Pub Date : 2022-09-15DOI: 10.17212/1994-6309-2022-24.3-22-39
A. Ilinykh, V. Banul, D. Vorontsov
Introduction. There are different rail machining technologies designed to eliminate defects on the tread surface and extend the life cycle of rails. The most used is the technology of grinding rails with rotating grinding wheels using rail-grinding trains. Its main disadvantage is the low working speed of the grinding train that requires the organization of track possessions with stopping the movement of trains along the haul. To perform preventive rail grinding with minimal metal removal from the rail head, passive grinding technologies using grinding wheels have become widespread in last years. Passive grinding is when there is no power on the grinding wheel to rotate it actively. Such methods make it possible to achieve high speeds of the grinding train, and the work can be carried out in the train schedule without closing the stage. Currently, passive grinding technologies are relatively new and do not have the necessary scientific basis for optimizing the machining process. The aim of the work is to perform theoretical studies of kinematic and force analyzes of two methods of rail passive grinding: the periphery and the end face of the grinding wheel. Methodology of the work is kinematic and power calculations of rail grinding schemes. Results and discussion. Within the framework of theoretical studies, a kinematic and force analysis of two methods of passive grinding are carried out, on the basis of which the optimal conditions for its implementation are determined. It is established that the method of passive grinding by the periphery of the wheel has a 20 % higher productivity and energy efficiency of the process before end passive grinding due to the higher rotation speed of the grinding wheel with equal forces of pressing it to the rail. At the same time, passive grinding with the end of the wheel is distinguished by a twice greater range of change in both the speed of the grinding wheel rotation and the force of its pressing that makes it possible to achieve greater metal removal at equal speeds of the grinding trains. In conclusion, promising tasks for further research in the field of passive rail grinding are formulated.
{"title":"Theoretical analysis of passive rail grinding","authors":"A. Ilinykh, V. Banul, D. Vorontsov","doi":"10.17212/1994-6309-2022-24.3-22-39","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.3-22-39","url":null,"abstract":"Introduction. There are different rail machining technologies designed to eliminate defects on the tread surface and extend the life cycle of rails. The most used is the technology of grinding rails with rotating grinding wheels using rail-grinding trains. Its main disadvantage is the low working speed of the grinding train that requires the organization of track possessions with stopping the movement of trains along the haul. To perform preventive rail grinding with minimal metal removal from the rail head, passive grinding technologies using grinding wheels have become widespread in last years. Passive grinding is when there is no power on the grinding wheel to rotate it actively. Such methods make it possible to achieve high speeds of the grinding train, and the work can be carried out in the train schedule without closing the stage. Currently, passive grinding technologies are relatively new and do not have the necessary scientific basis for optimizing the machining process. The aim of the work is to perform theoretical studies of kinematic and force analyzes of two methods of rail passive grinding: the periphery and the end face of the grinding wheel. Methodology of the work is kinematic and power calculations of rail grinding schemes. Results and discussion. Within the framework of theoretical studies, a kinematic and force analysis of two methods of passive grinding are carried out, on the basis of which the optimal conditions for its implementation are determined. It is established that the method of passive grinding by the periphery of the wheel has a 20 % higher productivity and energy efficiency of the process before end passive grinding due to the higher rotation speed of the grinding wheel with equal forces of pressing it to the rail. At the same time, passive grinding with the end of the wheel is distinguished by a twice greater range of change in both the speed of the grinding wheel rotation and the force of its pressing that makes it possible to achieve greater metal removal at equal speeds of the grinding trains. In conclusion, promising tasks for further research in the field of passive rail grinding are formulated.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49593044","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-78-90
A. Burkov, M. Kulik, Alexander Belya, V. Krutikova
Introduction. Austenitic stainless steel AISI 304 is the most widely used type of stainless steel. However, it is subject to wear due to relatively low hardness, and also begins to oxidize intensively in air at a temperature above 800 °C. The use of coatings based on chromium boride can improve its tribotechnical properties and oxidation resistance. The purpose of the work: to study the effect of chromium diboride concentration in the anode mixture on the structure, wear behavior, oxidation resistance and corrosion properties of electric spark coatings on AISI 304 steel. The research methods. Electric spark treatment of AISI 304 steel was carried out in a mixture of iron granules with the addition of CrB2 powder in amount of 5, 10 and 15 vol.%. The structure of the coatings was studied by X-ray analysis, scanning electron microscopy, and electron dispersion spectroscopy analysis. The wear resistance of the coatings was studied under dry friction condition at a load of 10 N. The oxidation resistance test was carried out at a temperature of 900 °C for 100 hours. Results and Discussion. According to X-ray analysis, it is shown that under the conditions of electric spark exposure, CrB2 interacts with iron melt; this has resulted in the formation of chromium and iron borides. Corrosion properties, microhardness, coefficient of friction and wear are investigated in comparison with AISI 304 steel. Samples with coatings showed a lower corrosion potential and corrosion current density compared to the substrate in 3.5% NaCl solution and from 5 to 15 times higher oxidation resistance. The microhardness of the coatings increased from 6.25 to 7.60 GPa with an increase in the addition of chromium diboride in the electrode mixture. The coefficient of friction and the wear rate of all coatings were lower than that of AISI 304 stainless steel, while the coating prepared with the addition of 5 vol.% chromium diboride had the best tribotechnical characteristics.
{"title":"Electrospark deposition of chromium diboride powder on stainless steel AISI 304","authors":"A. Burkov, M. Kulik, Alexander Belya, V. Krutikova","doi":"10.17212/1994-6309-2022-24.2-78-90","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-78-90","url":null,"abstract":"Introduction. Austenitic stainless steel AISI 304 is the most widely used type of stainless steel. However, it is subject to wear due to relatively low hardness, and also begins to oxidize intensively in air at a temperature above 800 °C. The use of coatings based on chromium boride can improve its tribotechnical properties and oxidation resistance. The purpose of the work: to study the effect of chromium diboride concentration in the anode mixture on the structure, wear behavior, oxidation resistance and corrosion properties of electric spark coatings on AISI 304 steel. The research methods. Electric spark treatment of AISI 304 steel was carried out in a mixture of iron granules with the addition of CrB2 powder in amount of 5, 10 and 15 vol.%. The structure of the coatings was studied by X-ray analysis, scanning electron microscopy, and electron dispersion spectroscopy analysis. The wear resistance of the coatings was studied under dry friction condition at a load of 10 N. The oxidation resistance test was carried out at a temperature of 900 °C for 100 hours. Results and Discussion. According to X-ray analysis, it is shown that under the conditions of electric spark exposure, CrB2 interacts with iron melt; this has resulted in the formation of chromium and iron borides. Corrosion properties, microhardness, coefficient of friction and wear are investigated in comparison with AISI 304 steel. Samples with coatings showed a lower corrosion potential and corrosion current density compared to the substrate in 3.5% NaCl solution and from 5 to 15 times higher oxidation resistance. The microhardness of the coatings increased from 6.25 to 7.60 GPa with an increase in the addition of chromium diboride in the electrode mixture. The coefficient of friction and the wear rate of all coatings were lower than that of AISI 304 stainless steel, while the coating prepared with the addition of 5 vol.% chromium diboride had the best tribotechnical characteristics.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42816327","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-39-49
Y. Loginov, G. Shimov, N. Bushueva
Introduction. It is noted that extrusion is the main procurement process in the aluminum alloys forming operations. At the same time, the process has such a disadvantage as the nonstationarity of the metal plastic flow. The work aim is to establish the inhomogeneity deformation level of the pressed rod front part by numerical simulation using the finite element method. The study objectives are to formulate the extrusion process boundary conditions, to obtain a solution and to evaluate the inhomogeneity degree. Research methods: the finite element method was used to evaluate the deformed state. The actions sequence included the creation of primary deformation zone shape and the tool configuration. The mutual movement of the tool and the deformable material is set using the appropriate boundary conditions. The deformable medium is a ductile material with power-law hardening, the physical and mechanical properties correspond to the aluminum alloy of the 6000 series. Results and discussion: It is revealed that the strain degree in the pressed rod front part is extremely nonuniform distributed; differences above 300% are recorded. The strain degree distribution dependences in the rod cross sections are constructed depending on the distance from the front end at different relative radial coordinates. It is revealed that the rod central layers acquire a constant level of the strain degree earlier than the peripheral layers. The stationary process is achieved with less metal motion. The work result application scope is the technological study of rational metal cutting of aluminum alloys at the extrusion final stage in order to use recyclable waste more rationally. Conclusions. In the extrusion process with a low elongation ratio, the strain degree is distributed nonuniform both along the press rod cross and along its length. The rod front part remains weakly deformed both at the periphery and in the center in the nonstationary initial extrusion stage. It often forces to send for remelting due to the insufficiently developed metal structure. At the same time, if the limits on the minimum possible degree of deformation are set, then using the results of the calculation by the finite element method, the minimum length of the metal to be removed can be set, thereby reducing the mass of waste sent for remelting.
{"title":"Deformations in the nonstationary stage of aluminum alloy rod extrusion process with a low elongation ratio","authors":"Y. Loginov, G. Shimov, N. Bushueva","doi":"10.17212/1994-6309-2022-24.2-39-49","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-39-49","url":null,"abstract":"Introduction. It is noted that extrusion is the main procurement process in the aluminum alloys forming operations. At the same time, the process has such a disadvantage as the nonstationarity of the metal plastic flow. The work aim is to establish the inhomogeneity deformation level of the pressed rod front part by numerical simulation using the finite element method. The study objectives are to formulate the extrusion process boundary conditions, to obtain a solution and to evaluate the inhomogeneity degree. Research methods: the finite element method was used to evaluate the deformed state. The actions sequence included the creation of primary deformation zone shape and the tool configuration. The mutual movement of the tool and the deformable material is set using the appropriate boundary conditions. The deformable medium is a ductile material with power-law hardening, the physical and mechanical properties correspond to the aluminum alloy of the 6000 series. Results and discussion: It is revealed that the strain degree in the pressed rod front part is extremely nonuniform distributed; differences above 300% are recorded. The strain degree distribution dependences in the rod cross sections are constructed depending on the distance from the front end at different relative radial coordinates. It is revealed that the rod central layers acquire a constant level of the strain degree earlier than the peripheral layers. The stationary process is achieved with less metal motion. The work result application scope is the technological study of rational metal cutting of aluminum alloys at the extrusion final stage in order to use recyclable waste more rationally. Conclusions. In the extrusion process with a low elongation ratio, the strain degree is distributed nonuniform both along the press rod cross and along its length. The rod front part remains weakly deformed both at the periphery and in the center in the nonstationary initial extrusion stage. It often forces to send for remelting due to the insufficiently developed metal structure. At the same time, if the limits on the minimum possible degree of deformation are set, then using the results of the calculation by the finite element method, the minimum length of the metal to be removed can be set, thereby reducing the mass of waste sent for remelting.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48262556","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-25-38
E. Shlykov, Timir Ablyaz, K. Muratov
Introduction. Polymer composite materials (PCM) are used to improve the mechanical properties and increase the working period of products. For the processing of products made of PCM, the use of electrophysical processing methods is standard. One of these methods is copy-piercing electrical discharge machining (EDM). The use of such methods for processing PCM is due to its high physical and mechanical characteristics and the complexity of processing by blade methods. Considering the fact that the PCM element is a binder – epoxy resin, which is destroyed at the edges of the resulting holes and grooves during EDM, PCM can be considered difficult to process. During the EDM of holes in PCM products, the temperature rises, and inefficient cooling often occurs in the processing zone. The paper is devoted to theoretical simulation in the Ansys package, which makes it possible to evaluate the impact of flushing method on the efficiency of the EDM of PCM products based on numerical simulation in finite element analysis software systems. The aim of the work is to increase the productivity of the processes of EDM for PCM products. Methods. Experimental studies were carried out according to the method of a classical experiment on a copy-piercing electrical discharge Smart CNC machine. The workpiece was processed at a constant voltage U = 50 V, pulse on-time Ton = 100 µs and current: I = 10 A. For theoretical simulation of the flow, the ANSYS CFX 20.1 software was used. Flow distribution simulation was carried out at three processing depths (2 mm, 10 mm, 15 mm), as well as at three nozzle inclination angles (15°, 45°, 75°). Results And Discussion. The analysis of the data obtained showed that in the case of the EDM of PCM, the angle of the location of the flushing nozzles should be taken into account in order to increase the productivity of processing deep, blind holes. It is established that the highest performance value is achieved when the nozzles are located at an angle of 15˚. The laminar motion prevails. With this arrangement of the nozzles, the value of the liquid pressure and the removal of the sludge are stable both with the EDM of PCM to a depth of 2 mm, and when processing to a depth of 15 mm. It is noted that for processing holes with a depth of 10 mm or more, it is worth considering the angle of inclination of the flushing nozzle for effective processing, it is necessary to remove eroded particles from the gap. In the process of conducting an experimental study, when processing holes with a depth of 15 mm, sticking of sludge to the electrode-tool was observed, as well as the closure of the EDM process, the occurrence of secondary discharges in the processing zone, which caused the processing to stop.
{"title":"Theoretical simulation of the process interelectrode space flushing during copy-piercing EDM of products made of polymer composite materials","authors":"E. Shlykov, Timir Ablyaz, K. Muratov","doi":"10.17212/1994-6309-2022-24.2-25-38","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-25-38","url":null,"abstract":"Introduction. Polymer composite materials (PCM) are used to improve the mechanical properties and increase the working period of products. For the processing of products made of PCM, the use of electrophysical processing methods is standard. One of these methods is copy-piercing electrical discharge machining (EDM). The use of such methods for processing PCM is due to its high physical and mechanical characteristics and the complexity of processing by blade methods. Considering the fact that the PCM element is a binder – epoxy resin, which is destroyed at the edges of the resulting holes and grooves during EDM, PCM can be considered difficult to process. During the EDM of holes in PCM products, the temperature rises, and inefficient cooling often occurs in the processing zone. The paper is devoted to theoretical simulation in the Ansys package, which makes it possible to evaluate the impact of flushing method on the efficiency of the EDM of PCM products based on numerical simulation in finite element analysis software systems. The aim of the work is to increase the productivity of the processes of EDM for PCM products. Methods. Experimental studies were carried out according to the method of a classical experiment on a copy-piercing electrical discharge Smart CNC machine. The workpiece was processed at a constant voltage U = 50 V, pulse on-time Ton = 100 µs and current: I = 10 A. For theoretical simulation of the flow, the ANSYS CFX 20.1 software was used. Flow distribution simulation was carried out at three processing depths (2 mm, 10 mm, 15 mm), as well as at three nozzle inclination angles (15°, 45°, 75°). Results And Discussion. The analysis of the data obtained showed that in the case of the EDM of PCM, the angle of the location of the flushing nozzles should be taken into account in order to increase the productivity of processing deep, blind holes. It is established that the highest performance value is achieved when the nozzles are located at an angle of 15˚. The laminar motion prevails. With this arrangement of the nozzles, the value of the liquid pressure and the removal of the sludge are stable both with the EDM of PCM to a depth of 2 mm, and when processing to a depth of 15 mm. It is noted that for processing holes with a depth of 10 mm or more, it is worth considering the angle of inclination of the flushing nozzle for effective processing, it is necessary to remove eroded particles from the gap. In the process of conducting an experimental study, when processing holes with a depth of 15 mm, sticking of sludge to the electrode-tool was observed, as well as the closure of the EDM process, the occurrence of secondary discharges in the processing zone, which caused the processing to stop.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49046950","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-6-24
S. Timofeev, A. Grinek, A. Hurtasenko, I. Boychuk
Introduction. The development of a method for controlling the accuracy parameters of large axisymmetric bodies is an urgent task that is being solved by specialists from various industries. Application for adjustment and correction of machining based on the measurement of surface shape parameters directly during machining is shown. Purpose of work is to improve mobile processing technologies using special measuring devices and processing module. For this, the problems of development and analysis of mathematical models that describe the process of basing and machining of a riding ring as a cylindrical object with a non-stationary axis of rotation is solved. A study of the methodology is carried out, control schemes are designed, and equipment for processing mobile devices is developed. The methods of research are the analysis of the developed mathematical models, taking into account the assignment of effective technological modes. Three-dimensional and simulation modeling of processing, hardware-software implementation of proposed solutions, and statistical processing of measurement results are carried out. Results and discussion. The algorithm and methodology are tested with a three-dimensional simulation model. The presented methodology for measuring and calculating the allowance for mechanical restoration can significantly reduce machining time compared to active form control and compared to the traditional method of assigning an allowance for machining. The measurement and adjustment of the allowance based on the measurement data is not carried out after each measurement, but only in the case of transition to finishing transitions or for accuracy control. It is determined that by providing a single technological base for each individual technological transition within the framework of the mobile technology of machining of the rolling surface of the riding rings of technological drums, the accuracy and speed of processing increase. An original design of the device for monitoring parameters is developed; an experimental assembly and a laboratory model of the riding ring are made.
{"title":"Machining technology, digital modelling and shape control device for large parts","authors":"S. Timofeev, A. Grinek, A. Hurtasenko, I. Boychuk","doi":"10.17212/1994-6309-2022-24.2-6-24","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-6-24","url":null,"abstract":"Introduction. The development of a method for controlling the accuracy parameters of large axisymmetric bodies is an urgent task that is being solved by specialists from various industries. Application for adjustment and correction of machining based on the measurement of surface shape parameters directly during machining is shown. Purpose of work is to improve mobile processing technologies using special measuring devices and processing module. For this, the problems of development and analysis of mathematical models that describe the process of basing and machining of a riding ring as a cylindrical object with a non-stationary axis of rotation is solved. A study of the methodology is carried out, control schemes are designed, and equipment for processing mobile devices is developed. The methods of research are the analysis of the developed mathematical models, taking into account the assignment of effective technological modes. Three-dimensional and simulation modeling of processing, hardware-software implementation of proposed solutions, and statistical processing of measurement results are carried out. Results and discussion. The algorithm and methodology are tested with a three-dimensional simulation model. The presented methodology for measuring and calculating the allowance for mechanical restoration can significantly reduce machining time compared to active form control and compared to the traditional method of assigning an allowance for machining. The measurement and adjustment of the allowance based on the measurement data is not carried out after each measurement, but only in the case of transition to finishing transitions or for accuracy control. It is determined that by providing a single technological base for each individual technological transition within the framework of the mobile technology of machining of the rolling surface of the riding rings of technological drums, the accuracy and speed of processing increase. An original design of the device for monitoring parameters is developed; an experimental assembly and a laboratory model of the riding ring are made.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49363068","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-50-66
S. Sundukov
Introduction. The main problem in obtaining welded joints is the nonuniform heating of the joint zone, which leads to differences in the structure and properties of the weld metal and the base metal. One of the ways to intensify the welding process is the use of ultrasonic vibrations. As a result of the analysis of methods for introducing ultrasonic vibrations into the melting zone, a method of superimposing vibrations on the elements to be welded was chosen for experimental studies. This method makes it possible to influence the welded elements throughout the entire welding cycle from the melt bath to complete crystallization of the metal. Methods. Experimental studies were carried out on plates made of carbon structural steel St3 (ASTM A568M, AISI 1017, DIN 17100) and aluminum deformable non-hardened alloy AMg4 (EN AW-5086, AW-AL Mg4, 5086). As a source of oscillations, a rod magnetostrictive oscillatory system was used, the end of which was rigidly fixed on one of the welded plates. To determine the places of application of the oscillation source and the welding zone, a calculation method is proposed based on the equality of the resonant frequencies of the used oscillatory system and the natural frequency of bending vibrations of the welding component. It is shown that the optimal places for the application of vibrations and welding will be the antinodes of oscillations, which have the maximum amplitude. Welds were obtained by the method of semi-automatic gas metal arc welding. Results and Discussion. Microstructural study of obtained samples showed a significant decrease in the proportion of dendritic segregation. The changes in the structure are the result of the effects that occur in the liquid melt when ultrasonic vibrations are introduced. The main effects are sound pressure, cavitation and acoustical streaming. The structure change mechanism consists in the dispersion of growing dendrites and crystallization nuclei under the action of shock waves and cumulative jets that occur when cavitation bubbles collapse. The formed fragments of dendrites are new crystallization nuclei that propagate through the melt pool under the action of acoustic currents. Then the process is repeated. The resulting effects affect the kinetics of the crystallization process – the degree of supercooling increases, the number of crystallization nuclei formed per unit time increases, and the rate of its growth decreases. Changes in the structure of the weld metal lead to an increase in the quality of the welded joint, which reduces welding deformations, increases the tensile strength and significantly increases ductility.
介绍。焊接接头的主要问题是接头区加热不均匀，导致焊缝金属和母材的组织和性能存在差异。强化焊接过程的方法之一是使用超声波振动。通过对将超声振动引入熔区方法的分析，选择了在待焊构件上叠加振动的方法进行实验研究。这种方法可以在从熔浴到金属完全结晶的整个焊接周期中影响被焊接元件。方法。在碳素结构钢St3 (ASTM A568M, AISI 1017, DIN 17100)和铝可变形非硬化合金AMg4 (EN AW-5086, AW-AL Mg4, 5086)板上进行了实验研究。作为振荡源，采用棒磁致伸缩振荡系统，其末端刚性固定在其中一块焊接板上。为了确定振荡源的应用位置和焊接区域，提出了一种基于所用振荡系统的谐振频率与焊接构件弯曲振动固有频率相等的计算方法。结果表明，振动和焊接的最佳应用位置是振幅最大的振荡正极。采用半自动气体保护金属电弧焊进行焊接。结果和讨论。所得样品的显微组织研究表明，枝晶偏析的比例显著降低。结构的变化是在引入超声波振动时发生在液体熔体中的效应的结果。主要的影响是声压、空化和声流。其结构变化机制是在空化气泡崩塌时产生的激波和累积射流作用下生长的枝晶和结晶核的弥散。形成的枝晶碎片是在声电流作用下在熔池中传播的新的结晶核。然后重复这个过程。由此产生的影响影响结晶过程的动力学——过冷程度增加，单位时间内形成的结晶核数量增加，其生长速度降低。焊缝金属结构的变化导致焊接接头质量的提高，从而减少了焊接变形，提高了抗拉强度，并显著提高了延展性。
{"title":"Features of the superposition of ultrasonic vibrations in the welding process","authors":"S. Sundukov","doi":"10.17212/1994-6309-2022-24.2-50-66","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-50-66","url":null,"abstract":"Introduction. The main problem in obtaining welded joints is the nonuniform heating of the joint zone, which leads to differences in the structure and properties of the weld metal and the base metal. One of the ways to intensify the welding process is the use of ultrasonic vibrations. As a result of the analysis of methods for introducing ultrasonic vibrations into the melting zone, a method of superimposing vibrations on the elements to be welded was chosen for experimental studies. This method makes it possible to influence the welded elements throughout the entire welding cycle from the melt bath to complete crystallization of the metal. Methods. Experimental studies were carried out on plates made of carbon structural steel St3 (ASTM A568M, AISI 1017, DIN 17100) and aluminum deformable non-hardened alloy AMg4 (EN AW-5086, AW-AL Mg4, 5086). As a source of oscillations, a rod magnetostrictive oscillatory system was used, the end of which was rigidly fixed on one of the welded plates. To determine the places of application of the oscillation source and the welding zone, a calculation method is proposed based on the equality of the resonant frequencies of the used oscillatory system and the natural frequency of bending vibrations of the welding component. It is shown that the optimal places for the application of vibrations and welding will be the antinodes of oscillations, which have the maximum amplitude. Welds were obtained by the method of semi-automatic gas metal arc welding. Results and Discussion. Microstructural study of obtained samples showed a significant decrease in the proportion of dendritic segregation. The changes in the structure are the result of the effects that occur in the liquid melt when ultrasonic vibrations are introduced. The main effects are sound pressure, cavitation and acoustical streaming. The structure change mechanism consists in the dispersion of growing dendrites and crystallization nuclei under the action of shock waves and cumulative jets that occur when cavitation bubbles collapse. The formed fragments of dendrites are new crystallization nuclei that propagate through the melt pool under the action of acoustic currents. Then the process is repeated. The resulting effects affect the kinetics of the crystallization process – the degree of supercooling increases, the number of crystallization nuclei formed per unit time increases, and the rate of its growth decreases. Changes in the structure of the weld metal lead to an increase in the quality of the welded joint, which reduces welding deformations, increases the tensile strength and significantly increases ductility.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43768528","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-91-101
P. Gulyashinov, U. Mishigdorzhiyn, N. Ulakhanov
Introduction. Boriding and aluminizing are among the effective methods for improving the performance properties (corrosion resistance, heat resistance and wear resistance) of machine parts and tools. Solid-phase methods of carrying out techniques of thermochemical treatment (TCT) require long-term exposure at elevated temperatures, which negatively affects the structure and properties of the base material. From these positions, the selection of reasonable temperature-time parameters of solid-phase boriding and aluminizing processes is an urgent task. The purpose of this work is to assess the effect of low-temperature boriding and aluminizing processes on the structure and microhardness of diffusion layers on the surface of low-carbon steels. The paper considers two grades of steels with a carbon content of up to 0.4%: low-carbon steel St3 and alloy steel 3Cr2W8V. The use of the second steel is due to the need to identify the effect of alloying elements in steel on the thickness of diffusion layers and its composition. Powder mixtures based on boron carbide and aluminum carbide are selected as sources of boron and aluminum. Results and discussions. It is found at a process temperature of 900 °C and holding for 2 hours after boriding, iron borides are formed on the surface of both steels. At the same time, two borides FeB and Fe2B are detected on St3 steel by X-ray phase analysis (XRD), and only the Fe2B phase is detected on 3Cr2W8V steel. After aluminizing, aluminum-containing phases such as Al5Fe2, Na3AlF6 and Al2O3 are formed in both steels. The thickness of the resulting diffusion layer on St3 after boriding is 35 μm, after aluminizing – 65 μm. The thickness of the diffusion layer on 3Cr2W8V steel is equal to 15 μm after boriding and 50 μm after aluminizing, which is significantly less than on carbon steel and is obviously due to the effect of alloying elements. It is established that TCT leads to a significant increase in the microhardness of the samples surface. Thus, the maximum microhardness of St3 steel increased to 2,000 HV, and the maximum microhardness of 3Cr2W8V steel increased to 1,700 HV after boriding. The microhardness after aluminizing is comparable for both steels and is equal to 1,000-1,100 HV. Elemental analysis of the upper sections of the diffusion layers shows that the content of boron (7-9%) and aluminum (50-53%) corresponds to the detected XRD iron borides and aluminides. In all cases, there is a gradual decrease in the diffusing elements in the direction from the surface to the base.
{"title":"Influence of boriding and aluminizing processes on the structure and properties of low-carbon steels","authors":"P. Gulyashinov, U. Mishigdorzhiyn, N. Ulakhanov","doi":"10.17212/1994-6309-2022-24.2-91-101","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-91-101","url":null,"abstract":"Introduction. Boriding and aluminizing are among the effective methods for improving the performance properties (corrosion resistance, heat resistance and wear resistance) of machine parts and tools. Solid-phase methods of carrying out techniques of thermochemical treatment (TCT) require long-term exposure at elevated temperatures, which negatively affects the structure and properties of the base material. From these positions, the selection of reasonable temperature-time parameters of solid-phase boriding and aluminizing processes is an urgent task. The purpose of this work is to assess the effect of low-temperature boriding and aluminizing processes on the structure and microhardness of diffusion layers on the surface of low-carbon steels. The paper considers two grades of steels with a carbon content of up to 0.4%: low-carbon steel St3 and alloy steel 3Cr2W8V. The use of the second steel is due to the need to identify the effect of alloying elements in steel on the thickness of diffusion layers and its composition. Powder mixtures based on boron carbide and aluminum carbide are selected as sources of boron and aluminum. Results and discussions. It is found at a process temperature of 900 °C and holding for 2 hours after boriding, iron borides are formed on the surface of both steels. At the same time, two borides FeB and Fe2B are detected on St3 steel by X-ray phase analysis (XRD), and only the Fe2B phase is detected on 3Cr2W8V steel. After aluminizing, aluminum-containing phases such as Al5Fe2, Na3AlF6 and Al2O3 are formed in both steels. The thickness of the resulting diffusion layer on St3 after boriding is 35 μm, after aluminizing – 65 μm. The thickness of the diffusion layer on 3Cr2W8V steel is equal to 15 μm after boriding and 50 μm after aluminizing, which is significantly less than on carbon steel and is obviously due to the effect of alloying elements. It is established that TCT leads to a significant increase in the microhardness of the samples surface. Thus, the maximum microhardness of St3 steel increased to 2,000 HV, and the maximum microhardness of 3Cr2W8V steel increased to 1,700 HV after boriding. The microhardness after aluminizing is comparable for both steels and is equal to 1,000-1,100 HV. Elemental analysis of the upper sections of the diffusion layers shows that the content of boron (7-9%) and aluminum (50-53%) corresponds to the detected XRD iron borides and aluminides. In all cases, there is a gradual decrease in the diffusing elements in the direction from the surface to the base.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42899713","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}
Pub Date : 2022-06-15DOI: 10.17212/1994-6309-2022-24.2-67-77
Yuriy Podgornyj, T. Martynova, V Yu Skeeba
Introduction. The problem of regulating speed fluctuations for any mechanism is essential, because the time interval of this movement is the working time during which the main technological operation is performed. In this case, the question may arise about the regulation of motion speeds both during acceleration, idling of the machine, and during the execution of the main technological operation. The main qualitative indicator of the satisfactory operation of any machine is the motion irregularity ratio, the value of which depends on the ratio of the maximum, minimum and average speeds of the drive shaft. Particularly acute is the problem of determining the motion irregularity ratio of the machine, taking into account the characteristics of the motor. In this case, the machine is considered as a system consisting of a single mass. The elasticity of the elements included in the machine is neglected. An analysis of the scientific literature in this area indicates that insufficient attention is paid to the study of rotation irregularities and its influence on the dynamics of mechanisms, especially when it comes to solving equations taking into account the characteristics of the motor. The purpose of this work is to develop a methodology that allows determining and regulate the non-uniform rotation of the drive shaft, taking into account the characteristics of the motor, the forces of useful resistance and the inertia of the masses of the mechanism. The relevance of the study is due to the lack of a unified methodology that allows adjusting the non-uniform rotation of the drive shaft at the stage of designing mechanisms of this type. Theory and methods. It is proposed to use the Lagrange equation of the second kind to determine the equation of machine motion in differential form. Mathematical simulation is carried out using the Mathcad and KOMPAS-3D application packages. Results and discussion. A methodology is presented that makes it possible to regulate the non-uniform rotation of the shaft. The CAE of the Mathcad system are used to determine the value of the irregularity ratio and patterns of change in these indicators are identified for total operating values that are in the range of 22-46 Nm. An analysis of the results of the calculations performed indicates that the irregularity ratio of the drive shaft rotation is 0.101. It is possible to change this ratio by changing the reduced moment of inertia by installing an additional flywheel or changing the torque of the motor shaft. The obtained results of the research made it possible to develop specific recommendations for the modernization of the drive designs for machines for mixing bulk materials and to outline ways for further research in this direction.
{"title":"On the issue of limiting the irregular motion of a technological machine within specified limits","authors":"Yuriy Podgornyj, T. Martynova, V Yu Skeeba","doi":"10.17212/1994-6309-2022-24.2-67-77","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.2-67-77","url":null,"abstract":"Introduction. The problem of regulating speed fluctuations for any mechanism is essential, because the time interval of this movement is the working time during which the main technological operation is performed. In this case, the question may arise about the regulation of motion speeds both during acceleration, idling of the machine, and during the execution of the main technological operation. The main qualitative indicator of the satisfactory operation of any machine is the motion irregularity ratio, the value of which depends on the ratio of the maximum, minimum and average speeds of the drive shaft. Particularly acute is the problem of determining the motion irregularity ratio of the machine, taking into account the characteristics of the motor. In this case, the machine is considered as a system consisting of a single mass. The elasticity of the elements included in the machine is neglected. An analysis of the scientific literature in this area indicates that insufficient attention is paid to the study of rotation irregularities and its influence on the dynamics of mechanisms, especially when it comes to solving equations taking into account the characteristics of the motor. The purpose of this work is to develop a methodology that allows determining and regulate the non-uniform rotation of the drive shaft, taking into account the characteristics of the motor, the forces of useful resistance and the inertia of the masses of the mechanism. The relevance of the study is due to the lack of a unified methodology that allows adjusting the non-uniform rotation of the drive shaft at the stage of designing mechanisms of this type. Theory and methods. It is proposed to use the Lagrange equation of the second kind to determine the equation of machine motion in differential form. Mathematical simulation is carried out using the Mathcad and KOMPAS-3D application packages. Results and discussion. A methodology is presented that makes it possible to regulate the non-uniform rotation of the shaft. The CAE of the Mathcad system are used to determine the value of the irregularity ratio and patterns of change in these indicators are identified for total operating values that are in the range of 22-46 Nm. An analysis of the results of the calculations performed indicates that the irregularity ratio of the drive shaft rotation is 0.101. It is possible to change this ratio by changing the reduced moment of inertia by installing an additional flywheel or changing the torque of the motor shaft. The obtained results of the research made it possible to develop specific recommendations for the modernization of the drive designs for machines for mixing bulk materials and to outline ways for further research in this direction.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43284345","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}
Pub Date : 2022-03-15DOI: 10.17212/1994-6309-2022-24.1-23-32
D. Gubin, A. Kisel’
Introduction. One of the most important tasks in cutting metals and alloys is the control of the temperature factor, since temperature is one of the limitations in determining cutting conditions. This approach makes it possible to determine rational (in some cases, optimal) milling modes. Experimental methods for determining the temperature are labor-consuming, costly and not always available. The labor-consuming nature lies in the need for constant adjustment of experimental equipment due to changing cutting conditions, electrical insulation of the tool and workpiece, the appearance of parasitic electrical micro-voltage (if we are talking about temperature measurement methods with thermocouples), constant calibration of instruments and selection of thermal radiation coefficients (if we are talking about non-contact measurement methods). In this regard, there is a need for a theoretical determination of temperatures during milling with minimal use of experimental data. The purpose of the work: to develop a method for theoretical calculation of temperature during milling (cutting) of nickel-based heat-resistant materials on the example of 56% Ni -Cr-W Mo-Co-Al alloy (56% Ni, 0.1% C, 10% Cr, 6.5% W, 6% Al, 6.5% Mo, 0.6% Si, 13 % Co, 1% Fe). Research methodology. To determine theoretically the cutting temperatures, a mathematical model is formed that takes into account the mechanical and thermophysical properties of the material being processed and its change depending on the temperature variations during milling, the geometry of the cutting tool and the features of the schematization of the milling process. The experimental part of the study is carried out on a console milling machine KFPE-250 with a CNC system Mayak-610. The 56% Ni -Cr-W Mo-Co-Al material is processed with a Seco JS513050D2C.0Z3-NXT cutter with different speeds and feeds. The temperature is measured using a Fluke Ti400 thermal imager. Results and discussion. A theoretical model for calculating the temperature (for the group of 77% Ni - Cr - Ti - Al - B, 66% Ni - Cr - Mo - W - Ti - Al, 73% Ni-Cr-Mo-Nb-Ti-Al and 56% Ni -Cr-W Mo-Co-Al alloys) during milling of heat-resistant nickel-based alloys is developed, which makes it possible to predict the temperature value at the face and flank of the tool when changing cutting conditions (speed, feed, depth, cutting tool geometry), as well as the cutting temperature. An analysis of the experimental and theoretically predicted values of the cutting temperature showed a satisfactory agreement between the corresponding values.
{"title":"Calculation of temperatures during finishing milling of a nickel based alloys","authors":"D. Gubin, A. Kisel’","doi":"10.17212/1994-6309-2022-24.1-23-32","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.1-23-32","url":null,"abstract":"Introduction. One of the most important tasks in cutting metals and alloys is the control of the temperature factor, since temperature is one of the limitations in determining cutting conditions. This approach makes it possible to determine rational (in some cases, optimal) milling modes. Experimental methods for determining the temperature are labor-consuming, costly and not always available. The labor-consuming nature lies in the need for constant adjustment of experimental equipment due to changing cutting conditions, electrical insulation of the tool and workpiece, the appearance of parasitic electrical micro-voltage (if we are talking about temperature measurement methods with thermocouples), constant calibration of instruments and selection of thermal radiation coefficients (if we are talking about non-contact measurement methods). In this regard, there is a need for a theoretical determination of temperatures during milling with minimal use of experimental data. The purpose of the work: to develop a method for theoretical calculation of temperature during milling (cutting) of nickel-based heat-resistant materials on the example of 56% Ni -Cr-W Mo-Co-Al alloy (56% Ni, 0.1% C, 10% Cr, 6.5% W, 6% Al, 6.5% Mo, 0.6% Si, 13 % Co, 1% Fe). Research methodology. To determine theoretically the cutting temperatures, a mathematical model is formed that takes into account the mechanical and thermophysical properties of the material being processed and its change depending on the temperature variations during milling, the geometry of the cutting tool and the features of the schematization of the milling process. The experimental part of the study is carried out on a console milling machine KFPE-250 with a CNC system Mayak-610. The 56% Ni -Cr-W Mo-Co-Al material is processed with a Seco JS513050D2C.0Z3-NXT cutter with different speeds and feeds. The temperature is measured using a Fluke Ti400 thermal imager. Results and discussion. A theoretical model for calculating the temperature (for the group of 77% Ni - Cr - Ti - Al - B, 66% Ni - Cr - Mo - W - Ti - Al, 73% Ni-Cr-Mo-Nb-Ti-Al and 56% Ni -Cr-W Mo-Co-Al alloys) during milling of heat-resistant nickel-based alloys is developed, which makes it possible to predict the temperature value at the face and flank of the tool when changing cutting conditions (speed, feed, depth, cutting tool geometry), as well as the cutting temperature. An analysis of the experimental and theoretically predicted values of the cutting temperature showed a satisfactory agreement between the corresponding values.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44614904","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}
Pub Date : 2022-03-15DOI: 10.17212/1994-6309-2022-24.1-61-72
Y. Korobov, H. Alwan, A. Makarov, V. Kukareko, V. Sirosh, M. Filippov, S. Estemirova
Introduction. Reliability-critical components of equipment working in contact with high-speed liquid media (for example, turbine blades of hydroelectric power stations, pump impellers, ship propellers) are subjected to one of the types of wear – cavitation erosion. The current study aims to select and scientifically substantiate the type of coating and its structural-phase state for the effective protection of parts from cavitation erosion. Research methods. The study carries out a comparative analysis of differences in the cavitation erosion resistance of characteristic austenitic steels, in the form of bulk material (316L) and coatings (E308L, 60Cr8TiAl), used for protection against cavitation Arc surfacing, i.e. MMA and MIG, is used for depositing the coatings. The tests are carried out on an original installation for evaluating the cavitation resistance of materials with applying ultrasound and the electrical potential difference. Results and Discussion. The results show that the 60Cr8TiAl has a higher resistance to cavitation erosion than that of E308L and 316L by 4 and 10 times, respectively. The structural factors that determine the resistance to cavitation erosion damage are identified to analyze the reasons for the differences in material resistance. Firstly, a strong dependence of the cavitation erosion resistance of austenitic steels on the intensity of the deformation martensitic transformation, developing under the influence of cavitation, is confirmed. This structural transformation contributes to an increase in cavitation resistance of the surface layer. In metastable austenitic steel, a deformation martensite (α′) is formed in the surface layer during the initial test period. This causes an increase in hardness, dissipation of the energy of external action, and the appearance of compressive stresses that prevent the occurrence of microcracks. Subsequently, additional hardening of the previously formed dispersed crystals of α′-martensite occurs. In 60Cr8TiAl, these effects are significantly stronger than that of E308L and 316L due to the higher level of metastability of austenite and formation of carbon deformation martensite.
{"title":"Comparative study of cavitation erosion resistance of austenitic steels with different levels of metastability","authors":"Y. Korobov, H. Alwan, A. Makarov, V. Kukareko, V. Sirosh, M. Filippov, S. Estemirova","doi":"10.17212/1994-6309-2022-24.1-61-72","DOIUrl":"https://doi.org/10.17212/1994-6309-2022-24.1-61-72","url":null,"abstract":"Introduction. Reliability-critical components of equipment working in contact with high-speed liquid media (for example, turbine blades of hydroelectric power stations, pump impellers, ship propellers) are subjected to one of the types of wear – cavitation erosion. The current study aims to select and scientifically substantiate the type of coating and its structural-phase state for the effective protection of parts from cavitation erosion. Research methods. The study carries out a comparative analysis of differences in the cavitation erosion resistance of characteristic austenitic steels, in the form of bulk material (316L) and coatings (E308L, 60Cr8TiAl), used for protection against cavitation Arc surfacing, i.e. MMA and MIG, is used for depositing the coatings. The tests are carried out on an original installation for evaluating the cavitation resistance of materials with applying ultrasound and the electrical potential difference. Results and Discussion. The results show that the 60Cr8TiAl has a higher resistance to cavitation erosion than that of E308L and 316L by 4 and 10 times, respectively. The structural factors that determine the resistance to cavitation erosion damage are identified to analyze the reasons for the differences in material resistance. Firstly, a strong dependence of the cavitation erosion resistance of austenitic steels on the intensity of the deformation martensitic transformation, developing under the influence of cavitation, is confirmed. This structural transformation contributes to an increase in cavitation resistance of the surface layer. In metastable austenitic steel, a deformation martensite (α′) is formed in the surface layer during the initial test period. This causes an increase in hardness, dissipation of the energy of external action, and the appearance of compressive stresses that prevent the occurrence of microcracks. Subsequently, additional hardening of the previously formed dispersed crystals of α′-martensite occurs. In 60Cr8TiAl, these effects are significantly stronger than that of E308L and 316L due to the higher level of metastability of austenite and formation of carbon deformation martensite.","PeriodicalId":42889,"journal":{"name":"Obrabotka Metallov-Metal Working and Material Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45272211","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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