Pub Date : 2023-09-18DOI: 10.17073/0368-0797-2023-3-311-319
A. I. Gordienko, I. V. Vlasov, Yu. I. Pochivalov
The effect of accelerated cooling after cross-helical rolling of X70 low-carbon steel on the formation of structures and mechanical properties under static tension and impact bending was investigated. The use of interrupted accelerated cooling of steel after cross-helical rolling with exposure at 530 °C (mode I ) and continuous accelerated cooling (mode II ) leads to the formation of different types and ratios of structures in steel. After rolling according to mode I , the structure is characterized by the presence of ferrite, troostite, granular bainite, and fine Fe 3 C carbides. After rolling according to mode II , the structure is characterized by the formation of lath bainite and large sections of the martensitic-austenitic (MA) component up to 1 – 2 µm in size. It is shown that a decrease in the fineness of ferrite grains in steel after cross-helical rolling in modes I and II from 12 to 4.6 – 4.3 μm, the formation of a bainitic phase, and hardening of the matrix with carbides led to an increase in the yield strength of steel up to 440 and 490 MPa and tensile strength up to 760 and 880 MPa. Carrying out helical rolling according to mode I makes it possible to significantly increase the low-temperature fracture toughness of steel (KCV –70 °С = 160 J/cm 2 ) compared to the hot-rolled state (KCV –70 °С = 11 J/cm 2 ) and reduce the cold brittleness of steel to the temperatures below –50 °C. The use of continuous accelerated cooling (mode II ) does not allow increasing the cold resistance of steel due to the formation of the lath bainite structure and large areas of the MA component.
{"title":"Effect of accelerated cooling after cross-helical rolling on formation of structure and low-temperature fracture toughness of low-carbon steel","authors":"A. I. Gordienko, I. V. Vlasov, Yu. I. Pochivalov","doi":"10.17073/0368-0797-2023-3-311-319","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-3-311-319","url":null,"abstract":"The effect of accelerated cooling after cross-helical rolling of X70 low-carbon steel on the formation of structures and mechanical properties under static tension and impact bending was investigated. The use of interrupted accelerated cooling of steel after cross-helical rolling with exposure at 530 °C (mode I ) and continuous accelerated cooling (mode II ) leads to the formation of different types and ratios of structures in steel. After rolling according to mode I , the structure is characterized by the presence of ferrite, troostite, granular bainite, and fine Fe 3 C carbides. After rolling according to mode II , the structure is characterized by the formation of lath bainite and large sections of the martensitic-austenitic (MA) component up to 1 – 2 µm in size. It is shown that a decrease in the fineness of ferrite grains in steel after cross-helical rolling in modes I and II from 12 to 4.6 – 4.3 μm, the formation of a bainitic phase, and hardening of the matrix with carbides led to an increase in the yield strength of steel up to 440 and 490 MPa and tensile strength up to 760 and 880 MPa. Carrying out helical rolling according to mode I makes it possible to significantly increase the low-temperature fracture toughness of steel (KCV –70 °С = 160 J/cm 2 ) compared to the hot-rolled state (KCV –70 °С = 11 J/cm 2 ) and reduce the cold brittleness of steel to the temperatures below –50 °C. The use of continuous accelerated cooling (mode II ) does not allow increasing the cold resistance of steel due to the formation of the lath bainite structure and large areas of the MA component.","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135257636","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 : 2023-08-19DOI: 10.17073/0368-0797-2023-4-498-507
O. V. Glushakova, O. P. Chernikova
Currently, a new development trend is being formed in the world associated with the decarbonization of economies. This process is based on the institutionalization of ESG-principles – an approach to doing business, characterized by the involvement of companies in solving environmental, social and governance problems. The process of institutionalization of ESG-principles at the international level was initiated in 1948 with the adoption of the Universal Declaration of Human Rights under the auspices of the UN. The active involvement of Russia in the formation of the institutional framework in the field of ESG has begun only in 2020. The reason for this was the ratification of a number of international documents, as well as the active promotion of climate policy by many countries of the world. The stages of the institutionalization process at the international level discussed in detail in Report 1. The decarbonization of economies creates development risks for industries whose products are characterized by high carbon and energy intensity. Ferrous metallurgy also belongs to them. This report presents the results of a study of the effectiveness of measures taken by the Russian Government in the field of reducing atmospheric air pollution in large industrial centers of the ferrous metallurgy based on data from the Unified Information System for Monitoring Air Quality, as well as the results of an analysis of the ESG-practices of the largest Russian ferrous enterprises and compliance with carbon intensity and energy intensity of their products according to the criteria of sustainable (including green) development projects established in our country. As a result of the study, it was found that despite the use of ESG-principles in their activities, the specific emissions of CO 2 -equivalent of the largest iron and steel enterprises significantly exceed the criteria for sustainable (including green) development projects established by the Russian Government.
{"title":"Institutionalization of ESG-principles at the international level and in the Russian Federation, their impact on ferrous metallurgy enterprises. Part 2","authors":"O. V. Glushakova, O. P. Chernikova","doi":"10.17073/0368-0797-2023-4-498-507","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-498-507","url":null,"abstract":"Currently, a new development trend is being formed in the world associated with the decarbonization of economies. This process is based on the institutionalization of ESG-principles – an approach to doing business, characterized by the involvement of companies in solving environmental, social and governance problems. The process of institutionalization of ESG-principles at the international level was initiated in 1948 with the adoption of the Universal Declaration of Human Rights under the auspices of the UN. The active involvement of Russia in the formation of the institutional framework in the field of ESG has begun only in 2020. The reason for this was the ratification of a number of international documents, as well as the active promotion of climate policy by many countries of the world. The stages of the institutionalization process at the international level discussed in detail in Report 1. The decarbonization of economies creates development risks for industries whose products are characterized by high carbon and energy intensity. Ferrous metallurgy also belongs to them. This report presents the results of a study of the effectiveness of measures taken by the Russian Government in the field of reducing atmospheric air pollution in large industrial centers of the ferrous metallurgy based on data from the Unified Information System for Monitoring Air Quality, as well as the results of an analysis of the ESG-practices of the largest Russian ferrous enterprises and compliance with carbon intensity and energy intensity of their products according to the criteria of sustainable (including green) development projects established in our country. As a result of the study, it was found that despite the use of ESG-principles in their activities, the specific emissions of CO 2 -equivalent of the largest iron and steel enterprises significantly exceed the criteria for sustainable (including green) development projects established by the Russian Government.","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135969040","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 : 2023-08-19DOI: 10.17073/0368-0797-2023-4-445-458
Yu. L. Krutskii, T. S. Gudyma, T. M. Krutskaya, А. О. Semenov, A. V. Utkin
The properties, application, and methods for producing chromium and zirconium carbides are considered. These carbides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Chromium and zirconium carbides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technology. Chromium carbide is used mainly as component of surfacing mixtures to create protective coatings that resist intensive abrasive wear, including at elevated temperatures (up to 800 °C) in oxidizing environments. This compound is also used in the manufacture of tungsten-free hard alloys and carbide steels. Chromium carbide, along with vanadium carbide, is used as a grain growth inhibitor in WC – Co hard alloys. Powdered zirconium carbide can be used to polish the surface of items made of ferrous and non-ferrous metals. The properties of refractory compounds depend on the content of impurities and dispersion (particle size). To solve a specific problem associated with the use of refractory compounds, it is important to choose the right method for their preparation, to determine the permissible content of impurities in the initial components. This leads to the existence of different methods for the synthesis of carbides. The main methods for their preparation are: synthesis from simple substances (metals and carbon), metallothermal and carbothermal reduction. Plasma-chemical synthesis (vapor-gas phase deposition) is also used to obtain carbide nanopowders. A characteristic is given to each of these methods. Information on the possible mechanism of the processes of carbothermal synthesis is presented.
{"title":"Carbides of transition metals: Properties, application and production. Review. Part 2. Chromium and zirconium carbides","authors":"Yu. L. Krutskii, T. S. Gudyma, T. M. Krutskaya, А. О. Semenov, A. V. Utkin","doi":"10.17073/0368-0797-2023-4-445-458","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-445-458","url":null,"abstract":"The properties, application, and methods for producing chromium and zirconium carbides are considered. These carbides are oxygen-free refractory metal-like compounds. As a result, they are characterized by high values of thermal and electrical conductivity. Their hardness is relatively high. Chromium and zirconium carbides exhibit significant chemical resistance in aggressive environments. For these reasons, they have found application in modern technology. Chromium carbide is used mainly as component of surfacing mixtures to create protective coatings that resist intensive abrasive wear, including at elevated temperatures (up to 800 °C) in oxidizing environments. This compound is also used in the manufacture of tungsten-free hard alloys and carbide steels. Chromium carbide, along with vanadium carbide, is used as a grain growth inhibitor in WC – Co hard alloys. Powdered zirconium carbide can be used to polish the surface of items made of ferrous and non-ferrous metals. The properties of refractory compounds depend on the content of impurities and dispersion (particle size). To solve a specific problem associated with the use of refractory compounds, it is important to choose the right method for their preparation, to determine the permissible content of impurities in the initial components. This leads to the existence of different methods for the synthesis of carbides. The main methods for their preparation are: synthesis from simple substances (metals and carbon), metallothermal and carbothermal reduction. Plasma-chemical synthesis (vapor-gas phase deposition) is also used to obtain carbide nanopowders. A characteristic is given to each of these methods. Information on the possible mechanism of the processes of carbothermal synthesis is presented.","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135970191","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 : 2023-08-19DOI: 10.17073/0368-0797-2023-4-471-478
R. R. Shartdinov, A. A. Babenko, A. G. Upolovnikova, A. N. Smetannikov
The effect of basicity and content of boron oxide on viscosity, crystallization temperature, phase composition, and structure of the СаО – SiO2 – B 2 O 3 – 12 % Cr 2 O 3 – 3 % Аl 2 O 3 – 8 % МgO fluorine-free slag system in the range of boron oxide content 3 – 6 % and basicity 1.0 – 2.5 is studied by vibrational viscometry, thermodynamic phase composition modeling (HSC Chemistry 6.12 (Outokumpu)), and Raman spectroscopy. It was found that physical properties of the studied slags mainly depend on the balance between the degree of structure polymerization, nature of the bond with it, and phase composition. With a low basicity of 1.0, slags are “long” and an increase in the content of boron oxide from 3 to 6 % makes them more fusible, reducing the crystallization temperature of the slag from 1340 to 1224 °C, and its viscosity from 1.0 – 0.8 to ~0.25 Pa·s at 1600 – 1660 °C, despite the significant complication of the structure, reflected in the growth of the bridging oxygen index BO from 1.10 to 1.49. With an increase in basicity, slags transfer from “long” to “short” and the content of calcium oxide increases, which, being a donor of free oxygen ions (O 2– ), acts as a modifier of the slag structure. Thus, with a basicity of B = (CaO/SiO 2 ) = 2.5, slags have a simpler structure (BO = 0.50 – 0.53) relative to slags with a basicity of 1.0, while the addition of boron oxide complicates it only slightly (an increase in BO from 0.5 up to 0.53). Increasing the concentration of B 2 O 3 lowers the crystallization temperature from 1674 to 1605 °C and the viscosity from 1.0 to 0.3 Pa·s at 1660 °C as a result of the formation of low-melting compounds (mostly 2CaO·B 2 O 3 ).
碱度和氧化硼含量的影响粘度、结晶温度、相组成、和结构的СаО-二氧化硅- B 2 O 3 - 12% Cr 2 O 3 - 3%Аl 2 O 3 - 8%М无氟渣系统氧化硼含量3 - 6%的范围和碱度1.0 - 2.5是振动粘度测定法,研究了热力学相成分建模(HSC化学6.12(奥托昆普集团股价)),和拉曼光谱。研究发现，所研究的炉渣的物理性能主要取决于结构聚合程度、与之结合的性质和相组成之间的平衡。当碱度为1.0时，炉渣呈“长”状，当氧化硼含量从3%增加到6%时，炉渣更易熔，熔渣的结晶温度从1340℃降低到1224℃，在1600 ~ 1660℃时，炉渣的黏度从1.0 ~ 0.8℃降低到~0.25 Pa·s，尽管其结构明显复杂，但桥接氧指数BO从1.10提高到1.49。随着碱度的增加，炉渣由“长”向“短”转变，氧化钙含量增加，作为游离氧离子(o2 -)的供体，对炉渣结构起着改性剂的作用。因此，当碱度为B = (CaO/ sio2) = 2.5时，矿渣的结构相对于碱度为1.0的矿渣更简单(BO = 0.50 - 0.53)，而添加氧化硼仅使其稍微复杂化(BO从0.5增加到0.53)。随着b2o3浓度的增加，结晶温度从1674℃降至1605℃，1660℃时粘度从1.0℃降至0.3 Pa·s，形成低熔点化合物(主要为2CaO·b2o3)。
{"title":"Physical properties and structure of boron-containing slags during reduction period of AOD process","authors":"R. R. Shartdinov, A. A. Babenko, A. G. Upolovnikova, A. N. Smetannikov","doi":"10.17073/0368-0797-2023-4-471-478","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-471-478","url":null,"abstract":"The effect of basicity and content of boron oxide on viscosity, crystallization temperature, phase composition, and structure of the СаО – SiO2 – B 2 O 3 – 12 % Cr 2 O 3 – 3 % Аl 2 O 3 – 8 % МgO fluorine-free slag system in the range of boron oxide content 3 – 6 % and basicity 1.0 – 2.5 is studied by vibrational viscometry, thermodynamic phase composition modeling (HSC Chemistry 6.12 (Outokumpu)), and Raman spectroscopy. It was found that physical properties of the studied slags mainly depend on the balance between the degree of structure polymerization, nature of the bond with it, and phase composition. With a low basicity of 1.0, slags are “long” and an increase in the content of boron oxide from 3 to 6 % makes them more fusible, reducing the crystallization temperature of the slag from 1340 to 1224 °C, and its viscosity from 1.0 – 0.8 to ~0.25 Pa·s at 1600 – 1660 °C, despite the significant complication of the structure, reflected in the growth of the bridging oxygen index BO from 1.10 to 1.49. With an increase in basicity, slags transfer from “long” to “short” and the content of calcium oxide increases, which, being a donor of free oxygen ions (O 2– ), acts as a modifier of the slag structure. Thus, with a basicity of B = (CaO/SiO 2 ) = 2.5, slags have a simpler structure (BO = 0.50 – 0.53) relative to slags with a basicity of 1.0, while the addition of boron oxide complicates it only slightly (an increase in BO from 0.5 up to 0.53). Increasing the concentration of B 2 O 3 lowers the crystallization temperature from 1674 to 1605 °C and the viscosity from 1.0 to 0.3 Pa·s at 1660 °C as a result of the formation of low-melting compounds (mostly 2CaO·B 2 O 3 ).","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135969038","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 : 2023-08-19DOI: 10.17073/0368-0797-2023-4-479-484
B. Suleimen, S. P. Salikhov, F. Sh. Sharipov, V. E. Roshchin
Selective solid-phase reduction of iron and phosphorus in oolite ores of the Lisakovsky and Ayat deposits was experimentally studied. Using X-ray phase analysis, the phase composition of the initial ores and samples after reduction roasting was determined. Goethite, magnetite and quartz were found in the ores of both deposits. Phosphorus in the ore of the Ayat deposit is in the form of aluminum phosphate and iron hydrophosphate, and in the samples of the Lisakovsky ore – as a component of calcium hydrophosphate. Experiments on reduction roasting were carried out in a resistance furnace at 1000 °C with holding time of 5 h. After roasting in CO atmosphere, α-Fe appears in the samples, while phosphorus remains as a component of iron, calcium and aluminum phosphates. After roasting in a mixture with graphite, phosphorus is reduced by solid carbon from iron and calcium phosphates and passes into metal, but remains as a component of aluminum phosphate. Studies using microroentgenospectral analysis show that phosphorus content in the metal phase after reduction with solid carbon is 2.0 – 3.5 at. %. When CO is reduced in the atmosphere, phosphorus in the metallic phase is practically not detected. At the same time, the amount of residual iron in the oxide phase after carbon monoxide reduction significantly exceeds the amount of iron after reduction in a mixture with carbon. The experimental results confirm the possibility of selective reduction of iron by carbon oxide CO without phosphorus reduction.
{"title":"Selective solid-phase reduction of iron in phosphorous oolite ores","authors":"B. Suleimen, S. P. Salikhov, F. Sh. Sharipov, V. E. Roshchin","doi":"10.17073/0368-0797-2023-4-479-484","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-479-484","url":null,"abstract":"Selective solid-phase reduction of iron and phosphorus in oolite ores of the Lisakovsky and Ayat deposits was experimentally studied. Using X-ray phase analysis, the phase composition of the initial ores and samples after reduction roasting was determined. Goethite, magnetite and quartz were found in the ores of both deposits. Phosphorus in the ore of the Ayat deposit is in the form of aluminum phosphate and iron hydrophosphate, and in the samples of the Lisakovsky ore – as a component of calcium hydrophosphate. Experiments on reduction roasting were carried out in a resistance furnace at 1000 °C with holding time of 5 h. After roasting in CO atmosphere, α-Fe appears in the samples, while phosphorus remains as a component of iron, calcium and aluminum phosphates. After roasting in a mixture with graphite, phosphorus is reduced by solid carbon from iron and calcium phosphates and passes into metal, but remains as a component of aluminum phosphate. Studies using microroentgenospectral analysis show that phosphorus content in the metal phase after reduction with solid carbon is 2.0 – 3.5 at. %. When CO is reduced in the atmosphere, phosphorus in the metallic phase is practically not detected. At the same time, the amount of residual iron in the oxide phase after carbon monoxide reduction significantly exceeds the amount of iron after reduction in a mixture with carbon. The experimental results confirm the possibility of selective reduction of iron by carbon oxide CO without phosphorus reduction.","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135969039","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 : 2023-08-18DOI: 10.17073/0368-0797-2023-4-442-444
A. A. Kruglyakov, S. O. Rogachev, A. V. Molyarov
Steels with regulated austenitic transformation during exploitation (RATE) are a new class of ferritic-based tungsten-free tool steels for hot forming. The study obtained quantitative data on the high-temperature strength of RATE steel of new composition after quenching and tempering. The stress-strain curves are plotted and the tendency of steel to strain hardening at temperatures of 450 and 750 °C is estimated. It was established that at a temperature of 750 °C, corresponding to the operating temperature, RATE steel has a stronger tendency to work hardening than at a temperature of 450 °C.
{"title":"High-temperature strength of die steel with regulated austenitic transformation during exploitation after quenching and tempering","authors":"A. A. Kruglyakov, S. O. Rogachev, A. V. Molyarov","doi":"10.17073/0368-0797-2023-4-442-444","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-442-444","url":null,"abstract":"Steels with regulated austenitic transformation during exploitation (RATE) are a new class of ferritic-based tungsten-free tool steels for hot forming. The study obtained quantitative data on the high-temperature strength of RATE steel of new composition after quenching and tempering. The stress-strain curves are plotted and the tendency of steel to strain hardening at temperatures of 450 and 750 °C is estimated. It was established that at a temperature of 750 °C, corresponding to the operating temperature, RATE steel has a stronger tendency to work hardening than at a temperature of 450 °C.","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136064776","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 : 2023-08-17DOI: 10.17073/0368-0797-2023-4-434-441
M. Yu. Panchenko, K. A. Reunova, A. S. Nifontov, E. A. Kolubaev, E. G. Astafurova
The authors studied the influence of volume fraction and morphology of δ-ferrite on hydrogen embrittlement of austenitic stainless steel 08Kh19N9T obtained by electron beam additive manufacturing. It is experimentally shown that in additively-manufactured samples, long lamellae of δ-ferrite form a dense “net” of interphase boundaries (austenite/δ-ferrite, the volume fraction of the δ-phase is 20 %) and contribute to the hydrogen accumulation. Also, being the “easy” ways for the diffusion of hydrogen atoms, the dendritic lamellae of ferrite provide hydrogen transport deep into the samples. Post-production solid-solution treatment (at T = 1100 °C, 1 h) leads to a significant decrease in the fraction of δ-ferrite in steel (up to 5 %) and partial dissolution of dendritic lamellae. A decrease in the volume fraction of ferrite and a change in its morphology hinder the diffusion of hydrogen deep into the samples and its accumulation during electrolytic hydrogen-charging and subsequent deformation. It contributes to a decrease in the total concentration of hydrogen dissolved in the steel samples. Despite the lower concentration of dissolved hydrogen in the solid-solution treated samples, the solid-solution strengthening by hydrogen atoms is higher ((Delta sigma _{0.2}^{rm{H}}) = 73 MPa) than for the initial samples with a high content of δ-ferrite ((Delta sigma _{0.2}^{rm{H}}) = 55 MPa). The solid-solution treated samples are characterized by a smaller thickness of the brittle surface hydrogen-charged layer and a lower hydrogen embrittlement index compared to the post-produced samples ( D H = 55 ± 12 µm, I H = 32 % for initial samples and D H = 29 ± 7 µm, I H = 24 % for samples after post-production solid-solution treatment).
研究了δ-铁素体体积分数和形貌对电子束增材制造奥氏体不锈钢08Kh19N9T氢脆的影响。实验结果表明，在增材制造的样品中，δ铁素体长片状形成致密的奥氏体/δ铁素体相界面“网”，δ相的体积分数为20 %) and contribute to the hydrogen accumulation. Also, being the “easy” ways for the diffusion of hydrogen atoms, the dendritic lamellae of ferrite provide hydrogen transport deep into the samples. Post-production solid-solution treatment (at T = 1100 °C, 1 h) leads to a significant decrease in the fraction of δ-ferrite in steel (up to 5 %) and partial dissolution of dendritic lamellae. A decrease in the volume fraction of ferrite and a change in its morphology hinder the diffusion of hydrogen deep into the samples and its accumulation during electrolytic hydrogen-charging and subsequent deformation. It contributes to a decrease in the total concentration of hydrogen dissolved in the steel samples. Despite the lower concentration of dissolved hydrogen in the solid-solution treated samples, the solid-solution strengthening by hydrogen atoms is higher ((Delta sigma _{0.2}^{rm{H}}) = 73 MPa) than for the initial samples with a high content of δ-ferrite ((Delta sigma _{0.2}^{rm{H}}) = 55 MPa). The solid-solution treated samples are characterized by a smaller thickness of the brittle surface hydrogen-charged layer and a lower hydrogen embrittlement index compared to the post-produced samples ( D H = 55 ± 12 µm, I H = 32 % for initial samples and D H = 29 ± 7 µm, I H = 24 % for samples after post-production solid-solution treatment).
{"title":"Effect of morphology and volume fraction of δ-ferrite on hydrogen embrittlement of stainless steel produced by electron beam additive manufacturing","authors":"M. Yu. Panchenko, K. A. Reunova, A. S. Nifontov, E. A. Kolubaev, E. G. Astafurova","doi":"10.17073/0368-0797-2023-4-434-441","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-434-441","url":null,"abstract":"The authors studied the influence of volume fraction and morphology of δ-ferrite on hydrogen embrittlement of austenitic stainless steel 08Kh19N9T obtained by electron beam additive manufacturing. It is experimentally shown that in additively-manufactured samples, long lamellae of δ-ferrite form a dense “net” of interphase boundaries (austenite/δ-ferrite, the volume fraction of the δ-phase is 20 %) and contribute to the hydrogen accumulation. Also, being the “easy” ways for the diffusion of hydrogen atoms, the dendritic lamellae of ferrite provide hydrogen transport deep into the samples. Post-production solid-solution treatment (at T = 1100 °C, 1 h) leads to a significant decrease in the fraction of δ-ferrite in steel (up to 5 %) and partial dissolution of dendritic lamellae. A decrease in the volume fraction of ferrite and a change in its morphology hinder the diffusion of hydrogen deep into the samples and its accumulation during electrolytic hydrogen-charging and subsequent deformation. It contributes to a decrease in the total concentration of hydrogen dissolved in the steel samples. Despite the lower concentration of dissolved hydrogen in the solid-solution treated samples, the solid-solution strengthening by hydrogen atoms is higher ((Delta sigma _{0.2}^{rm{H}}) = 73 MPa) than for the initial samples with a high content of δ-ferrite ((Delta sigma _{0.2}^{rm{H}}) = 55 MPa). The solid-solution treated samples are characterized by a smaller thickness of the brittle surface hydrogen-charged layer and a lower hydrogen embrittlement index compared to the post-produced samples ( D H = 55 ± 12 µm, I H = 32 % for initial samples and D H = 29 ± 7 µm, I H = 24 % for samples after post-production solid-solution treatment).","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136337491","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 : 2023-08-17DOI: 10.17073/0368-0797-2023-4-485-491
O. S. Lekhov, A. V. Mikhalev, S. O. Nepryakhin
The substantiation of the relevance of obtaining continuous cast steel pipe hollow billet is given from the position of improving the quality of pipes made of carbon and alloy steels is given. The article presents an assessment of the quality of the inner surface of pipes made of solid steel pipe billet. A new technology is proposed for the production of hollow steel pipe billets on a resource-saving unit of combined continuous casting and deformation. The photo of the continuous casting and deformation section of JSC Ural Pipe Plant is given, where a pilot unit of combined continuous casting and deformation is installed. The paper presents the results of a theoretical study of stress-strain state of the mandrel and sections of a pipe billet when it is compressed by the strikers of the unit of combined continuous casting and deformation. The authors discuss the general model of the mold – striker system. The initial data on calculation, dimensions of the hollow pipe billet and a description of the calibration of strikers for compression of a hollow steel billet are given. The temperature field of a hollow billet was determined. To simulate the stress-strain state of the metal in the roll pass and the mandrel, four contact pairs were considered. Calculations were made by the finite element method. The dimensions of the final element in the roll pass of hollow billet were determined. The authors established the values and patterns of changes in metal displacements and axial stresses in the roll pass during the production of hollow steel billets in the unit of combined continuous casting and deformation (strikers are made along a constant radius). The stress state of metal in the roll pass was assessed from the standpoint of improving the quality of hollow steel billets.
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Pub Date : 2023-08-17DOI: 10.17073/0368-0797-2023-4-492-497
G. E. Levshin
The paper describes design features, methodology and results of the study of 10 induction electromagnetic crucible furnaces with a C -shaped magnetic core (MC). The core is covered by turns of an electric coil (EC) of small volume up to ~14.56 dm3. The furnaces have MC from a set of used transformer plates with a working volume of ~ 28.5 – 30.8 dm3, a capacitor bank (CB), the number of turns w = 23 – 50 of copper or aluminum wire, voltage 380 – 390 V, frequency 50 Hz. The water-cooled EC is placed in a rubber tank and creates a horizontal electromagnetic flow with induction of ≈70 mT, which is amplified by MC and directed beyond EC into a larger working volume of ~30.7 dm3 between its poles with induction up to ≈100 mT. When placing a steel crucible in the volume, induction increases up to 125 – 150 mT and the experimental furnace EMC‑30.7‑23A with a capacity of 44 kVA allows melting 21 kg of silumin at a speed of 10 °C/min in 65 min, which is faster than in the resistance furnace СAT‑0.16 with a power of 40 kW in 2 h. With strong compression of MC plates, the noise decreases from 80 – 85 to 40 – 48 dB. To increase the furnace efficiency, it is proposed to use pole plates with a width of 155 mm, mineral wool in the thermal insulation of the crucible, tuning capacitors in CB, and EC from copper cable. For melting of high-temperature alloys, it is advisable to connect this furnace to a step-up transformer in order to increase the current density from 3.7 to the permissible 20 A/mm2, power in the EC – CB circuit, and EC induction. The authors suggest to continue research on electromagnetic furnaces made from cheap transformer scrap to determine the scope.
{"title":"Investigation of electromagnetic furnaces with a C-shaped magnetic core","authors":"G. E. Levshin","doi":"10.17073/0368-0797-2023-4-492-497","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-492-497","url":null,"abstract":"The paper describes design features, methodology and results of the study of 10 induction electromagnetic crucible furnaces with a C -shaped magnetic core (MC). The core is covered by turns of an electric coil (EC) of small volume up to ~14.56 dm3. The furnaces have MC from a set of used transformer plates with a working volume of ~ 28.5 – 30.8 dm3, a capacitor bank (CB), the number of turns w = 23 – 50 of copper or aluminum wire, voltage 380 – 390 V, frequency 50 Hz. The water-cooled EC is placed in a rubber tank and creates a horizontal electromagnetic flow with induction of ≈70 mT, which is amplified by MC and directed beyond EC into a larger working volume of ~30.7 dm3 between its poles with induction up to ≈100 mT. When placing a steel crucible in the volume, induction increases up to 125 – 150 mT and the experimental furnace EMC‑30.7‑23A with a capacity of 44 kVA allows melting 21 kg of silumin at a speed of 10 °C/min in 65 min, which is faster than in the resistance furnace СAT‑0.16 with a power of 40 kW in 2 h. With strong compression of MC plates, the noise decreases from 80 – 85 to 40 – 48 dB. To increase the furnace efficiency, it is proposed to use pole plates with a width of 155 mm, mineral wool in the thermal insulation of the crucible, tuning capacitors in CB, and EC from copper cable. For melting of high-temperature alloys, it is advisable to connect this furnace to a step-up transformer in order to increase the current density from 3.7 to the permissible 20 A/mm2, power in the EC – CB circuit, and EC induction. The authors suggest to continue research on electromagnetic furnaces made from cheap transformer scrap to determine the scope.","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136337632","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 : 2023-08-17DOI: 10.17073/0368-0797-2023-4-421-426
A. S. Simachev, T. N. Oskolkova, R. A. Shevchenko
The paper considers the effect of combined electromechanical processing in three different modes on the structure and hardness of the surface layers of 40Kh steel, which was in a normalized state (the original structure). The modes differ from each other by the different applied load and the number of pulses. The applied load in modes 1 and 2 (current strength 39 kA, pulse time 0.02 s, number of pulses 1) is 100 and 250 MPa, respectively. A distinctive feature of mode 3 compared to mode 2 is a greater number of pulses (two). Metallographically it was established that in all three cases a hardened surface layer of different thickness (from 300 to 1200 μm) with a hardness of 593 – 598 HV is formed, consisting of two zones (a surface zone with a structure of fine-needle martensite; a transition zone smoothly transitioning into the initial ferrite structure). The transition zone (treatment according to mode 1 ) in its structure contains martensite and ferrite. The transition zone (mode 2 processing) consists of a Widemannstett structure. A more substantial surface heating zone according to this mode (700 μm) in comparison with the processing according to mode 1 (300 μm) in combination with intensive heat removal contributed to the formation of a Widmanstett structure, which is defective and unacceptable for operation. The transition zone with the processing according to mode 3 has the structure of martensite and ferrite. The formation of a defective Widmanstett structure in the transition zone does not occur, since 2 times more pulses are used during processing than in mode 2 . This contributes to the heating of the surface layer to a greater depth (1200 μm), and, consequently, the structure formation in the transition zone occurs from the intercritical interval Ag 3 – Ag 1 .
{"title":"Influence of combined electromechanical processing modes of 40Kh steel on its structure and hardness","authors":"A. S. Simachev, T. N. Oskolkova, R. A. Shevchenko","doi":"10.17073/0368-0797-2023-4-421-426","DOIUrl":"https://doi.org/10.17073/0368-0797-2023-4-421-426","url":null,"abstract":"The paper considers the effect of combined electromechanical processing in three different modes on the structure and hardness of the surface layers of 40Kh steel, which was in a normalized state (the original structure). The modes differ from each other by the different applied load and the number of pulses. The applied load in modes 1 and 2 (current strength 39 kA, pulse time 0.02 s, number of pulses 1) is 100 and 250 MPa, respectively. A distinctive feature of mode 3 compared to mode 2 is a greater number of pulses (two). Metallographically it was established that in all three cases a hardened surface layer of different thickness (from 300 to 1200 μm) with a hardness of 593 – 598 HV is formed, consisting of two zones (a surface zone with a structure of fine-needle martensite; a transition zone smoothly transitioning into the initial ferrite structure). The transition zone (treatment according to mode 1 ) in its structure contains martensite and ferrite. The transition zone (mode 2 processing) consists of a Widemannstett structure. A more substantial surface heating zone according to this mode (700 μm) in comparison with the processing according to mode 1 (300 μm) in combination with intensive heat removal contributed to the formation of a Widmanstett structure, which is defective and unacceptable for operation. The transition zone with the processing according to mode 3 has the structure of martensite and ferrite. The formation of a defective Widmanstett structure in the transition zone does not occur, since 2 times more pulses are used during processing than in mode 2 . This contributes to the heating of the surface layer to a greater depth (1200 μm), and, consequently, the structure formation in the transition zone occurs from the intercritical interval Ag 3 – Ag 1 .","PeriodicalId":35527,"journal":{"name":"Izvestiya Vysshikh Uchebnykh Zavedenij. Chernaya Metallurgiya","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136337492","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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