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To quickly obtain the fatigue life of cranes in service, the metal structure that determines the crane life is anchored. Meanwhile, the fast prediction method of fatigue life of crane metal structures based on the Stacking ensemble learning model is proposed. Firstly, in line with the structural stress method, the global rough model of the metal structure is established by the co-simulation technology to obtain the fatigue damage regions of the structure. The local fine model is constructed by local cutting and boundary condition transplantation to determine the critical weld at the failure regions. Secondly, through weld definition, equivalent structural stress acquisition, and fatigue life calculation, the sample data set with lifting load and trolley running position as input and fatigue life cycle times as output is constructed. Then, the Stacking integrated learning model combining gradient boosting, ridge regression, Extra Trees, and linear is built. On this basis, combined with the Miner theory, the rapid prediction of crane fatigue life is realized. Finally, the proposed method is applied to the QD40t × 22.5 m × 9 m general bridge crane. The results show that the life sample set constructed by the structural stress method is more accurate and reasonable than the nominal, hot spot, and fracture mechanics methods. The life prediction results of the Stacking integration model were improved by 6.3 to 49.2% compared to the single model. The method has theoretical and practical significance in reducing accidents and ensuring the safe operation of cranes. [ABSTRACT FROM AUTHOR]

The results of modeling and research of casting, rolling, and extrusion processes for producing wire from AleZr system alloys and determining its physical and mechanical properties have been presented. When implementing combined processes for processing aluminum alloys, the number of operations is significantly reduced, productivity and yield are increased. As a result of the conducted research, the influence of alloy preparation modes and their chemical composition on the physical, mechanical and electrical properties of longish semifinished products from AleZr system alloys obtained by combined rollingextrusion (CRE) and ingotless rolling-extrusion (IRE) methods were investigated. The simulation of the CRE process for one of these alloys of the system was carried out in the DEFORM 3D software package using data on its rheological properties obtained by the hot torsion method. Based on the modeling results, the optimal modes for conducting experimental studies were selected. The features of metal forming were experimentally studied, the temperature-velocity and technological parameters of combined processing were found, as well as the properties of cast billets, including those obtained using an electromagnetic mold (EMM). The results of experimental studies of the CRE and IRE processes suggest that it is possible to obtain longish deformed semifinished products from alloys AleZr system with a level of physical, mechanical and electrical properties that meet international standards. At all technological stages, including drawing, the structure of the metal was studied, and data on the physical and mechanical properties of hot-extruded rods and wire in cold-deformed and annealed states was obtained. The heat resistance of wire made from the investigated alloys was studied and it was found that after testing at a temperature of 280 °C and a holding time of 1 h, it satisfies the requirements of the AT3 type standard with a maximum permissible long-term operating temperature of 210 °C. Recommendations are given for industrial implementation; alloys containing 0.15e0.20% zirconium and 0.10e0.15% iron are recommended for the manufacture of AT1 type wire without heat treatment, as well as 0.25e0.30% Zr and 0.2e0.25% Fe for AT3 wire type with heat treatment. [ABSTRACT FROM AUTHOR]

The current study investigates the development of a replica molding process for hypervariable microstructures. Initially, the mold deformation theory for these hypervariable microstructures was derived. Based on this theory, a metal material with magnetic properties was selected as the structural material to create a negative Poisson's ratio (NPR) geometric structure. The experimental results, obtained by fabricating the NPR geometric mold layer with a metal material with adjustable magnetic properties and controlling microstructure deformation indirectly, validate the deformation theory and its predictions. These results demonstrate that the developed molding process, integrated with the magnetic NPR regulation system, exhibits excellent stability and replication capability. In this study, at the zero height (z = 0) position on the interface between the NPR geometric structure layer and the Polydimethylsiloxane (PDMS), the variation becomes more pronounced with increasing distance from the center of the microstructure. Furthermore, the tendency of the function curve varies accordingly. The primary cause is the lack of constraints on the free ends of both sides and the excessive constraints on the intermediate parts. Under the conditions in this study, the maximum ratio of its influence on the radial diameter thickness was 2.1%. This innovative process facilitates the rapid imprinting of microstructural components and offers the advantage of efficient molding. [ABSTRACT FROM AUTHOR]

Abstract To quickly obtain the fatigue life of cranes in service, the metal structure that determines the crane life is anchored. Meanwhile, the fast prediction method of fatigue life of crane metal structures based on the Stacking ensemble learning model is proposed. Firstly, in line with the structural stress method, the global rough model of the metal structure is established by the co-simulation technology to obtain the fatigue damage regions of the structure. The local fine model is constructed by local cutting and boundary condition transplantation to determine the critical weld at the failure regions. Secondly, through weld definition, equivalent structural stress acquisition, and fatigue life calculation, the sample data set with lifting load and trolley running position as input and fatigue life cycle times as output is constructed. Then, the Stacking integrated learning model combining gradient boosting, ridge regression, Extra Trees, and linear is built. On this basis, combined with the Miner theory, the rapid prediction of crane fatigue life is realized. Finally, the proposed method is applied to the QD40t × 22.5 m × 9 m general bridge crane. The results show that the life sample set constructed by the structural stress method is more accurate and reasonable than the nominal, hot spot, and fracture mechanics methods. The life prediction results of the Stacking integration model were improved by 6.3 to 49.2% compared to the single model. The method has theoretical and practical significance in reducing accidents and ensuring the safe operation of cranes.

The results of modeling and research of casting, rolling, and extrusion processes for producing wire from Al–Zr system alloys and determining its physical and mechanical properties have been presented. When implementing combined processes for processing aluminum alloys, the number of operations is significantly reduced, productivity and yield are increased. As a result of the conducted research, the influence of alloy preparation modes and their chemical composition on the physical, mechanical and electrical properties of longish semifinished products from Al–Zr system alloys obtained by combined rolling-extrusion (CRE) and ingotless rolling-extrusion (IRE) methods were investigated. The simulation of the CRE process for one of these alloys of the system was carried out in the DEFORM 3D software package using data on its rheological properties obtained by the hot torsion method. Based on the modeling results, the optimal modes for conducting experimental studies were selected. The features of metal forming were experimentally studied, the temperature-velocity and technological parameters of combined processing were found, as well as the properties of cast billets, including those obtained using an electromagnetic mold (EMM). The results of experimental studies of the CRE and IRE processes suggest that it is possible to obtain longish deformed semifinished products from alloys Al–Zr system with a level of physical, mechanical and electrical properties that meet international standards. At all technological stages, including drawing, the structure of the metal was studied, and data on the physical and mechanical properties of hot-extruded rods and wire in cold-deformed and annealed states was obtained. The heat resistance of wire made from the investigated alloys was studied and it was found that after testing at a temperature of 280 °C and a holding time of 1 h, it satisfies the requirements of the AT3 type standard with a maximum permissible long-term operating temperature of 210 °C. Recommendations are given for industrial implementation; alloys containing 0.15–0.20% zirconium and 0.10–0.15% iron are recommended for the manufacture of AT1 type wire without heat treatment, as well as 0.25–0.30% Zr and 0.2–0.25% Fe for AT3 wire type with heat treatment.

Публикуемые данные представляют собой первые результаты исследования железного кинжала из Центрального Казахстана (IV—V вв.). Выявлено, что все операции ковки и термической обработки проводились при температуре ниже 727°С. Твердость по шкале Виккерса составила 244 HV5. Анализ доли карбидов в железе свидетельствует, что состав металла соответствует стали заэвтектического состава, при этом доля карбидов в колониях достигает уровня доэвтектического чугуна. Высокая доля карбидов сферической формы в сочетании с матрицей из феррита придает кинжалу при сравнительно небольшой твердости высокую пластичность, коррозионную стойкость и хорошие режущие свойства. Технология термической обработки, которую применил древний мастер, обеспечила такому металлу довольно высокие эксплуатационные характеристики, повышающие режущие свойства и стойкость оружия в использовании.

The electromagnetic wave energy emitted by wireless communication equipment in coal mines can be coupled and absorbed by surrounding metal structures, which poses a risk of igniting explosive gases in the mine. The existing research on the safety of underground metal structure coupled electromagnetic waves only focuses on the analysis of the energy of metal structure equivalent impedance model coupled electromagnetic waves. It lacks research on the energy storage process of metal structure coupled electromagnetic wave energy accumulated over time. In order to solve the above problems, an equivalent energy storage structure model suitable for studying the coupling-accumulation-release electromagnetic wave energy of metal structures is proposed, namely the metal structure equivalent capacitive energy storage model and the metal structure equivalent inductive energy storage model. Firstly, by using a low attenuation transmission line model, the relationship between the output power of the transmitting antenna, the distance between the transmitting antenna and the metal structure, and the induced voltage at the receiving end is derived. Secondly, an equivalent energy storage model of metal structure is established. The mathematical relationship between the receiving end parameters and the discharge spark energy is derived. The influence of the receiving end parameters on the discharge spark energy is analyzed. Finally, the mathematical relationship between the output power of the transmitting antenna, the distance between the transmitting antenna and the metal structure, and the discharge spark energy is derived by analyzing the relationship between the induced voltage at the receiving end and the effective value of the induced voltage. The influence of the output power of the transmitting antenna and the distance between the transmitting antenna and the metal structure on the discharge spark energy is analyzed. The theoretical reference safety points of the equivalent energy storage models of the two metal structures are given under the condition of other parameters being determined. The simulation results show the following points. ① For the equivalent capacitive energy storage model of metal structures, the discharge spark energy increases with the increase of the effective values of the equivalent energy storage capacitor and the induced voltage at the receiving end, and the safety point shifts to the left. The safety requirements for the effective values of the equivalent energy storage capacitor and the induced voltage at the receiving end become stricter. ② The energy of the discharge spark increases with the increase of the transmitting antenna power, and decreases with the increase of the distance between the transmitting antenna and the metal structure. The theoretical reference safety point of the equivalent capacitive energy storage model of the metal structure is obtained. ③ For the equivalent inductive energy storage model of metal structures, the discharge spark energy increases with the increase of the effective values of the equivalent energy storage inductance and the induced voltage at the receiving end, and the safety point shifts to the left. The safety requirements for the effective values of the equivalent energy storage inductance and the induced voltage at the receiving end become stricter. ④ The energy of the discharge spark increases with the increase of the transmitting antenna power, and decreases with the increase of the distance between the transmitting antenna and the metal structure. The theoretical reference safety point of the equivalent inductive energy storage model of the metal structure is obtained. ⑤ Comparing the theoretical reference safety points of two metal structure energy storage models, it is concluded that the danger of the metal structure equivalent capacitive energy storage model is much greater than that of the metal structure equivalent inductive energy storage model.

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The behavior of a structure under the influence of external factors is determined by three key groups of parameters the metal composition (chemical, structural, and deformation). Obtaining information about these parameters directly on the structure will effectively solve the problem of assessing its actual technical condition. The problem of nondestructive evaluation of the chemical composition of metal is solved using portable spectrometers. A Microlab-Z2 diagnostic complex has been developed to evaluate the other two groups of parameters. It has two functional blocks. The surface preparation unit ensures that the surface of the construction site has a roughness, flatness, and level of applied mechanical hardening corresponding to the laboratory preparation of metallographic specimens. The research unit is a platform on which a metallographic microscope and a portable microhardness tester are installed. It allows metallographic research with magnification up to ×1000, surface microindentation, measurement of microhardness values at load of 0–200 gf, and optical study of the morphology of imprints in any spatial position. The reliability of the data obtained by the Microlab-Z2 diagnostic complex has been confirmed during comparative tests with stationary equipment. An assessment of structure parameters and contamination of metal with nonmetallic inclusions, assessment of the degree of hardening and embrittlement of metal, and detection of aging processes can be performed with the help of the developed device. The use of the Microlab-Z2 diagnostic complex for operational nondestructive evaluation of structural and deformation parameters of metal structures will allow reaching a qualitatively different level of efficiency in performing production and acceptance testing of manufactured products, assessing the maintainability of defects, planning repairs and other compensating measures, and industrial safety expertise. [ABSTRACT FROM AUTHOR]

This article presents the study of the effect of ultrafine titanium monocarbide (TiC) powder on the formation of the deposited metal structure. The effective particle size of the powder for the welding bath inoculation of low-carbon and low-alloy steels should be at least 600–700 nm (0.6–0.7 μm). The use of an inoculator powder with a more dispersed fraction was inappropriate from thermodynamic and economic points of view. With the increase in the content of ultrafine TiC powder in the coating of welding electrodes (0%–10%), the crystallites in the deposited metal decreased in size by 8–9 times, and they acquired a more equilibrium state (the shape factor increased by two times). The addition of various amounts of TiC powder to the melt of the welding bath did not result in a noticeable hardening of the deposited metal (Vickers hardness: 188–197 HV). [ABSTRACT FROM AUTHOR]

Coating, as one of the significant applications in the building and construction sector, is crucial to prevent steel from reaching critical temperature and fire-induced structural collapse. This article reviews the current use of conventional coatings and assesses the potential use of novel geopolymer coatings on the metal substrate, particularly on the steel structure. The conventional passive fireproofing systems, including cement-based coatings and intumescent coatings, exhibit unavoidable limitations either due to the high thickness and weight or poor thermal and chemical resistance of the coating. Thus, innovations in conventional and novel coatings are constantly developing and growing rapidly. In recent years, geopolymer coatings have attracted much attention due to their higher mechanical strength and excellent resistance to chemicals and heat. Moreover, the green and environmentally friendly characteristics make geopolymer an admirable coating material for many applications. The main challenge that lies in the development of geopolymer coating is the interfacial bonding with the metal structure. Therefore, the influencing factors, including precursor materials, alkaline activator, and curing processes on the adhesion and thermal and chemical resistance of the geopolymer coating have been well explored. The performance comparison between these coatings indicates that geopolymer coating offers a superior mechanical and thermal performance, along with a substantially lower environmental impact compared with cement-based coating. This suggests that geopolymer coatings have great potential for fire protection on steel structures. [ABSTRACT FROM AUTHOR]

When the metal structures distributed in the underground roadway are in the near-field of the large loop transmitting antenna, they will couple the electromagnetic wave energy of the large loop transmitting antenna. Once the metal structure has a breakpoint and friction occurs, it may produce friction discharge spark and ignite gas. This poses a threat to the safety of coal mine. In order to solve this problem, the safety of electromagnetic wave energy of underground metal structure near-field coupled large loop transmitting antenna is analyzed from two aspects of near-field coupling risk coefficient and safe distance. By establishing the equivalent circuit of electromagnetic wave energy of metal structure near-field coupled large loop transmitting antenna, the expressions of near-field coupling risk coefficient and safe distance between metal structure and large loop transmitting antenna are derived. The influence of the radius of the large loop transmitting antenna, the radius of the equivalent receiving coil of the metal structure, the friction discharge spark load and the distance between the metal structure and the large loop transmitting antenna on the near-field coupling risk coefficient and the safe distance are analyzed. The simulation results show that the near-field coupling risk coefficient increases slightly at first and then decreases slightly or increases all the time with the increase of the radius of the large loop transmitting antenna. Under certain conditions, the friction discharge spark load can make the near-field coupling risk coefficient reach the peak value. When the radius of the large loop transmitting antenna is greater than or equal to the radius of the equivalent receiving coil of the metal structure, the near-field coupling risk coefficient at the peak value may exceed the critical value 0.46 of the near-field coupling risk coefficient. This may cause danger. When the radius of the large loop transmitting antenna is smaller than the radius of equivalent receiving coil of the metal structure, the near-field coupling risk coefficient at the peak value is less than the critical value 0.46 in most cases. This will not cause danger in most cases. Under certain conditions, the radius of the large loop transmitting antenna can make the near-field coupling risk coefficient reach the peak value. The near-field coupling risk coefficient at the peak value first increases and then decreases with the increase of the radius of equivalent receiving coil of the metal structure. It is more likely to exceed the critical value 0.46 of the near-field coupling risk coefficient, which is likely to cause danger in the gas environment. The safe distance increases with the increase of the radius of the large loop transmitting antenna. The safety of the electromagnetic wave energy on the friction discharge spark load decreases with the increase of the radius of the large loop transmitting antenna. When the radius of the large loop transmitting antenna is greater than or equal to the radius of the equivalent receiving coil of the metal structure, the safe distance increases with the increase of the radius of the equivalent receiving coil of the metal structure. The safety of the electromagnetic wave energy on the friction discharge spark load decreases with the increase of the radius of the equivalent receiving coil of the metal structure. When the radius of the large loop transmitting antenna is smaller than the radius of the equivalent receiving coil of the metal structure, the safe distance first increases slowly and then decreases with the increase of the radius of the equivalent receiving coil of the metal structure. The safety of the electromagnetic wave energy on the friction discharge spark load first decreases and then increases with the increase of the radius of the equivalent receiving coil of the metal structure.

This article presents the results of the analysis of the patent situation in the field of 3D printing technologies with metals and materials based on them and the prospects for their development. In the development of the life cycle of patenting laser additive technologies in Russia in 2000–2020, three main stages can be distinguished, namely, Stage I for 2000–2008, Stage II for 2009–2015, and Stage III for 2016–2020. In terms of the applicability of patent solutions in the field of laser additive technologies, the most developed industries are the mechanical engineering and metallurgical industries. The leaders of patenting in the Russian Federation territory are BASF and Siemens (Germany) and Airbus Operation (France). The leading countries where applicants strive to obtain patents are the USA, Russia, China, Japan, and the countries of the European Union. Three main directions can be distinguished among the main trends in the development of laser additive technologies: development of basic cultivation technologies (development of effective technological modes) of products and technologies of combined processing (e.g., deformation, thermal, and thermal–deformation); development of devices and equipment for additive manufacturing, including special equipment that ensures high-quality geometric parameters and improves the performance properties of the product during the production process; and development and creation of new powder materials and their compositions with a given granulometric composition and technologies for their production. [ABSTRACT FROM AUTHOR]

Copyright of VLC Arquitectura is the property of VLC Arquitectura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Metal structure and equipment are scattered and diverse in hydropower and water conservancy projects. There are many participants and a large amount of information in the whole process of metal structure mid equipment design and manufacturing. "Information islands" exist among project participants, mid the level of informatization and digitization needs to be further improved. Relying on Lidi, 'Wudongde Hydropower Station mid other projects, with the help of BIM technology, research was carried out in the aspects of model database construction, engineering drawing expression, digital design and handover of metal structure equipment. The simulation function of knowledge engineering and ergonomics was deeply applied in the aspects of virtual product experience, virtual manufacturing, operation and maintenance, in order to provide a reference for the application of BIM technology for the similar engineering metal structures. [ABSTRACT FROM AUTHOR]

The metal structures distributed in underground coal mine roadways can be equivalent to the receiving antenna to absorb electromagnetic wave energy and release the energy in the form of discharge sparks under specific conditions. The accumulated energy has the risk of igniting explosive gas. In order to solve the problem, the conditions of ignition of gas by discharge spark when the metal structure is equivalent to the receiving antenna are analyzed, and the calculation expression of the maximum power that can be absorbed by the discharge spark as load is derived. It is concluded that when the gas volume fraction is 8.5% and the metal structure is equivalent to the receiving antenna, the maximum allowable power that the discharge spark will not ignite the gas is 2.8 W. Wireless Insite electromagnetic simulation software is used to simulate the maximum power that can be absorbed by the discharge spark as load under different working conditions of the radio frequency equipment. The results show that the greater the output power of radio frequency equipment, the lower the working frequency of radio frequency equipment, the closer the metal structure to radio frequency equipment, the greater the load maximum power that can be absorbed, the greater the potential safety hazard of gas ignited by discharge spark. When the minimum safety distance between the transmitting antenna of the radio frequency equipment and the metal structure is 0.1 m, the discharge sparks generated by the radio frequency electromagnetic radiation energy in the frequency band below 800 MHz of the radio frequency equipment have the possibility of igniting gas. The discharge sparks generated by the radio frequency electromagnetic radiation energy in the frequency band above 890 MHz of the radio frequency equipment in the metal structure are intrinsically safe and will not ignite gas.

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose. Analyzing the stress distribution in the metal structure of the gantry crane under the cyclic operation mode and identifying stress concentrators in the crane column to assess the survivability of the machine. Methodology. In order to achieve the objective, the methods employed included analytical calculation method, finite element method, as well as differential and integral calculus methods. To study the state of the metal structure of the gantry crane, namely the column, the program Solid Works and its application Simulation were used. Findings. Using the CAD/CAE-system, the loaded condition of the metal structure of the gantry crane was modeled and the maximum working loads were determined, and a calculated scheme of their operation was constructed. The method is presented for calculation of survivability of load-bearing elements of the crane taking into account coefficients of intensity and concentration of stresses which allow defining speed of growth of cracks in dangerous stress zones of a metal structure. Originality. The existing methods for designing crane metal structures gained their traction. The integrated technique for assessing crane reliability has been suggested for the first time. This technique is focused on estimating the survivability of components elements. For the first time solid-state models of the crane and its column have been developed; the analysis of the stress-strain state of the column was performed, maximum stresses were determined, stress concentration points in the metal structure of the column were identified and recommendations for improvement of stress zones were presented. Practical value. The presented method for assessing the reliability of metal structures of gantry cranes can be implemented in the practice of design organizations for the development, design of new gantry cranes and modernization of existing ones. The obtained results provide an opportunity to assess the accumulated damage in the elements of the metal structure, to predict the development of defects to a critical size, as well as to decide on the further operability of a gantry crane. [ABSTRACT FROM AUTHOR]

The results of studies of the process of obtaining wire for the manufacture of jewelry chains from new nickel-free 585 gold fineness alloys are presented. New 585 gold fineness alloys, alloyed with palladium, silver and other elements, and as modifiers – with rhodium and ruthenium in the stated quantities have been proposed. By modeling the process of section rolling of rods in octagonal calibers using the variation method of minimum total power, the broadening of the metal and the energy-power parameters of rolling rods from the investigated alloys have been determined. The regularities of their change have been found. Software has been developed for designing processes for the production of longish deformed semi-finished products and technological modes of rolling and drawing of new gold alloys. With the help of experimental studies, the adequacy of the results of calculations and modeling was checked, and new data were obtained on the mechanical properties of the metal and its structure. It has been found that the proposed alloys and the modes of their processing using the processes of section rolling and drawing make it possible in industrial conditions to obtain jewelry wire with a diameter of up to 0.25 mm with the level of mechanical and operational properties required for chain tying. [ABSTRACT FROM AUTHOR]

Features of centrifugal plasma surfacing using powders of three different alloying systems based on iron and nickel were studied. It is found that at centrifugal plasma surfacing the iron-based test powder has the best welding-technological properties. It allows producing deposited metal of 200Kh15D2MS2R type. The layer deposited with this powder, has a microstructure of uniform height and ensures increase of the sleeve wear resistance 5 – 6 times, compared to batch-produced ones, which are made from steel 70 and quenched by SHF. A design of the bushing component is proposed with replaceable surfaced sleeve, which is more adaptable to fabrication and allows repairing it by simple replacement of the worn sleeve. [ABSTRACT FROM AUTHOR]

Features of centrifugal plasma surfacing using powders of three different alloying systems based on iron and nickel were studied. It is found that at centrifugal plasma surfacing the iron-based test powder has the best welding-technological properties. It allows producing deposited metal of 200Kh15D2MS2R type. The layer deposited with this powder, has a microstructure of uniform height and ensures increase of the sleeve wear resistance 5-6 times, compared to batch-produced ones, which are made from steel 70 and "uenched by HFC. A design of the bushing component is proposed with replaceable surfaced sleeve, which is more adaptable to fabrication and allows repairing it by simple replacement of the worn sleeve. [ABSTRACT FROM AUTHOR]

The main content of this article is the reduction of safety problems and risks in civil engineering from the point of view of science in civil engineering. The technology of protecting buildings and structures from corrosion and thermal effects on metal structures requires an increase in the corrosion resistance of structures.

Proceeding from published data, the influence of modification and microalloying by boron, titanium, tungsten, zirconium, yttrium, etc., on the deposited metal structure, mechanical and service properties is shown. It is demonstrated that addition of these elements or their compounds with carbon and nitrogen in the quantity of up to 0.2 %, allows producing a fine-grained, homogeneous structure of metal, a more uniform distribution of alloying elements, that makes a positive effect on the values of strength, ductility, wear and heat resistance. It was determined that, introducing small additives of boron or its compounds (in the quantity of up to 0.2%), cerium or yttrium (in the quantity of up to 0.015 % of each), or application of complex master alloys, which can have the above-mentioned elements in their composition, as well as such modifiers, as zirconium, titanium carbides and borides or tungsten carbides, looks promising in terms of increase of wear and heat resistance of the deposited metal. Proceeding from the performed analysis, it was also shown that addition of titanium and zirconium diborides to the composition of flux-cored wire charge, promotes activation of the processes of formation of molten metal drops at the electrode wire tip, resulting in improvement of the quality of metal transfer in the welding arc, that leads to greater values of the coefficients of alloying element transition into the deposited metal and improves deposited bead formation. 28 Ref., 1 Tabl., 7 Fig. [ABSTRACT FROM AUTHOR]

Proceeding from published data, the influence of modification and microalloying by boron, titanium, tungsten, zirconium, yttrium, etc., on the deposited metal structure, mechanical and service properties is shown. It is demonstrated that addition of these elements or their compounds with carbon and nitrogen in the quantity of up to 0.2 %, allows producing a fine-grained, homogeneous structure of metal, a more uniform distribution of alloying elements, that makes a positive effect on the values of strength, ductility, wear and heat resistance. It was determined that introducing small additives of boron or its compounds (in the quantity of up to 0.2 %), cerium or yttrium (in the quantity of up to 0.015 % of each), or application of complex master alloys, which can have the above-mentioned elements in their composition, as well as such modifiers, as zirconium, titanium carbides and borides or tungsten carbides, looks promising in terms of increase of wear and heat resistance of the deposited metal. Proceeding from the performed analysis, it was also shown that addition of titanium and zirconium diborides to the composition of flux-cored wire charge, promotes activation of the processes of formation of molten metal drops at the electrode wire tip, resulting in improvement of the quality of metal transfer in the welding arc that leads to greater values of the coefficients of alloying element transition into the deposited metal and improves deposited bead formation. [ABSTRACT FROM AUTHOR]

A literature review of the main methods of modification and microalloying of deposited metal was made. It was shown that, in contrast to the term «microalloying», the term «modification» should consider not only a method of introducing small additives of chemical elements or their compounds into the deposited metal but also various physical effects or technological processes aimed at achieving the same goal – refinement of micro- and macrostructure of metal, cleaning of grain boundaries and boundary zones, improving the complex of technological, mechanical and operational properties of steels and alloys. Examples of such physical effects are application of vibrations to a product in the process of surfacing; input of power from a pulsed heat source; pulsed electrode or filler wire feed; application of sources with modulation of welding current; external electromagnetic effect, etc. The classification of modification methods depending on the scheme of their implementation and impact on the properties of the deposited metal is given. The main advantages and disadvantages of methods of introducing modifying and microalloying additives into the deposited metal are shown. It was determined that from the considered methods of modification, the chemical method is the simplest and the most rational, which implies introducing modifier elements into the deposited metal directly through the charge of flux-cored electrode wires. This method is technologically and economically simple and versatile, and can be used with minor changes in electric arc, electroslag and plasma surfacing. 33 Ref., 1 Tabl., 3 Fig. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A literature review of the main methods of modification and microalloying of deposited metal was made. It was shown that, in contrast to the «microalloying» term, the «modification» term should mean not only a method of introducing small additives of chemical elements or their compounds into the deposited metal but also various physical effects or technological processes aimed at achieving the same goal - refinement of micro- and macrostructure of metal, cleaning of grain boundaries and near-boundary zones, improving the complex of technological, mechanical and operational properties of steels and alloys. Examples of such physical effects are application of vibrations to a product in the process of surfacing; input of energy from a pulsed heat source; pulsed electrode or filler wire feed; application of sources with modulation of welding current; external electromagnetic effect, etc. The classification of modification methods, depending on the scheme of their implementation and impact on the properties of the deposited metal is given. The main advantages and disadvantages of methods of introducing modifying and microalloying additives into the deposited metal are shown. It was determined that from the considered methods of modification, the chemical method is the simplest and the most rational, which implies introducing modifiers into the deposited metal directly through the charge of flux-cored electrode wires. This method is technologically and economically simple and versatile, and can be used with minor changes in electric arc, electroslag and plasma surfacing. 33 Ref., 1 Table, 3 Figures. [ABSTRACT FROM AUTHOR]

The results of the first stage of ultrasonic studies of the metal structure of pipelines of thermal power plants in operation are presented. The tests were carried out on metal of steel grades 15Kh1M1F and St20 with different operating life (operating time). The metal samples were subjected to metallographic analysis, the received data (the average grain size the distribution variance ) was used for theoretical calculation of the parameters of ultrasonic pulses of the bottom signal in metal. Quantitative data were obtained on the effect of the thickness of the couplant layer (the gap) between the transducer and the test object at operating frequencies of 5.0, 7.5 and 10 MHz for various values of the average grain size in metal. Examples of calculated and experimental pulses and signal spectra for a frequency of 5 MHz are given. [ABSTRACT FROM AUTHOR]

Friction stir welding may be used to create butt joints of an aluminum matrix composite dispersion-hardened by SiC particles. With increase in content of the reinforcing SiC particles, the range of welding conditions producing defect-free joints is significantly narrowed. In cyclic loading, the joints begin to fail from the weld surface. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the structure and properties of a wire with a diameter of 0.5 mm from an alloy of the Al-REM system with a rare-earth metal content of 7–9%. Wire obtained as a result of the implementation of the technology of its manufacture using the methods of casting into an electromagnetic mold (EMM), continuous extruding, and drawing. The rheological properties of the metal of continuously cast round billets from the experimental alloy obtained using an electromagnetic mold are determined. The modeling and analytical assessment of the possibility of carrying out the process of combined rolling-extruding (CRE) of such billets in a closed box-type roll groove of a continuous extruding unit are carried out. The features of metal shaping have been studied. The temperature-speed and technological parameters were found at which the CRE process can be carried out in a stable mode of operation. Data have been obtained for the forces acting on the die and rolls during rolling-extruding. The results of experimental studies of the process of obtaining longish deformed semi-finished products from an experimental alloy on the laboratory unit CRE-200 and the pilot plant unit CRE-400 are presented. The structure of the metal has been studied; data on the ultimate tensile strength, yield strength, relative elongation, and electrical resistance of hot-extruded rods and wires in cold-worked and annealed states have been obtained. It was found that the proposed processing modes make it possible to obtain by the method of combined rolling-extruding rods with a diameter of 9 mm in industrial conditions from longish billets with a diameter of 18 mm, cast by means of EMM. Wire in a cold-deformed and annealed state with a diameter of 0.5 obtained by drawing from the rods with a diameter of 9 mm from an experimental alloy of the Al-REM system containing 7–9% rare-earth metals with the required physical and mechanical properties. [ABSTRACT FROM AUTHOR]

In order to quantitatively characterize the ability of PVD(physical vapor deposition) film sensors to detect cracks in metallic structures, the process parameters applied to LY12-CZ aluminium alloys were first optimized using orthogonal tests, and coin shape, 1mm concentric dual ring shape, 0.5mm concentric tricyclic shape PVD film sensors were prepared on three groups of specimen with central hole using these parameters. Subsequently, the on-line monitoring experiment of fatigue cracks was carried out under laboratory conditions, the potential output signals of the PVD film sensors and microscope observations were compared and analysed. Finally, the probability of detection curves of all kinds of PVD thin-film sensors and PVD film sensor in different shapes were plotted separately using the improved crack size separation method and binomial distribution detection model. PVD thin-film sensors have 93.56% detection probability for cracks with length greater than 0.99mm at 95% confidence level. Compared to coin-shaped thin-film sensors, concentric ring shape film sensors are more sensitive to cracks smaller than 0.5mm, and the sensors with finer channel width have the higher probability of detection on small size cracks.

The traditional methods for geometric estimation of the shape of various objects, including materials science, based on approximate approximation of the structure of the object under study by geometric figures, for example, lines, segments, planes, polygons, polyhedra, spheres. All these techniques are based on a classical Euclidean geometry with an integer topological dimension. For a quantitative description of fractals, one quantity is enough - the fractal dimension or a some parameter that describes the invariability of statistical characteristics when the scale changes. An analysis of traditional methods for studying the structure of metals – optical microscopy, in particular, quantitative metallography, electronic microstructure, and crystallographic texture by structural analysis, indicates that none of them can be universal and suitable for solving the full scope of the tasks of identifying quantitative characteristics of a metal by analysis its structure. In a metallography, fractal analysis refers to the microscopic images of the surfaces of materials. In this case, using fractal characteristics, one can describe the structure and mechanical properties of materials, like the degree of surface roughness, chemical surface changes, deformation of materials, etc. This article describes the application of the fractal analysis method to the general concept of the metal structure described by GOST 5639-82 and 8233-56. With the help of a software tool written by the author that allows you to quickly calculate the fractal dimension, the calculated fractal dimension of the metal structure about various magnifications and various balls of grains. The described algorithm for searching for fractal dimension and an example of the use of software for quick search of fractal dimension. The analysis of the influence of structural parameters on the value of fractal dimension is carried out. The choice of ferrite-pearlite steels is reasoned and it is analyzed which metal structures it is possible to further apply the fractal analysis method and look for correlations with physicomechanical properties.