PROCEDURE FOR SELECTING A RATIONAL TECHNOLOGICAL MODE FOR THE PROCESSING OF CAST IRON MELT ON THE BASIS OF GRAPH-ANALYTICAL PROCESSING OF THE DATA OF SERIAL SMELTINGS Текст научной статьи по специальности «Химические технологии»

PROCEDURE FOR SELECTING A RATIONAL TECHNOLOGICAL MODE FOR THE PROCESSING OF CAST IRON MELT ON THE BASIS OF GRAPH-ANALYTICAL PROCESSING OF THE DATA OF SERIAL SMELTINGS

Denys Nikolaiev

Department of Foundry Production, National Technical University «Kharkiv Polytechnic Institute», Kharkiv, Ukraine E-mail: litvo11@kpi.kharkov.ua

ORCID: https://orcid.org/QQQQ-Q002-8324-176Q

ARTICLE INFO

Article history: Received date 08.09.2022 Accepted date 20.10.2022 Published date 30.10.2022

Section: Metallurgy

DOI

10.21303/2313-8416.2022.002774

KEYWORDS

utilization of armored vehicles cast iron with lamellar graphite cast iron microstructure alloying modification

ABSTRACT

The object of research: cast iron grade DSTU EN 1561 (EN-GJL-200), used for the manufacture of body parts for mechanical engineering.

Investigated problem: the choice of the technological mode of the process of producing cast iron under conditions of multifactorial influence on the formation of its microstructure. The main scientific results: A procedure for truncation of the influencing factors on the formation of the microstructure is proposed, which is a consistent reduction of data from serial smeltings to uniform conditions allowed by the actual data set. Common conditions mean the closeness of the chemical composition of the melt, which makes it possible to compare the effectiveness of the applied modifiers in combination with microalloying in terms of cast iron microstructure indicators. The proposed data truncation procedure made it possible, by creating conditions for comparing the efficiency of FeSi75 and FeSi-65CaBaSr2 modifiers, to develop a rational technological regime for melt processing. It has been established that the compared modifiers have the same effect on the size of graphite - its content is (50-51) ^m, however, the use of FeSi65CaBaSr2 in combination with an alloying complex (0.27 %Cr+0.083 %Ni+0.048 %Ti+0.155 %Cu+0.018 %V) makes it possible to obtain an average amount of pearlite of 96 % in the microstructure. The area of practical use of the results of the study: the results obtained can be used in foundries or metallurgical shops of industrial enterprises as part of a general technology for producing cast iron of various grades, developed for cases of incomplete control of the quality of charge materials. Such a situation occurs, for example, when the charge is formed from dismantled armored vehicles that cannot be restored due to destruction on the battlefield.

Innovative technological product: iron smelting technology that allows the possibility of minimizing the cost of smelting in terms of the use of modifiers and alloying ferroalloys The scope of the technological innovative product: technological regimes for the production of cast iron.

© The Authnr(s) 2021. This is an open access article under the Creative Commons CC BY license

1. Introduction

1.1. The object of research

Cast iron grade DIN 1691-GG-20 (ASTN A48 Class 30), used for the manufacture of body parts.

1. 2. Problem description

The number of destroyed russian armored vehicles during the hostilities on the territory of Ukraine, which cannot be restored, is in the thousands. It can be used for remelting and further use of the resulting product in metallurgy - for the production of rolled products, profiles, etc., or in foundry production - for the further manufacture of shaped castings used in machine parts for various applications. The components of this technique are heterogeneous in material, mainly steel and cast iron, heavily covered with products of combustion and chemical processes (rust), as well as heavily contaminated. The melt of a charge consisting of such components is not completely controlled in terms of chemical composition; therefore, the initial composition of the melt immediately after smelting requires adjustments and the use of special technological solutions. The purpose of such solutions is to select the modes of out-of-furnace processing, including modification combined with alloying, as well as other

metallurgical processes focused on melt purification, which make it possible to obtain ferrous alloys of different grades based on a "single" melt. A "single" melt can be understood as an alloy having the same or similar composition in terms of the content of chemical elements, subject to further modification and alloying to meet the requirements for the quality of the finished product. The object under consideration, cast iron, is an alloy that is sensitive to various smelting and cooling conditions, which manifests itself in the formation of various microstructures that determine the final mechanical properties. The control of the processes of formation of the microstructure is carried out mainly by modification, the modes of which must be justified and be, if not optimal, then rational for the given production conditions.

1. 3. Suggested solution to the problem

Despite many years of searching for universal solutions regarding the choice of modifiers and modification technologies, they have not been successful. The reason for this is the variety of influencing factors and production conditions, so solutions for specific objects and production conditions are practically feasible. Priority is given to an integrated approach, which involves the use of melt modification [1] together with alloying at tapping from the furnace. In this case, special attention should be paid to the correct selection of elements that promote and prevent graphitiza-tion [2, 3]. The process of graphitization is one of the alternatives in terms of the formation of the microstructure, since it is possible for metastable processes to occur in the crystallizing alloy. If it is impossible to control the cooling rate and, as a result, crystallization, artificial methods are resorted to, based on taking into account the cooling rate of the casting in the mold [4].

The choice of rational technological regimes should be based on analytical dependencies connecting the factors of the technological process of obtaining an alloy with the required quality indicators. The most common approach is based on the construction of such dependences, in which the properties of the alloy are determined as a function of the chemical composition [5-7] or technological factors of thermal treatment [8]. At the same time, the values of the quality index are considered to be normally distributed, which makes it possible to estimate the proportion of scrap by non-compliance with the quality requirements of the alloy for further analysis and identification of factors leading to scrap [9, 10]. However, the construction of such dependences is associated with the need to solve the problem of the multifactorial influence on the quality indicators of the alloy. This forces researchers to reduce the dimension of the problem by fixing some of the input variables of the process at some level or in some range of values. An example is the idea of using the intelligent methodology for the study of large systems (IMLS) for processing the experimental data of serial industrial melts [11]. The limitation of all the results obtained in the above studies is the artificial underestimation of the dimension of the factor space. In addition, the alloy is considered from the standpoint of a "black box", which is quite reasonable from the point of view of quickly obtaining important practical results that make it possible to control the processes of smelting, out-of-furnace and thermal treatment. However, from the point of view of revealing the mechanism of action of individual factors or their combinations on the properties under study, it is important to introduce the formation of a microstructure into consideration. This is explained by the fact that the action of modifiers on the melt, alone or in combination with other modifiers or alloying additives, leads precisely to the regulation of the processes of microstructure formation. Especially important in this case is the solution of the problem of choosing the conditions under which it is possible to compare the effect of modification and alloying factors [11, 12].

The aim of the study: to choose rational technological modes of out-of-furnace processing, based on the available data on the chemical composition and microstructure of cast iron, by truncation of the number of factors influencing the formation of the microstructure.

2. Materials and Methods

The hypothesis of the study was that, based on the available data on the chemical composition and microstructure of cast iron, it is possible to assess the degree of influence of alternative modifiers on the formation of the microstructure of cast iron that differ in chemical composition. The validity of such a statement follows from the obvious fact that both the chemical composition and technological factors influence the formation of the microstructure. Therefore, different chemical compositions of melts treated with alternative modifiers do not allow one to evaluate the effectiveness of each of the modifiers.

The study was of an analytical nature - to theoretically determine rational technological regimes from the available primary data of serial melts containing the chemical compositions and microstructures of cast iron treated with two modifiers: FeSi75 [13] and FeSi65CaBaSr2 [14]. According to the data of [13, 14], smelting was carried out in an electric arc furnace with processing of the FeSi75 smelting (series 1) or in an induction furnace with processing of the FeSi65CaBaSr2 smelting (series 2).

The data were converted to a form that reduces the dimension by calculating the carbon equivalent using the well-known formula

Ceqv = C (%) + 0.3Si ( %)-0.03 Mn (%).

(1)

The validity of this approach follows from the fact that the position of the eutectic point in the Fe-C state diagram is one of the determining factors for determining the phase ratio and their chemical composition. The position of this point is dynamic and depends on the content of silicon and manganese.

The content of sulfur and phosphorus was in acceptable small amounts, therefore it was not taken into account.

The output variables of the process were the amount of pearlite (P, %) and graphite fineness (GF, ^m). The data of metallographic analysis on the evaluation of these components of the microstructure in the axial zone and on the periphery of the sample were averaged.

The input and output variables for the melt modified with FeSi75 are given in Table 1, and for the melt modified with FeSi„CaBaSr_, in Table 2.

65 2'

Table 1

Input and output variables for a melt modified with FeSi75

Melt Line Input variables - chemical composition of the alloy, % Output variables - microstructure parameters

No. number C eqv Cr Ni Ti Cu V P, % GF, ^m

010 1 4.12 0.09 0.22 0.022 0.09 0.0011 67.5 35

011 2 4.1 0.09 0.22 0.022 0.09 0.0011 62.5 57.5

012 3 4.07 0.09 0.21 0.022 0.09 0.0011 65 52.5

013 4 4.19 0.1 0.23 0.022 0.09 0.001 57.5 67.5

020 5 4.07 0.1 0.22 0.022 0.09 0.0015 82.5 35

021 6 4.04 0.09 0.22 0.021 0.09 0.0013 82.5 35

022 7 4.06 0.09 0.23 0.022 0.09 0.0015 65 67.5

023 8 4.15 0.09 0.2 0.021 0.08 0.0013 65 57.5

030 9 4.18 0.1 0.21 0.021 0.09 0.0013 65 46.25

031 10 4.31 0.1 0.21 0.021 0.09 0.0013 65 57.5

032 11 4.28 0.09 0.21 0.022 0.09 0.0016 65 57.5

033 12 4.33 0.1 0.2 0.021 0.09 0.0019 60 35

Table 2

Input and output variables for the melt modified with FeSi65CaBaSr2

Melt Line Input variables - chemical composition of the alloy, % Output variables - microstructure parameters

No. number C eqv Cr Ni Ti Cu V P, % GF, ^m

1-0 1 3.58 0.11 0.07 0.03 0.06 0.01 96 53.3

1-1 2 3.93 0.13 0.07 0.03 0.14 0.02 92 35

1-2 3 4.06 0.17 0.08 0.06 0.15 0.02 96 35

1-3 4 4.59 0.24 0.11 0.03 0.13 0.01 96 67.5

2-1 5 4.06 0.12 0.09 0.03 0.06 0.009 96 67.5

2-2 6 3.8 0.12 0.07 0.02 0.12 0.008 96 35

2-3 7 3.88 0.14 0.1 0.07 0.16 0.02 100 35

2-4 8 3.85 0.12 0.09 0.03 0.15 0.01 100 53.3

3-0 9 3.77 0.08 0.08 0.03 0.06 0.009 100 67.5

3-1 10 3.75 0.1 0 0.03 0.17 0.01 96 67.5

3-2 11 4.14 0.37 0.09 0.07 0.16 0.02 100 67.5

3-3 12 3.76 0.12 0.1 0.02 0.11 0.008 96 67.5

Statistical data processing included the calculation of sample functions - the mathematical expectation of the content of each element in each of the series of smeltings and the value of the standard deviation:

_ 1 N

X =-V X,., (2)

Nj-t " W

1 N — V

—X -x )

N -1' '

sx = -x) , (3)

where X. - the content of the element of chemical composition and the value of the carbon equivalent, %, Sx - the standard deviation of the content of this element of the chemical composition and the value of the carbon equivalent, %, N - the number of experimental points in each series of smeltings, according to which the statistical characteristics are calculated. A series of smeltings No. 1 - modification of FeSi75, a series of smeltings No. 2 - modification of FeSi65CaBaSr2. The field of deviations of carbon equivalent values was calculated by the formula

/~iFeSi75 , y-/'/-iFeSi75\ _ ¿rtFeSi75

Ceqv min,max = M ( Ceqv ) + tSX , (4)

FeSi 65 CaBaSr 2 i , /'/^FeSi65CaBaSr2 ¿oFeSi65CaBaSr2 /.-n

Ceqv, min,max = M (Ceqv, ) + tSX , (5)

where M ( C^175 ), M (cFqvSi65CaBaSr2 ) - the mathematical expectation of the value of the carbon equivalent in the modification of FeSi75 and FeSi65CaBaSr2, respectively, calculated by formula (1), SXFeSi75, sXeSi65CaBaSr2 -the standard deviation of the value of the carbon equivalent in the modification of FeSi75 and FeSi65CaBaSr2, respectively,

t - the value of Student's distribution for significance level a=0.05.

3. Results

The proposed procedure for data truncation in order to create conditions for comparing the effectiveness of modifiers includes the following steps:

1. Construction of combined circular diagrams with the results of chemical analysis applied to them for both series of smeltings.

2. A visual assessment of the values that are clearly falling out in absolute value for each input variable and their conditional removal from the sample for further analysis.

3. Formation of a new data sample that does not include deleted elements.

4. Calculation of sample functions according to formulas (2) and (3).

5. Comparison between the mathematical expectations for each input variable for both series of smeltings and combining the results if the mathematical expectations in both series are equal.

6. Calculation of the lower and upper dispersion fields of carbon equivalent values for both series of smeltings according to formulas (4) and (5).

7. Calculation of the domain of determination of the value of C according to the rule

eqv 0

IrcFeSi65CaBaSr2 . cFeSi75 1 -f cFeSi65CaBaSr2 < cFeSi75

L eqv max; eqv min J f eqv min eqv (6)

rcFeSi75 . cFeSi65CaBaSr2 1 -f cFeSi75 < cFeSi65CaBaSr2

L eqv min > eqv max J J eqv min eqv m

min ?

where Cemqivn,max - the range of carbon equivalent values within which the basic chemical composition of the alloy can be considered the same for both series of smeltings. This means that it is possible to compare the effect of modifiers on the microstructure by "equalizing" the basic chemical composition, estimated by the value of the carbon equivalent.

8. Calculation of the average value of the output variable for both series of smeltings and assessment of the joint effect on the microstructure of the modifier and alloying elements, the content of which in the series is different from each other.

In Fig. 1-6 there are combined chemical composition pie charts for both series of smeltings.

Fig. 1. Combined C chart

ö eqv

Fig. 2. Combined Cr content chart

-Ni FeSi65CaBaSr2, % -Ni_FeSi75 Fig. 3. Combined Ni content chart

The implementation of item 2 of the proposed procedure leads to a truncated sample by excluding from it the lines describing the chemical compositions No. 3, 4, 7, 8, 10, 11. The resulting sample is shown in Tables 3, 4, and the results of calculating the sample functions are given in Table 5.

Table 6 shows the results of calculations of the lower and upper dispersion fields of carbon equivalent values for both series of smeltings (items 4-6 of the proposed procedure)

Fig. 4. Combined Ti content chart

Fig. 5. Combined Cu content chart

Fig. 6. Combined V content chart

It can be seen from Table 6 that the condition CeFqvi65CaBaSr2min < CFqvSl75min is satisfied, so the range of carbon equivalent values within which the basic chemical composition of the alloy can be considered the same for both series of smeltings has the form Cmq",max = [3,93; 4,24]. Therefore, paragraph 7 of the proposed procedure has been completed, and the sample for paragraph 8 takes the form presented in Table 7. It includes all rows in which the value of the carbon equivalent falls within the range of Cmq"'max = [3,93; 4,24], including rows conditionally removed from the original sample In Item 2.

Table 3

Truncated sample for series No.1

Line number Input variables - chemical composition of the alloy, % Output variables - microstructure parameters

C Cr Ni Ti Cu V P, % GF, ^m

1 4.12 0.09 0.22 0.022 0.09 0.0011 67.5 35

2 4.1 0.09 0.22 0.022 0.09 0.0011 62.5 57.5

3 4.07 0.09 0.21 0.022 0.09 0.0011 65 52.5

4 4.19 0.1 0.23 0.022 0.09 0.001 57.5 67.5

5 4.07 0.1 0.22 0.022 0.09 0.0015 82.5 35

6 4.04 0.09 0.22 0.021 0.09 0.0013 82.5 35

7 4.06 0.09 0.23 0.022 0.09 0.0015 65 67.5

8 4.15 0.09 0.2 0.021 0.08 0.0013 65 57.5

9 4.18 0.1 0.21 0.021 0.09 0.0013 65 46.25

10 4.31 0.1 0.21 0.021 0.09 0.0013 65 57.5

11 4.28 0.09 0.21 0.022 0.09 0.0016 65 57.5

12 4.33 Table 4 0.1 0.2 0.021 0.09 0.0019 60 35

Truncated sample for series No.2

Line number Input variables - chemical composition of the alloy, % Output variables - microstructure parameters

C eqv Cr Ni Ti Cu V P, % GF, ^m

1 3.58 0.11 0.07 0.03 0.06 0.01 96 53.3

2 3.93 0.13 0.07 0.03 0.14 0.02 92 35

5 4.06 0.12 0.09 0.03 0.06 0.009 96 67.5

6 3.8 0.12 0.07 0.02 0.12 0.008 96 35

9 3.77 0.12 0.09 0.03 0.15 0.01 100 67.5

12 3.76 Table 5 0.08 0.08 0.03 0.06 0.009 96 67.5

Sample function values for input variables

Sample function Input variables - chemical composition of the alloy, %

C eciv Cr Ni Ti Cu V

M ( C FeSi 75 ) eqv ' 4.16 0.09 0.22 0.02 0.09 0

r> FeSi 75 SX 0.101 0.005 0.01 0.001 0.003 0

M (CFeSi 65 CaBaSr 2 ) 3.82 0.11 0.08 0.03 0.1 0.01

o FeSi 65 CaBaSr 2 SX 0.164 0.018 0.01 0.004 0.043 0.004

Table 6

The results of calculations of the lower and upper dispersion fields of carbon equivalent values

Parameters

Numerical values

tSF

tS

FeSi 65 CaBaSr 2

-iFeSi65CaBaSr2

-iFeSi 65 CaBaSr 2

0.222 3.93 4.38 0.422 3.4 4.24

C

C

Table 7

A truncated sample for calculating the carbon equivalent, within which the basic chemical composition of the alloy can be considered the same

Input variables - chemical composition of the alloy, %

number C eqv Cr Ni Ti Cu V

2 3.93 0.13 0.07 0.03 0.14 0.02

5 4.06 0.12 0.09 0.03 0.06 0.009

1 4.12 0.09 0.22 0.022 0.09 0.0011

2 4.1 0.09 0.22 0.022 0.09 0.0011

3 4.07 0.09 0.21 0.022 0.09 0.0011

4 4.19 0.1 0.23 0.022 0.09 0.001

5 4.07 0.1 0.22 0.022 0.09 0.0015

6 4.04 0.09 0.22 0.021 0.09 0.0013

7 4.06 0.09 0.23 0.022 0.09 0.0015

8 4.15 0.09 0.2 0.021 0.08 0.0013

9 4.18 0.1 0.21 0.021 0.09 0.0013

3 4.06 0.17 0.08 0.06 0.15 0.02

14 4.14 0.37 0.09 0.07 0.16 0.02

Note: the numbers of the lines corresponding to the smelting data of series No. 1 are marked in blue, and the numbers of series No. 2 are marked in red.

The calculation of sample functions according to formulas (2) and (3) leads to the following result: M (C™i75 )= M (CF^65 0^2 ) = 4.09, Sf"75 = S!FeSl65CaB!lSr2 = 0.069 . The final form of the sample for assessing the joint effect of the modifier and alloying elements, the content of which in the series is different from each other, on the amount of pearlite and graphite dispersion is presented in Table 8.

Table 8

The final form of the sample for assessing the combined effect of the modifier and alloying elements

Input variables - chemical composition of the alloy, % Output variables - microstructure parameters

C Cr Ni Ti Cu V P, % GF, ^m

2 4.09 0.1 0.07 0.02 0.09 0.02 92 35

5 4.09 0.1 0.09 0.02 0.09 0.01 96 67.5

1 4.09 0.1 0.22 0.02 0.09 0 67.5 35

2 4.09 0.1 0.22 0.02 0.09 0 62.5 57.5

3 4.09 0.1 0.22 0.02 0.09 0 65 52.5

4 4.09 0.1 0.22 0.02 0.09 0 57.5 67.5

5 4.09 0.1 0.22 0.02 0.09 0 82.5 35

6 4.09 0.1 0.22 0.02 0.09 0 82.5 35

7 4.09 0.1 0.22 0.02 0.09 0 65 67.5

8 4.09 0.1 0.22 0.02 0.09 0 65 57.5

9 4.09 0.1 0.22 0.02 0.09 0 65 46.25

3 4.09 0.17 0.08 0.06 0.15 0.02 96 35

14 4.09 0.37 0.09 0.07 0.16 0.02 100 67.5

Note: blue color indicates the results for series No. 1, red color --for series No. 2, black color - "single" data that can be used as a general when identifying the influence of modifiers and alloying elements

From Table 8 and based on the results of calculations of the average value of the amount of pearlite and graphite dispersion, it can be seen that the use of the FeSi65CaBaSr2 modifier makes it possible to obtain 96 % pearlite in the alloy matrix, while the use of the FeSi75 modifier makes it possible to obtain only 68 % pearlite in the alloy matrix. The average graphite size when using both modifiers is approximately the same: 51 ^m in the case of FeSi65CaBaSr2 and 50 ^m in the case of FeSi75.

Based on this, and using the data on out-of-furnace processing given in [14], rational technological modes of melt processing can be as follows:

- modifier FeSi65CaBaSr2 in the amount of 0.3 % of the mass of liquid metal with a fraction of 1-10 mm or "chips" technology: thickness with a fraction of 0.5-3 mm, length up to 50 mm,

- cast iron temperature before inoculation - 1400-1450 °C,

- method of input - into the ladle when issuing the melt from the furnace,

- alloying complex: (0.27 %Cr+0.083 %Ni+0.048 %Ti+0.155 %Cu+0.018 %V),

It is important to note that such regimes are selected if the value of the carbon equivalent corresponds to the condition M (Ceqv) = 4.09, SX = 0.069.

4. Discussion

The results of data processing by truncation of the original sample allow to establish factors that increase and decrease the values of the output variables of the process - the average amount of perlite and the average size of graphite (Table 8). Thus, it can be seen that in order to obtain a higher amount of perlite, it is necessary to jointly treat the melt with the FeSi65CaBaSr2 modifier, reduce the nickel content while increasing the content of chromium, titanium, copper and vanadium. Thus, it is impossible to single out the influence of the modifier factor separately. The increase in the amount of perlite under the action of these factors is justified, since Cr and V are strong carbide-forming elements, and the influence of Ti and Cu is twofold. At the same time, the ratio Cr:Ni=3.25:1 somewhat falls outside the range Cr:Ni=3:1-1 recommended by practice or the range given in [15], recommended for the manufacture of the same grade of cast iron for casting automotive parts - from Cr:Ni=2.2:1-2.4:1 to Cr:Ni=1.76:1. The introduction of additional vanadium and the associated increase in the amount of perlite does not contradict the conclusions of [16], where it is shown that the introduction of vanadium leads to an increase in the hardness of HB cast iron. This is indirect evidence that the amount of pearlite in the matrix increases, since it is known that the hardness of cast iron increases with increasing pearlite content.

However, it should be especially noted that the use of the proposed mode does not cause a change in the microstructure of the graphite size, in comparison with the use of the FeSi75 modifier. Therefore, from the point of view of the effect on the tensile strength, the use of the more expensive modifier FeSi65CaBaSr2 may not be justified, since the tensile strength depends mainly on the size and content of graphite in cast iron.

The results of the study are limited by the range of content of alloying elements in each series of smeltings, shown in Table 1 and Table 2.

The disadvantage of the study is related to the presence of a small sample of data. However, this is a common problem in obtaining real data when conducting serial smeltings. It is also possible to note the non-rigorous data screening procedure based on visual analysis of pie charts (Fig. 1-5). More rigorous is the test of the statistical hypothesis about the presence of anomalous data. When comparing the average content of the elements of the chemical composition of the alloy treated with alternative modifiers, the procedure for testing the statistical hypothesis of the form is more accurate:

where e - the boundary of the critical region, chosen to be symmetric and determined from the formula

H : Xj = X2,

(7)

which can be considered rejected if the following condition is met:

T >e,

(8)

(9)

T - a function determined by the formula

T=

X, - X.

(10)

In formula (10), the following notation is used: X1, X2 - mathematical expectations of the content of the element in series of smeltings 1 and 2, respectively, X1, X2 - estimates of the dispersion of the content of the element in series of smeltings 1 and 2, respectively.

In formula (5) ®(X) - the normalized normal distribution function.

Nevertheless, the proposed graph-analytical method of analysis is convenient for practical use, as it allows pre-processing of data by truncating the sample without resorting to mathematical calculations that underlie statistical hypothesis testing. The results obtained will not be accurate, but for a preliminary assessment they can be recommended.

Further development of work in relation to the studied types of modifiers may be in conducting additional experimental-industrial smeltings in order to increase the sample size and verify the results of the cast iron microstructure.

5. Conclusions

The proposed data truncation procedure made it possible, by creating conditions for comparing the effectiveness of modifiers, to develop a rational technological regime for processing the melt, which makes it possible to obtain a high content of perlite in the microstructure. This mode involves the use of the FeSi65CaBaSr2 modifier together with an alloying complex (0.27 %Cr+ +0.083 %Ni+0.048 %Ti+0.155 %Cu+0.018 %V) and provides an average amount of pearlite of 96 % in the microstructure. The proposed technological regime is justified if the value of the carbon equivalent corresponds to the condition M (Ceqv) = 4.09, SX = 0.069.

It is shown that the compared modifiers FeSi75 and FeSi65CaBaSr2 have the same effect on the graphite size - its content is (50-51) ^m. Therefore, if it is necessary to increase the tensile strength of cast iron, the choice of modifier from the two compared is not important. In this case, preference can be given to FeSi75, as a less scarce modifier, choosing another alloying complex to increase the amount of pearlite. When comparing the result on this indicator, such an alloying complex should provide an increase of about 31 % in order to achieve equal values in relation to the use of the FeSi65CaBaSr2 modifier.

Based on the fact that one should strive to obtain a matrix close in terms of pearlite content to 100 % and the presence of graphite of small sizes (high dispersion) in the absence of cementite (Fe3C in the microstructure) in the structure, the proposed technological mode of melt processing can be considered rational.

Conflict of interest

The authors declare that there is no conflict of interest in relation to this paper, as well as the published research results, including the financial aspects of conducting the research, obtaining and using its results, as well as any non-financial personal relationships.

Funding

The study was performed without financial support.

Data availability

Data will be made available on reasonable request

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Demin, D. (2017). Strength analysis of lamellar graphite cast iron in the «carbon (C) - carbon equivalent (Ceq)» factor space in the range of C = (3,425-3,563) % and Ceq = (4,214-4,372) %. Technology Audit and Production Reserves, 1(1(33)), 24-32. doi: https://doi.org/10.15587/2312-8372.2017.93178

Demin, D. (2017). Synthesis of nomogram for the calculation of suboptimal chemical composition of the structural cast iron on the basis of the parametric description of the ultimate strength response surface. ScienceRise, 8 (37), 36-45. doi: https:// doi.org/10.15587/2313-8416.2017.109175

Radchenko, A. A., Alekseenko, Yu. N., Chumachenko, V. Y., Bohdan, V. V. (2016). Determination of optimum heat treatment conditions for hardness criterion of multicomponent steel based on fuzzy mathematical simulation. ScienceRise, 6 (2 (23)), 6-9. doi: https://doi.org/10.15587/2313-8416.2016.69969

Seliverstov, V., Boichuk, V., Dotsenko, V., Kuzmenko, V. (2018). Stability assessment of 30XHM. steel melting process in electric arc furnaces on the basis of technological audit of serial meltings. Technology Audit and Production Reserves, 6 (1 (44)), 14-18. doi: https://doi.org/10.15587/2312-8372.2018.149263

Dymko, E. P., Belik, N. N., Zolotareva, A. V., Kiiashko, S. Iu., Demina, A. V. (2016). Kompiuterno-integrirovannye tekh-nologii v liteinom proizvodstve: voprosy upravleniia kachestvom olivok. Visnik NTU "KhPI», 17 (1189), 41-46 Zraichenko-Polozentcev, A. V., Koval, O. S., Demin, D. A. (2011). Evaluation of potential reserves of production for melting synthetic iron. Technology Audit and Production Reserves, 1 (1 (1)), 7-15. doi: https://doi.org/10.15587/2312-8372.2011.4081 Demin, D. A., Koval, O. S., Kostik, V. O. (2013). Technological audit of modifying cast iron for casting autombile and road machinery. Technology Audit and Production Reserves, 5 (1 (13)), 58-63. doi: https://doi.org/10.15587/2312-8372.2013.18398 Demin, D. A. (2000). Statisticheskoe modelirovanie zavisimostei mezhdu strukturnymi sostavliaiushchimi chuguna, modifit-cirovannogo ferrosilitciem. Vestnik Kharkovskogo gosudarstvennogo politekhnicheskogo universiteta, 119, 36-39. Demin, D. A., Zraichenko-Polozentcev, A. V. (2008). Rezultaty promyshlennykh issledovanii tekhnologii modifitcirovaniia sinteticheskogo chuguna. Visnik Natcionalnogo tekhnichnogo universitetu „KhPI", 12, 78-81

Lysenkov, V., Demin, D. (2022). Reserves of resource saving in the manufacture of brake drums of cargo vehicles. Science-Rise, 3, 14-23. doi: https://doi.org/10.21303/2313-8416.2022.002551

Frolova, L., Barsuk, A., Nikolaiev, D. (2022). Revealing the significance of the influence of vanadium on the mechanical properties of cast iron for castings for machine-building purpose. Technology Audit and Production Reserves, 4 (1 (66)), 6-10. doi: https://doi.org/10.15587/2706-5448.2022.263428