Este trabalho apresenta um modelo inovador de coletor solar plano, com placa absorvedora fabricada por Estampagem Incremental e Soldagem FSW (Friction Stir Welding). Esta placa absorvedora é constituída de duas chapas de alumínio AA1200-H14 com espessura de 1 mm, estampadas e soldadas em simetria, a fim de que na união das chapas sejam deixados canais para passagem de água. Neste estudo foi realizada a caracterização do material por Ensaio de Tração e Ensaio Nakajima. Para determinação dos parâmetros de Estampagem Incremental foram realizados 16 experimentos com ferramenta de diâmetro df = 9,5 mm, variando a rotação de N = 50 rpm a 800 rpm e o incremento vertical de Δz = 2 mm a 0,2 mm, mantendo o avanço em = 250 mm/min. E também foram realizados 3 experimentos com ferramenta df = 22 mm, variando o incremento vertical de Δz = 2 mm a 0,5 mm, mantendo a rotação em N = 50 rpm e o avanço em = 250 mm/min. Para determinação dos parâmetros de Soldagem FSW foram realizados 4 experimentos com ferramenta de ombro de diâmetro 8 mm e pino roscado M3x0,5, mantendo a rotação em N = 1500 rpm e variando o avanço entre = 100 mm/min a 400 mm/min. Em seguida foi fabricado um protótipo de placa absorvedora de coletor solar com área de 0,12 m². Nos experimentos realizados foi constatado que é possível obter maiores deformações na Estampagem Incremental do que na Estampagem Convencional e que as deformações são mais elevadas quando se utiliza menores diâmetros, maiores rotações e menores incrementos verticais da ferramenta. Na Soldagem FSW não foi constatada influência na qualidade do cordão de solda em relação à variação do avanço da ferramenta. Neste estudo também se verificou que é possível fabricar protótipos de placas absorvedoras de coletores solares pelos processos de Estampagem Incremental e Soldagem FSW. No entanto, para coletores em tamanho comercial, novos estudos são necessários para melhorar a forma de fixação das chapas durante a Soldagem FSW. / This work presents an innovative model of flat plate solar collector, with absorber plate manufactured using Incremental Sheet Forming (ISF) and Friction Stir Welding (FSW). This absorber plate consists of two AA1200-H14 aluminum sheets with a thickness of 1 mm, stamped and welded in symmetry, in order to leave channels for the passage of water. In this study the characterization of the material by Nakajima Test and Traction Test was performed. In order to determine the parameters of ISF, 16 experiments were performed with a tool of diameter df = 9.5 mm, varying the rotation speed of N = 50 rpm at 800 rpm and the step down of Δz = 2 mm to 0.2 mm, maintaining the feed rate at = 250 mm/min. Also, 3 experiments with tool df = 22 mm were performed, varying the step down of Δz = 2 mm to 0.5 mm, maintaining the rotation speed at N = 50 rpm and the feed rate at = 250 mm/min. For determination of FSW parameters, 4 experiments with 8 mm diameter shoulder tool and M3x0.5 pin were performed, maintaining the rotation speed at N = 1500 rpm and varying the feed rate from = 100 mm/min to 400 mm/min. A prototype solar collector absorber plate with a 0.12 m² area was then manufactured. In the experiments carried out, it was found that it is possible to obtain greater deformations in the ISF than in the Conventional Stamping and that the deformations are higher when using smaller diameters, higher rotations and smaller step downs of the tool. In FSW, no influence was observed in the quality of the weld bead in relation to the variation of the tool feed rate. In this study it was also verified that it is possible to manufacture prototypes of solar collector absorber plates by the processes of ISF and FSW. However, for commercial size collectors, further studies are needed to improve the way the plates are fixed during FSW.

As ligas de alumínio AA2024 e AA7050 tradicionalmente são utilizadas na fabricação de estruturas da fuselagem e da asa de aeronaves. Normalmente, a união dos componentes dessas estruturas é realizada por rebites, já que processos de soldagem com fusão produziriam defeitos indesejáveis. O processo de soldagem por fricção linear com mistura ou Friction Stir Welding (FSW) é uma alternativa à união de chapas de ligas de alumínio por rebites haja vista que não há fusão do material durante a união. No presente trabalho estudou-se o comportamento eletroquímico e a caracterização microestrutural de uma junta sobreposta, composta por um perfil extrudado da liga AA7050-T76511 e uma chapa da liga AA2024-T3, ambos previamente anodizados, soldada por fricção linear com mistura. O comportamento eletroquímico foi avaliado através da utilização da Técnica de Varredura com Eletrodo Vibratório (SVET), medidas do potencial de corrosão e curvas de voltametria cíclica em solução de 0,1 M de NaCl. Correntes anódicas mais intensas foram medidas na região da solda e ainda verificou-se que esta possui menores potenciais de pite e corrosão do que ambas as ligas. Também foi constatada a presença de corrosão intercristalina em ambas as ligas e na região da solda, porém com maior severidade na liga AA2024-T3. / AA2024 and AA7050 aluminum alloys are traditionally used in the manufacture of fuselage structures and aircrafts wings. Usually, the component union of these structures is made using rivets since weld process with melting will produce unwanted defects. The Friction Stir Welding (FSW) process is an alternative way to replace the traditional rivet union of aluminum alloys in the aeronautical and aerospace industries since the material does not melt during the joint. In the present work it has been studied the electrochemical behavior and microstructural characterization of a lap joint composed of an extruded profile of AA7050-T76511 alloy and a sheet of AA2024-T3 alloy, both of them previously anodized and jointed by friction stir welding. The electrochemical behavior was evaluated by means of Scanning Vibrating Electrode Technique (SVET), measurements of the corrosion potential and cyclic voltammetry in 0,1 M NaCl. Higher anodic currents were found in the weld region, moreover this region has the lowest pit and corrosion potential. Intercrystalline corrosion was found in both alloys and in the weld region, with the highest intensity in the AA2024-T3 alloy.

O processo de soldagem por atrito linear com mistura (SALM), ou Friction Stir Welding, surgiu do desejo de se aplicar os princípios e vantagens da soldagem em estado sólido do processo por atrito tradicional em outras geometrias que não fossem axi-simétricas. Assim, foi acrescentada uma velocidade de translação e uma ferramenta rotativa especial, sendo possível realizar cordões de solda em ligas antes com soldabilidade bem ruim. O fator chave para se ter uma solda por atrito linear com mistura sã é a combinação correta entre o a geometria da ferramenta, os parâmetros de soldagem e o fluxo de material durante a soldagem. O lado do avanço, em relação à velocidade de translação da ferramenta, está sob tração, enquanto que o lado do retrocesso está sob compressão. Cada um destes lados possui características diferenciadas, tanto microestruturais como de propriedades mecânicas. O objetivo deste trabalho é caracterizar o cordão de solda feito em liga AA6063T6 com 3 mm de espessura. O material foi soldado com uma ferramenta tipo Three flats, com rotação de 1120 rpm e velocidade de soldagem de 5,3 mm/s. Os corpos de prova foram caracterizados por microscopia óptica, microdureza e ensaio de tração. Os resultados mostraram que o cordão de solda é assimétrico, sendo 20% maior do lado do avanço da ferramenta. Além disto, houve um refino de grão e, na transição entre a zona termomecanicamente afetada (ZTMA) e a zona afetada pelo calor (ZAC), os grãos alongados apresentaram fator de forma maior no lado do avanço (entre 1,73 e 2,74) do que no lado do retrocesso (entre 1,40 e 1,59). As extensões da zona termomecanicamente afetada e da zona afetada pelo calor são maiores do lado do avanço que do lado do retrocesso. / Friction Stir Welding process arose from a desire to apply the principles and benefits of traditional solid state friction welding friction in non axi-symmetric geometries. Thus, it was added a traveling speed and a special rotating tool that allows welding aluminum alloys with bad weldability. The key factor to have a linear friction welding with sound bead is a combination of tool geometry, welding parameters and material flow during welding, which is under tension stress in the advancing side and in compression in the retrieving side. Thus, each side has different microstructures and mechanical properties. The objective of this work is to characterize the 3,0 mm weld bead of an alloy 6063 T6. This material was welded with a tool type \"Three flats\" with a rotation speed of 1120 rpm and welding traveling speed of 5.3 mm/s. The samples were characterized by optical microscopy, microhardness testing and tensile test. The results showed that the weld bead is asymmetric, with an area 20% higher in the advancing side. Moreover, a grain refining process occurred in the weld bead and, in the transition region between thermomechanically affected zone (TMAZ) and heat affected zone (HAZ) the elongated grains presented a shape factor higher in the advancing side (1,73 to 2,74) than in the retrieving side (1,40 to 1,59). Also, the thermomechanically affected zone and the heat affected zone presented a larger width in the advancing side than in the retrieving side.

As ligas de alumínio AA2024 e AA7050 tradicionalmente são utilizadas na fabricação de estruturas da fuselagem e da asa de aeronaves. Normalmente, a união dos componentes dessas estruturas é realizada por rebites, já que processos de soldagem com fusão produziriam defeitos indesejáveis. O processo de soldagem por fricção linear com mistura ou Friction Stir Welding (FSW) é uma alternativa à união de chapas de ligas de alumínio por rebites haja vista que não há fusão do material durante a união. No presente trabalho estudou-se o comportamento eletroquímico e a caracterização microestrutural de uma junta sobreposta, composta por um perfil extrudado da liga AA7050-T76511 e uma chapa da liga AA2024-T3, ambos previamente anodizados, soldada por fricção linear com mistura. O comportamento eletroquímico foi avaliado através da utilização da Técnica de Varredura com Eletrodo Vibratório (SVET), medidas do potencial de corrosão e curvas de voltametria cíclica em solução de 0,1 M de NaCl. Correntes anódicas mais intensas foram medidas na região da solda e ainda verificou-se que esta possui menores potenciais de pite e corrosão do que ambas as ligas. Também foi constatada a presença de corrosão intercristalina em ambas as ligas e na região da solda, porém com maior severidade na liga AA2024-T3. / AA2024 and AA7050 aluminum alloys are traditionally used in the manufacture of fuselage structures and aircrafts wings. Usually, the component union of these structures is made using rivets since weld process with melting will produce unwanted defects. The Friction Stir Welding (FSW) process is an alternative way to replace the traditional rivet union of aluminum alloys in the aeronautical and aerospace industries since the material does not melt during the joint. In the present work it has been studied the electrochemical behavior and microstructural characterization of a lap joint composed of an extruded profile of AA7050-T76511 alloy and a sheet of AA2024-T3 alloy, both of them previously anodized and jointed by friction stir welding. The electrochemical behavior was evaluated by means of Scanning Vibrating Electrode Technique (SVET), measurements of the corrosion potential and cyclic voltammetry in 0,1 M NaCl. Higher anodic currents were found in the weld region, moreover this region has the lowest pit and corrosion potential. Intercrystalline corrosion was found in both alloys and in the weld region, with the highest intensity in the AA2024-T3 alloy.

A crescente escassez dos recursos energéticos renováveis, bem como o contínuo aumento dos seus custos tem requerido nas últimas décadas uma redução drástica no consumo de energia utilizada para o transporte de cargas e passageiros. A indústria siderúrgica pode contribuir decisivamente neste contexto, disponibilizando no mercado aços de maior resistência mecânica, os quais podem ser utilizados em estruturas mais esbeltas. Os aços com elevados teores de Mn (15-30%) representam um desenvolvimento muito recente de ligas ferrosas puramente austeníticas, que reúnem resistência mecânica elevada e grande ductilidade. Além disso, trata-se de ligas de baixo custo devido à eliminação dos elevados teores de Ni necessários para a estabilização da austenita e ao reduzido tempo de processamento, que dispensa tratamentos térmicos e processamentos termomecânicos controlados. Por outro lado, a redução de peso estrutural no setor automobilístico requer não somente a pesquisa de novos aços, mas também a utilização de componentes híbridos, resultantes, entre outros, da união dos aços austeníticos alto Mn com aços comerciais estruturais de alta resistência e baixa liga (ARBL). Nesta dissertação, estudou-se, portanto, a soldabilidade pelo processo de fricção e mistura mecânica (SFMM) de aço austenítico alto Mn com efeito TRIP (plasticidade induzida por transformação martensítica) com aço ARBL processado termomecanicamente tipo XABO500 (ThyssenKrupp Steel, limite de escoamento > 460 MPa). As placas de aço TRIP foram fabricadas na EESC-USP com composição Fe-22.5% Mn-0.4% C através de fundição sob atmosfera protetora de argônio, tratamento térmico de homogenização e laminação a quente a 1150°C. As juntas dissimilares TRIP-ARBL foram produzidas com chapas de 3.5 mm de espessura. Os ensaios de soldagem SFMM foram conduzidos com ferramenta de compósito PCBN-WRe. O aporte térmico de soldagem foi variado através do uso de três velocidades de rotação da ferramenta: 300, 400 e 500 rpm, e o avanço foi de 100 mm/min. Dois deslocamentos (offsets) da ferramenta foram investigados: +1.0 e +2.0 mm em direção ao aço TRIP. Os resultados revelaram um acabamento superficial satisfatório das juntas soldadas com 300 e 400 rpm. A penetração de soldagem aumentou com a velocidade de rotação da ferramenta e com um maior deslocamento da ferramenta em direção ao aço TRIP devido ao crescimento do aporte térmico. A SFMM produziu em ambos os lados das juntas dissimilares uma microestrutura caracterizada apenas por zona de mistura (ZM) e zona termicamente afetada (ZTA), não sendo observada a formação de zonas termomecanicamente afetadas (ZTMA). Na ZM do aço ARBL, a SFMM produziu uma microestrutura polifásica, contendo misturas de ferrita acicular, bainita e martensita. O lado TRIP da ZM não exibiu sinais de transformação martensítica induzida por deformação e sofreu recristalização dinâmica com a formação de uma austenita refinada em comparação com o metal de base. A junta produzida com menor aporte térmico (300 RPM e Offset +1) apresentou os maiores picos de dureza na ZM do aço TRIP devido à maior taxa de resfriamento e, consequentemente, a microestrutura mais fina. Apesar dos maiores picos de dureza, a junta produzida com 300 RPM e Offset +1 apresentou o melhor desempenho no ensaio de tração, atingindo o maior percentual de alongamento a fratura e rompendo no metal de base ARBL. Isso se deve provavelmente à formação de ferrita acicular mais fina na ZM do aço ARBL com microestrutura entrelaçada e de maior tenacidade, se comparado com o metal de base ARBL. / The increasing scarcity of renewable energy resources and their continuously rising costs have required in the last decades a drastic reduction in the energy consumption for the transportation of goods and passengers. The steel industry can decisively contribute in this context by providing the market with steel grades of increased mechanical strength, which can be incorporated into light-weight structures. Steels with high Mn contents (15-30%) represent a recent development of austenitic ferrous alloys that combine elevated mechanical strength with high ductility. In addition, those steel grades correspond to low cost alloys due to the replacement of the high Ni contents necessary to stabilize the austenite as well as the reduced manufacturing time that does not involve subsequent heat treatments or controlled thermo-mechanical processing. On the other hand, the reduction of structural weight in the automotive sector does not only require the research on novel steels, but also the use of hybrid components that result among others from joining austenitic high-Mn steels to commercial structural high-strength low-alloyed (HSLA) steel grades. In this work, we studied therefore the friction stir weldability of an austenitic high-Mn steel with TRIP (transformation induced plasticity) effect to the thermomechanically processed HSLA XABO500 steel grade (ThyssenKrupp Steel, yield strength > 460 MPa). High-Mn TRIP steel plates were produced at the EESC-USP with the chemical composition of Fe-22.5% Mn-0.4% C by casting under protective argon atmosphere, followed by homogenization treatment and hot rolling at 1150°C. The dissimilar TRIP-HSLA joints were produced using 3.5 mm thick plates. The friction stir welding (FSW) experiments were carried out with a tool made of a PCBN-WRe composite. The heat input was varied by using three tool rotational speeds: 300, 400 and 500 rpm. The welding speed was set to 100 mm/min. Two different tool offsets were investigated: +1.0 and +2.0 mm towards the high-Mn TRIP steel. The results revealed that a satisfactory surface finishing is achieved for the butt-joints produced with 300 and 400 rpm. The welding penetration increased for higher tool rotational speeds and larger tool offsets towards the TRIP steel because of an increased heat input. FSW produced at both sides of the dissimilar joints a microstructure characterized by only stir zone (SZ) and heat-affected zone (HAZ). Thermo-mechanical affected zones (TMAZ) could not be observed. In the SZ of the HSLA steel, FSW produced a multiphase microstructure that contains a mixture of acicular ferrite, bainite and martensite. The TRIP side of the SZ did not exhibit traces of strain induced martensitic transformation and underwent dynamic recrystallization with the formation of a fine-grained austenite in comparison to the base material. The butt-joint produced with the lowest heat input (300 RPM and Offset +1) developed the highest hardness peaks in the SZ of the TRIP steel because of the increased cooling rate and, consequently, the more refined microstructure. In spite of the hardest zones, the butt-joint produced with 300 RPM and offset +1 achieved the best performance in the tensile tests by reaching the largest elongation to fracture and having the failure in the HSLA base material. This is likely promoted by the formation of a more refined acicular ferrite in the SZ of the HSLA steel with interpenetrated microstructure and enhanced toughness in comparison to the HSLA base material.

Slitiny hliníku řad 2XXX a 7XXX nejsou shledávány jako svařitelné s použitím tradičních metod svařování. Jsou však široce používány v leteckých a kosmických konstrukcích. Obvyklý způsob jejich spojování je pomocí nýtování. Nově vznikající technologie lineárního svařování třením rotujícím nástrojem (Friction Stir Welding - FSW) již ukázala slibné výsledky při svařování těchto slitin. V této práci jsme prozkoumali aplikace technologie FSW v leteckých konstrukcích zejména jako náhradu nýtování na panelech vyztužených stringery. Sestavili jsme výrobní postup pro daný panel a navrhli další kroky k jeho optimalizaci. Dále jsme sestavili znalostní bázi základních svařovacích parametrů a porovnali jsme nýtování a FSW na jednoduchém modelu využitím metody konečných prvků a s cílem identifikovat rozdíly v charakteru rozložení napětí v těchto vzorcích.

This research demonstrates the use of friction stir welding (FSW) to join dissimilar (Al-Mg) metal alloys. The main challenges in joining different, dissimilar metal alloys is the formation of brittle intermetallic compounds (IMCs) in the stir zone affecting mechanical properties of joint significantly. In this present study, FSW joining process is used to join aluminum alloy AA2139 and magnesium alloy WE43. The 9.5 mm thick plates of AA2139 and WE43 were friction stir butt welded. Different processing parameters were used to optimize processing parameters. Also, various weldings showed a crack at interface due to formation of IMCs caused by liquation during FSW. A good strength sound weld was obtained using processing parameter of 1200 rev/min rotational speed; 76.2 mm/min traverse speed; 1.5 degree tilt and 0.13 mm offsets towards aluminum. The crack faded away as the tool was offset towards advancing side aluminum. Mostly, the research was focused on developing high strength joint through microstructural control to reduce IMCs thickness in Al-Mg dissimilar weld joint with optimized processing parameter and appropriate tool offset.

Master's thesis deals with consideration possibility of conventional and unconvetional welding methods of wrought magnesium alloys. Methods of Friction Stir Welding, Pulsed Nd:YAG laser and Continuous Fiber laser was used to join magnesium alloy sheets AZ31, AZ61, ZE10 and ZE41. For studying influence of processing parameters on microstructure and mechanical properties were used methods of light microscopy, scanning electron microscopy, tensile tests and microhardness measurements. The results of tensile tests show that from the point of view of keeping ultimate tensile strength is the best methods for welding magnesium alloys Friction Stir Welding. Compared with Nd:YAG laser, fiber laser give better properties of welds. From comparing microstructure and mechanical properties . It wasn't found publications about Friction Stir Welding of magnesium ZE alloys or about FSW sheets with thickness only 0,8 mm and 1,6 mm.

The penchant towards development of high performance materials for light weighting engineering systems through various thermomechanical processing routes has been soaring vigorously. Friction stir processing (FSP) - a relatively new thermomechanical processing route had shown an excellent promise towards microstructural modification in many Al and Mg alloy systems. Nevertheless, the expansion of this process to high temperature materials like titanium alloys and steels is restricted by the limited availability of tool materials. Despite it challenges, the current thesis sets a tone for the usage of FSP to tailor the mechanical properties in titanium alloys and steels. FSP was carried out on three near beta titanium alloys, namely Ti6246, Ti185 and Tiβc with increasing β stability index, using various tool rotation rates and at a constant tool traverse speed. Microstructure and mechanical property relationship was studied using experimental techniques such as SEM, TEM, mini tensile testing and synchrotron x-ray diffraction. Two step aging on Ti6246 had resulted in an UTS of 2.2GPa and a specific strength around 500 MPa m3/mg, which is about 40% greater than any commercially available metallic material. Similarly, FSP on an ultra-high strength steel―Eglin steel had resulted in a strength greater than 2GPa with a ductility close to 10% at around 4mm from the top surface of stir zone (SZ). Experimental techniques such as microhardness, mini-tensile testing and SEM were used to correlate the microstructure and properties observed inside SZ and HAZ's of the processed region. A 3D temperature modeling was used to predict the peak temperature and cooling rates during FSP. The exceptional strength ductility combinations inside the SZ is believed to be because of mixed microstructure comprised of various volume fractions of phases such as martensite, bainite and retained austenite.

In this study tools consisting of a 5mm cylindrical pin and a 12mm shoulder held by a simple tool holder were used to compare the wear of 11 tooling materials. The objective was to determine if using these tools in a spot welding configuration to simulate friction stir welding could differentiate the potential performance of tooling materials. All tools were made of varying percentages of polycrystalline cubic boron nitride (PCBN), tungsten (W) and rhenium (Re). The materials are referred to herein as GV1, GV2, G1, G2, G3, G4, G5, G6, G7, G8 and G9.The tools were run to 205 welds if they did not fracture first. The grades averaged the following quantities of welds before fracture failure GV-1:0; GV-2:200; G1:82; G2:204; G3:205; G4:205; G5:96; G7:102.73; G8:21.2; G9:38.5. Of the tools that ran the full 205 welds without chipping, the average calculated volume loss, which was the best indication of wear, was as follows G2:1.83%; G3:2.53%; G4:2.41%; G5:1.93%; and G7:2.30%.The study showed that G2 had the least wear and G6 had the most wear, of those tools that completed all 205 spot welds. Fracture was the failure mode of all grades with over 70% CBN content. It was found that small CBN grain size was not correlated to better wear performance, as has been seen in a prior study.