Aviation operational nowcasting systems

Presentación realizada en la 3rd European Nowcasting Conference, celebrada en la sede central de AEMET en Madrid del 24 al 26 de abril de 2019

THE OPTIMISATION OF LASER WELDING PROCESS PARAMETERS OF 7020 ALUMINIUM ALLOY

В работе изучено влияние технологических параметров процесса лазерной сварки на геометрию сварного шва, включая грублину и ширину, а также влияние соотношения различных параметров, например, мощность лазерного пучка и скорость его движения.Laser welding has been proven to be promising for the aerospace industry. Welds with high aspect ratio are produced with lower heat input compared with conventional welding is given, combining the trials with Nd:YAG laser and existing knowledge in the referred literature. In this work, we studied the effect of process parameters on weld profile geometry including penetration depth and width on top surfaces and interfaces as well as its quality at different process parameters such as Laser power and speed.The work was performed as part of the state work "Carrying out of research work (basic research, applied research and experimental development)" state task MES of Russia in the sphere of scientific activities 2014-2016. (Task № 2014/113)

Evaluation of the microstructure and mechanical properties of a new modified cast and laser-melted AA7075 alloy

The mechanical properties and microstructure of as-cast and homogenized AA7075 were investigated. This alloy was modified by adding transition elements 0.3%Sc + 0.5%Zr, 1%Ti + 0.2%B, and 1%Fe + 1%Ni for use in additive manufacturing applications. After adding Ti + B and Sc + Zr, the structure became uniform and finer with the formation of the Al3(Sc, Zr) and TiB2 phases. Coarse structures were obtained with the formation of an extremely unfavorable morphology, close to a needle-like structure when Fe + Ni was added. The mechanical properties of the modified alloys were increased compared to those of the standard alloy, where the best ultimate tensile strength (UTS) and yield strength (YS) were obtained in the AA7075-TiB alloy compared to the standard alloy in as-cast and homogenized conditions, and the highest hardness value was provided by Fe + Ni additives. The effect of the laser melting process on the microstructure and mechanical properties was investigated. Single laser melts were performed on these alloys using 330 V and a scanning speed of 8 mm/s. During the laser melting, the liquation of the alloying elements occurred due to non-equilibrium solidification. A change in the microstructures was observed within the melt zone and heat-affected zone (HAZ). The hardness of the laser-melted zone (LMZ) after adding the modification elements was increased in comparison with that of the standard alloy. Corrosion testing was performed using a solution of 100 mL distilled water, 3.1 g NaCl, and 1 mL HCl over 5, 10, and 30 min and 1 and 2 h. The corrosion resistance of the alloy modified with FeNi was low because of the non-uniform elemental distribution along the LMZ, but in the case of modification with ScZr and TiB, the corrosion resistance was better compared to that of the standard alloy. © 2019 by the authors.Ministry of Science and Higher Education of the Russian FederationThe author (Asmaa M. Khalil) gratefully acknowledges financial support from the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of MISiS (Support project for young research engineers)

Features of Structure Formation in an Al–Fe–Mn Alloy upon Crystallization with Various Cooling Rates

Abstract: Specific features of the microstructure formation of an Al–2.5% Fe–1.5% Mn alloy owing to the cooling rate during casting and during laser melting are studied in this work. An analysis of the microstructure in the molten state shows that, with an increase in the cooling rate during crystallization from 0.5 to 940 K/s, the primary crystallization of the Al6(Mn,Fe) phase is almost completely suppressed and the volume of the nonequilibrium eutectic increases to 43%. The microstructures of the Al–2.5% Fe–1.5% Mn alloy after laser melting are characterized by the presence of crystals of an aluminum matrix of a dendritic type with an average cell size of 0.56 μm, surrounded by an iron-manganese phase of eutectic origin with an average plate size of 0.28 μm. The primary crystallization of the Al6(Mn,Fe) phase is completely suppressed. The formation of such a microstructure occurs at cooling rates of 1.1 × 104–2.5 × 104 K/s, which corresponds to the cooling rates implemented in additive technologies. At the boundary between the track and the base metal and between the pulses, regions were revealed consisting of primary crystals of the Al6(Mn,Fe) phase formed by the epitaxial growth mechanism. The size of the primary crystals and the width of this zone depends on the size of the eutectic plates and the size of the dendritic cell located in the epitaxial layer. After laser melting, the Al–2.5% Fe–1.5% Mn alloy has a high hardness at room temperature (93 HV) and, after heating up to 300°C, it has a high thermal stability (85 HV). The calculated yield strength of the Al–2.5% Fe–1.5% Mn alloy after laser melting is 227 MPa. The combination of its ultrafine microstructure, high processibility during laser melting, hardness at room and elevated temperatures, and high calculated yield strength make the Al–2.5% Fe–1.5% Mn alloy a promising alloy for use in additive technologies. © 2021, Allerton Press, Inc

Influence of Adding Modifying Elements and Homogenization Annealing on Laser Melting Process of the Modified Alznmgcu with 4%si Alloys

AlZnMgCu, the high-strength aluminum alloy, is unsuitable for laser melting applications due to its high hot cracking sensitivity and large solidification temperature range. Adapting this alloy for laser melting processing is a high-demand research issue for extending its use. Thus, this paper investigates the effect of adding 4%Si, 4%Si-Sc + Zr, 4%Si-Ti + B, and homogenization annealing on the laser melting process (LMP) of AlZnMgCu alloy. Homogenization annealing at 500◦ C for 6.5 h was selected to dissolve most of the low melting temperature phases into the grain matrix and perform stable alloys for the LMP. The pulsed laser melting process (PLM) was performed on the as-casted and the homogenized samples. The microstructures of the as-casted, the homogenized alloys, and after the LMP were evaluated. In addition, the hardness of the base metal (BM) and laser melted zone (LMZ) were measured. The results revealed that the microstructure was enhanced and refined in the as-cast state by adding the modifiers due to the increasing nucleation potency of solidification sites and the formation of primary Al3 (Ti, Zr, Sc) phases. The average grain size was decreased by 15.6 times when adding 4%Si + 0.4%Zr + 0.29%Sc, while it decreased by 10.2 times when adding 4%Si + 1%Ti + 0.2%B. The LMZ of the as-casted samples exhibited a non-uniform distribution of the grains and the elements after the LMP. This was attributed to the evaporation of Zn, Mg during the high laser power process besides the non-uniform distribution of elements and phases in samples during casting. After the laser treating of the homogenized samples with 4%Si-Sc + Zr, uniform columnar grains were formed in the direction of the laser. The presence of Ti and B changed the crystallization nature, resulting in the LMZ with very fine and equiaxed grains due to forming many nucleation centers during solidification. The hardness values have positively increased due to Si addition and adding a combination of Ti + B and Sc + Zr. The maximum hardness was 153.9 ± 5 HV achieved in the LMZ of the homogenized samples of 4%Si + 1%Ti + 0.2%B. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was partially funded by Russian Foundation for Basic Research (RFBR) with project number 19-38-60037

Evaluation of Microstructure and Hardness of Novel Al-Fe-Ni Alloys with High Thermal Stability for Laser Additive Manufacturing

The microstructure and phase composition of cast and laser-melted Al-Fe-Ni alloys were investigated.Two main phases—Al3(Ni,Fe) and Al9FeNi—were formed in the as-cast state. A fine microstructure without porosity or solidification cracks was observed in the Al-Fe-Ni alloys after laser treatment. The hardness of the laser-melted alloys was 2.5–3 times higher than the hardness of the as-cast alloys owing to the formation of an aluminum-based solid solution and fine eutectic particles. The formation of the primary Al9FeNi phase was suppressed as a result of the high cooling rate. Annealing these alloys at temperatures less than 300°C demonstrated the high thermal stability of the microstructure while maintaining the hardness. The Al-Fe-Ni alloys investigated in this study are promising heat-resistant materials for additive manufacturing because of their fine, stable structure, and the low interdiffusion coefficients of Fe and Ni. © 2020, The Minerals, Metals & Materials Society.Loginova I.S. would like to thank Dr. Solonin A.N. for valuable discussions regarding the structure formation process. This project and all the experiments were funded by RFBR, Project Number 19-38-60037

Влияние Zr, Sc, Ti, B Fe и Ni на микроструктуру сплава aa7075 при лазерной обработке

In the present work the wrought aluminium alloy AA7075 modified with 0,3%Sc+0,5%Zr, 1%Тi+0,2 %B and 1%Fe+1%Ni to refine and uniform the grain structure, to decrease the effective solidification range to decrease the hot crack formation during rapid solidification after laser processing was studied.В настоящей работе исследован высокопрочный сплав AA7075, дополнительно легированный 0,3%Sc+0,5%Zr, 1%Ti+0,2%B и 1%Fe+1%Ni для повышения сопротивляемости сплава образованию горячих трещин и однородности структуры

Structural and Phase Transformations in Al–Fe–Ni Alloy during Local Laser Exposure in Additive Technology

В ходе исследования были изучены микроструктура и фазовый состав сплавов Al–Fe–Ni в литом состоянии и после лазерного плавления. После лазерной обработки в сплавах Al–Fe–Ni формировалась тонкая дендритная микроструктура без пористости и кристаллизационных трещин. Твердость сплавов лазерной обработки была в 2,5–3 раза выше твердости литых сплавов за счет образования твердого раствора на основе алюминия и мелких эвтектических частиц.In the course of the study, the microstructure and phase composition of Al–Fe–Ni alloys in the cast state and after laser melting were studied. After laser melting, a thin dendritic microstructure without porosity and crystallization cracks was formed. The hardness of laser-treated alloys was 2,5–3 times higher than in cast alloys due to formation of aluminium-based solid solution and fine eutectic particles.Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта (№ 19–38–60037).The research was carried out with the financial support of the RFBR as part of a scientific project (№ 19–38–60037)

Investigation of Non-Equilibrium Structural-Phase Transformations and Development of Methods for Control of Structure Formation of Aluminum-Based Alloys under Local Beam Influence

В настоящей статье изучено формирование микроструктуры в сплавах систем Al–ПМ, Al–Mg–ПМ и Al–Cu–Mg–Mn–ПМ (где ПМ — переходные металлы Fe, Ni, Cr, Mn, Zr) в зависимости от мощности лазерного излучения, температуры и структуры подложки и стратегии сканирования лазерного луча. Также сформирована база микроструктур и размеров структурных составляющих сплавов в зависимости от условий кристаллизации. Разработан алгоритм и создана компьютерная модель, позволяющая моделировать процесс кристаллизации сплавов, используя вероятности за рождения и роста зерен.The formation of the microstructure in alloys of the Al–PM, Al–Mg–PM, and Al–Cu–Mg–Mn–PM systems (where PM are transition met als Fe, Ni, Cr, Mn, Zr) depending on the laser power, temperature, and substrate structures and laser beam scanning strategies were investigated. A database of microstructures and sizes of structural components of alloys has been formed depending on the conditions of crystallization. An algorithm has been developed and a computer model has been created that makes it possible to simulate the process of crystallization of alloys using the probabilities of grain nucleation and growth.Работа выполнена при финансовой поддержке Российского Фонда Фундаментальных Исследований (проект №19-38-60037 «Перспектива»).The work was carried out with the financial support of the Russian Foundation for Basic Research (project No. 19–38–60037 “Perspektiva”)

ИССЛЕДОВАНИЕ ЭВОЛЮЦИИ СТРУКТУРЫ ДВУХФАЗНОГО ТИТАНОВОГО СПЛАВА В ПРОЦЕССЕ ТЕРМОДЕФОРМАЦИОННОЙ ОБРАБОТКИ

This paper studies Ti–3,5Fe–4Cu–0,2B two-phase titanium alloy behavior during its thermal deformation processing under uniaxial compression. Boron was added to obtain a fine-grained structure in the cast state. Samples of alloys 6 mm in diameter were obtained by melting pure components in a vacuum induction furnace with their subsequent crystallization into a solid copper mold. Uniaxial compression tests with a true strain of 0,9 were performed using the Gleeble 3800 thermal-mechanical physical simulation system at 750, 800 and 900 °C and strain rates of 0,1; 1 and 10 s–1. Scanning electron microscopy was used to study the microstructure of the alloy in its initial and deformed states. A model of flow stress dependence on temperature and strain rate was built as a result of the tests. It is shown that pressure treatment involves recrystallization of the initial cast structure containing solid solutions based on α-Ti, β-Ti and titanium diboride aggregates. During the deformation process, the volume fraction of α-titanium solid solution grains decreases with rising temperature, and the fraction of the β phase, on the contrary, increases. In this case, the average grain size of solid solutions based on α-Ti and β-Ti varies insignificantly after deformation in almost all of the studied modes. It is shown that the preferred mode of hot pressure treatment for obtaining a high complex of mechanical properties in the investigated alloy is a temperature range of 750– 800 °C, since α-phase grain sizes increase from 2,2 to 4,5 μm with an increase in temperature to 900 °C.Исследовано поведение двухфазного титанового сплава Ti–3,5Fe–4Cu–0,2B в процессе термодеформационной обработки на одноосное сжатие. Бор вводили для получения в литом состоянии мелкозернистой структуры. Образцы сплавов диаметром 6 мм получали путем сплавления чистых компонентов в вакуумной индукционной печи и последующей ускоренной кристаллизации в массивной медной изложнице. Испытания на одноосное сжатие с истинной деформацией 0,9 проводили на комплексе физического моделирования термомеханических процессов «Gleeble 3800» при температурах 750, 800 и 900 °С и скоростях деформации 0,1; 1 и 10 с–1. Микроструктуру сплава в исходном и деформированном состояниях изучали с помощью сканирующей электронной микроскопии. В результате испытаний построена модель зависимости напряжения течения от температуры и скорости деформации. Показано, что в процессе обработки давлением происходит рекристаллизация исходной литой структуры, содержащей твердые растворы на основе α-Ti, β-Ti и колонии диборида титана. В процессе деформации с повышением температуры объемная доля зерен твердого раствора на основе α-титана уменьшается, а доля β-фазы, наоборот, возрастает. При этом средний размер зерен твердых растворов на основе α-Ti и β-Ti меняется незначительно после деформации почти по всем исследованным режимам. Показано, что предпочтительным режимом горячей обработки давлением для получения высокого комплекса механических свойств в изучаемом сплаве является диапазон температур 750–800 °С, так как размер зерен α-фазы увеличивается с 2,2 до 4,5 мкм при повышении температуры до 900 °С