RU2704678C1 - Method of cast iron modifying and modifier for implementation of method - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to metallurgy and foundry production and can be used for production of modified cast iron for manufacture of high-wear parts of machines. Proposed method comprises production of cast iron melt, overflow of melt into ladle and introduction of modifier into ladle. Modifier used is a product obtained by flotation of dust of gas-cleaning structures of furnaces of technical silicon and/or ferrosilicon and consisting of carbon of nanosize value in amount of 91–95 wt% and impurities of 5–9 wt%, which is introduced into ladle in form of tablets in amount of 0.20–0.50 wt% of cast iron weight.EFFECT: invention increases strength of cast iron and increases service life of cast iron articles.3 cl, 1 tbl

Description

Technical field

The invention relates to metallurgy and foundry, and can be used to produce modified cast iron, which is used for the manufacture of wearing parts of machines.

State of the art

For foundry needs, cast iron is obtained in induction furnaces, while carbon in cast iron can be in various forms, which have a significant impact on the quality characteristics of cast iron products. The ductile shape of graphite reduces the strength of cast iron. Higher strength are cast iron with spherical or fibrous forms of graphite. These cast iron structures are achieved using various modifiers that change the shape of graphite, which leads to a significant increase in the strength characteristics of cast iron products.

A known method of modifying cast iron with spherical graphite (RF patent 2500824, С22С 1/10, published December 10, 2013), including filling the coating material in the form of Barrier-200 fluxerlite powder on a cast iron mirror and introducing a solid modifier into the cast iron melt in the form of a solid cerium-magnesium-nickel additive, loading a layer of coating material onto the melt mirror and holding it until a dense viscous layer is formed, filling the second layer of coating material and introducing a solid modifier into the melt, followed by filling the injection site ryachim cover material, wherein the solid cerium-magnesium-nickel dopant in an amount of 0.8-1.2% by weight of modified iron lead to iron for 5 seconds. The disadvantage of this method is the reduced quality of castings due to the uneven distribution of the modifier over the volume of the melt and the ingress of non-metallic inclusions from fragments of the covering material into the castings.

A known method of modifying cast iron (RF patent 2422546, C22C 37/04, C21C 1/10, publ. 06/27/2011), including the treatment of molten cast iron in the ladle with a solid modifier and filling on the mirror of cast iron coating material, where as a coating material is used fluxerlite powder "Barrier-200", in an amount of 0.4% by weight of cast iron, and as a solid modifier, crushed cerium additive containing 20-90% cerium, in an amount of 0.1-0.35% by weight of cast iron, and magnesium-containing ligature containing 4-8% magnesium in an amount of 1.5% by weight of cast iron. The disadvantage of this method is the uneven distribution of solid alloyed additives.

A known method of producing high-strength cast iron with spherical form of graphite from the source (patent RF 2586730, C21C 1/00, C22C 37/04, publ. March 25, 2015), including the melting of the mixture to the melting temperature, analysis of the sulfur content in the melt, subsequent modification in the ladle with a ligature containing rare-earth metals and a magnesium-containing modifier, the modification is carried out at a sulfur content of 0.01-0.50% with overheating of the melt to 1480-1520 ° C, while the above-mentioned modifier and ligature are placed on the bottom of the bucket, heated to 750-800 ° C, layer by layer in VI e modifier layer, dusting powder in the form of magnetically slag, a subsequent ligature layer and a final powdering layer in the form of crushed cast iron with slag-forming additives, while the bucket is filled with melt in a period of 1 to 1.50 min, after which the modified cast iron is held for 8 -9 minutes The disadvantage of this method is the insufficiently effective effect of the modifier due to the duration of the exposure of the modifier to the melt, which leads to the loss of the modifier.

There is a method of modifying cast iron melt with a complex modifier (RF patent 2588965, С21С 1/10, С22С 37/04, publ. 07/10/2016), in the form of gas purification dust of electrothermal silicon production, containing components in the following ratio, wt. %: SiO ₂ 75 ÷ 95, SiC 4.0 ÷ 41.0, С _free 3.0 ÷ 7.0, MgO 0.4 ÷ 1.2, Al ₂ O ₃ 0.5 ÷ 1.0, Fe ₂ O ₃ 0.3 ÷ 0.9, CaO 1.0 ÷ 2.0, other 0.8 ÷ 2.3, while the mass of the modifier sent for modification is maintained within 0.05 ÷ 0.1% of the mass melt.

By technical nature, by the presence of common features, this technical solution was adopted as the closest analogue.

The disadvantage of this method is the insufficiently high quality of cast iron due to the significant amount of non-metallic impurities introduced with a modifier in the form of refractory oxides of magnesium, aluminum and calcium.

SUMMARY OF THE INVENTION

The basis of the invention is a task aimed at improving the consumer properties of cast iron.

The technical result is to increase the strength of cast iron, which increases the service life of cast iron products.

The technical result is achieved due to the fact that in the method of producing pig iron modification, including cast iron melt, pouring the melt into the ladle and introducing a modifier into the ladle, it is new that the product obtained by flotation of dust from gas treatment plants of technical silicon furnaces and / or ferrosilicon and consisting of carbon nanoscale in an amount of 91-95 wt. % and impurities 5-9 wt. %, which is introduced into the bucket in the form of tablets in an amount of 0.20-0.50 wt. % by weight of cast iron.

The technical result is also achieved due to the fact that the modifier obtained by flotation of dust from gas treatment facilities of technical silicon and / or ferrosilicon furnaces is used and consists of nanosized carbon in the amount of 91-95 wt. % and impurities 5-9 wt. %

The invention is illustrated by an additional clarifying feature. So the modifier contains impurities in the form of fine oxides of aluminum, silicon, titanium, magnesium and silicon carbide.

The implementation of the method

Cast iron is smelted in an induction furnace, the melting volume was 240 kg. The modifier, for example, in the form of tablets, is loaded into a ladle and poured with molten cast iron, aging is carried out and samples are taken to determine the qualitative characteristics of the obtained modified cast iron. Several melts were carried out with different amounts of modifier, and the effect of the modifier on the mechanical properties of gray cast iron grades СЧ 10 - СЧ15 was evaluated.

The evaluation of the modifier showed a significant increase in the mechanical properties of gray cast iron of the grade СЧ10-СЧ15 to the level of the grade СЧ30-СЧ35. In modified samples, carbon of nanosized quantities retains its shape, which determines the increase in the strength of cast iron. Table 1 shows the modifier test results.

 Studies of the samples showed that the modifier, consisting of carbon nanoscale quantities, conducted in cast iron in an amount of 0.20-0.55 wt. % by weight of cast iron (examples 2-6), increases the mechanical strength of cast iron. With the introduction of the modifier in an amount of less than 0.20 wt. % and more than 0.5 wt. % by weight of cast iron slightly increase the mechanical properties of cast iron. Optimum for improving the mechanical properties of cast iron is the amount of modifier 0.20-0.50 wt. % by weight of cast iron.

Claims (3)

1. A method of producing modified cast iron, including producing a molten cast iron, pouring the melt into a ladle and introducing a modifier into the ladle, characterized in that the product obtained by flotation of dust from gas treatment plants of technical silicon and / or ferrosilicon and consisting of nanosized carbon is used as a modifier in an amount of 91-95 wt.% and impurities 5-9 wt.%, which is introduced into the bucket in the form of tablets in an amount of 0.20-0.50 wt.% by weight of cast iron. 2. Modifier for cast iron containing nanosized carbon and impurities, characterized in that it is obtained by flotation of dust from gas treatment plants of technical silicon and / or ferrosilicon furnaces and consists of nanosized carbon in an amount of 91-95 wt.% And impurities 5-9 wt. .%. 3. The modifier according to claim 2, characterized in that it contains impurities in the form of finely dispersed oxides of aluminum, silicon, titanium, magnesium and silicon carbide.