Vol 16, No 4 (2014)
- Year: 2014
- Articles: 13
- URL: https://ered.pstu.ru/index.php/mm/issue/view/287
- DOI: https://doi.org/10.15593/.v16i4
ARTICLES
Simulation and optimization Electron beam welding steels
Abstract
Considered multi-objective optimization process, electron beam welding (EBW) using the experimental data obtained during the execution of welding passes on samples of austenitic steel. The application of statistical approach to the analysis of the geometric characteristics of the zones of penetration provides a fairly accurate model of the process EBW, which describe the dependence of the geometry of the welds on stainless steel from the parameters of welding. Solved a number of specific tasks related to improving the quality of welds in the EBW data steels. Developed a graphical user interface allowing the selection and optimization of process parameters EBW to obtain welds with specified performance characteristics. The resulting models are applicable in the computer expert system, which can be developed to support operators in the selection of welding modes in accordance with customer requirements and technical standards. Such systems can be used in education and training of operators and in forecasting and optimization techniques of electron beam welding.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):7-21
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NCREASE IN IMPACT STRENGTH OF STRUCTURAL STEELS BY THE CARBIDE-FREE-BAINITE FORMATION
Abstract
Structure and mechanical properties of chrome-nickel-molybdenum steels with carbon content from 0,1 to 0,4 % after slow continuous cooling in the bainitic temperature range with cooling rate V cool = 5 °С/min were investigated. It was shown that at carbon content about 0,10-0,15 % after such heat treatment the structure of carbide-free-bainite represented as two-phase mixture of carbon depleted bainitic ferrite and carbon enriched retained austenite with different morphology were formed in steel. It was found that such carbide-free-bainite possesses significantly more high values of impact strength in comparison with bainite containing carbide precipitations having practically the identical level of hardness and strength. Retained austenite in such carbide-free-bainite is substantially enriched with carbon and contain the considerable part of steel total carbon content. The impact strength level increase is associated with the presence of significant quantity of carbon enriched retained austenite in carbide-free-bainite. It was assumed that for steels with bainitic structure formed under continuous cooling the carbon share content in retained austenite can characterize the morphological peculiarities of the phase transformation structural constituent (carbide-free-bainite ore bainite with carbides) and impact strength level of steel.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):22-30
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Effect of the frictional treatment on the structure and wear resistance of the surface layer of tItanium bt1-0, subject to nitriding
Abstract
The effect of severe plastic deformation under the condition of dray sliding friction on the structure and wear resistance of the surface layer of the titanium VT1-0 subject to nitriding has been investigated. It has been shown, that this frictional treatment results in a nanocrystalline structure of a-phase in the surface layer thickness to 10μm. Presence of this structure on the titanium surface activate diffusion saturation with nitrogen atoms of the surface during following gas nitriding to temperatures 650-750 °С (holding for 2 h). Appearance of the nanocrystalline nitride TiN in deformed titanium take place at the relatively low temperature and short holding. A quantity of the nitridig phase, formed in layer of thickness to 10μm attains tens of volume percent, that ensures the elevate level of microhardness of the deformed and nitrided titanium surface. Previous severe plastic deformation has a bad effect on the fatigue wear resistance of the titanium surface subject to nitrogenization, that is due to increased brittleness of the deformed and nitrided titanium.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):31-48
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Investigation of fluorescence’s properties of the ZrO2-2Y2O3-4CeO2+3%Al2O3 nanopowder for further study of the distribution of nanoparticle using imaging method in vivo
Abstract
The increasing use of nanomaterials raises concerns about the long-term effects and chronic exposure to nanoparticles on human health. Among the techniques that are currently the most developed and reliable with regard to detection and identification of synthetic nanoparticles is electron microscopy. It allows determining the number, size, shape, crystalline structure, chemical composition of electron-dense substances in the size range 1-100 nm. However, to examine and identify the distribution and accumulation of engineered nanoparticles in the body of an animal is required not only electron microscopy, as well as a visualization camera, where we can to study the distribution of nanoparticles in the body of the animal in the dynamics at the same time without killing the animal. In the study was used a complex of equipment for the visualization of nanoparticles in the body of the animal. Photon Imager Optima - Bioscape Lab (France) and TECAN SpectraFlour are included in this complex. First one is used for the visualization of static and dynamic processes, when the nanopowders are administered to the laboratory animal. The second one is a multifunctional instrument of measuring of fluorescence and absorption of light. This research will allow better understanding the behavior of the biodistribution of nanoparticles in vivo and allowing the use of the data obtained in the study of the practical use of the toxicity of nanomaterials.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):49-56
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INVESTIGATION OF STRUCTURE AND PROPERTIES OF CARBURIZED LAYERS IN LOW-CARBON CARBURIZING STEELS
Abstract
There have been investigated structure, phase composition and properties of carburized layers in steels 20Kh, 20KhN3A and 20KhN3A obtained by different variants of carburizing (3 variants: solid carburizing, gas and carburizing fluidized bed). Some aspects of retained austenite formation in gradient layers of widely applied carburizing steels are analyzed and specified in greater detail with the help of layer-by-layer X-ray analysis. There have been defined such parameters of retained austenite as distribution in carburized layer depth, concentration of carbon, stress condition. Extreme distribution of retained austenite in surface layer after carburizing and following standard heat treatment of the steels has been shown. Great quantity of retained austenite in carburized layers after final heat treatment (about 50 % of retained austenite in extreme point) does not lead to sudden decrease of microhardness in layer depth. Microhardness is distributed in layer depth intimately, without jumps after all variants of carburizing. There have been shown some difference between the definition of quantity of retained austenite by standard carburized layer structure scale and by layer-to-layer X-ray Diffraction analysis.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):57-70
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Laser welding in a vacuum - Promising welding manufacturing techniques for critical applications
Abstract
Laser welding is the method of fusion welding, and on the energy density - a highly concentrated energy sources - such as electron beam and plasma welding. Interest in laser welding due advantages that distinguish it from other welding methods such as: heat-affected zone during laser welding is very small, this ensures that the properties of the starting material and minimum deformation of workpieces; High accuracy and productivity of the process of laser welding; laser welding provides a significant depth of penetration at small width of the weld; equipment and operating costs for laser welding require a much smaller investment than the closest analogue - electron beam welding. Currently, laser welding is mainly applied to welding products of small thickness. The paper considers the current state of research in the field of laser welding in a vacuum, provide high efficiency metal penetration compared to laser welding using welding protection zone with inert gases. The advantages of laser welding in vacuum to electron beam welding, the competition which is possible while reducing the cost of high-power industrial laser.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):71-81
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ON THE PROBLEM OF DUST TECHNOGENIC AND AS A PROTECTION AGAINST IT
Abstract
The analysis of possible measures to protect electrical equipment from aggressive technological dust. Object of research are electronic boards, taken from one and the same equipment after their failure. The reasons that led to a massive failure of the electronic circuit boards. Presented photographs confirming the negative impact of external environment on tehnizirovannoy performance characteristics studied boards. Research causes massive failure of electronic equipment provides a method of protecting plants from all sorts of sizes of dust, including dust nanoscale. In this connection, attention is drawn to the efficiency of the system “Ecovesta”. In connection with the problem of capturing dust particles nano further improved “Ecovesta” system by carrying out works to strengthen the effect of cleansing the environment and equipment from dust. In this high-speed rotation mode used water. The result is a structure with a water tight organization of the structural elements in the form of fibers and other complicated structures and air spaces are connected by jumpers, forming a stable effectively trap dust and nanoscale dimensions larger system “Ecovesta”.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):82-96
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THE POSSIBILITY OF MULTILAYER METALLIC MATERIALS FOR THE MANUFACTURE OF HIGH PRESSURE CYLINDERS
Abstract
The paper presents the results of a study on the creation of multilayer metallic materials for constructional purposes. Based on the literature review found that the main limiting factor in creating containers high and ultrahigh pressure are considerations for safe operation. One of the parameters that determine the safe and reliable operation is shatterproof bottle of destruction, which is defined by a set of high values of impact strength and fracture toughness of the material. This explains the limited use of existing high-strength structural materials for lightweight high pressure cylinders. We show that a promising approach to solving the problem by creating seamless cylinders may be using multilayer (from one hundred to two thousand layers) materials based on structural steels. Preparation of such a structure, the material that is based on one of the metal may in particular if the initial composition involved alloys having different crystal structure. A characteristic of such materials is an unusual combination of mechanical properties. At very low ductility along the rolled stock in impact strength in the direction perpendicular to the rolling direction is significant. The investigation results, according to the author, give hope for the possible use of such materials for the manufacture of pressure vessels in the future.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):97-106
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RESEARCH OF PARAMETRES STABILITY OF AN OPTICAL FIBER OF PANDA TYPE UNDER EXTERNAL MECHANICAL AND TEMPERATURE INFLUENCES
Abstract
Work is devoted to research of influence of external mechanical and temperature factors on parametres stability of a optical fiber of PANDA type used in coherent communication systems and interferometric gauges. Researches were spent in the conditions of industrial experiment with use of a method of the parametric analysis and reflectometry. The four-factor model of the first order has been applied to the parametric analysis. In the capacity of optimisation parametres used criterion of ability to preserve polarisation in the time of passage of radiation longwise of optical fibre - extinction factor (h-parametre). By means of pulsed reflectometry has been investigated a signal attenuation in a fibre, which make it possible to consider size of an absolute tension of a fibre. By researches it is established that in the range of operational temperatures (0-40 °С) the temperature factor does not exert an appreciable impact on parametres of polarisation of radiation in a fibre. Researches of influence of length of a fibre, tension and diameter of the accepting coil on the extinction coefficient have shown that the most significant factors are diameter of the coil and length of a fibre. Also it is established that bending deformations in a fibre have great value and that are the prevailing factor of loss of power in a fibre. The increase in diameter of the accepting coil decrease a size of bending deformations. The analysis of reflectogram is show's that transition from one layer of spooling to another layer leads to abrupt change of parametres of dispersion of radiation. On the basis of results of researches are made recommendations about updating of technological process of rewind of an optical fibre.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):107-112
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INVESTIGATION OF PROCESS OF DYNAMIC RECRYSTALLIZATION DURING HOT DEFORMATION BASED ON PHYSICAL MODELING ON GLEEBLE 3500 SYSTEM
Abstract
Multicyclic deformation of steel 20 on physical modeling complex Gleeble 3500 with 4 treatment regimes was conducted. 1 - compression, 2 - tension-compression, 3 - 20 cycles of tension-compression from 1100 to 870 oC, 4 - 20 cycles of isothermal tension-compression at 870 oC. True strain during treatment with 1st and 2nd regimes was ε = 0,4 and with 3rd and 4th regimes was ε = 8. Influence of thermo mechanical treatment on dynamic recrystallization process and complex of mechanical and microstructure steel 20 parameters formation was investigated. It was found that the true stress does not depend on the loading scheme, compression or tension, and depends on the the strain. It was established that the thermal deformation processing mode determines the mutual relation of the hardening and softening processes. Thus, the treatment with the 3rd regime led to a continuous stress increase, while the treatment with the 4th regime led to continuous stress decrease. This is due to the predominance of the softening processes speed such as dynamic recovery and dynamic recrystallization processes over the strain hardening. It is shown that multicyclic deformation leads to oriented structure formation in the steel.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):113-123
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FORMATION OF MICROSTRUCTURE AND PROPERTIES OF THE COMPOSITION "HARDFACING LAYER-BASE METAL" IN THE ULTRASONIC WAVE
Abstract
Ultrasonic treatment of the melt welding pool and heat affected zone (HAZ) is a hot research topic; however, it is hard to introduce ultrasound into working area. In this paper, the resonant method of introduction of ultrasonic oscillations with formation of a standing ultrasonic wave (frequency 18 kHz) was realized. Number of investigated technological parameters was minimized: welding current (180-240 А); the preheating temperature of the base metal (20-200 °С); length of the plate corresponds to the value of the acoustic wavelength (λ) in the low-carbon steel. Using different waveguides allows you to change the intensity of the ultrasonic treatment by varying the amplitude (ξ = 4.8; 9; and 18 microns). The effect of ultrasonic treatment on the melt metal of system Ni-Cr-C-B-Si and heat affected zone is studied. Formation of structure and properties for the hardfacing coating in an standing ultrasonic wave was considered. The microstructure of the treated area is significantly refined (the fragmentation of dendrites and inclusions was found). The effective technological parameters of ultrasonic field and plasma-arc hardfacing were established.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):124-132
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INSTRUMENTS OF LEAN PRODUCTION FOR THE BENEFIT TO THE RUSSIAN COMPANIES
Abstract
In its quest to quit international market Russian enterprises are seeking new ways of competitive advantage. Competitive advantage can only be achieved by high quality and low costs. Quality - investment object, above all, the internal. Today as never before enterprises are key objectives: to improve profitability, the level of organization of production, the efficiency of business processes, reduce costs, improve competitiveness, customer satisfaction. The paper considers one of the options to improve the competitiveness of Russian enterprises based application of the concept of Lean Production. The purpose of the article - to identify methods and techniques for solving the priorities of Russian industrial enterprises. Provides a brief historical background of occurrence of the concept of "lean production". Analyzed different perspectives and approaches to the definition of "lean production". The results of analysis tools concept of "lean production" in terms of reducing the loss of seven types: excess production and inventory, unnecessary movement of material waiting and delays, over-treatment, excessive movement of the workers and the need for improvements and corrections. Identified tools of lean production, helps to reduce activities that do not add value to the product of the consumer: System 5S, Kaizen, the system TPM, Kanban, Andon, just-in time, quick changeover, standardization works and ect.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):133-139
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PHYSICS-CHEMICAL METHODS OF STUDIES OF SOLID PART WELDING FUMES
Abstract
The welding fumes is one of the worst aspects which influence to health of welders, in that reason the question of study that substance is very important. The solid of welding fumes consist from fine particles of different size and shape, which can stay in lung and other tissues of human body in long time, it can be provocateur reduce of labor productivity and can be reason of professional illness. The studies about solid part of welding fumes very popular in English language science press because influence to evaluation of effectivity manufacturing and volume of insurance for workers. In Russian science press papers about this topic usually describe results of individual studies or show only medical aspects. In differences from that papers, this show review of the most modern methods of studies solid part of welding fumes - scanning electron scanning microscopy, photon correlation spectroscopy, X-ray microprobe analysis, examples of results and recommendation for understanding of results. All question which was described in paper produced on base practical experience of authors and it giving useful information for different readers and give important information about sampling of solid part welding fumes.
Bulletin PNRPU. Mechanical engineering, materials science. 2014;16(4):140-150
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