RU1770436C - Briquette for cast iron modifying - Google Patents

Abstract

The invention can be used in the manufacture of a briquette for modifying cast iron, mainly with an ermicular form of graphite, which is used to produce castings operating under thermocyclic loads. Essence: the briquette contains, mls.%: Magnesium 6-8, graphite 2-5, titanium 4-12, iron 25-35, pulverized waste from the production of ligature FOMg 5 20-35, copper - the rest.

Description

The invention relates to metallurgy, in particular to the modification of cast iron mainly with a vermicular form of graphite used for castings operating under thermocyclic loads.

The purpose of the invention is to increase the heat resistance of cast iron, as well as the degree of absorption of magnesium.

The essence of the invention lies in the fact that the briquette for modifying cast iron, containing magnesium, graphite and iron, additionally contains titanium, copper and pulverized waste from the production of FSMg5 ligature in the following ratio, May%:

Magnesium 6-8

Graphite 2-5

Titanium 4-12

Iron 25-35

Dusty waste from the production of ligatures FSMgB20-35 Copper The rest. The results of comparative tests of briquettes of known and claimed composition are given in table. 1 and table 2. As can be seen from the tables, the use of briquettes of the claimed composition provides, in comparison with the known ones, a higher level of heat resistance of cast iron and the degree of assimilation of magnesium (composition 4-6, 8, 9, 10).

With a decrease in the content of magnesium, graphite, iron, titanium and dusty waste from the production of FSMg5 ligatures in briquettes below the stated limits, the modification efficiency decreases, resulting in a decrease in the temperature resistance of cast iron (composition No. 7, Table 2).

The content of the components in the briquette is justified by the following: magnesium in the range of 6-8 wt.% (Together with titanium and copper) ensures the production of cast iron with vermicular graphite and with high physical and mechanical properties, and also helps to increase the dissolution rate of the briquette. When the magnesium content is below 6% (composition 3) in the core of massive castings, plate-shaped graphite appears, which leads to a decrease in strength

VI

I

With

with

and in viscosity. With a magnesium content of more than 8%, the degree of absorption of magnesium by cast iron decreases, a strong pyroeffect takes place, and the amount of spherical graphite increases in the structure of cast iron, which is accompanied by a decrease in heat conductivity and, accordingly, heat resistance (composition

7).

Graphite in the amount of 2-5 wt.% Provides an improvement in the fillability ™ and the formed ™ briquette during compression, and in liquid iron its particles act as additional centers of graphitization, contributing to the formation of vermicular graphite in the core of massive castings. With a graphite content of less than 2%, such an effect is insignificant, and with an increase of more than 5%, the mechanical strength of the briquette upon modification decreases (composition 7).

Titanium in an amount of 4-12 wt.% Together with magnesium and copper promotes the formation of vermicular graphite. When its content is less than 4, it does not provide uniform vermicular graphite in the structure of cast iron (composition 3), and with an increase in its content more than 12% (N 7) the briquette density decreases and the pyroeffect increases.

Pulverized wastes from the production of FSMGB master alloys within the range of 20-35% reduce the cost and increase the dissolution rate of briquettes, increase the degree of magnesium absorption. With a decrease in the ligature content in the briquette composition below 20% (composition 3), the dissolution rate of the briquettes decreases, and with an increase in excess of 35% (composition 7), the strength and density of the briquettes decrease. They are poorly absorbed by metal.

Iron within the range of 25-35% increases the strength of the briquette and plays the role of a suspension additive, providing an increase in the strength and isotropy of the material of the castings, which has a beneficial effect on heat resistance. A decrease in its content in the briquette below 25% will decrease the inoculating effect (composition 3), and an increase in excess of 35% (composition 7) will reduce the solubility of the briquettes and the absorption of magnesium by cast iron.

Copper in the composition of the briquette acts as a binder and a weighting additive. In addition, it contributes to the production of vermicular graphite and increases the strength of cast iron. A decrease in its content in the briquette below 5% (composition 7) reduces its strength and specific gravity. Deterioration of its absorption by metal. An increase in copper content in excess of 35% (composition 3) reduces the number of modifier elements in the briquette and does not provide a high level of heat resistance.

EXAMPLE In the induction furnace IChT-b, cast iron of the following composition is smelted (May.%): C - 3.41; Si 2.24; P - 0.17; S is 0.03. Before the metal is released, briquettes are introduced to the bottom of the bucket in an amount of 1.8% by weight

metal of the following composition (wt.%): magnesium - 7; graphite - 3.5; iron - 30; dusty waste from the production of FSMg5 ligature - 27.5; titanium - 8; the rest is copper. The temperature of the produced metal is 1420 ° C. After completion of the process of dissolving the briquettes, slag is downloaded from the metal surface, samples are taken to determine the composition and properties of the metal, and molds of chill molds for rolling rolls are poured. results

studies of the composition, structure and properties of modified cast iron are given in table. 2. The use of a briquette of the claimed composition provides an increase in the heat resistance of cast iron by 24-29% and the degree of assimilation of magnesium by 27-32%. In the case of casting chill molds for rolling rolls, this will provide an increase in their durability, a decrease in metal consumption and an improvement in the quality of the rolls.

The economic effect of using a briquette of the claimed composition to produce chill molds for rolling rolls will amount to 592 thousand rubles.

Formula A from Breteni

Cast iron briquette,

containing magnesium, graphite and iron, characterized in that, in order to increase the heat resistance of cast iron, the degree of absorption of magnesium, it further comprises titanium,

copper and pulverized waste production of the FSM g5 ligature in the following ratio of components, wt.%:

Magnesium 6-8

Graphite. 2-5

Titanium 4-12

Iron 25-35

Dusty wastes from the production of FSM master alloy g520-35

Copper The rest.

Table 1

The compositions of the investigated briquettes

- briquette-analogue (A.S. I, 11); briquette prototype (a.s. f. t6l124).

Benchmark Results

- briquette / analogue (A. s. K 1YU9M2); - briquette prototype (a, p. tf 461124); ) - briquette of the claimed composition

- iron-silicon-magnesium-Calcium ligature;

Table 2