SU1731853A1 - Modifying mixture for producing high-strength foundry iron - Google Patents

Abstract

The invention relates to foundry, in particular, to mixtures for producing high-strength cast iron. Essence: the modifying mixture containing magnesium alloy with zinc and aluminum and ferrosilicate also contains ferrosilicon in the following ratio of components, wt%: magnesium alloy 15-25; ferrosilicobarium 5-10; ferrosilicon stop Magnesium alloy additionally contains rare-earth metals and chlorides of alkali and alkaline earth metals, and as such an alloy they use remelting of machining and foundry production of magnesium-containing alloys in the following ratio of components, wt.%: Aluminum 2-10; zinc 0.1-0.8; REM 4,5-6; chlorides of alkali and alkaline earth metals 3-5; magnesium stop The use of this mixture makes it possible to improve the filling of the molds and reduce the waste during the chill casting of 1 hp. f-ly, 1 tabl,

Description

The invention relates to foundry, in particular, to mixtures for producing high-strength cast iron.

Known modifying mixtures containing magnesium component and ferrosilicobarium.

A disadvantage of the known mixture is the unsatisfactory filling of the molds and the consequent increased scrap rate of the castings during chill casting due to the low fluidity of the iron treated with the known mixture.

Closest to the invention is a modifying mixture for producing high-strength cast iron containing 10-50% by weight of silicobar; the rest is shavings of magnesium alloy, while shavings of magnesium alloy also contain aluminum and zinc.

However, the cast iron treated with the known mixture, which has a low fluidity, does not fill the mold well enough, especially when producing thin-walled chill castings. In connection with this, there is an increased spoilage of such castings, in particular, in spas and underfilling.

The disadvantages of the known mixture are also the unsatisfactory filling of the molds and the increased scrap rate of the castings during the chill casting.

The purpose of the invention is to eliminate these drawbacks, to improve the mold filling capacity and to reduce the cast iron castings.

This goal is achieved due to the fact that the modifying mixture to produce high-strength cast iron containing magnesium alloy with zinc and aluminum and

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ferrosiliconium, additionally contains ferrosilicon in the following ratio, wt.%: magnesium alloy 15-25; ferrosilicobarium 5-10; ferrosilicon is the rest, while the magnesium alloy additionally contains REM and chlorides of alkali and alkaline earth metals, and as such an alloy, remelting of the waste from the processing and foundry production of magnesium-containing alloys in the following ratio, wt.%: aluminum, 2.0- 10.0; zincO, 1-0.8; RZM4.5-6.0; alkali and alkaline earth metal chlorides 3.0-5.0; magnesium else.

The introduction of a modifying mixture of a complex containing ferrosilicon, rare-earth metals, alkali metal chlorides and alkali metals (the last two components in the magnesium alloy composition) in combination with aluminum makes it possible to improve mold filling during the chill casting process by increasing the fluidity of cast iron and reduce the waste of castings spa m and underfill.

The introduction of rare-earth metals and alkali metal chlorides and alkali metals in the magnesium alloy composition and the use of waste from the machining and foundry production of magnesium-containing alloys as such an alloy can improve the mold filling capacity and reduce scrap and underfilling scrap during the chill casting by increasing the modifying effect of the mixture to the melt associated with a significant decrease in the oxidation of the metal components of the mixture.

The use of waste from the machining and foundry production of magnesium-containing alloys makes it possible to utilize the waste and thereby significantly reduce the cost of the modifying mixture.

A decrease in the content in the modifying mixture of a magnesium alloy (less than 15 wt.%) Leads to a deterioration in the shape of graphite in the iron due to insufficient magnesium content in whom.

Increasing the magnesium alloy content in the modifying mixture (more than 25 wt.%) When producing castings in a chill mold is not economically justified and leads, moreover, to the appearance of structurally free carbides, reduced casting of cast iron and increased casting by spam and underpouring, possibly also cracking in castings.

A decrease in the content of ferrosilicobari in the modifying mixture (less than 5 wt.%) Leads to a decrease in the fluidity of cast iron, worsening the filling of molds.

and, consequently, an increase in the marriage of castings for spas and underfilling.

Increasing the content of ferrosilicobar in the modifying mixture (more than 10

wt.%) does not lead to a further increase in the fluidity of cast iron, reducing the marriage of castings, but increases the cost of the modifying mixture,

Reducing the aluminum content in magnesium alloy, which is used as a remelting of machining waste and foundry production of magnesium-containing alloys (less than 2 May.%), Leads to a deterioration of the fluidity of cast iron, deterioration of mold during chill casting and increased castings.

Increasing the aluminum content in the magnesium alloy, which is used as a remelting of machining waste and

foundry production of magnesium-containing alloys (more than 10 wt.%), leads to a deterioration of the shape of graphite in the iron due to de-globulization, to a decrease in the mechanical characteristics of the iron and to an increase in

marriage castings.

The limits of the zinc content are determined by the raw materials and the technology for the remelting of waste from mechanical processing and foundry.

magnesium alloys.

A decrease in the content of rare-earth metals in magnesium alloy below the lower limit (less than 4.5 May%) leads to a decrease in the fluidity of cast iron, deterioration in filling capacity.

forms and, consequently, to an increase in the marriage of castings in the spa and underfilling.

Increasing the content of rare-earth metals in magnesium alloy, which is used as a remelting of waste from the machining and foundry production of magnesium-containing alloys (more than 6.0 wt.%), Leads to some deterioration in the filling of forms and is not economically justified.

Reducing the content of chlorine alkaline earth metals

and alkali metals in magnesium alloy less than the lower limit (less than 3.0 wt.%) causes a decrease in the fluidity of cast iron, deterioration of mold filling capacity and, as a consequence, an increase in casting loss in spam and

underfill.

Increasing the content of alkali metal chlorides and alkali metals in magnesium alloy, which is used as a remelting of machining and foundry waste

the production of magnesium-containing alloys, (more than 5.0 wt.%), leads to an increased release of harmful substances into the atmosphere during the processing of cast iron, causes deterioration

working conditions.

PRI me R. Under the conditions of the foundry, a comparative evaluation of the effectiveness of the proposed and known modifying mixtures is carried out.

In a laboratory mixer, modifying mixtures are produced, which include in the manufacture of the proposed mixture - remelting of machining waste and foundry production of magnesium-containing alloys, containing, in wt.%: AI 2-10; Zn 0.1-0.8; Nd (P3M) 4.5-6.0; Na, K, Md, Ca chlorides 3.0-5.0; Md the rest, ferrosilicobarium brand FSB-15; ferrosilicon brand FS75, in the manufacture of a mixture by a known method; shavings of magnesium alloy ML5; ferrosilicobarium brand FSB-15.

These components (except chips) were crushed to particles up to 20 mm in size and stirred in a laboratory mixer with a capacity of 30 liters for 15 minutes.

The table shows the composition of the modifying mixtures and their amount with the introduction of the melt.

The original cast iron of chemical composition, wt.%: C 3.4-3.5; Si 2.1-2.2; Mp 0.5-0.6; S to 0.04; F up to 0.08, is produced at an industrial frequency ICTT 2.5 in an induction furnace, is discharged into a 250 kg bucket and treated in an autoclave chamber of the proposed and known modifying mixtures. The duration of mixing of the cast iron with the modifying mixture in all cases is 90 s, the air pressure in the autoclave is 0.48 MPa. Modifying the mixture according to a known method was introduced in an amount equal to the proposed (1.3 wt.%), And also in the amount of 0.6 wt.%.

After the completion of the cast iron treatment in an autoclave and slag removal, a U-shaped Nehacdi-Samarin chill sample was poured with the melt to determine the filling with a U-shaped channel of 9 mm. filling temperature 1400 ° C. Then cast iron

at 1320-1280 ° C, the chill castings of the current production of the slider are poured, the piston with a minimum wall thickness of 12 mm.

Chill Form Filling

casting is estimated by the length of the metal-filled U-shaped channel of the described sample, the data are given in the table.

Record also the number of castings defective in spas and underfilling, cast in each variant.

From the data in the table shows that the use of the proposed modifying mixture with the proposed

the contents of the components provides a significant improvement in the mold filling capacity and a significant reduction in the rejection of castings during the chill casting.

Claims (2)

1. A modifying mixture to produce high-strength cast iron containing magnesium alloy with zinc and aluminum and ferrosilicobarium, characterized in that, in order to improve filling the molds and reducing scrap castings during the chill casting, the mixture additionally contains ferrosilicon in the following ratio, wt.%; magnesium alloy 15-25; ferrosilicobarium 5-10; ferrosilicon the rest, while the magnesium alloy additionally contains rare-earth metals and chlorides of alkali and alkaline earth metals in the following ratio of components, wt.%: aluminum 2.0-10.0; zinc 0.1-0.8; RZM 4.5-6.0; alkali and alkaline earth metal chlorides 3.0-5.0; magnesium else. 2. A mixture according to claim 1, characterized in that the remelting of the waste of machining and foundry production of magnesium-containing alloys is used as a magnesium alloy.