270 240 205 615 5.9 245 298 278 247 215 615 5.9 242 296 270 241 210 620 6.0 240 295 272 242 212 620 5.9 220 321 278 243 204 620 5.9 215 330 282 240 201 615 6.0