A. Nuradinov, V. Shkolyarenko, O. Chistyakov, I. Nuradinov, N.F. Zibeline
It is known that the alloys of the Al-Zn-Mg-Cu and Al-Mg-Cu systems have a very wide crystallization interval (over 100°C) and therefore the technology of roll pouring-rolling of sheet blanks from such alloys has not yet been developed. In this regard, the development of scientific and technological foundations of roll casting for such a range of aluminum alloys is an important scientific and practical task. The purpose of this work is to determine the possibility of aluminum alloys B95 and D16 (crystallization intervals are 160°C and 132°C, respectively) for casting-rolling based on the analysis of the effect of cooling intensity on their structure and mechanical properties. The research was carried out on full-scale samples of B95 and D16 alloys by comparing the obtained experimental values. Determination of the temperature parameters of phase transformations in the studied alloys was carried out using the Derivatograph Q-1500-D device. As a result of the tests, the curves of the differential thermal analysis and the fraction of the liquid phase depending on the temperature were obtained. Based on the results of the research, the suitability of B95 and D16 aluminum alloys for casting and rolling has been substantiated. It was found that the size of α-phase grains for B95 and D16 alloys as the cooling rate increases decreases to 120...200 μm (for cooling rates of 2.5...8.8°С/s), and to 40...70 μm (for cooling rates cooling ~1000°С/s). It has been proven that the hardness of B95 and D16 aluminum alloys mainly depends on the α-phase, therefore, when developing roll casting modes, it is advisable to take into account the hardening features of this structural component (α-phase). At the same time, it should be noted that at the intensity of heat removal, which is typical for roll crystallizers, the obtained sheet blanks from the studied alloys will have dispersed crystal structures with a uniform distribution of phase components along their cross sections. A natural consequence of such primary crystalline structures of cast blanks will be a guaranteed high level of strength characteristics of sheet metal rolled from them. Keywords: cooling rate, alloy, crystallization, structure, phase composition, metal rolling
{"title":"Effect of cooling rate during crystallization on the structure of B95 and D16 alloys","authors":"A. Nuradinov, V. Shkolyarenko, O. Chistyakov, I. Nuradinov, N.F. Zibeline","doi":"10.15407/mom2023.02.036","DOIUrl":"https://doi.org/10.15407/mom2023.02.036","url":null,"abstract":"It is known that the alloys of the Al-Zn-Mg-Cu and Al-Mg-Cu systems have a very wide crystallization interval (over 100°C) and therefore the technology of roll pouring-rolling of sheet blanks from such alloys has not yet been developed. In this regard, the development of scientific and technological foundations of roll casting for such a range of aluminum alloys is an important scientific and practical task. The purpose of this work is to determine the possibility of aluminum alloys B95 and D16 (crystallization intervals are 160°C and 132°C, respectively) for casting-rolling based on the analysis of the effect of cooling intensity on their structure and mechanical properties. The research was carried out on full-scale samples of B95 and D16 alloys by comparing the obtained experimental values. Determination of the temperature parameters of phase transformations in the studied alloys was carried out using the Derivatograph Q-1500-D device. As a result of the tests, the curves of the differential thermal analysis and the fraction of the liquid phase depending on the temperature were obtained. Based on the results of the research, the suitability of B95 and D16 aluminum alloys for casting and rolling has been substantiated. It was found that the size of α-phase grains for B95 and D16 alloys as the cooling rate increases decreases to 120...200 μm (for cooling rates of 2.5...8.8°С/s), and to 40...70 μm (for cooling rates cooling ~1000°С/s). It has been proven that the hardness of B95 and D16 aluminum alloys mainly depends on the α-phase, therefore, when developing roll casting modes, it is advisable to take into account the hardening features of this structural component (α-phase). At the same time, it should be noted that at the intensity of heat removal, which is typical for roll crystallizers, the obtained sheet blanks from the studied alloys will have dispersed crystal structures with a uniform distribution of phase components along their cross sections. A natural consequence of such primary crystalline structures of cast blanks will be a guaranteed high level of strength characteristics of sheet metal rolled from them. Keywords: cooling rate, alloy, crystallization, structure, phase composition, metal rolling","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42695409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The possibility of replacing the piston eutectic alloy of the Al-Si-Cu system AK12M2MgN, which was produced at OJSC "Zaporizhsky Aluminum Combine" from primary aluminum, with AK12M2MgNZH with an increased iron content, which will allow expanding the raw material base of production due to the use of scrap and waste. It is proposed to solve this problem by introducing into the technological process of processing the melt with a unipolar pulsed electric current during pouring according to specially developed modes. To investigate this possibility, experiments were conducted on the effect of electric current on the microstructure, phase composition of AK12M2MgN and AK12M2MgNZH alloys and their mechanical properties at temperatures of 20 oC and 300 oC. The melt was treated with an electric current in the following modes: electric current density (j) 100 - 400 A/cm2, pulse frequency (ν) 50 - 2000 Hz. The phase composition of alloys is considered. It is shown that the main iron-containing phase of the AK12M2MgN alloy is (Fe,Mn)3Si2AI15 (α) in the form of branched eutectic crystals. The acicular β-FeSiAI5 phase is practically absent. Unlike AK12M2MgN, the composition of AK12M2MgNZH alloy includes β-FeSiAl5 intermetallic and primary coarse crystals of (Fe,Mn)3Si2AI15 phase. After treatment of alloys in the liquid state with pulsed electric current in different modes, their microstructure and phase composition change significantly. The degree of differentiation of eutectic components increases. In particular, the linear size of eutectic silicon crystals, depending on the density and frequency of the electric current, decreases by 2-3 times. Primary crystals of the intermetallic (Fe,Mn)3Si2Al15 are formed in the AK12M2MgN alloy, which in cross-section have the appearance of compact, close to globular crystals. X-ray spectral studies have shown that despite the same crystallographic structure, eutectic and primary crystals of the (Fe,Mn)3Si2Al15 phase differ in the higher concentration of iron, manganese, copper and nickel in the latter. In the composition of the AK12M2MgNZH alloy, there is practically no acicular intermetallic β-FeSiAl5, the formation of which is one of the main reasons for the decrease in mechanical properties. Similar to the AK12M2MgN alloy, compact crystals of the primary phase (Fe,Mn)3Si2Al15 and a significant amount of the π-FeMg3Si6Al8 phase appear. Such structural changes ensured an increase in the mechanical properties at 20 and 300 oC of both the AK12M2MgN alloy and AK12M2MgNZH. The highest properties of both alloys are achieved at j = 100 A/cm2; ν = 1000 ‒ 2000 Hz. The characteristics of mechanical properties increase from 25 % to 40 %. The structural and phase changes caused by the processing of the AK12M2MgNZH melt with an electric current according to experimentally established modes provide it with mechanical properties at the level of the AK12M2MgN alloy with several higher heat resistance indicators. In addition, treatment o
{"title":"The structure, phase composition and properties of the AK12M2MgN alloy with increased iron content treated in the liquid state with an electric current","authors":"А. Prіgunova, Y. Zhydkov, V. D. Babiuk","doi":"10.15407/mom2023.02.003","DOIUrl":"https://doi.org/10.15407/mom2023.02.003","url":null,"abstract":"The possibility of replacing the piston eutectic alloy of the Al-Si-Cu system AK12M2MgN, which was produced at OJSC \"Zaporizhsky Aluminum Combine\" from primary aluminum, with AK12M2MgNZH with an increased iron content, which will allow expanding the raw material base of production due to the use of scrap and waste. It is proposed to solve this problem by introducing into the technological process of processing the melt with a unipolar pulsed electric current during pouring according to specially developed modes. To investigate this possibility, experiments were conducted on the effect of electric current on the microstructure, phase composition of AK12M2MgN and AK12M2MgNZH alloys and their mechanical properties at temperatures of 20 oC and 300 oC. The melt was treated with an electric current in the following modes: electric current density (j) 100 - 400 A/cm2, pulse frequency (ν) 50 - 2000 Hz. The phase composition of alloys is considered. It is shown that the main iron-containing phase of the AK12M2MgN alloy is (Fe,Mn)3Si2AI15 (α) in the form of branched eutectic crystals. The acicular β-FeSiAI5 phase is practically absent. Unlike AK12M2MgN, the composition of AK12M2MgNZH alloy includes β-FeSiAl5 intermetallic and primary coarse crystals of (Fe,Mn)3Si2AI15 phase. After treatment of alloys in the liquid state with pulsed electric current in different modes, their microstructure and phase composition change significantly. The degree of differentiation of eutectic components increases. In particular, the linear size of eutectic silicon crystals, depending on the density and frequency of the electric current, decreases by 2-3 times. Primary crystals of the intermetallic (Fe,Mn)3Si2Al15 are formed in the AK12M2MgN alloy, which in cross-section have the appearance of compact, close to globular crystals. X-ray spectral studies have shown that despite the same crystallographic structure, eutectic and primary crystals of the (Fe,Mn)3Si2Al15 phase differ in the higher concentration of iron, manganese, copper and nickel in the latter. In the composition of the AK12M2MgNZH alloy, there is practically no acicular intermetallic β-FeSiAl5, the formation of which is one of the main reasons for the decrease in mechanical properties. Similar to the AK12M2MgN alloy, compact crystals of the primary phase (Fe,Mn)3Si2Al15 and a significant amount of the π-FeMg3Si6Al8 phase appear. Such structural changes ensured an increase in the mechanical properties at 20 and 300 oC of both the AK12M2MgN alloy and AK12M2MgNZH. The highest properties of both alloys are achieved at j = 100 A/cm2; ν = 1000 ‒ 2000 Hz. The characteristics of mechanical properties increase from 25 % to 40 %. The structural and phase changes caused by the processing of the AK12M2MgNZH melt with an electric current according to experimentally established modes provide it with mechanical properties at the level of the AK12M2MgN alloy with several higher heat resistance indicators. In addition, treatment o","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48179773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the modern proposed methods actively used for diagnosing metal structures is the method of fractal analysis. This method seeks to find the conjunction between the fractal dimension of individual components of the metal structure and its mechanical properties. The comprehensive use of microanalysis and fractal analysis allows not only for comparing structural characteristics but also for finding a numerical parameterization of the elements of this structure. The problem of advance the mechanical properties of welded joints in metal structures remains relevant due to the constant increase in high-strength low-alloy steels used in welded structures. As known, the mechanical properties of welded joints are determined by their structural components, including non-metallic inclusions. A purely qualitative assessment based on the DSTU 8966:2019 standard does not provide an opportunity for a thorough analysis of such an important characteristic as the distribution of inclusions by size and the character of their distribution in the metal matrix. Existing knowledge is based on the peculiarities of the influence of non-metallic inclusions on the mechanical properties of steel welded joints, which requires constant expansion and deepening cognitions, as this work aims to do. The method of fractal analysis allows considering non-metallic inclusions as voids in the metal matrix, which enables parameterization of the inclusion characteristics in the metal structure. The paper describes a methodology that takes into account the distance between inclusions as well as the size of inclusions, which differently affect the mechanical characteristics of the samples. In particular, this article is a continuation of the work [1], which describes an approach to finding relationships between fractal dimensions and mechanical properties. This work focuses on the impact of proposed inoculants on mechanical properties through the distribution of inclusions throughout the metal sample. Keywords: fractal, inclusion, microstructure, inoculants, distribution
{"title":"Fractal parameterization of the inclusion distribution density in the welded joint metal structure","authors":"V. V. Holovko, O. Shtofel, T. Chyzhska","doi":"10.15407/mom2023.02.059","DOIUrl":"https://doi.org/10.15407/mom2023.02.059","url":null,"abstract":"One of the modern proposed methods actively used for diagnosing metal structures is the method of fractal analysis. This method seeks to find the conjunction between the fractal dimension of individual components of the metal structure and its mechanical properties. The comprehensive use of microanalysis and fractal analysis allows not only for comparing structural characteristics but also for finding a numerical parameterization of the elements of this structure. The problem of advance the mechanical properties of welded joints in metal structures remains relevant due to the constant increase in high-strength low-alloy steels used in welded structures. As known, the mechanical properties of welded joints are determined by their structural components, including non-metallic inclusions. A purely qualitative assessment based on the DSTU 8966:2019 standard does not provide an opportunity for a thorough analysis of such an important characteristic as the distribution of inclusions by size and the character of their distribution in the metal matrix. Existing knowledge is based on the peculiarities of the influence of non-metallic inclusions on the mechanical properties of steel welded joints, which requires constant expansion and deepening cognitions, as this work aims to do. The method of fractal analysis allows considering non-metallic inclusions as voids in the metal matrix, which enables parameterization of the inclusion characteristics in the metal structure. The paper describes a methodology that takes into account the distance between inclusions as well as the size of inclusions, which differently affect the mechanical characteristics of the samples. In particular, this article is a continuation of the work [1], which describes an approach to finding relationships between fractal dimensions and mechanical properties. This work focuses on the impact of proposed inoculants on mechanical properties through the distribution of inclusions throughout the metal sample. Keywords: fractal, inclusion, microstructure, inoculants, distribution","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47643729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The features of the structure, the nature of the distribution of alloying elements and impurities between the structural components of sheet low-alloy steels that have undergone heat treatment with exposure in the intercritical temperature interval (ICTI), the structure formation and mechanical properties of these steels after the combined regimes of heat treatment with exposure in the ICIT were investigated. The analysis of the distribution of elements among the structural components of the studied low-alloy steels allowed us to establish that during heat treatment with direct exposure in the ICTI, such elements as manganese, chromium, aluminum, vanadium, sulfur, and phosphorus are concentrated mainly in the strengthening martensitic-bainite phase, while nickel, silicon and titanium are evenly distributed between the strengthening phase and ferrite. The conducted research on the example of sheet low-alloy steel 14G2 shows that the effects of grinding of ferritic grain, peаrlitic and martensitіс (bainite) components during combined processing with exposure in ICTI can be caused by implementation at low (450-550ºС) temperatures of isothermal decomposition the mechanism of multiple nucleation of ferrite microcrystals. It was established that the combined regimes with exposure in ICTI allow, without the application of hardening and tempering operations, to achieve in sheet low-alloy steel 14G2 mechanical properties at the level of strength class 390 according to DSTU 8541:2015 with yield strength values of 422-425 МPа and with high plasticity and impact viscosity Therefore, the use of these modes in a modified form can be recommended for the creation of end-to-end energy-saving technologies of heat treatment with exposure in the ICTI of low-alloyed steel sheet in the flow of thick-sheet mills equipped with normalization units. Keywords: structure formation, intercritical temperature interval, isothermal decomposition, martensitic-bainite phase, combined regime.
{"title":"Структуроутворення та властивості листових конструкційних сталей при режимах ординарної та комбінованої термічної обробки з витримкою в міжкритичному інтервалі температур","authors":"V. L. Plyuta, G. Levchenko, A. Nesterenko","doi":"10.15407/mom2023.01.046","DOIUrl":"https://doi.org/10.15407/mom2023.01.046","url":null,"abstract":"The features of the structure, the nature of the distribution of alloying elements and impurities between the structural components of sheet low-alloy steels that have undergone heat treatment with exposure in the intercritical temperature interval (ICTI), the structure formation and mechanical properties of these steels after the combined regimes of heat treatment with exposure in the ICIT were investigated. The analysis of the distribution of elements among the structural components of the studied low-alloy steels allowed us to establish that during heat treatment with direct exposure in the ICTI, such elements as manganese, chromium, aluminum, vanadium, sulfur, and phosphorus are concentrated mainly in the strengthening martensitic-bainite phase, while nickel, silicon and titanium are evenly distributed between the strengthening phase and ferrite. The conducted research on the example of sheet low-alloy steel 14G2 shows that the effects of grinding of ferritic grain, peаrlitic and martensitіс (bainite) components during combined processing with exposure in ICTI can be caused by implementation at low (450-550ºС) temperatures of isothermal decomposition the mechanism of multiple nucleation of ferrite microcrystals. It was established that the combined regimes with exposure in ICTI allow, without the application of hardening and tempering operations, to achieve in sheet low-alloy steel 14G2 mechanical properties at the level of strength class 390 according to DSTU 8541:2015 with yield strength values of 422-425 МPа and with high plasticity and impact viscosity Therefore, the use of these modes in a modified form can be recommended for the creation of end-to-end energy-saving technologies of heat treatment with exposure in the ICTI of low-alloyed steel sheet in the flow of thick-sheet mills equipped with normalization units. Keywords: structure formation, intercritical temperature interval, isothermal decomposition, martensitic-bainite phase, combined regime.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44914836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
During the operation of soil tillage machines, their working bodies, which are in direct contact with the soil, are exposed to abrasive wear, high contact and dynamic loads, as well as the corrosive effect of the soil. Heavy operating conditions cause intensive wear of such parts. Therefore, works related to increasing the wear resistance of materials intended for the manufacture of working bodies of tillage machines (ploughshares, cultivator paws, disks, chisels, etc.) are relevant. The main strengthening technologies presented on the market for the working bodies of tillage machines are considered. Data on the percentage ratio of the market volume by certain types of strengthening were collected and analyzed. Separate characteristics of the considered methods of strengthening tillage bodies are shown in comparison. To ensure wear resistance and technical resource at the same level as the best foreign analogues, it is recommended that tillage bodies be made by casting from high-strength cast iron, heat treated, reaching its bainite metal base, saturated with carbides, in particular on the surface. It is advisable that one surface layer of the metal be of increased hardness, which will meet the condition of self-sharpening of the working organs during wear. Two methods of hardening are considered to fulfill this condition, in which water is used as a cooling medium for heat treatment of the plow blade. At the same time, a new feature of the isothermal tempering of ploughshares developed by us is the use of heated metal equipment, in the given examples of the quality of which ploughshare casting was used repeatedly. The features and advantages of cooling castings in a fluidized bed of sand are also considered. Replacing expensive materials, alloys and technologies with the use of unalloyed high-strength cast iron with a wear-resistant structure, as well as the use of low-cost casting methods together with thermal strengthening will lead to a significant reduction in the cost of the working bodies of tillage machines. Keywords: technologies of strengthening, quenching, wear, working bodies of soil tillage machines, plow, high -strength cast iron.
{"title":"Сучасні технології зміцнення робочих органів ґрунтообробних машин","authors":"V.S. Doroshenko, P.B. Kaliuzhnyi","doi":"10.15407/mom2023.01.034","DOIUrl":"https://doi.org/10.15407/mom2023.01.034","url":null,"abstract":"During the operation of soil tillage machines, their working bodies, which are in direct contact with the soil, are exposed to abrasive wear, high contact and dynamic loads, as well as the corrosive effect of the soil. Heavy operating conditions cause intensive wear of such parts. Therefore, works related to increasing the wear resistance of materials intended for the manufacture of working bodies of tillage machines (ploughshares, cultivator paws, disks, chisels, etc.) are relevant. The main strengthening technologies presented on the market for the working bodies of tillage machines are considered. Data on the percentage ratio of the market volume by certain types of strengthening were collected and analyzed. Separate characteristics of the considered methods of strengthening tillage bodies are shown in comparison. To ensure wear resistance and technical resource at the same level as the best foreign analogues, it is recommended that tillage bodies be made by casting from high-strength cast iron, heat treated, reaching its bainite metal base, saturated with carbides, in particular on the surface. It is advisable that one surface layer of the metal be of increased hardness, which will meet the condition of self-sharpening of the working organs during wear. Two methods of hardening are considered to fulfill this condition, in which water is used as a cooling medium for heat treatment of the plow blade. At the same time, a new feature of the isothermal tempering of ploughshares developed by us is the use of heated metal equipment, in the given examples of the quality of which ploughshare casting was used repeatedly. The features and advantages of cooling castings in a fluidized bed of sand are also considered. Replacing expensive materials, alloys and technologies with the use of unalloyed high-strength cast iron with a wear-resistant structure, as well as the use of low-cost casting methods together with thermal strengthening will lead to a significant reduction in the cost of the working bodies of tillage machines. Keywords: technologies of strengthening, quenching, wear, working bodies of soil tillage machines, plow, high -strength cast iron.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44665380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The analysis of the state of production of wear-resistant materials showed that one of the promising directions for improving their quality is the use of bimetallic castings, which have a complex of properties differentiated by the volume and surfaces of the products. However, the problem of obtaining a high-quality connection of the base and the working layer has not been solved until now. The article examines the influence of the chemical composition, temperature parameters, and mass ratio of alloys of bimetallic pairs on the process of bimetallic castings formation. The purpose of the study was to study the growth kinetics and structural-phase composition of the transition diffusion layers of bimetallic castings depending on the chemical composition, temperature parameters and the ratio of the masses of the alloys of the bimetallic pairs. As a research result, it was established that the formation of transition layers of bimetallic castings is determined by the processes of diffusion and structural-phase transformations in the interaction zone - "solid - liquid metal". The processes largely depends on the chemical composition of bimetallic pairs, temperature parameters, and the mass ratio of the layers. It was determined that in bimetallic castings obtained by pouring liquid metal onto a preheated solid billet, the transition layer is characterized by the presence of two zones - pearlitic, from the side of the base metal and without the carbide region of the matrix of the working layer. It has been established that the formation of transition layers in bimetallic castings obtained by successive pouring of melts into the mold through autonomous pouring systems is accompanied by the saturation of steel by carbon from cast iron to a depth of 600-800 microns and the formation of a zone with a lamellar pearlite structure along the border of the alloy junction, and the transition layer between cast iron and steel consists of pearlite in the form of a narrow strip and a zone of chromic ferrite from the side of cast iron. As a result of the study of the peculiarities of the formation of transitional layers of bimetallic castings when liquid metal is poured onto a solid billet, it was established that the degree of dissolution of the base metal in liquid cast iron increases with an increase of the billet preheating temperature and the temperature of the melt, as well as the ratio of the mass of liquid cast iron to a unit surface area of the metal base. At the same time, the rate of dissolution is proportional to the gradient between the temperatures of the contact surface and the cast iron solidus. It was established that the formation of a reliable diffusion bond for bimetallic pairs "carbon (low-alloy) steel - high-chromium cast iron" is ensured if the temperature of the contact surface exceeds the temperature of the eutectic transformation of cast iron. The mechanism is revealed of formation of the transition zone structure. The materials of the art
{"title":"Дослідження процесу формування біметалевих виливків дробильно-розмельного обладнання","authors":"Ye. Aftandiliants","doi":"10.15407/mom2023.01.003","DOIUrl":"https://doi.org/10.15407/mom2023.01.003","url":null,"abstract":"The analysis of the state of production of wear-resistant materials showed that one of the promising directions for improving their quality is the use of bimetallic castings, which have a complex of properties differentiated by the volume and surfaces of the products. However, the problem of obtaining a high-quality connection of the base and the working layer has not been solved until now. The article examines the influence of the chemical composition, temperature parameters, and mass ratio of alloys of bimetallic pairs on the process of bimetallic castings formation. The purpose of the study was to study the growth kinetics and structural-phase composition of the transition diffusion layers of bimetallic castings depending on the chemical composition, temperature parameters and the ratio of the masses of the alloys of the bimetallic pairs. As a research result, it was established that the formation of transition layers of bimetallic castings is determined by the processes of diffusion and structural-phase transformations in the interaction zone - \"solid - liquid metal\". The processes largely depends on the chemical composition of bimetallic pairs, temperature parameters, and the mass ratio of the layers. It was determined that in bimetallic castings obtained by pouring liquid metal onto a preheated solid billet, the transition layer is characterized by the presence of two zones - pearlitic, from the side of the base metal and without the carbide region of the matrix of the working layer. It has been established that the formation of transition layers in bimetallic castings obtained by successive pouring of melts into the mold through autonomous pouring systems is accompanied by the saturation of steel by carbon from cast iron to a depth of 600-800 microns and the formation of a zone with a lamellar pearlite structure along the border of the alloy junction, and the transition layer between cast iron and steel consists of pearlite in the form of a narrow strip and a zone of chromic ferrite from the side of cast iron. As a result of the study of the peculiarities of the formation of transitional layers of bimetallic castings when liquid metal is poured onto a solid billet, it was established that the degree of dissolution of the base metal in liquid cast iron increases with an increase of the billet preheating temperature and the temperature of the melt, as well as the ratio of the mass of liquid cast iron to a unit surface area of the metal base. At the same time, the rate of dissolution is proportional to the gradient between the temperatures of the contact surface and the cast iron solidus. It was established that the formation of a reliable diffusion bond for bimetallic pairs \"carbon (low-alloy) steel - high-chromium cast iron\" is ensured if the temperature of the contact surface exceeds the temperature of the eutectic transformation of cast iron. The mechanism is revealed of formation of the transition zone structure. The materials of the art","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43612687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The friction mechanisms of brake pads made of cast iron and composite material (rubber-asbestos or rubber-free mixtures, including those with cast-iron inserts) on the surface of wheels of railway rolling stock were analysed. Values of the friction coefficient are given. The main role in the mechanism of friction of cast iron pads on the surface of railway wheels belongs to the microstructure of cast iron, namely, the amount, shape, distribution in volume of graphite inclusions, dispersion of pearlite and cementite inclusions, and the construction of phosphide eutectics. The friction mechanism of pads made of composite material on the wheel surface is determined by the content and properties of the components from which the composite rubber mixture is formed, their chemical and granulometric composition, as well as the degree of burnout of the composite rubber mixture during the operation of the brake pads. It is shown that due to the lack of regulation in the standards and technical conditions for composite blocks of the percentage content of ingredients and their chemical composition in the composite material, its properties and the value of the coefficient of friction are uncontrolled. Cyclic temperature changes on the contact surface of the brake pads with the wheels during train braking and high peak temperatures (up to 800 °C) in individual periods of braking lead to changes in the structure and properties of the surface layer of the metal of the wheels and the material of the brake pads. This is reflected in the frictional characteristics of the friction process of brake pads with wheels. The disadvantage of brake pads made of composite material is their low thermal conductivity compared to cast iron pads. As a result, the temperature in the contact zone of composite pads with wheels increases more than when using pads made of cast iron. The hydrodynamic effects of moisture (water) in the contact zone of brake pads with the surface of vehicle wheels are considered from the standpoint of classical tribology approaches. The microrelief of the working surface of the brake pads was studied. The influence of various factors on the coefficient of friction of the brake pads on the surface of the wheels is shown. Recommendations are provided for improving standards and technical conditions for brake pads made of cast iron and other materials. Keywords: brake pads, wheels of railway transport, friction, cast iron, composite materials, surface microrelief.
{"title":"Механізм тертя гальмових колодок з чавуну та композиційного матеріалу по поверхні коліс залізничного транспорту","authors":"","doi":"10.15407/mom2023.01.018","DOIUrl":"https://doi.org/10.15407/mom2023.01.018","url":null,"abstract":"The friction mechanisms of brake pads made of cast iron and composite material (rubber-asbestos or rubber-free mixtures, including those with cast-iron inserts) on the surface of wheels of railway rolling stock were analysed. Values of the friction coefficient are given. The main role in the mechanism of friction of cast iron pads on the surface of railway wheels belongs to the microstructure of cast iron, namely, the amount, shape, distribution in volume of graphite inclusions, dispersion of pearlite and cementite inclusions, and the construction of phosphide eutectics. The friction mechanism of pads made of composite material on the wheel surface is determined by the content and properties of the components from which the composite rubber mixture is formed, their chemical and granulometric composition, as well as the degree of burnout of the composite rubber mixture during the operation of the brake pads. It is shown that due to the lack of regulation in the standards and technical conditions for composite blocks of the percentage content of ingredients and their chemical composition in the composite material, its properties and the value of the coefficient of friction are uncontrolled. Cyclic temperature changes on the contact surface of the brake pads with the wheels during train braking and high peak temperatures (up to 800 °C) in individual periods of braking lead to changes in the structure and properties of the surface layer of the metal of the wheels and the material of the brake pads. This is reflected in the frictional characteristics of the friction process of brake pads with wheels. The disadvantage of brake pads made of composite material is their low thermal conductivity compared to cast iron pads. As a result, the temperature in the contact zone of composite pads with wheels increases more than when using pads made of cast iron. The hydrodynamic effects of moisture (water) in the contact zone of brake pads with the surface of vehicle wheels are considered from the standpoint of classical tribology approaches. The microrelief of the working surface of the brake pads was studied. The influence of various factors on the coefficient of friction of the brake pads on the surface of the wheels is shown. Recommendations are provided for improving standards and technical conditions for brake pads made of cast iron and other materials. Keywords: brake pads, wheels of railway transport, friction, cast iron, composite materials, surface microrelief.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45090387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. P. Gaponova, V. Okhrimenko, N.V. Tarelnik, O.M. Myslyvchenko
The work shows studies aimed at developing methods for protection of structural steels on the example of steels 20 and 40, from wear, using the electricity spark alloying (ESA), by applying the nitrogen-like mixture on the treated surface with subsequent vanity of steel electrode appropriate to the material of the workpiece. To increase the thickness of the surface layer and the best adhesion of the coating is offered in front of the ESA electrode-tools made of steel of the corresponding brand, to form a mold of aluminum, using an electrode from the aluminum bar of the brand of blood pressure. Metrolographic studies were performed and the distribution of microtrandomness in the coating. Studies have shown that nitrogen -containing coatings consist of a "white" layer ", which smoothly goes into the diffusion zone and base metal. The obtained coatings have the highest thickness of "white layer" 110-130 microns. The results of the study of the micro-hardness of the obtained nitrogen-containing coatings indicate an increase in hardness to 9700-9910 MPa. The phase composition of nitrogen coatings is represented by a alloy solid and cubic iron nitride, aluminum dissolves in nitride and ferrite. The considered methods of application of nitrogen -containing coatings can be used to strengthen the surface of responsible parts and elements of pumping and compressor equipment: end surfaces of rings, for protective bushings; piston machines, mechanisms that have increased wear of the product, etc. Keywords: electro-spark alloying, microstructure, nitriding, steel, phase analysis.
{"title":"Вдосконалення технології азотування методом електроіскрового легування","authors":"O. P. Gaponova, V. Okhrimenko, N.V. Tarelnik, O.M. Myslyvchenko","doi":"10.15407/mom2023.01.058","DOIUrl":"https://doi.org/10.15407/mom2023.01.058","url":null,"abstract":"The work shows studies aimed at developing methods for protection of structural steels on the example of steels 20 and 40, from wear, using the electricity spark alloying (ESA), by applying the nitrogen-like mixture on the treated surface with subsequent vanity of steel electrode appropriate to the material of the workpiece. To increase the thickness of the surface layer and the best adhesion of the coating is offered in front of the ESA electrode-tools made of steel of the corresponding brand, to form a mold of aluminum, using an electrode from the aluminum bar of the brand of blood pressure. Metrolographic studies were performed and the distribution of microtrandomness in the coating. Studies have shown that nitrogen -containing coatings consist of a \"white\" layer \", which smoothly goes into the diffusion zone and base metal. The obtained coatings have the highest thickness of \"white layer\" 110-130 microns. The results of the study of the micro-hardness of the obtained nitrogen-containing coatings indicate an increase in hardness to 9700-9910 MPa. The phase composition of nitrogen coatings is represented by a alloy solid and cubic iron nitride, aluminum dissolves in nitride and ferrite. The considered methods of application of nitrogen -containing coatings can be used to strengthen the surface of responsible parts and elements of pumping and compressor equipment: end surfaces of rings, for protective bushings; piston machines, mechanisms that have increased wear of the product, etc. Keywords: electro-spark alloying, microstructure, nitriding, steel, phase analysis.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47870600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Loktionov-Remizovsky V. A., Shipitsyn S. Y., Novitsky V. G., Kiryakova N. V., Yurchenko P. S., Oleksenko I.V.
The intensity of wear of graphitized eutectoid steels with a carbon content in the range of 1.1÷1.7%, by weight was investigated. The effectiveness of the effect of copper doping on the wear of eutectoid steels in the cast state has been determined. It was established that under conditions of dry friction by sliding and taking into account the friction parameters in the sealing units the temperature on the worn surface and in the thin near-surface layer should exceed 1100 0С, at such temperatures and copper content more than 12%, by weight, in the binary system Fe-Cu there is a two-phase region +-phase, and - phase, exists in the state of liquid and acts as a lubricant, the wear mode goes from dry to limiting. Lines of existence of -phases in the liquid state are constructed. The results of studies of the effect of copper on the intensity of wear of steels with different carbon content, under conditions of dry friction by slipping, indicated that regardless of the amount of carbon, doping of alloys with copper significantly reduces their intensity of wear to copper content at the level of 10-12%, by weight, a further increase in copper doping equalizes the effectiveness of the impact and reduces the intensity of wear. Alloying of steels with copper of 12% or more causes the formation of a copper phase film on the friction surface. Under the condition of alloying steel with copper less than 12%, the steel structure contains -phase, as a product of a three-phase eutectoid reaction and as a decomposition product of supersaturated solid iron solution. As the copper content in steel increases, the amount of copper phase in the steel structure and its amount on the contact surface increases, after reaching the copper content in the steel sufficient to form the primary grains of the copper phase, the formation of a stable layer of copper on the contact surface begins, which is the constant boundary layer of copper -phase in the liquid state. Keywords: steel, copper, carbon, alloying, wear resistance, friction.
{"title":"The effectiveness of the effect of copper doping on the wear of eutectoid steels","authors":"Loktionov-Remizovsky V. A., Shipitsyn S. Y., Novitsky V. G., Kiryakova N. V., Yurchenko P. S., Oleksenko I.V.","doi":"10.15407/mom2022.04.030","DOIUrl":"https://doi.org/10.15407/mom2022.04.030","url":null,"abstract":"The intensity of wear of graphitized eutectoid steels with a carbon content in the range of 1.1÷1.7%, by weight was investigated. The effectiveness of the effect of copper doping on the wear of eutectoid steels in the cast state has been determined. It was established that under conditions of dry friction by sliding and taking into account the friction parameters in the sealing units the temperature on the worn surface and in the thin near-surface layer should exceed 1100 0С, at such temperatures and copper content more than 12%, by weight, in the binary system Fe-Cu there is a two-phase region +-phase, and - phase, exists in the state of liquid and acts as a lubricant, the wear mode goes from dry to limiting. Lines of existence of -phases in the liquid state are constructed. The results of studies of the effect of copper on the intensity of wear of steels with different carbon content, under conditions of dry friction by slipping, indicated that regardless of the amount of carbon, doping of alloys with copper significantly reduces their intensity of wear to copper content at the level of 10-12%, by weight, a further increase in copper doping equalizes the effectiveness of the impact and reduces the intensity of wear. Alloying of steels with copper of 12% or more causes the formation of a copper phase film on the friction surface. Under the condition of alloying steel with copper less than 12%, the steel structure contains -phase, as a product of a three-phase eutectoid reaction and as a decomposition product of supersaturated solid iron solution. As the copper content in steel increases, the amount of copper phase in the steel structure and its amount on the contact surface increases, after reaching the copper content in the steel sufficient to form the primary grains of the copper phase, the formation of a stable layer of copper on the contact surface begins, which is the constant boundary layer of copper -phase in the liquid state. Keywords: steel, copper, carbon, alloying, wear resistance, friction.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43565106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, was conducted research to improve the structure and properties of cast magnesium alloy NZ30K by doping with gold, for use in osteosynthesis. Gold is a safe alloying element for the human body. The effect of alloying 0.05%, 0.1% and 0.2% Au of magnesium alloy NZ30K was investigated in this work. A qualitative and quantitative assessment of the structural components of the alloy was carried out. It was shown that gold was part of the complex doped intermetallic phases, which were additional centers of crystallization. It was established that the optimal complex of properties is achieved by introducing 0.1%Au. At the same time, the average grain size is reduced by 52.4% compared to the original alloy. It was found that for the NZ30K+0.1%Au alloy, simultaneous increase in the strength limit by 7.8% and increase in the relative elongation by almost two times was observed. It was investigated the possibility of using a biodegradable magnesium alloy in the manufacture of fixators during osteosynthesis, biocorrosion processes. It was found that the addition of 0.1% Au slows down the biocorrosion processes and contributes to maintaining a high level of strength limit (σB = 200MPa) after exposure for 6 months in a gelofusin solution. Therefore, gold is a promising material for improving the structure and improving the properties of biodegradable magnesium alloy implants. Keywords: NZ30K, gold, biodegradable implants, microstructure, X-ray spectral microanalysis, mechanical properties, biocorrosion.
{"title":"The influence of gold alloying on the structure and properties of the NZ30K magnesium alloy","authors":"Greshta V. L., Shalomeev V. A., Dzhus A.V.","doi":"10.15407/mom2022.04.003","DOIUrl":"https://doi.org/10.15407/mom2022.04.003","url":null,"abstract":"In this work, was conducted research to improve the structure and properties of cast magnesium alloy NZ30K by doping with gold, for use in osteosynthesis. Gold is a safe alloying element for the human body. The effect of alloying 0.05%, 0.1% and 0.2% Au of magnesium alloy NZ30K was investigated in this work. A qualitative and quantitative assessment of the structural components of the alloy was carried out. It was shown that gold was part of the complex doped intermetallic phases, which were additional centers of crystallization. It was established that the optimal complex of properties is achieved by introducing 0.1%Au. At the same time, the average grain size is reduced by 52.4% compared to the original alloy. It was found that for the NZ30K+0.1%Au alloy, simultaneous increase in the strength limit by 7.8% and increase in the relative elongation by almost two times was observed. It was investigated the possibility of using a biodegradable magnesium alloy in the manufacture of fixators during osteosynthesis, biocorrosion processes. It was found that the addition of 0.1% Au slows down the biocorrosion processes and contributes to maintaining a high level of strength limit (σB = 200MPa) after exposure for 6 months in a gelofusin solution. Therefore, gold is a promising material for improving the structure and improving the properties of biodegradable magnesium alloy implants. Keywords: NZ30K, gold, biodegradable implants, microstructure, X-ray spectral microanalysis, mechanical properties, biocorrosion.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47685252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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