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The seawater circulation pump is a significant piece of equipment in coastal nuclear power plants that is susceptible to erosion and corrosion in the seawater. In this work, CeO2-modified cobalt-based composite coatings were prepared on the surface of martensitic stainless steel by direct laser deposition. The effect of CeO2 on the phase composition, microstructure, microhardness, corrosion resistance, and erosion properties of the cobalt-based composite coatings was systematically investigated. While the addition of CeO2 did not affect the phase composition of the coatings that comprised γ-Co, γ-Ni, M7C3, and M23C6 (M = Cr, W, Fe) metallic carbides, the eutectic organization showed an obvious phenomenon of contiguous aggregation. Microscopic pores were found in the coatings with 2 wt.% CeO2, and the number of pores increased with the increase in CeO2 content. Despite the higher self-corrosion potential (−0.27668 V) of cobalt-based alloy coating compared to the substrate (−0.37019 V), indicating enhanced corrosion resistance, the difference in self-corrosion potential among coatings with varying CeO2 addition amounts is small (0.027 V), and the corrosion current densities are within one order of magnitude (10−8 A/cm2). These findings suggest that the addition of CeO2 has no significant impact on the coating’s corrosion resistance.

Тема выпускной квалификационной работы: «Формирование структурно-фазового состояния в ÑÑƒÐ´Ð¾ÑÑ‚Ñ€Ð¾Ð¸Ñ‚ÐµÐ»ÑŒÐ½Ñ‹Ñ ÑÑ‚Ð°Ð»ÑÑ Ð¿Ñ€Ð¸ прямом лазерном выращивании». Данная работа посвящена исследованию структурно-фазового состояния мартенситно-ÑÑ‚Ð°Ñ€ÐµÑŽÑ‰Ð¸Ñ ÑÑ‚Ð°Ð»ÐµÐ¹, Ð¿Ð¾Ð»ÑƒÑ‡ÐµÐ½Ð½Ñ‹Ñ Ð¼ÐµÑ‚Ð¾Ð´Ð¾Ð¼ прямого лазерного выращивания, в частности 06Ð¥15Н4ДМ и разработки режима термообработки. Задачи работы включают в себя изучение исследований по термообработке мартенситно-ÑÑ‚Ð°Ñ€ÐµÑŽÑ‰Ð¸Ñ ; подбор режимов для термообработки; исследование структуры образцов после гомогенизационного отжига, старения и Ð¸Ñ Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¸Ñ ÑÐ²Ð¾Ð¹ÑÑ‚Ð². По результатам Ð¿Ñ€Ð¾Ð²ÐµÐ´ÐµÐ½Ð½Ñ‹Ñ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸Ð¹ выбрать режим, позволяющий получать наилучшие Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¸Ðµ Ñ Ð°Ñ€Ð°ÐºÑ‚ÐµÑ€Ð¸ÑÑ‚Ð¸ÐºÐ¸. В результате проведен гомогенизационный отжиг образцов при температуре выдержки 1000, 1100 и 1200°С и времени выдержки 1, 2, 4 и 6 часов. Проведен подбор режима старения. Исследовано влияние температуры и времени выдержки на формирование и рост Ð½Ð¾Ð²Ñ‹Ñ Ð·ÐµÑ€ÐµÐ½, выделение и рост Ð²Ñ‚Ð¾Ñ€Ð¸Ñ‡Ð½Ñ‹Ñ Ñ„Ð°Ð·, изменение микроструктуры. Изучены Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¸Ðµ свойства образцов, такие как микротвердость, прочность и пластичность. В результате проведенной выпускной квалификационной работы рекомендован режим термической обработки, состоящий из гомогенизации (Т=1200°С, t=6ч), закалки (Т=1060°С, t=3ч) и последующего тройного отпуска (Т=620-625°С, t=5ч), в результате которого образуется мелкодисперсная структура отпущенного мартенсита, обеспечивающая удовлетворительные Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¸Ðµ свойства.Â, The theme of the final qualifying work: “Formation of the structural-phase state in shipbuilding steels during Direct Laser Deposition”. This work is devoted to the study of the structural-phase state of martensitic-aging steels obtained by direct laser cultivation, in particular 06Cr15Ni4CuMo and the development of a heat treatment regime. The tasks of the work include the study of studies on the heat treatment of maraging; the selection of modes for heat treatment; the study of the structure of samples after homogenization, tempering and their mechanical properties. Based on the results of the conducted research, choose the mode that allows to obtain the best mechanical characteristics. As a result, homogenization of samples was carried out at holding temperatures of 1000, 1100 and 1200 °C and an annealing time of 1, 2, 4 and 6 hours. The selection of the tempering mode was carried out. The influence of temperature and time on the development and growth of new grains, the formationand growth of secondary phases and the change in the microstructure are studied. The mechanical properties of the samples, such as micro-hardness, strength, and ductility, were studied.As a result of the final qualification work, the recommended mode is a heat treatment consisting of homogenization (T=1200°C, t=6h), quenching (T=1060°C, t=3h) and subsequent triple tempering (T=620-625°C, t=5h), which forms a finely dispersed structure of tempered martensite, providing satisfactory mechanical properties.

In the present work, the mechanical properties of the DLD-processed Ti-6Al-4V alloy were obtained by tensile tests performed at different temperatures, ranging from 20 °C to 800 °C. Thereby, the process conditions were close to the conditions used to produce large-sized structures using the DLD method, resulting in specimens having the same initial martensitic microstructure. According to the obtained stress curves, the yield strength decreases gradually by 40% when the temperature is increased to 500 °C. Similar behavior is observed for the tensile strength. However, further heating above 500 °C leads to a significant increase in the softening rate. It was found that the DLD-processed Ti-6Al-4V alloy had a Young’s modulus with higher thermal stability than conventionally processed alloys. At 500 °C, the Young’s modulus of the DLD alloy was 46% higher than that of the wrought alloy. The influence of the thermal history on the stress relaxation for the cases where 500 °C and 700 °C were the maximum temperatures was studied. It was revealed that stress relaxation processes are decisive for the formation of residual stresses at temperatures above 700 °C, which is especially important for small-sized parts produced by the DLD method. The coefficient of thermal expansion was investigated up to 1050 °C.

For improving the wear properties of NiCrAlY, the 10 wt %, 20 wt % and 30 wt % ZrO2-added NiCrAlY samples were prepared by ultrasonic-assisted direct laser deposition, respectively. The results showed that the ultrasonic-assisted direct laser deposition can realize the ZrO2-added NiCrAlY preparation. Furthermore, due to the cavitation effect and agitation of the ultrasound in the molten pool, ultrasonic-assisted could make the upper surface of the samples smoother and flatter, and it also improved the microstructural homogeneity. The microstructure was mainly composed of columnar dendrites, and most of ZrO2 particles were located in the intergranular regions. The principal phase constituents were found to contain γ-Ni and t-NiZr2, and the amorphous (Ni, Zr) intermetallic phase generated, because of more rapid solidification after ultrasound assisted. The microhardness was improved slightly with the increase of ZrO2 contents, rising from 407.9 HV (10% ZrO2) to 420.4 HV (30% ZrO2). Correspondingly, wear mass loss was decreased with the maximum drop 22.7% of 30% ZrO2 compared to that of 10% ZrO2, and wear mechanisms were mainly abrasive wear with slightly adhesive wear. After applying ultrasound, the oxide islands in samples disappeared, and more ceramic particles were retained. Thus, the hardness and wear performance of the samples were improved.

In additive manufacturing (AM), the technology and processing parameters are key elements that determine the characteristics of samples for a given material. To distinguish the effects of these variables, we used the same AISI 316L stainless steel powder with different AM techniques. The techniques used are the most relevant ones in the AM of metals, i.e., direct laser deposition (DLD) with a high-power diode laser and selective laser melting (SLM) using a fiber laser and a novel CO2 laser, a novel technique that has not yet been reported with this material. The microstructure of all samples showed austenitic and ferritic phases, which were coarser with the DLD technique than for the two SLM ones. The hardness of the fiber laser SLM samples was the greatest, but its bending strength was lower. In SLM with CO2 laser pieces, the porosity and lack of melting reduced the fracture strain, but the strength was greater than in the fiber laser SLM samples under certain build-up strategies. Specimens manufactured using DLD showed a higher fracture strain than the rest, while maintaining high strength values. In all the cases, crack surfaces were observed and the fracture mechanisms were determined. The processing conditions were compared using a normalized parameters methodology, which has also been used to explain the observed microstructures.

Functionally graded material (FGM) based on Inconel 625 and AISI 431 stainless steel powders was produced by applying the direct laser deposition (DLD) process. The FGM starts with layers of Inconel 625 and ends with layers of 431 stainless steel having three intermediate zones with the composition (100-X)% Inconel 625-X% 431 stainless steel, X = 25, 50, and 75, in that order. This FGM was deposited on a 42CrMo4 steel substrate, with and without preheating. Microstructures of these FGMs were evaluated, while considering the distribution of chemical composition and grain structure. Microstructures mainly consisted of columnar grains independent of preheating condition, epitaxial growth was observed. The application of a non-preheated substrate caused the formation of planar grains in the vicinity of the substrate. In addition, hardness maps were produced. The hardness distribution across these FGMs confirmed a smooth transition between deposited layers, however, the heat-affected zone was greatly influenced by the preheating condition. This study suggests that an optimum Inconel 625/AISI 431 FGM obtained by DLD should not exceed 50% AISI 431 stainless steel.

In this study, direct laser deposition (DLD) of nickel-based superalloy powders (Inconel 625) on structural steel (42CrMo4) was analysed. Cladding layers were produced by varying the main processing conditions: laser power, scanning speed, feed rate, and preheating. The processing window was established based on conditions that assured deposited layers without significant structural defects and a dilution between 15 and 30%. Scanning electron microscopy, energy dispersive spectroscopy, and electron backscatter diffraction were performed for microstructural characterisation. The Vickers hardness test was used to analyse the mechanical response of the optimised cladding layers. The results highlight the influence of preheating on the microstructure and mechanical responses, particularly in the heat-affected zone. Substrate preheating to 300 °C has a strong effect on the cladding/substrate interface region, affecting the microstructure and the hardness distribution. Preheating also reduced the formation of the deleterious Laves phase in the cladding and altered the martensite microstructure in the heat-affected zone, with a substantial decrease in hardness.

In this study, the deposition of martensitic stainless-steel (Metco 42C) powder on 42CrMo4 structural steel by direct laser deposition (DLD) was investigated. Clads were produced by varying the laser power, scanning speed, feed rate, and preheating. The effect of these processing variables on the microstructure and microhardness of the clads was analyzed, as well as their soundness, yield (measured by dilution), and geometric characteristics (height, width, and depth). The complex interaction of the evaluated processing variables forced the application of complex parameters to systematize their effect on the clads. A genetic optimization algorithm was performed to determine the processing conditions warranting high-quality clads, that is, sound clads, metallurgically bonded to the substrate with required deposition yield.

This article presents the results of the metal deposition process using additive materials in the form of filler wire and metal powder. An important problem in wire deposition using a CO2 laser was overcome by using a combination of the abovementioned methods. The deposition of a multicomponent alloy—Inconel 625—on a basic substrate such as structural steel is presented. The authors propose a new approach for stopping carbon and iron diffusion from the substrate, by using the Semi-Hybrid Deposition Method (S-HDM) developed by team members. The proposed semi-hybrid method was compared with alternative wire and powder deposition using laser beam. Differences of S-HDM and classic wire deposition and powder deposition methods are presented using metallographic analysis, within optic and electron microscopy. Significant differences in the obtained results reveal advantages of the developed method compared to traditional deposition methods. A comparison of the aforementioned methods performed using nickel based super alloy Inconel 625 deposited on low carbon steel substrate is presented. An alternative prototyping approach for an advanced high alloy materials deposition using CO2 laser, without the requirement of using the same substrate was presented in this article. This study confirmed the established assumption of reducing selected components diffusion from a substrate via buffer layer. Results of metallographic analysis confirm the advantages and application potential of using the new semi-hybrid method for prototyping high alloy materials on low alloy structural steel substrate.

This research explores the importance of the powder feedstock characteristics on the manufacturing of martensitic stainless steel elements by Laser Metal Deposition (LMD). Water- and gas-atomised (WA and GA respectively) powders are the most common feedstock material used in LMD. The atomisation process medium influences powder properties including particle size distribution, inner and outer morphology, and microstructure. In this work, commercial WA and GA powders of AISI 431 stainless steel alloy were used to produce LMD coatings under identical deposition parameters. It was found that the powder processing route significantly affected the powder’s morphology, and this led to large changes in the laser energy absorbance during LMD. Consequently, significant changes in the microstructure of the deposited layer were observed. The parts manufactured with WA powder presented a duplex structure composed of martensite and ferrite, while a predominantly martensitic structure was verified in the GA deposition. The microstructural differences led to a wear rate reduction by a factor of 35 and a gain of 150 mV in pitting potential in the GA material. Though, the application of GA powder increased the production cost by 53% due to its lower deposition efficiency and higher retail price. The marked differences have all been attributed to the characteristics of the starting powder feedstock. This work highlights that the properties of the powder feedstock are a critical parameter in determining the properties of the LMD material, and emphasises the importance of the powder processing route on the energy absorption during LMD. Refereed/Peer-reviewed

Nowadays, additive manufacturing (AM) makes possible the production of complex metallic parts, and the use of the titanium alloy known as Ti6Al4V with AM has become a common application through the industry. One of the most promising designs for AM is the use of lattice structures that offer lightweight parts with high strength and damping properties. Due to these features, its importance is increasing day by day in sectors requiring high technology such as aerospace. In this study, two different 2D lattice structure specimens having the same lattice density but one with wall thickness, the other one without wall thickness, have been produced with the Electron Beam Melting method and their tensile strength has experimented. Comparing the strain of both specimens, the wall thickness greatly affects the strain values. According to both FEM and tensile tests, the samples with wall thickness demonstrated improved tensile strength behavior. Production was carried out with the same production parameter values. Fracture surfaces are scanned with the Scanning Electron Microscope (SEM). Hoy en día, la fabricación aditiva (AM) hace posible la producción de piezas metálicas complejas, y el uso de la aleación de titanio conocida como Ti6Al4V con AM se ha convertido en una aplicación común en la industria. Uno de los diseños más prometedores para AM es el uso de estructuras de celosía que ofrecen piezas livianas con propiedades de alta resistencia y amortiguación. Debido a estas características, su importancia está aumentando día a día en sectores que requieren alta tecnología como el aeroespacial. En este estudio, dos especímenes de estructura de celosía 2D diferentes que tienen la misma densidad de celosía, pero uno con espesor de pared, el otro sin espesor de pared, se han producido con el método de fusión por haz de electrones y se ha experimentado su resistencia a la tracción. Comparando la deformación de ambas muestras, el espesor de la pared afecta en gran medida los valores de deformación. De acuerdo con las pruebas FEM y de tracción, las muestras con espesor de pared demostraron un comportamiento mejorado de la resistencia a la tracción. La producción se llevó a cabo con los mismos valores de los parámetros de producción. Las superficies de las fracturas se escanean con el microscopio electrónico de barrido (SEM).

This study investigates the feasibility of in-situ manufacturing of a functionally graded metallic-regolith. To fabricate the gradient, digital light processing, an additive manufacturing technique, and spark plasma sintering were selected due to their compatibility with metallic-ceramic processing in a space environment. The chosen methods were first assessed for their ability to effectively consolidate regolith alone, before progressing to sintering regolith directly onto metallic substrates. Optimized processing conditions based on the sintering temperature, initial powder particle size, and different compositions of the lunar regolith powders were identified. Experiments have successfully proven the consolidation of lunar regolith simulants at 1050°C under 80 MPa with digital light processing and spark plasma sintering, while the metallic powders can be fully densified at relatively low temperatures and a pressure of 50 MPa with spark plasma sintering. Furthermore, the lunar regolith and Ti6Al4V gradient was proven to be the most promising combination. While the current study showed that it is feasible to manufacture a functionally graded metallic-regolith, further developments of a fully optimized method have the potential to produce tailored, high-performance materials in an off-earth manufacturing setting for the production of aerospace, robotic, or architectural components., SPOOL, Vol. 8 No. 2: Cyber-physical Architecture #4

This article presents the results of the metal deposition process using additive materials in the form of filler wire and metal powder. An important problem in wire deposition using a CO2 laser was overcome by using a combination of the abovementioned methods. The deposition of a multicomponent alloy—Inconel 625—on a basic substrate such as structural steel is presented. The authors propose a new approach for stopping carbon and iron diffusion from the substrate, by using the Semi-Hybrid Deposition Method (S-HDM) developed by team members. The proposed semi-hybrid method was compared with alternative wire and powder deposition using laser beam. Differences of S-HDM and classic wire deposition and powder deposition methods are presented using metallographic analysis, within optic and electron microscopy. Significant differences in the obtained results reveal advantages of the developed method compared to traditional deposition methods. A comparison of the aforementioned methods performed using nickel based super alloy Inconel 625 deposited on low carbon steel substrate is presented. An alternative prototyping approach for an advanced high alloy materials deposition using CO2 laser, without the requirement of using the same substrate was presented in this article. This study confirmed the established assumption of reducing selected components diffusion from a substrate via buffer layer. Results of metallographic analysis confirm the advantages and application potential of using the new semi-hybrid method for prototyping high alloy materials on low alloy structural steel substrate.

Funkcionalno gradientni materiali (FGM) imajo pomemben potencial na različnih inženirskih področjih kot so orodjarstvo, avtomobilska, letalska in vesoljska industrija ter energetika. Pri izdelavi FGM s procesom laserske direktne depozicije (LDD) je ključnega pomena dovod homogene mešanice prahu na mesto depozicije v ustreznem razmerju masnih deležev izbranih komponent. To zahteva ustrezno nadgradnjo obstoječega sistema za LDD kovinskega prahu. V ta namen smo okarakterizirali odzivni čas diskastega podajalnika ter čas potovanja prahu od diska do mesta depozicije ter preverili sestavo komponent mešanice prahu na mestu depozicije prahu. Na osnovi rezultatov smo prilagodili obstoječi krmilni algoritem. Z nadgrajenim sistemom smo izdelali različne primere tanko stenskih FGM vzorcev iz komponent prahu nerjavnega jekla 316L in inconela 718 ter jih ovrednotili. Iz rezultatov je razvidno, da s tovrstno nadgradnjo dosežemo ustrezna razmerja in primerno homogenost mešanice, ki zagotavljajo izdelavo FGM z željeno materialno sestavo. Functionally graded materials (FGMs) have a high potential in various engineering branches such as toolmaking, energetics, automotive, and aerospace engineering. In fabrication of FGM by laser direct deposition (LDD) it is crucial to deliver homogenous mixture of powders with selected ratios of component mass flow into the deposition spot. For this purpose, the existing LDD system had to be accordingly upgraded. To achieve this, the response time of disc powder feeder and the powder travel time were characterized as well as the composition of the delivered powder was validated. Based on the results, the existing control algorithm was modified. Various examples of thin wall FGM samples composed of stainless steel 316L and Inconel 718 were fabricated with the upgraded LDD system and evaluated. The results have confirmed that using the upgraded system, the predefined ratios and homogeneity of the powder mixture were achieved, assuring fabrication of FGMs with desired material composition properties.

International audience; Laser Cladding is one of the leading additive manufacturing technologies enabling the repair of metallic components. Their fatigue reliability depends directly on the material microstructure and consequently on the process parameters. This study highlights the influence of the interlayer dwell time on single-track walls for Inconel 718 repaired components. EBSD analyses show that dwell time both reduces grain size and creates a textural stretch of the microstructure. An optimal dwell time between the writing of successive layers can then be introduced to target a specified microstruc-ture gradient at the interface between the original part and the repaired deposit.

The arrival on the market of a new kind of CNC machines which can both add and remove material to an object paved the way to a new approach to the problem of repairing damaged components. The additive operation is performed by a Direct Laser Deposition (DLD) tool, while the subtractive one is a machining task. Up to now, repair operations have been carried out manually and for this reason they are errors prone, costly and time consuming. Refurbishment can extend the life of a component, saving raw materials and resources. For these reasons, using a precise and repeatable CNC machine to repair valuable objects is therefore very attractive for the sake of reliability and repeatability, but also from an economical and environmental point of view. One of the biggest obstacles to the automation of the repairing process is represented by the fact that the CAM software requires a solid CAD model of the damage to create the toolpaths needed to perform additive operations. Using a 3D scanner the geometry of the damaged component can be reconstructed without major difficulties, but figuring out the damage location is rather difficult. The present work proposes the use of octrees to automatically detect the damaged spot, starting from the 3D scan of the damaged object. A software named DUOADD has been developed to convert this information into a CAD model suitable to be used by the CAM software. DUOADD performs an automatic comparison between the 3D scanned model and the original CAD model to detect the damaged area. The detected volume is then exported as a STEP file suitable to be used directly by the CAM. The new workflow designed to perform a complete repair operation is described placing the focus on the coding part. DUOADD allows to approach the repairing problem from a new point of view which allows savings of time and financial resources. The successful application of the entire process to repair a damaged die for injection molding is reported as a case study. In the last part of this work the strategies used to apply new material on the worn area are described and discussed. This work also highlights the importance of using optimal parameters for the deposition of the new material. The procedures to find those optimal parameters are reported, underlying the pros and cons. Although the DLD process is very energy efficient, some issues as thermal stresses and deformations are also reported and investigated, in an attempt to minimize their effects.

The present work seeks to extend the level of understanding of the stress field evolution during direct laser deposition (DLD) of a 3.2 mm thick multilayer wall of Ti-6Al-4V alloy by theoretical and experimental studies. The process conditions were close to the conditions used to produce large-sized structures by the DLD method, resulting in specimens having the same thermal history. A simulation procedure based on the implicit finite element method was developed for the theoretical study of the stress field evolution. The accuracy of the simulation was significantly improved by using experimentally obtained temperature-dependent mechanical properties of the DLD-processed Ti-6Al-4V alloy. The residual stress field in the buildup was experimentally measured by neutron diffraction. The stress-free lattice parameter, which is decisive for the measured stresses, was determined using both a plane stress approach and a force-momentum balance. The influence of the inhomogeneity of the residual stress field on the accuracy of the experimental measurement and the validation of the simulation procedure are analyzed and discussed. Based on the numerical results it was found that the non-uniformity of the through-thickness stress distribution reaches a maximum in the central cross-section, while at the buildup ends the stresses are distributed almost uniformly. The components of the principal stresses are tensile at the buildup ends near the substrate. Furthermore, the calculated equivalent plastic strain reaches 5.9% near the buildup end, where the deposited layers are completed, while the plastic strain is practically equal to the experimentally measured ductility of the DLD-processed alloy, which is 6.2%. The experimentally measured residual stresses obtained by the force-momentum balance and the plane stress approach differ slightly from each other.

Данная выпускная квалификационная работа посвящена построению модели, которая бы позволила определить размер включений γ'-фазы, выпадающей в пересыщенном твёрдом растворе в процессе прямого лазерного выращивания в зависимости от условий обработки. Задачи, решаемые в ходе работы: 1. Решение задачи о распространении тепловых полей от распреде-лённого лазерного источника. При этом отдельно решаются задача о нагреве частиц присадочного порошка и задача о нагреве поверхности полубесконеч-ного тела лазерным источником. 2. Решение задачи о росте интерметаллидной фазы Ni3Al, совместно решая задачу об изменении концентрации Al на поверхности растущего включения. 3. Провести верификацию построенной модели на основании данных исследования. Анализ результатов работы показал, что построенная модель выдаёт удовлетворительные результаты, однако на режимах, для которых характерны высокие мощности лазерного источника, наблюдаются большие отклонения от экспериментальных значений. Данные отклонения коррелируют с количеством выпадающих карбидов, что в свою очередь связано с высокими температурами обработки на данных режимах. Для уточнение данной модели требуется включить в модельное описание образование различных фаз с их взаимным влиянием через концентрацию примесей в твёрдом растворе, а также сложное легированное состояние γ'-фазы., The given work is devoted to the construction of a model that makes it possible to determine the size of the precipitates of the γ' - phase forming in a permeated solid solution during direct laser deposition, depending on the processing modes. This research set the following goals: 1. Solution of the problem of propagation of thermal fields from a distributed laser source. In this case, the problem of heating the particles of the filler powder and the problem of heating the surface of a semi-infinite body with a laser source are solved separately. 2. Solving the problem of growth of the intermetallic phase of Ni3Al, jointly solving the problem of changing the concentration of Al on the surface of the growing precipitate. 3. Perform verification of the constructed model based on the research data. The analysis of the results showed that the constructed model gives satisfactory results. However, large deviations from the experimental values are observed in the modes characterized by high power of the laser source. These deviations correlate with the amount of carbides that fall out, which in turn is associated with high processing temperatures in these modes. To refine this model, it is necessary to include in the model description the formation of different phases with their mutual influence through the concentration of impurities in a solid solution, as well as the complex doped state of the γ'-phase.

В данной работе описаны методы повышения коэффициента использованного материала в прямом лазерном выращивании. Для этого проведен литературный обзор существующих технологий повышения коэффициента эффективности процесса аддитивных технологий. Проведен эксперимент по замеру коэффициента захвата порошка струйных сопел. Полученные данные верифицированы с данными, полученными во время реального процесса прямого лазерного выращивания, выявлено различия между данными, получаемыми во время реального процесса и данными полученными на экспериментальном стенд. Построен график зависимости ширины наплавляемого валика от коэффициента эффективности процесса. Из данного графика получена аппроксимационная кривая и формула для расчета коэффициента эффективности процесса в зависимости от ширины наплавляемого валика. Проведена оценка рисков, влияющих на эффективность процесса прямого лазерного выращивания. Показаны возможные пути решения данных рисков. Выявлен коэффициент способный нивелировать опасность данных рисков с минимальными тратами эффективности процесса. Описана методика расчета количества порошка, требуемого на поддержание стабильного процесса прямого лазерного выращивания., This paper describes methods for increasing the efficiency of the material used in direct laser deposition. For this purpose, a review of the literature on existing technologies for improving the efficiency of the additive technology process was conducted. An experiment was conducted to measure the powder capture coefficient by jet nozzles. The data obtained were compared with the data obtained in the real process of direct laser deposition, and differences were found between the data obtained in the real process and the data obtained on the experimental stand. A graph of the dependence of the width of the deposited roller on the efficiency of the process is constructed. From this graph, an approximation curve and a formula for calculating the efficiency of the process depending on the width of the deposited roller are obtained. The risks affecting the efficiency of the direct laser deposition process were assessed. Possible ways to solve these risks are shown. A coefficient has been determined that can neutralize the risk of these risks at a minimum cost to the efficiency of the process. A method for calculating the amount of powder required to maintain a stable process of direct laser deposition is described.

Особенности формирования равновесной α+β структуры в двухфазном сплаве ВТ6 после прямого лазерного выращивания с последующей термической обработкой. Данная работа посвящена исследованию влияния температуры и времени отжига образцов, полученных методом прямого лазерного выращивания на макро-и микроструктуру, микротвердость, прочность и пластичность. Задачи работы включают в себя изучение мировых исследований по термообработке титановых сплавов; подбор режимов для термообработки; исследование макро-и микроструктуры образцов после отжига и их механических свойств. По результатам проведенных исследований выбрать режим, позволяющий получать наилучшие механические характеристики. Кроме того, одной из задач является исследование влияние термической обработки без вакуума на окисление образов. В результате проведен отжиг образцов при температуре выдержки от 600 °С до 1050°С и времени выдержки 1, 2 и 4 часа. Исследовано влияние тем-пературы и времени выдержки на формирование и рост новых зерен, выделение и рост вторичных фаз, толщину α-пластин, изменение микроструктуры. Изучены механические свойства образцов, такие как микротвердость, прочность и пластичность. Проведены измерения глубины и микротвердости альфированного слоя, образующегося в образцах при температуре отжига от 750 °С. Альфированный слой находится в пределах шероховатости поверхности изделий, полученных методом прямого лазерного выращивания. В результате проведенной выпускной квалификационной работы рекомендованы режимы: 850 °С, 4 часа; 900 °С 1-2 часа.Для снятия остаточных напряжений после выращивания рекомендуется предварительная термическая обработка, состоящая из отжига при 600 ° С и выдержки в течение 2-хчасов., Features of formation of an equilibrium α+β structure in a two-phase VT6 alloy after direct laser deposition with subsequent heat treatment. his work is devoted to the study of the influence of temperature and annealing time on samples obtained by direct laser growth on macro-and microstructure, microhardness, strength and ductility. The research set the following goals: The goals of the work include the study of world resear cheson the heat treat-ment of titanium alloys; selection of modes for heat treatment; study of macro-and microstructure of samples after annealing and their mechanical properties. Based on the results of the study, choose a mode that allows you to get the best mechanical characteristics. In addition, one of the tasks is to study the effect of heat treatment without vacuum on the oxidation of images.As a result,the samples were annealed at an exposure temperature from 600 ° С to 1050 ° С and an annealing timeof 1, 2, and 4 hours. The influence of temperature and time on the development and growth of new grains, the formationand growth of secondary phases, the thickness of the α-plate, and the change in the microstructure are studied. The mechanical properties of the samples, such as microhardness, strength, and ductility, were studied. The depth and microhardness of the alpha layer formed in the samples at temperatures from 750 °C were measured. Alpha layer is within the roughness of the surface of samples, obtained by direct laser deposition.As a result of the final qualification work, the recommended modes are: 850 °C, 4 hours; 900° C 1-2 hours.To relieve the residual stresses after growing the part is recommended pre-heattreatment consisting of annealing at 600 ° C and holding for 2 hours