SU1497256A1 - Inoculant for cast iron - Google Patents

Abstract

The invention relates to the field of ferrous metallurgy, in particular, to alloys-modifiers used for the production of high-strength nodular cast iron. The purpose of the invention is to increase the crack resistance of high-strength cast iron in a cast state. The modifier contains magnesium, calcium, barium, rare earth metals, zirconium, aluminum, iron, carbon, lithium, silicon in the following ratio of components, wt.%: Magnesium 1.5-4.5

calcium 0.8-5.0

barium 0.1-3.5

rare earth metals 0.5-4.0

zirconium 0.2-10.0

aluminum 0.5-8.0

iron 10.0-27.0

carbon 0.5-5.0

lithium 0,2-2,0

silicon else. Additional input to the lithium modifier when changing the ratio of other components provides a 2-3 times increase in crack resistance of high-strength cast iron in the cast state due to a more uniform distribution of non-metallic inclusions, a decrease in their number and an improvement in the form of graphite. 1 tab.

Description

Invention relates to black

metallurgy,

in particular, to alloy modifiers used for the production of high-strength nodular cast iron.

The purpose of the invention is to increase the crack resistance of high-strength cast iron in a cast state.

This goal is achieved by the fact that a modifier containing magnesium, calcium, barium, rare earth metals, 1C1RKONY, aluminum, iron, carbon, and silicon, additionally contains lithium in the following ratio of tonnes, wt.%:

Magnesium

Calcium

Barium

Rare earth

metals

Zirconium

Aluminum

Iron

Carbon

Lithium

Silicon

1.5-4.5 0.8-5.0 0.1-3.5

0.5-4.0 0.2-10.0 P, 5-8.0 10.0-27.0 0.5-5.0 0.2-2.0 Else Lithium, in the composition of the ms dictater, containing Mai iun i, allows, at a lower consumption of mod |) cyclone, to improve shape, reduce shape and decrease

4 WITH 1C SL

but

3149

number of graphite inclusions. This is due to the fact that lithium, which is a full desulfurizer, releases magnesium and rare-earth metals to affect the shape of graphite. It affects the kinetics of the release and coagulation of non-metallic inclusions, the homogeneity of the structure and the density of the metal, which increases its crack resistance and mechanical properties. When the content is less than 0.2%, the positive effect of lithium is not observed, the content of more than 2% is limited by the method of obtaining the modifier and is impractical due to its inefficient use. Calcium in the modifier helps to obtain high-strength cast iron without black spots, reduces the volume of shrink holes, together with magnesium promotes crystallization of graphite and 1-shaped form. Being a graphitizer, calcium crushes the inclusions of graphite, improving its spherical shape, which contributes to the enhancement of the mechanical properties of the cast iron.

When the calcium content in the modifier is less than 0.8%, the danger of contamination of the pig iron with non-metallic inclusions in the form of black spots appears, as a result of which the plastic properties of the iron and S1py deteriorate significantly (crack resistance increases) low-tech, requiring the use of superheated iron and thinning fluxes to eliminate its slagging,

Bapi-rii is one of the most active graphitizing IX and refining elements. When the content of barium is less than 0.1%, its graphitizing effect is not observed. With an increase in the content of more than 3.5%, barium promotes crystallization of graphite in a metastable system, reducing crack resistance, and worsens the sanitary and hygienic conditions in the foundry. .

Rare-earth metals have a significant spheroidizing effect, actively refining the metal, including neutralizing the antiglobulizing effect of demodifying metals. When the modifier contains less than 0.5% of REM, the deglobuling effect of aluminum is activated. The maximum amount of rare-earth metals (4.0%) makes it possible to stably obtain fully spherical graphite with minimum magnesium in the absence of cementite in the structure of castings.

Zirconium is an element contributing to an increase in the survivability of the modifier and an increase in the amount of ferrite in the structure of a thin-walled chill casting. Zirconium is no less active than calcium and barium, refines cast iron and helps to improve the shape of graphite, especially in cast iron with a low sulfur content. However, the improved zirconium content in the modifier (more than 10%) contributes to the formation of cementite. With a content of less than 0.2%, no positive effect on the properties of the cast iron is observed,

Aluminum is an active graphitizer; however, with its increased content (more than 8%), graphite crystallizes in a lamellar form, especially at a reduced (less than 0.5%) content of rare-earth metals. In addition, an increased porosity and film formation are observed in castings. ) the aluminum content in the ligature is less than 0.5%; its greasy effect is not observed.

The carbon in the cast iron contributes to the formation of the centers of crystallization of graphite, eliminating churning, reducing shrinkage and increasing the flowability of the cast iron, which is important for a thin-walled chill mold with a complex configuration. In addition, carbon, together with silicon, contributes to an increase in the amount of ferrite. When the carbon content is less than 0.5%, nucleation of graphite is ineffective, and at a higher (more than 5.0%) spelle begins to form, deteriorating the properties of cast iron.

The lower limit of magnesium (15%) is determined as a minimum, at which spherical shape is obtained in the structure of cast iron of graphite with a maximum content of calcium, rare-earth metals and zirconium, while the content of magnesium in the amount of 4.5% is 4.5%, high-strength cast iron can be obtained with minimum quantities specified items. An increase in the magnesium content in the modifier of more than 4.5% leads to an increase in the amount of cementite in the iron structure and a decrease in crack resistance.

Iron and silicon are the basic components and their content is established from the condition of modifier smelting technology.

To determine the effect of element. Comrade, the entrance of the modifier into the composition of the modifier conducted comparative studies.

The chemical composition of the tested modifiers and data on the crack resistance of castings are given in the table.

Modifiers 1-5 are proposed compositions, 7 and 6 are compositions that go beyond the limits of the proposed, 8 and 9 are known compositions.

The smelting of the modifier of the proposed composition is carried out in an arc furnace, where, due to the high temperature in the arc zone, the processes of magnesium reduction from magnesite occur. The process is intensified by introducing into the mixture, in addition to magnesite, graphite (coke), flux (fluorspar), FS45 and FS65 ferrosilicon, and ferrosypicocyrcine and FCSO3,

injected magnesium - lithium chips, scrubbed off slag and poured it into metal wires 40-50 mm thick.

GraLitization modification was performed in dispensing buckets weighing 70 kg with ferrosilicon FS75 (consumption 0.2-0.3%) of the fraction 0-5 mm. Poured

10 casting hats of insulators into metal molds. Differential castings of complex configuration, weight of castings is 0.86-5.6 kg.

Modifiers of known and proposed compositions in the amount of 2.0% were treated with cast iron composition, wt.%: 3.3-3.6 carbon, 1.9-2.1 silicon, 0.03-0.05 sulfur, 0.5 -0.7 manganese, up to 0.1 chromium, up to 0.1 phosphorus,

20 The use of modifiers of the proposed composition for the production of high-strength iron makes it possible to increase the crack resistance of responsible castings by 2-3 times.

25

Claims (1)

Invention Formula A modifier for cast iron containing magnesium, calcium, barium, rarely. By adjusting the thermo-time regimes 30, earth metals, zirconium, melts, and by selecting the ratio of the compounds, iron, carbon, and silicon, the weight of the charge mixture can reach a certain level of content in the modifier. magnesium and others characterized in that, in order to increase the crack resistance of high strength cast iron in injected magnesium - lithium chips, scrubbed off slag and poured it into metal wires 40-50 mm thick. GraLitization modification was performed in dispensing buckets weighing 70 kg with ferrosilicon FS75 (consumption 0.2-0.3%) of the fraction 0-5 mm. Poured 0 casting of insulator caps into metal molds. Differential castings of complex configuration, weight of castings is 0.86-5.6 kg. Modifiers of known and proposed compositions in the amount of 2.0% were treated with cast iron composition, wt.%: 3.3-3.6 carbon, 1.9-2.1 silicon, 0.03-0.05 sulfur, 0.5 -0.7 manganese, up to 0.1 chromium, up to 0.1 phosphorus, 0 The use of modifiers of the proposed composition to obtain high-strength cast iron allows a 2-3-fold increase in the crack resistance of responsible castings. Invention Formula A modifier for cast iron containing magnesium, calcium, barium, rare earth metals, zirconium, copper oxide, iron, carbon and silicon, characterized in that, in order to increase the crack resistance of high strength cast iron in items. The REM of the cerium group in the form of the 5th state, it additionally contained FSFORMSO alloy, was introduced into the ladle under the melt stream upon discharge from the arc furnace, changing the mass flow rate of the alloy to saturate the modifier with these elements. The temperature of metal lithium in the following ratio components, wt.%: Magnesium1.5-4.5 Calcium0.8-5.0 40 Barium0,1-3,5 Rare Earth after melting in an electric furnace, it was kept in the range of 1480–1660 ° C for 30–50 min, depending on the composition of the modifier. The total melting time was 60-75 minutes. The melt from the furnace was released into an open bucket, kept until the temperature dropped to 1300-1320 C, condition, it additionally contains is lithium in the following ratio components, wt.%: Magnesium1.5-4.5 Calcium0.8-5.0 Barium0,1-3,5 Rare Earth metals0,5-4,0 Zirconium 0.2-10.0 Aluminum0.5-8.0 Iron10.0-27.0 Carbon 0.5-5.0 Lithium 0,2-2,0 Silicon Rest Table continuation