O estudo da usinagem em torneamento da superliga à base de níquel Pyromet 31v

The search for materials with higher properties and characteristics (wear resistance, oxidation, corrosion, etc.) has driven research of various materials. Among the materials that are being studied with such properties and characteristics are super alloys based on nickel which has an important role in the aeronautical, automotive, marine, production of gas turbines and now in space vehicles, rocket engineering , experimental aircraft, nuclear reactors, steam-powered plants, petrochemical and many other applications because besides having all the characteristics and properties mentioned above also have an excellent performance at high temperatures. The super alloy based on nickel studied in this work is the super alloy Pyromet 31v normally used in the manufacture of exhaust valves in common engines and diesel engines of high power by cater requirements such as mechanical strength and corrosion resistance at temperatures of approximately 815 ° C. The objective of this work is to produce results to demonstrate more specific information about the real influence of coatings on cutting tools and cutting fluids in turning and thus promote the optimization of the machining of these alloys. The super alloy Pyromet 31v was processed through turning, being performed with various machining parameters such as cutting speed, feed rate, depth in conditions of Minimum Amount of Fluid (MAF), abundant fluid, cutting tools with coating and without coating in early in his work life and with wear. After turning were obtained several samples of chips and the part generated during the machining process, was measured roughness of the material, subsequently made macrostructural analysis of the tools used order to detect possible wear and microstructural analysis of samples collected being that the latter was used for Optical Microscopy, Scanning Electron Microscopy (SEM) and ... (Complete abstract click electronic access below)

Análise microestrutural de tubos API P110, para prospecção de petróleo e gás, soldados pelo processo HF/ERW

On the grounds of the great advances achieved over recent years, the process HF/ERW (High-Frequency/Electric Resistance Welding)welded pipe have played an active role in the oil and gas industry for deep water applications, at high and extremely low temperatures, under high pressure and in highly corrosive environments, gradually replacing manufactured pipes by other processes. However, studies have shown that defects in the welded joints are a the leading causes of pipelines failures, which has required the determination of toughness values in this region, in compliance with the strict recommendations of the codes and standards with manufacturers and construction companies, on the oil and gas sector. As part of the validation process required toughness values, this research project focuses on a microstructural analysis in HF / ERW tubes microalloyed, steel grade API 5CT P110, designed to explore oil and gas in deep waters, the subject of strategic relevance to the country because of the recent discoveries in the Santos mega fields: Tupi and Libra (pre-salt). In this scientific work will be presented and discussed the results of mechanical tensile and Charpy, a few CTOD tests curves (showing the trend of toughness values to be obtained), and the microstructures of the base material obtained by optical microscopy, with special emphasis on the formation of nonmetallic inclusions in the welded joint

Tratamento de modificação de eutético da liga AA356

Alloy Al-7%Si-0,3Mg (AA356), having an excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability, high wear resistance, high strength to weight particularly in the automotive and aerospace engineering. The refinement of the structure aluminum silicon eutectic alloy is a fairly common practice in the casting, through the treatment knows as modification. You can get the modification for the addition of chemicals and rare earths, these have the ability to modify the structure of the eutectic, but only sodium and strontium produce a strong action modifier when used in low concentrations. The modifying effect of silicon grain turns into a fibrous form branched and enveloped by the metal matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. This work will be obtained AA356 alloy ingots using two different types of molds: metal mold and sand mold. Macrographs will be made in ingots obtained for observation of the macrostructures obtained in both types of ingots. Will be sampled at strategic locations of the ingots to correlate microstructure and cooling rate. The results showed that the material of the ingot has a strong influence on the resulting micro-andmacrostructure

Influência da aplicação de cargas estáticas axias e não axais em próteses parciais fixas de três elementos, análise pela extensometria

Um bloco de poliuretano recebeu três implantes de hexagono externo, no posicionamento compensado. Para cada implante foi conectado o pilar protético microunit. Foram realizados cinco enceramentos com três coifas plásticas cada um, que foram fundidos em monobloco numa liga de cobalto-cromo. Foram colados quatro extensomêtros tangenciando cada implante, sendo dois extensomêtros para o implante central. Após o acabamento, as estruturas foram fixadas nos respectivos locais com o parafuso de retenção com torque de 10 Ncm, obtidos com um torquímetro. Para aplicação de carga sobre os corpos-de-prova foram selecionados cinco pontos de aplicação de carga. O dispositivo de aplicação de carga–DAC foi utilizado 30 kg de cargas verticais estáticas, empregando uma ponta esférica de 2 mm de diamêtro, durante 10 segundos em cada um dos pontos estabelecidos, sendo, neste instante registradas as micro deformações de cada extensômetro. Foi utilizado o teste de análise de variância T Student e o nível de significância foi o valor convencional de 5%. Para cada implante foi analisada a microdeformação ocorrida. Os resultados obtidos mostraram que houve uma diferença estatisticamente significativa entre os pontos não-axiais D e E (t = 5,21 df = 4, p = 0,006 < 0,05) e não foi estatisticamente significativa para os dados axial entre os pontos B e C (t = 6, 57, df = 4, p = 0,003 < 0,05 / 3). Conclui-se que,a aplicação de carga ao redor de três implantes de hexágono externo no posicionamento compensado,mostra que os pontos não-axiais sofrem maior micro deformação do que os pontos axiais

Estudo da propagação de trinca por fadiga sob carregamento de amplitude variável

For engineering projects that require high reliability levels, is often not enough know only physical and chemical material properties. It’s necessary understand the failure mode of these materials in operation to ensure security level in the project and establish more stringent criteria in the analysis of structural integrity. Due to this need, aircraft industry has been using aluminum alloys in their designs and projects. “Currently more than 70% of aircraft structures are built of high strength aluminum alloys among which stand out 7075-T6 and 2024-T3 alloys, which are considered basics for being used in the new alloys development.” (PASTOUKHOV & VOORWALD, 1995). Some years ago ALCOA develops Al 2524 alloy that has emerged as refinement of Al 2024 (Al, Cu. Mg) alloy, with purpose of improve fracture toughness and fatigue resistance on structural components. The present research addresses testing of fatigue crack propagation under variable amplitude loading for Al 2024 alloy, observing the interaction effects from application of overhead blocks and plastic zone at the crack tip and makes an analysis of fracture surface images

Geografia dos movimentos socioterritoriais no Brasil de 2000 à 2012

The struggle for land is not a recent theme in Brazilian history. Since colonization, people have fought and resisted against oppression and injustice in the countryside, as can be evidenced by the highwaymen, peasant leagues and the war of Canudos. More recently, the struggle for land and agrarian reform can be evidenced by the struggles of the MST, CONTAG, CPT and other movements. For these movements, denominated as socioterritorial movements, land/territory is an essential condition for their existence and for the maintenance of their territoriality. The present paper examines the geography of socioterritorial moviments: the construction of the concept of socioterritorial movements and their forms of action and scales of actuation in the period 2000 to 2012, focusing on the movements that have been most active. These movements are studied through as analysis of data of the Land Struggle Data Base (Banco de Dados da Luta pela Terra –DATALUTA), print and digital media reports and a bibliographic survey of the literature. The action of socioterritorial movements can be studied through the forms of land occupations and demonstrations in the countryside which are the principal means of the struggle against large landholders, agribusiness and the State. These actions question the model of development which privileges agribusiness and, as such, are viewed by some as a hindrance to the development of the country. Over the years, the number of socioterritorial moviments, and their actions have oscillated due to a series of factors, such as repression (criminalization of members and violence against them), policies adopted by Brazilian governments and the contradictions inherent in very process of the spacialization of the struggle for land. These actions can be analyzed according to the scale of the struggle of the movements – municipal, micro-regional, state, macro-regional, and national

Analise do sistema de medição em peças aeronaúticas através do estudo de R&R (repetibilidade e reprodutibilidade)

The Measurement System Analysis (MSA - Measurement System Analysis) is a statistical methodology developed to study and analyze the behavior of the measurement systems, and, therefore, allow the increased of the confidence readings performed by measuring instruments. It’s widely used in the automotive industry since the 90’s and is a mandatory requirement for the approval of the parts according to ISO Standard of the automotive sector. However, the aerospace industry doesn’t require this type of Study, once which the vast majority of aeronautics parts have characteristics (dimensions) with very tight tolerances, closed, ie, at the home of microns. This work aims to create lists of recommendations for definitions of measuring instruments in developing of control plans, which correlates tolerances fields of characteristics for different settings and acceptance of the instrument, classified as optimum, recommended and not recommended, through of the study of R&R (Repeatability and Reproducibility) in aeronautics parts. Every methodology of the experimental part was based on modern strategy of continuous improvement, the DMAIC (Define Measure Analyze Implant Control), in order to achieve better measurement method used in the control of milling aeronautics parts, identifying and reducing the variations of the measurement process. The results of the R&R Study in large part of measuring instrument manuals were considered acceptable and/or recommended, ie with values of %P/T and %RR lower than 30%, providing statistical data which have enabled the elaboration of tables of recommendations, which, from this work, have turned into very important documents and aid for Process Engineering, having in their hands a technical study able to identify which is the most appropriate instrument to get a more robust dimensional... (Complete abstract click electronic access below)

Metodologia de determinação das curvas de probabilidade de falha S-N-P para uma liga de aluminio submetida a diferentes tratamentos termicos de solubilização e precipitação

The approach of the subject matter in this work relies on the fact that the reliability of methods for performance analysis of materials proves critical for the result. This work focused on the development and presentation of the methodology for lifting probability curves for fatigue test (SN) according to standard E739, this focus is justified by the fact that the results in fatigue test show considerable dispersion making it difficult to reading and interpretation of data, this dispersion arises because the phenomenon of rupture is strongly influenced by internal characteristics of the material, we can then have much data ranging from test to test. Thus we set out originally for a brief study of aluminum alloys in question, as well as the treatments to which they were subjected. We also studied the behavior of materials when subjected to cyclic loading, which configures process of fatigue failure, and even fatigue test method in question. This statistical analysis is based on the ASTM E739 standard, so its contents was studied in detail so that we could present in detail the methodology and raise SN curves for different aluminum alloy 7012 subjected to fatigue test. Data were collected from tests conducted in the department of materials from two samples of aluminum alloy 7012 solubilized and precipitated by different time intervals and assayed temperature fatigue-type traction-compression, these data were then analyzed and used to survey curves using the base as E739. After lifting the curve analyzed the characteristics of the test samples and their correlation with the test results. We confirmed the effectiveness of the method of statistical analysis by ASME E739, which allowed the reading of data without this method would be very difficult to have a reading and comparison of the results for the two types... (Complete abstract click electronic access below)

Um estudo sobre a preparação metalográfica da liga de aluminio AA7075-T6

The increasing technological innovation and demand for materials with better properties boosts research into new materials and new alloys. To do so, aluminum alloys are being developed, among them the AA7075-T6, having many applications in aerospace and military industries, machinery and equipment, molds for plastic injection and structures. To study and understand the properties, characteristics and especially the microstructure of the material, the metallographic preparation is essential. This paper presents new methodologies to achieve the metallography of samples of scrap alloy AA7075-T6, with emphasis on methods of polishing. For the five samples, the best results were those with specific grinding, the samples only going down on the sander. For polishing, the most effective method so far has been using the polishing cloth 16.3, of ATM enterprise, solution of diamond 3 μm, solution of diamond 1 μm, and colloidal solution of OP-S. For the etching, the reactive agent used was phosphoric acid (H3PO4) 85% P.A., as 90% in the proportion of distilled water to 10% acid. The best results were obtained in the attacks of 300 and 240 seconds, revealing the grain boundaries in most areas. Methodologies need more studies and more tests, but the results have proved to be satisfactory

Avaliação do comportamento mecânico sob deformação da liga Ti- 30Ta visando aplicações biomédicas

Titanium and its alloys have been used for biomedical applications due their excellent properties such as high corrosion resistance, biocompatibility and mechanical properites. In this study, microstructural and mechanical properties of Ti-30Ta alloy was evaluated during its processing. Ti-30Ta alloy ingots were produced from sheets of commercially pure titanium (99.9%) and tantalum (99.9%). Its melting was realized in arc melting furnace in an argon atmosphere. After homogenizing at 1200ºC, ingots were cold worked by swaging. Samples with 13 mm in diameter were obtained. They were forging at the reduction ratios of 15%. After deformation, microstructure was evaluated by optical microscopy in each condition. Also, Vickers microhardness of samples was measured and phase constitution was evaluated using XRD analysis

Análise da curva de resfriamento e refino de grão da liga de alumínio AA 356

The macrostructure of an alloy solidification in the raw state is of utmost importance due to its influence on mechanical properties. A structure showing columnar grains is generally undesirable in most applications of cast products and grain refining aims to suppress the formation of these grains and get a fine-grained equiaxed structure that improves the supply of liquid metal and the mechanical properties, as yield strength and tensile strength limit, as well as the tendency of formation of hot cracks. The type and size of grains formed are determined by chemical composition, cooling rate and the use of inoculum for grain refining. Titanium and boron are the major refiners in the aluminum industry and can be added to the molten metal in the form of alloys such as Al-Ti, Al-Ti-B or Al-B. In this paper we will discuss the information obtained from cooling curves and first derivative of the cooling curve to obtain the thermal parameters that influence the process of grain refining alloy AA 356.0

Avaliação de juntas soldadas em tubos de aço carbono submetidos a altas temperatura e pressões

The welding process in industrial piping is still the most effective way to ensure the durability and quality of the wide range of industrial process, although because of the high demand for energy and quality of the produced products, the piping has been constantly tested for high pressure applications and still high temperature. The welding method analyzed is the TIG (Tungsten Inert Gas) welding or GTAW (Gas-Shielded Tungsten Arc Welding), which ones have as principal feature the utilization of a not consumable tungsten electrode in the torch extremity , in this process is necessary a protective atmosphere of inert gas. The welding TIG advantage is the obtaining of a welded seam clean and with quality for not has slag after the welding. This work has as objective show the variability in the carbon steel piping welding parameters and by the tests in four proof bodies will be shown the influence of the variation of the welding methods in a welded seam. The tests will vary since the piece to be welded preparation, till penetrating liquid tests, welding macrography, welding x-ray and traction tests. Even been a clean and with quality welding is necessary a final inspection in the seam welded looking for defects almost inevitable resulted of the welded process, the obtained results have the objective of indicate and minimize the defects to ensure quality and durability of the welded seam

Estudo do efeito do modificador Al-Sr no tratamento de modificação do eutético da liga AA356

The AA356 alloy is an alloy widely used in the automotive industry and aerospace due to its excellent mechanical properties. Refining the structure of eutectic silicon aluminum alloys is a fairly common practice in the foundry through treatment known as modification. This can be achieved by modifying agent adding chemicals such as contained in groups I and IIa of the periodic table and rare earths (europium, céreioi, praseodymium, neodymium, etc.). Has the ability to modify the structure of the eutectic, but only sodium and strontium produce an action modifier strong when used in low concentrations. The modifying effect of the shafts turn silicon into a fibrous form and branched surrounded by metallic matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. In this work will be obtained ingots with and without the modifier type Al-10% Sr, made in sand molds and are generated and analyzed cooling curves and also the study of the macrostructure and microstructure of the solidified material. It was found that by adding the Al-Sr made shorten the solidification time and lower the grain size

Caracterização microestrutural de uma estrutura tubular aeronáutica submetida a sucessivos reparos de solda TIG

This work examines the possible effects of successive repair procedures on the microstructure of welded steel SAE 4130 by TIG welding process. Discussions and results were made about the metallographic analysis , non-metallic inclusions and microhardness tests , which were conducted on samples taken from the cradle engine component after the end of its life , a model airplane T-27 Tucano , made by EMBRAER and belonging were performed FAB . The choice of such component is due to the fact that this is critical to flight safety since it provides support for the aircraft engine . Thus regions of the weld metal , base metal and heat affected , with samples of the original weld bead , free of weld bead and also with four rework procedures for TIG welding zone were analyzed . It was found that after the fourth rework there is an increase in the amount of martensite , which may weaken the material with respect to resistance to fatigue. It was also found that the regions of the heat affected zone and weld metal have higher microhardness values when compared to those found in the base metal due to favoring the formation of ferritic and tempered martensite microstructures . Moreover, a welding process promotes a region with less non-metallic inclusions than metal base , which also explains the difference in the results obtained

Tratamento da superfície do alumínio via eletrólise a plasma

This paper presents the study on the application of the electrolytic plasma for surface treatment of aluminum. A bibliographical study on the material of interest was preliminarily performed and later designed and built an electrolytic cell, including the excitation source. Unlike conventional electrolysis process, the plasma assisted carry on in the non-linear region of characteristic current/voltage curve. Therefore it requires for the on set of the process that the power supply operates on harder conditions than those on high current process. The plasma produced during the present investigation has temperatures in the range o 6,0.10 3 -7,0 .10 3 K, well above those found in conventional chemical process. It also shows a particular dynamic to promote changes on surface and to produce new materials. The plasma is generated by microdischarge in vapor or gas bubbles involved in physic-chemical processes in electrode regions of the electrolytic cell. The electrode material was the aluminum (7075). The Process Electrolytic Plasma Processing (EPP) is sensitive to various parameters such as operating voltage, current density, electrolyte, concentration of electrolyte, geometry of reactor, temperature of electrolytic solution and dynamic of the fluid in the cell. The experiments were carried on in order to find parameters for a stable abd steady operation. The choice for the electrolytic was silicate/alkali solution in various concentrations to operate in various voltage as well. Plasma was produced on negative (cathode) and positive (anode) electrode, in specific conditions. A stable operation on the cathode process was obtained with low concentration of the electrolytic in aqueous solution, current density around 250V effective voltage. For the evolution of plasma in anodic process it was required higher concentrations and higher... (Complete abstract click electronic access below)