SU1308630A1 - Mixture for inoculating cast iron - Google Patents

Abstract

The invention relates to metallurgy, in particular, to modifier compositions for the production of cast iron, mainly with lamellar graphite. The purpose of the invention is to increase the strength and uniformity of the properties of cast iron in thick-walled and differential castings. The mixture for modifying cast iron comprises, in wt.%: High carbon ferrochrome 12-20; telurist antimony 0.05-0.10; a ligature with rare-earth metals on iron-silicon base 65-75 and ferromanganese high angle the rest. The mixture provides an increase in tensile strength by 10-14% and uniformity of the structure and hardness of cast iron over the cross section of differential and thick-walled castings more than 4.0 times. 2 tab. SS (L

Description

The invention relates to metallurgy, in particular, to modifier compositions for the production of cast iron, mainly with lamellar graphite.

The purpose of the invention is to increase the strength and uniformity of the properties of cast iron in thick-walled, and differential, castings.

Mixture for modifying cast iron

neck centers for the crystallization of graphite, which reduces the likelihood of structural-free cementite and increases the uniformity of the properties of cast iron,

In the composition of the mixture, high-carbon ferrochrome is used in pieces of T-4 mm in size, and high-carbon ferromanganese in pieces of 1-4 mm in size.

contains high carbon ferrochrome O antimony tellurium in the form of a compound

and ferromanganese, tellurium antimony and a ligature with rare-earth metals on an iron-silicon base in the following ratio of components, masd:

Sbje

15

High carbon ferrochrome

Tellurium antimony

Ligature with rare earth metals on iron-silicon basis.

Ferromanganese high carbon

12-20

65-75

Rest

25

thirty

The introduction of the mixture of antimony to telluric in the form of Sb Te compounds increases the strength and uniformity of the properties of cast iron in thick-walled and differential castings, since antimony and tellurium contribute to the perliteration of the metal base in thick

It prevents the formation of carbides, especially chromium, in thin sections of the casting, and tellurium contributes to the grinding of the eutectic grain.

The introduction of a mixture of ligatures 40 with rare-earth metals on an iron-silicon base not only provides a high degree of graphitization of cast iron, but also contributes to improving the shape, size and distribution of graphite 45 in a metal base and, as a consequence, to increase the strength and uniformity of the properties of cast iron in castings.

Use in the proposed composition of a mixture of high-carbon ferrochrome and ferromanganese with a content of 8 and 7% carbon, respectively, increases the graphitizing ability of the mixture and contributes to the grinding of graphite inclusions, since carbon of ferrochrome and ferromanganese is introduced into the molten cast iron melt. germination of the powder with particles less than 0.5 mm in size, a ligature with rare-earth metals on an iron-silicon base in pieces of 1-4 mm in size.

The mixture for modifying the cast iron is prepared by weighing the calculated doses of the components in accordance with the proposed quantitative ratio and depending on the mass of 0.05-0.120 modified metal.

The effectiveness of the mixture is revealed on cast iron containing,%: C, 2.95-3.06; Si 1.60-1.72; No. 0.50- 0.52; S 0,02-0,03, smelted in an acidic induction furnace and heated to 1450 ± 10 С, and then chilled

before ,

The components of the mixture for modification are introduced into the ladle in an amount of 0.15% of the mass of liquid iron. Pos. Leaves and slag removal pour molds to obtain samples and process samples.

In tab. 1 shows the compositions

35 proposed and known mixtures for the modification of cast iron.

In tab. Figure 2 shows the effect of these mixtures on the properties of modified cast iron.

40 The modifying effect of the proposed and well-known composition of the mixture is estimated by the value of chipping the sample with a size of 6565-12 mm, poured into a rod form with a 1-metal plate; largest tensile strength G samples cut from cylindrical billets with a diameter of 30 mm and a length of 280 mm; the fluctuation of hardness HB, the cross-sectional speed

 samples with steps of 4080120 mm thick and on the microstructure of thin sections prepared from samples after testing mechanical properties.

55 Strength and hardness tests, as well as microstructure studies, are carried out by standard methods.

From the table. 2, the test results show that optimum centers for the crystallization of graphite, which reduces the likelihood of structurally free cementite, and improves the uniformity of the properties of cast iron,

In the composition of the mixture, high-carbon ferrochrome is used in pieces of T-4 mm in size, and high-carbon ferromanganese in pieces of 1-4 mm in size.

Sbje

rum mene land

55 Strength and hardness tests, as well as microstructure studies, are carried out by standard methods.

From the table. 2 test results imply that the optimum mass fraction of high-carbon ferrochrome and ferromanganese, tellurium tellurium and ligatures with rare earth metals on an iron-silicon base B composition of the mixture is 5, respectively, in the range,%: 12-20, 9-16; 0.05-0.10 and 65-75 (compositions 1-3).

The introduction of high carbon ferrochrome in an amount of 12–20% increases the strength and uniformity (isotropy) of the properties of modified cast iron over the cross section of castings by introducing chromium and simultaneously contributes to the graphitization of cast iron by introducing carbon, which serves as additional centers of graphite crystallization.

When reducing the content of high-carbon ferrochrome in the composition of the modifier (composition 4), the strength characteristics of the modified cast iron deteriorate, and the variation of the hardness values in the casting walls of the differential castings differing in thickness varies.

due to

15

20

deterioration of the microstructure, a lesser degree of perlitization of metal, base, enlargement of the eutectic grain.

With an increase in the content of antimony tellurium in the composition of the mixture (composition 7), the strength of cast iron and the uniformity of hardness indicators over the cross section of the casting are given due to the appearance in the structure of carbides and the release of structural components, their unfavorable form, in particular, anomalous forms of graphite and a broken grid along the boundaries of eutectic grains.

A ligature with rare-earth metals on an iron-silicon base is introduced into the mixture in the range of 65-75%, which provides an increase in the modifying effect, strength and uniformity of the properties of cast iron in differential castings.

Decrease ligature content with

due to the deterioration of the structure of metallic rare earth metals on iron iron pig iron (the content of ferrite increases), the shape, size and distribution of inclusions of graphite. Increasing the content of high-carbon ferrochrome (composition 5) decreases the strength of cast iron and the uniformity of indicators, hardness over the cross section of thick-walled and differential castings due to an increase in the tendency of cast iron to

chipping, the occurrence of structural-free- 35 of the iron structure, mainly

cementite (especially in thin walls and edges of the casting), which hinders mechanical processing.

Introduction of high-carbon fer-. romarangants within 9–16% in the mixture's compound promotes an increase in the graphitizing ability and a better assimilation of the mixture in the molten iron, while ensuring a high level of the strength properties of the iron.

Tellurist antimony is introduced into the mixture in an amount of 0.05-0.10%. This content is optimal to ensure high perlitization ability and uniformity of properties over the section of thick-walled and differential castings.

shape, size and distribution of graphite inclusions.

An increase in the ligature content of rare-earth metals on an iron-silicon base in the mixture (composition 9) leads to a slight increase in chilling, the formation of gas porosity in the castings due to an increase in the amount of aluminum 5 introduced into the molten iron (2-6% contained in the alloy) and the cost of the mixture due to the high cost of rare-earth metals.

50

As follows from the test results given in table. 2, the treatment of liquid iron with the proposed mixture, as compared with the known, provides an increase in the modifying effect, which is expressed in increasing the tensile strength by 10-14% and the uniformity of the structure and hardness of the iron over the section of differential and thick-walled castings by more than 4.0 times .

When reducing the content of antimony telluric in the composition of the mixture (composition 6), its modifying effect deteriorates, the strength of cast iron decreases and the variation of hardness indicators over the section of thick-walled increases.

l 5).

1308630

and differential

deterioration of the microstructure, a lesser degree of perlitization of metal, base, enlargement of the eutectic grain.

With an increase in the content of antimony tellurium in the composition of the mixture (composition 7), the strength of cast iron and the uniformity of hardness indicators over the cross section of the casting are given due to the appearance in the structure of carbides and the release of structural components, their unfavorable form, in particular, anomalous forms of graphite ), and a broken mesh along the boundaries of eutectic grains.

A ligature with rare-earth metals on an iron-silicon base is introduced into the mixture in the range of 65-75%, which provides an increase in the modifying effect, strength and uniformity of the properties of cast iron in differential castings.

Decrease ligature content with

0

silicon base in the mixture (composition 8) leads to a deterioration of the modifying effect due to the prevalence of ferrochrome and ferromanganese, an increase in the carbon equivalent of cast iron and, consequently, to a decrease in the strength of cast iron and the uniformity of properties over the section of thick-walled castings due to deterioration

shape, size and distribution of graphite inclusions.

An increase in the ligature content of rare-earth metals on an iron-silicon base in the mixture (composition 9) leads to a slight increase in chilling, the formation of gas porosity in the castings due to an increase in the amount of aluminum introduced into the molten iron (2-6% contained in the ligature) and higher prices mixtures due to the high cost of rare-earth metals.

As follows from the test results given in table. 2, the treatment of liquid iron with the proposed mixture, as compared with the known, provides an increase in the modifying effect, which is expressed in increasing the tensile strength by 10-14% and the uniformity of the structure and hardness of the iron over the section of differential and thick-walled castings by more than 4.0 times .

The improvement of the properties of cast iron modified by the proposed mixture, as shown by metallographic studies, increases by increasing the degree of perlitetization of the metal base and its dispersion, improving the shape, size and distribution of the incorporation of graphite, increasing the homogeneity of the metal structure over the section of thick-walled and differential castings.

In addition, the proposed mixture has a high graphitizing ability due to the content of a significant amount of carbon serving as nucleation centers for the crystallization of graphite, which makes it possible to reduce the consumption of the mixture by 4-5 times, to reduce the loss of tempering in song forms with a residual moisture content not higher than 1.0 %

Thus, when using the proposed mixture for the modification of cast iron, the strength and uniformity of cast iron in thick-walled and differential castings are increased during out-of-mill processing of a liquid metal.

Claims (1)

 About formula of invention A mixture for the modification of cast iron, including, and ferrochrome and ferromanganese, which, in order to increase the strength and uniformity of the properties of cast iron in thick-walled and differential castings, it additionally contains an antimony telluric and ligature with rare-earth metals. J5 pills of the processed liquid metal-20 metals on iron-silicon osnol and save fuel or electricity in the smelting of iron The proposed mixture for modifying cast iron can be used in the production of castings of machine parts and equipment operating under conditions of friction, increased and prolonged mechanical loads and pressures. The most appropriate use of to produce the proposed mixture for modifying low-grade cast iron, smelted in electric furnaces on the charge with a significant proportion of steel scrap and intended to produce differential and massive west) 12 20 18,925 eleven 21 18 17 20 13 18 12.95 9 16 15.95 10.9 15.96 12.89 15.93 10.93 12 castings in song forms with a residual moisture content not exceeding 1.0%. Thus, when using the proposed mixture for modifying cast iron, the strength and uniformity of cast iron in thick-walled and differential castings during out-of-furnace treatment of liquid metal is increased. Invention Formula A mixture for modifying cast iron, including, and ferrochrome and ferromanganese, characterized in that, in order to increase the strength and uniformity of the properties of cast iron in thick-walled and differential castings, it additionally contains an antimony tellurite and a ligature with rare earth ve, while using high-carbon ferrochrome and ferromanganese in the following ratio of components, May.%: thirty High carbon ferrochrome Tellurium antimony Ligature with rare-earth metals on iron-silicon base Ferromanganese high carbon T a 12-20 0.05-0.1 65-75 The rest is blitz 75 70.9 65 73 68 66 70 64 76 Table 2