Field Of Metallurgy Research Articles

First-principles study on yttrium inclusions in micro alloyed steels

The removal and control of inclusions has always been a hot issue in the field of metallurgy, and rare earth modifying is a proven method. However, some rare earth inclusions cannot be accurately judged due to the necessary assumptions for thermodynamic calculations and the lack of certain thermodynamic data. On the other hand, most of the currently reported researches focus on the changes in the morphology of the inclusions, and rarely involve the inherent properties of the inclusions. To address these two deficiencies, this work investigated elaborately the stability, elastic modulus, elastic anisotropy and thermal expansion coefficient of yttrium (Y) inclusions in micro alloyed steels by first-principles calculation. Then, the role of yttrium inclusion in the initial stage of crack initiation was discussed. The results showed that it was practical to judge the possibility of unknown inclusions formation in steel by formation enthalpy. The inclusions were changed from Al2O3 to Y2O3, Y2O2S, YAlO3-Y2Si2O7 composite inclusions with yttrium treatment, which was consistent with the metallographic observations. The bulk modulus (B), shear modulus (G), Young’s modulus (E), and Poisson’s ratio (σ) were calculated in a framework of the Voigte-Reusse-Hill approximation. In light of B/G and σ values, Al2O3 showed apparent brittleness, and the toughness of yttrium inclusions were improved to varying degrees compared to Al2O3 inclusions. Moreover, the order of the degree of elastic anisotropy for these inclusions was Y2Si2O7 > Al2O3 > Y2O3 > Y2O2S > YAlO3. Furthermore, the thermal expansion coefficient of Y2O3, Y2O2S, YAlO3 inclusions at any temperature were greater than that of Al2O3 and were relatively close to that of Fe, whereas, Y2Si2O7 inclusion was much larger than that of Fe. Finally, the difference between yttrium inclusions and iron matrix in the aspect of incompressibility, brittleness, toughness, mechanical anisotropy, and thermal expansion was reduced significantly, thereby improving the consistency of the matrix, this could be used to explain the phenomenon of alleviating stresses concentration and delaying the formation of micro voids.

MECHANISMS AND DIRECTIONS OF FINANCING UKRAINIAN INDUSTRY IN THE POST-WAR PERIOD: THE WORLD EXPERIENCE

Introduction. Since February 2022, the Russian Federation has continued a full-scale war against Ukraine. Much of Ukraine’s property has been damaged, destroyed and confiscated. In addition, Ukraine has suffered significant losses of human capital. As the war continues, casualties are mounting. Of course, the most important priority today is to obtain as many heavy weapons as possible from Western partners in order to win the war as soon as possible. However, in addition to the military aspect, there is also the economic. To fight - you need resources. That is why the reconstruction of Ukraine should be planned today. To make Ukraine free, strong, modern and secure after the war, we need resources. Despite this, Ukraine must become the freest, most modern and safest country in Europe. So rebuilding Ukraine is not just something that we should do after the victory or in the next few years, but something that we should do right now. Materials and methods. Theoretical and methodological basis of research consists of scientific works, primarily foreign scientists. The study of the scientific problem is carried out with the help of critical and scientific analysis, methods of scientific generalization and systematization, induction and deduction. The findings, conclusions and recommendations are based on an integrated approach. Results and discussion. Currently, the issue of consolidation of resources for the full recovery of the domestic economy is relevant. The article considered the post-war reconstruction experiences of Israel, Japan, South Korea, Western Europe (primarily Germany), because they were able to bet on their strong sides and make significant progress. Conclusions. On the basis of international experience and considering the unprecedented financial, military and political support from external partners, it is important for Ukraine to set priorities for economic development. In our view, such priorities should be based on the development of strategic industrial activities, integrated into the global world and having multiplier effect in ensuring energy independence and formation of directions of technological breakthroughs, In this way, Ukraine will be able to integrate into the modern global redistribution of innovation activities and ensure equitable participation, in particular by developing the maximum possible degree of processing of final products for these purposes. In addition, strategic objectives should be formulated taking into account the need for full-scale industrial recovery using domestic resources, particularly for industrial activities such as titanium mining and deep processing, Lithium, aluminum and their basis for high-tech products for end users, as well as the creation of conditions for the production of nuclear energy and synthetic fuel. Stresses the importance of the prospects for the development of the above-mentioned industrial activities and the fact that Ukraine has a strong research base, scientific schools in the field of materials science, metallurgy and titanium engineering, lithium, aluminium, nuclear energy, synthetic fuel, etc. they have the opportunity to further competitive development of new breakthrough technologies and production at a high scientific and practical level.

Исследование порошка титана, полученного методом СВС-гидрирования и дегидрирования в вакуумной печи

The method of SHS (self-propagating high-temperature synthesis) allows the efficient synthesis of titanium hydride. The article presents new results of experimental studies of titanium powders synthesized by the method of SHS hydrogenation and dehydrogenation in a vacuum furnace. Changes in the microstructure, phase and chemical composition during hydrogenation-dehydrogenation of a titanium sponge were studied. The titanium sponge was hydrogenated in a high-pressure SHS reactor at a hydrogen pressure of 3 MPa. The content of oxygen and carbon impurities decrease in the process of SHS hydrogenation was found. After hydrogenation, the sponge is a single-phase δ-hydride of titanium with a tetragonal lattice, the particles have a fragmentary shape. In the obtained titanium hydride, an increased hydrogen content of 4.64 wt. % was noted. The hydrogenated titanium sponge was mechanically crushed in a drum-ball mill to a particle size of 40 – 250 microns. Dehydrogenation of titanium hydride powder was carried out in a vacuum furnace at a temperature of 850 °C for 220 minutes. Titanium after dehydrogenation is a single-phase α-titanium powder with a hexagonal close packed lattice, the size and shape of the particles have not changed. The technological process under study provides the possibility of obtaining high-quality titanium powders of the necessary granulometric composition for various fields of powder metallurgy.

Declaration of conformity in the field of metallurgical production

At present, the declaration of conformity in Russia is a priority form of confirmation of the conformity of products to the requirements of technical regulations. Technical regulations are documents containing mandatory requirements for products, methods and forms of assessment, approved by the decision of the Supreme Eurasian Economic Council, acting on the territory of the Eurasian Economic Union and being mandatory for execution and compliance. A list of technical regulations has been established, for compliance with which the declaration of conformity of products in the field of metallurgy is carried out. The sources of risk of the process of declaration of conformity have been identified and their causes have been established. Among these sources are selection of product samples; on-site testing of products, samples or their study as a representative of all subsequently manufactured products; assessment of test (research) results from the standpoint of visibility of product compliance with the requirements of technical regulations; production control; study of a sample for the planned production as a typical representative of a product used at hazardous production facilities; analysis of the technical documentation submitted by the applicant and its preliminary assessment; assessment of the risk of harm when applying the requirements proposed by the applicant; quality management system (QMS) certification. On the basis of risk management, conformity declaration schemes have been established, with the use of which the likelihood of products hazardous to the consumer appearing on the market is greatest - 1D, 3D. The content of the documentation on the applicant’s production control when declaring conformity is proposed - technological equipment, personnel, measuring instruments, documentation (design, technological, registration and accounting), infrastructure (territory, production facilities, transport, etc.), incoming control, special processes (operations), acceptance control and periodic testing, marking of finished products. A list of national standards of the Russian Federation is presented, which make it possible to implement all stages of the declaration of conformity by the applicant.

Important Key Process Simulations in the Field of Steel Metallurgy

During the last decade, the chair for ‘Simulation and Modelling of Metallurgical Processes’ (SMMP) has worked on different metallurgical processes with the highlights of the following five industrial relevant topics: (i) modelling the as-cast structures of large steel castings; (ii) exploring the formation mechanisms of macrosegregation; (iii) describing magnetohydrodynamic and electrochemical phenomena in remelting processes, (iv) understanding how solidification and flow can be influenced by magnetohydrodynamics during steel continuous casting; and (v) describing nozzle clogging in steelmaking processes. In this contribution, the main achievements from the group on the above five topics are briefly described.

Advanced Trends in Metallurgy and Weldability of High-Strength Cold-Resistant and Cryogenic Steels

Thermomechanical Controlled Processing (TMCP), the initial microstructure and mechanical properties of rolled products made of high-strength steels, have a significant influence on the properties and reliability of welded structures for low temperature and cryogenic service. This paper systematizes advanced research trends in the field of metallurgy and weldability of high-strength cold-resistant and cryogenic steels. The classification and properties of high-strength steels are given and TMCP diagrams and phase transformations are considered. Modern methods of improving the viscoplasticity of rolled steel and welded joints are analyzed. The problems of the weldability of high-strength steels are reduction of impact toughness at low temperatures, hydrogen embrittlement, anisotropy, and softening of welded joints in the heat-affected zone. The authors propose a systemic concept and methods for improving the metallurgy and weldability of high-strength steels for low temperature and cryogenic service.

A comparison of particle size distribution and morphology data acquired using lab-based and commercially available techniques: Application to stainless steel powder

The particle size distribution (PSD) and particle morphology of metal powders undoubtedly affects the quality of parts produced by additive manufacturing (AM). It is, therefore, crucial to accurately know the PSD and morphology of these powders. There exist several measurement techniques for these quantities, but since each method is based on different physical phenomena, which are sensitive to different aspects of a particle's shape and size, it is unclear how the measured PSDs and morphology compare to one another. In this study, five different techniques are used: sieve analysis, dynamic imaging analysis, laser diffraction analysis, X-ray computed tomography (XCT), and scanning electron microscopy. The first three are commonly used in the powder metallurgy field while the last two are laboratory-based tools capable of providing robust size and shape data. Nominally identical samples of stainless-steel powders were produced via riffling, and each technique was employed to measure effectively the same PSD and in some cases the morphology. In this paper, the differences among these measurement techniques are explored by a comparison of the measured results. Besides the random variations of the various measurement processes, the difference in the results is partly due to the fact that the particles are not perfectly spherical and that there are many multi-particles present. Each of these affect the principle of each method differently. Three-dimensional particle morphology and size data collected via XCT is used to provide insight regarding the discrepancies among other sizing and morphology measurement techniques.(Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.)

Structure and properties of near-a titanium products obtained by direct laser deposition and heat treatment

Advanced techniques of obtaining products require careful selection of materials for various industries. Titanium alloys are widely used in the aerospace, shipbuilding and mechanical engineering industries. The development of near-a titanium alloys should be considered a significant achievement in the field of metallurgy and heat treatment (HT) of titanium alloys. This article presents a study carried out with the aim of optimizing heat treatment modes for high-temperature titanium alloys obtained by direct laser deposition (DLD). Heat treatment was carried out in the temperature range (700-1000°C), covering three typical temperature ranges, i.e. the temperature range for the partial decomposition of martensite, the temperature range for the complete decomposition of martensite, and the phase transformation temperature were subsequently selected as the heat treatment temperatures. Based on metallographic analysis, the influence of heat treatment modes on the structure, as well as the tensile properties at room temperature, of TA15 titanium DLD-samples.

Contribution of soviet metallurgy to creation and serial production of KV heavy tank (1939 – 1941)

The KV heavy tank stays among the legends of the Great Patriotic War and one of the most recognizable combat vehicles of those years. The assessment of the tank, its design features and practice of operation, in scientific, popular science literature, and journalism, is still ambiguous: from praise to denial. Historical memory of this combat vehicle is actively living its life not only on pages of the books, but also in the virtual space, in the branches of thematic Internet forums and computer games. The heavy tank of KV series was developed and put into service at the very end of 1939. A new grade of 42S armor steel was created especially for it, which was distinguished by a relatively low content of alloying elements and high adaptability for mass production. The authors seriously studied the stages of armor production and the difficulties in its creation. They show the enormous contribution of metallurgists to the creation of a combat vehicle. As a result of engineering research and the decisive contribution of metallurgy, a formidable machine was obtained, possessing thick armor (75 mm) and quite powerful armament (76.2 mm cannon). At the same time, the tank had a whole range of disadvantages that reduce the effectiveness of its combat use. The general lack of development of the design and archaic technological solutions created serious problems both in the production and in the subsequent operation of this tank. History and tradition of searching the tank allows taking a fresh look at the long glorious traditions of the national engineering school in the field of metallurgy, and its decisive contribution to the Victory in the Great Patriotic War.

Study on the Characteristics of Schottky Temperature Detector Based on Metal/n-ZnO/n-Si Structures

Background: At present, the main problems of Micro-Electro-Mechanical Systems (MEMS) based temperature detector are the narrow range of temperature detection and difficulty in the measurement of high temperature. Besides, MEMS devices have different response characteristics for various surrounding temperature in the petrochemical and metallurgy application fields with hightemperature and harsh conditions. To evaluate the performance stability of the high-temperature MEMS devices, the real-time temperature measurement is necessary. Objective: A Schottky temperature detector based on the metal/n-ZnO/n-Si structures is designed to measure high temperature (523~873K) for MEMS devices with a large temperature range. Methods: By using the Finite Element Method (FEM), three different work function metals (Cu, Ni and Pt) contacting the n-ZnO were investigated to realize Schottky. At room temperature (298K) and high temperature (523~873K), the current densities with various bias voltages (J-V) were studied. Results: The simulation results show that the high-temperature response power consumption of three Schottky detectors of Cu, Ni and Pt decreases successively, which is 1.16 mW, 63.63 μW and 0.14 μW. The response temperature sensitivities of 6.35 μA/K, 0.78 μA/K, and 2.29 nA/K are achieved. Conclusion: The Cu/n-ZnO/n-Si Schottky structure could be used as a high-temperature detector (523~873K) for the high-temperature MEMS devices. It has a large temperature range (350K) and a high response sensitivity of 6.35 μA/K. Compared with the traditional devices, the Cu/n-ZnO/n-Si Schottky structure-based temperature detector has a low energy consumption of 1.16 mW, having potential applications in the high-temperature measurement of the MEMS devices.

Dewatering fine solid suspension by using steam pressure filtration

Steam pressure filtration is the combination of mechanical and thermal in one equipment. This process shows the advantages in comparison to conventional pressure filtration by the characteristic of its distinction mechanism. Application of steam pressure filtration can be listed: dewatering the suspension of fine solid, remove the contaminant, dangerous chemical, dissolved ions, protecting the human health as well as the environment. This paper shows the mechanism of steam pressure filtration as well as the result of tests, the comparison related to the efficiency between steam pressure filtration and conventional pressure filtration. The steam pressure filtration shows the high efficiency in mechanical displacement phase in both input parameters: solid volume fraction of suspension and the height of filter cake. The residual moisture content and saturation of filter cake using steam pressure filtration are lower 10÷20% than those values of filter cake using conventional pressure filtration. Moreover, some preliminary tests taking account to the drying phase of steam pressure filtration are also showed. The moisture of fine material filter cakes is around 6÷13%. Through the result of tests, interpretation and discussion, the application of steam pressure filtration is possible in the field of mineral processing and metallurgy.

Metallurgy and Material Science an Detailed Analysis

In the history of metallurgy, Gold, cleaned from metal ores and melted, was the first metal used by humans. During the advent of civilization, copper was introduced through the reduction process of oxides in traditional furnace. This process was considered the first chemical process of producing metals, and this was used in 4000 BC. Nonetheless, this process was gradually superseded by bronze i.e. alloy of copper with 10% tin, which is easier to cast and melt. Bronze was obtained through the mixture of tine retrieved from its oxides during the process of reduction or from the reduction of copper mixtures and tin ores. This age of civilization, i.e. 2400 BC was known as the Bronze age. With that regard, this paper focuses on the history of metallurgy with major focus on particular metals i.e. copper, iron and gold. In addition, this paper evaluates the contributions of scientists to the field of metallurgy.

Inclination Effect on Mixing Time in a Gas–Stirred Side–Blown Converter

Small‐scale physical models are commonly used to investigate gas‐stirred processes in steelmaking practice. The argon oxygen decarburization (AOD) converter is among various processes widely used in the metallurgy field and utilizes side blowing of oxygen and inert gas for mixing in the bath. Herein, the effect of the converter inclination on mixing time and jet‐penetration length with a side‐blown physical model is investigated. Scaling with the modified Froude number is applied on data from a real industrial AOD converter to achieve a system with reasonable gas flow rates. During the experiments, water is used to simulate liquid steel and air is blown through side‐mounted nozzles for stirring. A NaCl tracer is added and subsequent conductivity measurements are used to measure mixing time. Overall, the penetration length is shown to be independent of inclination angle. The mixing time is found to be influenced by the change of bath height to diameter ratio, change of geometry in the bath volume, gas flow rate, and the intensified wave motion at the interface caused by the inclination of the vessel. The mixing time increase with 14% when 14° angle is applied.

Діяльність В. М. Сойфера в галузі металургії та ливарництва

Діяльність В. М. Сойфера в галузі металургії та ливарництва

Effects of Composite Systems on Sintering Properties of Aluminum Oxide Ceramics

Because aluminum oxide ceramics have excellent properties, such as high strength, high hardness, good resistance to chemical corrosion, and chemical stability, aluminum oxide ceramics have been used widely in the fields of machinery, chemical industry, environment protection, electronic engineering, metallurgy, and composite materials. During the preparation of aluminum oxide ceramics, an appropriate composite system is important because it is effective for decreasing the sintering temperature and improving the properties of aluminum oxide ceramics. In the present work, powders of alumina, calcium oxide, zirconium dioxide, titanium dioxide, and silica sand were used as the main raw materials to design different composite systems, and then aluminum oxide ceramics were prepared via a semi-dry pressing method. Effects of different composite systems on the sintering property of aluminum oxide ceramics were studied. The results indicate that the CaO–SiO2–TiO2 system effectively improves the composition and structure of the aluminum oxide ceramic and significantly enhances the flexural strength of the aluminum oxide ceramic; the optimal formulation of adding CaO, SiO2, and TiO2 in the CaO–SiO2–TiO2 composite system is 4%, 2%, and 3%, respectively, and this formulation leads to a maximum flexural strength of 146.48 MPa; adding an appropriate amount of TiO2 can promote the formation of a corundum phase and refined grains and therefore enhances the fracture toughness of aluminum oxide ceramics.

Determination of the parameters of suspended particles using acoustic radiation

The flow of a gas or liquid can be visualized by detecting and analyzing sequential images of the particle distribution on the surface of the object under study through the determination of the motion parameters. However, this approach does not provide estimation of the mass and density of solid particles along with visualization of their distribution. We present the results of determining the mass and density of suspended particles using additional irradiation of the particle flux with acoustic radiation. The technique is based on the use of the method of visual processing of images of particle flows entrained by an acoustic field of a given frequency and amplitude for at least two periods of acoustic vibrations. Relaxation of the particles in the measuring plane «cut out» by the light «knife» was also taken into account. The basic mathematical expressions required for estimation of the mass, density, velocity field and shape of the particles using digital image processing and temperature measurement in the flow area are presented. The block diagram and design of the device used for the implementation of the proposed diagnostic method are presented. This technique can be used to determine the parameters of suspended particles in medicine, biology, ecology, powder metallurgy and other fields of science and technology.

Mechanical alloying of the immiscible Cu-60wt%Cr alloy: Phase transitions, microstructure, and thermodynamic characteristics

Solid state alloying of immiscible alloy systems such as Cu-Cr is an important field of physical metallurgy. Currently, non-equilibrium techniques are successfully applied in the synthesis of Cu-Cr alloys; however, the mechanism of formation of these alloys remains unclear due to the unavailability of data regarding their microstructure evolution and thermodynamic characteristics. In this work, a mechanical alloying (MA) Cu-60wt%Cr alloy is prepared by high-energy milling. The phase transitions, thermodynamic properties, and microstructure of this alloy are analyzed using X-ray diffraction, differential scanning calorimetry, and transmission electron microscope techniques. The obtained results demonstrate that the supersaturated Cr(Cu) solid solution alloy has a supra-nanometer-sized microstructure and is composed of crystalline and amorphous phases. To form the alloy, the localized Cu is first transformed into an amorphous state, then the disordered Cu atoms diffuse into the Cr matrix during the MA process. The diffusivity of Cr atoms in the Cu lattice is significantly hindered, even when the lattice is heavily defected.

Анализ взаимосвязи профессионально важных качеств специалиста и безопасности технологических процессов в металлургии

To ensure and maintain the level of safety at a metallurgical enterprise (as well as at any other hazardous production facility), it is advisable to select specialists with the appropriate professionally important qualities, prepare them for possible psychological stresses, teach them the correct methodology of performing work for avoiding possible injuries and accidents at the production site. Training and certification of managers are fixed in the relevant regulatory documents, but the professionally important qualities of the employee are not specified in any regulation documents. It is professionally important qualities that help an employee to cope with an emergency, correctly process the information received and quickly make the right decision, clearly follow the guidelines of the production instructions and rules. According to the statistics of incidents, many safety violations are committed by the employees not because of ignorance, but because of disregard for the written rules and regulations. Such incidents testify to the incomplete correspondence of the professionally important qualities of the employee to the chosen activity. The paper presents the results of a study of professional recruitment in the field of metallurgy, the main hazardous factors of production, statistical data on injuries and accidents at the metallurgical enterprises. By the method of expert assessments, the professionally important qualities required for the crane operator and operators of conveyor belts were revealed. Methodologies were selected that make it possible to determine the required professionally important qualities. In the course of the study a number of tests were conducted, which demonstrated that the respondents generally have satisfactory neuropsychic stability, as well as an adequate strategy for solving problems in stressful situations. This allowed to conclude that in a situation of increased psycho-emotional stress, a person will quickly and correctly assess the situation, then make the right decision or take an action that will not aggravate the situation.

Facile synthesis of MgO–Mg2SiO4 composite ceramics with high strength and low thermal conductivity

The recycling of solid waste is a win-win solution for humans and nature. For this purpose, magnesite tailings and silicon kerf waste were employed to prepare MgO–Mg2SiO4 composite ceramics by solid-state reaction synthesis in the present work. Then, effects of sintering temperature and raw material ratio on as-prepared ceramics were systematically studied. As-prepared ceramics showed improvement in their relative density (from 47.55%–68.12% to 90.96%–95.25%) and cold compressive strength (from 7.34–118.66 MPa to 303.39–546.65 MPa) with the increase in sintering temperature from 1300 to 1600 °C. In addition, it was found that Si promoted synthesis process of Mg2SiO4 phase through transient liquid phase sintering and Fe2O3 accelerated sintering process through activation sintering. Consequently, the presence of Mg2SiO4 phase effectively improved the density and strength of MgO–Mg2SiO4 composite ceramic, while reducing its thermal conductivity. This work provides a potential reutilization strategy for magnesite tailings, and as-prepared products are expected to be applied in fields of construction, metallurgy, and chemical industry.

Social no-go factors in mine site selection

When mining companies screen the attractiveness of potential mine sites (greenfield projects), the focus is typically on factors within the fields of geology, mining design, metallurgy, infrastructure, logistics, environment, and politics. Each category has ‘no-go factors’, the occurrence of which makes the company avoid activities in an area. However, social factors are not often part of the equation when calculating attractiveness scores at an early stage. We claim that social factors should be considered by identifying social thresholds and, furthermore, by including social no-go factors in the screening.This opinion piece draws on early findings from a larger research project on the sustainability of the mineral and metal industry. As part of the project, we have participated in discussions with companies, consultants, and researchers about the existing evaluation criteria generally used on greenfield projects. Based on this exercise, a site evaluation tool for mining companies is presently being developed. Based on our knowledge and experience with Social Impact Assessment and mining, we have proposed that social parameters, including no-go factors, are incorporated in the screening tool. This paper presents our arguments for the proposition.