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

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

Ensaio de ligações de estruturas de madeira por chapas com dentes estampados em quatro espécies da família leguminosas

In the last years, the use of industrialized systems of lattice structures of wood as an alternative in the construction processes, is becoming more popular in Brazil, mainly for their commitment to the environment.The industrialized system of wooden lattice structures consists in a production of lattice structures, composed of pieces of wood where their mechanical connections are made with the sheet multi-toothed connectors (CDE).Among the many challenges to make this system competitive, the whole system of the connections between the pieces of wood not only must show functionality, but also speed, strength, versatility and economy. Referenced at Brazilian Standard for Wood Structures (NBR 7190/1997 - Project of timber structures) the sheet multi-toothed connectors, are analyzed using three test methods: tensile strength parallel to grain, tensile strength normal to the fibers and shear strength, all of them in two positions, αCH0=0o e αCH0=90o to four types of wood: Angelim (Vatairea heteroptera Ducke); Red-Angico (Parapiptadenia rigida (Benth) Brenae); Garapa (Apuleia leiocarpa (Vog.) Macbr) and Jatoba (Hymenaea stilbocarpa Hayne), belonging to the Leguminosae family and founded in several regions of Brazil.The purpose of this manuscript consists to analyze the mechanical connections with the sheet multi-toothed connectors through tests from NBR7190/1997

Otimização de custo no processo de fabricação de mangueira hidráulica

A large part of hydraulic hoses is produced on a mandrel. The mandrel has longer length and circular profile being produced by extrusion of polyamide polymer, which in this case is imported, then the process is depending on the import process, which entails high shipping costs and fees. This work studies the production of recycled mandrel, using the mandrel that is out of dimensional to produce hoses. After the production of recycled mandrel mechanical tensile and hardness were performed both in the natural and recycled mandrel to compare them. It was observed that recycled mandrel presents the tensile properties and hardness superior to natural mandrel. Thus, this work will directly impact the company`s business ultimately reducing costs, reducing waste and reducing environmental impacts

Caracterização físico-mecânica de elementos estruturais roliços perfilados de Amaru

The study of physical and mechanical properties of wood is essential for its structural use and it is of great importance to the construction industry. Thus, this study aimed to determine the physical and mechanical properties of the wood Amaru - a hybrid of Eucalyptus, developed by Plantar Projects and Forest Products Ltda. In order to determine the properties of Amaru, round samples were used, which were provided to the Laboratory of Wood and Wooden Structures of the School of Engineering of São Carlos, University of São Paulo - LaMEM / EESC / USP. For the characterization of the physical properties, the apparent specific gravity and moisture content of the samples were determined. To the mechanical characterization, the following properties were evaluated: strength and stiffness in compression, strength and stiffness in bending, shear and tension. The procedures of the tests performed in this study were done according to the recommendations of the Brazilian Wood Standard ABNT NBR 7190:1997. The specimen used were confectioned in actual dimensions, according to as those used in the construction system proposed by Plantar. The results obtained from the tests performed showed that the mechanical properties approached the values proposed by the Wood Standard NBR 7190. The visual grading was important to provide a primary idea about the failure modes to be obtained from the tests performed. The bending test showed the modulus of elasticity (MOE) and Modulus of Rupture (MOR), which resulted in 15822 MPa and 101,7 MPa, respectively. The compression test resulted in values Ec0,m and fc0, 15698 MPa and 50,7 MPa. The tensile strength (ft0) of this hybrid was calculated and its value obtained was 60,8 MPa. The shear strength (fv0) was 8,2 MPa. The results obtained from the tests are the basis for engineers and architects to design structures using wood species Amaru

Reciclagem de poliestireno expandido: compósito com fibras de algodão para a confecção de placas de circuito impresso

In this work polymeric composites reinforced with cotton fibers, from the textile industry, were developed in order to manufacture printed circuit boards. It was used expanded polystyrene (EPS) as a thermoplastic matrix by melting it. For the obtention of 10% and 15% of fiber volume fraction in cotton fibers composites, it was used wasted cotton fibers as an incentive of recycling and reusing of the domestic and industrial wastes as well as for Expanded Polystyrene(EPS). The mechanical properties of the composites were evaluated by tensile and flexural strength from standardized test methods. Composites were characterized by a Scanning Electron Microscopy (SEM), Thermogravimetry (TG/DTG), Differential Scanning Calorimetry (DSC) and dielectric analysis. The analysis of the results showed that fiber in the composite directly influenced in the thermal and mechanical properties

Estudo das propriedades mecânicas do aço SAE 1312 modificado ao nióbio

The study of mechanical properties of high-alloy special steels is of great interest of the steel industry due to the great demand by companies that manufacture automotive components of high criticality, and also because of its high commercial value. However, the development of this type of alloy metals demand highly technical knowledge. Among these extremely important kinds of steel, the subject which is the interest of this study is the special steel modified by niobium. The manganese and niobium are the main alloying elements in the composition of these steels, both of them increase the stability of the austenite region, however, manganese increases the hardenability and tensile yield strength, and niobium increases the mechanical strength and promotes refining the grain. The mechanical characterization of steel SAE 1312 modified the niobium was made in order to gain a better understanding of the influence on the mechanical properties caused by aging at different temperatures and for different reductions in the drawing of gauge material. This characterization was made by means of tensile test and hardness. This material showed an increase in yield strength and hardness when gauge with large reductions during the wiredrawing, but when subjected to aging temperatures higher than 300 ° C had a slight loss of these properties

Preparação e caracterização da casca de banana prata particulada para aplicação com reforço em compósito de matriz de PEAD

The waste, exaggerated and incorrect disposal of biomass are common practices in modern times where everything is disposable. However the growing concern with the nature and the environment compel man to give nobler destinations for these products through sustainability and recycling of waste. Banana peel is a residual biomass, which is not consumed. It generates tons of waste per week in São Paulo city. This trash is disposed in dumps and landfills, which could be reduced by using it as reinforcement in natural composites. The high density polyethylene (HDPE) is a polymer derived from the ethylene polymerization and is easily recycled. Which makes it a sustainable material. In the present work characteristics of the natural composite composed with banana peel and high-density polyethylene were studied. It was noted that removing the lignin present in the banana peel, the fiber introduces a significant improvement in thermal resistance. The preparation of composite was made with a ratio of 5% and 10% of reinforcement in comparison with polymeric matrix mass. Composites were thermally, mechanically and microscopically characterized. The addition of fiber in the polymer increased the mechanical strength of the composite. The fiber surface treatment with distilled water removed the amorphous material present in the fibers, improving significantly thermal stability and increasing crystallinity of the celullose. The addition of 5% fiber in mass to the polymer increased significantly the tensile strength and elasticity modulus for the composite. With 10% of fiber addiction there were also an improvement when compared with pure HDPE, but when compared with 5% composite the mechanical properties are slightly lower. This may be due to the fiber particle size, which are small and eventually become a hub of tension ... (Complete abstract click electronic access below)

Avaliação da tenacidade em um aço microligado, grau API, para aplicação em linhas dutoviárias de petróleo e gás

In order to study the mechanical properties of micro alloyed steel API 5L X70, a material used to manufacture pipes for pipeline transportation lines for use in oil and gas, a study was made of toughness, tensile strength, impact strength, hardness and microstructure steel. To perform these various tests were made where they can acquire the characteristics of the material. Were performed at the Faculty of Engineering in Guaratinguetá in the Department of Materials and Technology and the tensile tests, Charpy impact test, metallography and hardness testing of material API 5L X70, all tests were done with the help of technical laboratories. With these data can be an analysis of the material about his tenacity, his toughness and fragility, its hardness, its yield strength and its maximum voltage. After being asked the analyzes discussed the results showed that the micro alloyed steel API 5L X70 steel is a very tenacious, it absorbs impact energy of 300 Joules though without a break for the full body of evidence showing its tenacity

Estudo da influência da adição de resíduos de óleo em concretos para aplicação em pavimentos

Pós-graduação em Engenharia Civil - FEIS

Cimentação de coroas com fosfato de zinco sobre munhões de liga de titânio, irradiados ou não por laser

By means of tensile strength, NiCr total crowns were removed from machine-made conical abutments composed by an Ti-6Al-4V alloy. In a total of 20 abutments, 10 were used with it surface presenting high smoothness and 10 abutments had its surfaces modifi ed by laser both cemented with zinc phosphate. The mechanical test was performed at a MTS 810 universal machine adjusted to a speed of 0.5 mm/m. The statistical analysis was done by Levene’s test, which showed homogeneity of variances among groups (F =2.21; p < 0.1). “Student t test” showed that signifi cant differences were found between groups. The modifi cation of the abutment surface through laser caused an increase in pull-out resistance of crowns cemented with zinc phosphate from 430.66 N to 1.514,87 N.

Concreto com adição de cinza de bagaço de cana-de-açúcar

Pós-graduação em Engenharia Civil - FEIS

Técnicas de caracterização microestrutural, por microscopia óptica e microscopia eletrônica de varredura, de aços bifásicos e multifásicos aplicados à indústria automobilística

This project developed microstructural characterization technics of commercial dualphase and multi-phasic (TRIP) steels that were provided by the automotive industry and are currently used as the raw material for the production of automobiles. Inserted in this context, there is the development of the advanced high strength steels in consonance with the ULSABAVC project, which aims the production of safe, economically viable and efficient in terms of fuel consumption vehicles for the 21st century. The micro-structural characterization of biphasic and multiphase steels was done by the identification and quantification of the coexistent phases. In this item, a special attention was given to the technics that were performed using optic microscopy and scanning electron microscopy. An important contribution to this work was the utilization of different alternative chemical reagents (Beraha, Heat-Tinting technics) in addition to the classical ones (Nital and LePera)already used conventionally by the UNESP's Group of Mechanical, Microstructural and Fractografic Characterization of Materials. The revealed microstructures were correlated with the materials' mechanical properties determined through traction tests, such as ultimate tensile strengths, yield strength and stretching important since the material has structural application in the automotive industry. As a result, it was observed the superiority concerning the studied mechanical properties for the biphasic and multiphasic steels when compared to the conventional carbon steels. Besides, it was perceived a large potential for the industrial scale utilization of the Heat Tinting technics in this field, seen its differentiation of the existent phases and easy reproducibility

Herbst esplinte metálico fundido: novo modelo de confecção com Duralay

A má oclusão de Classe II é originária de vários fatores etiológicos e uma das características mais comum desta má oclusão é a retrusão mandibular3, por esse motivo, os aparelhos de avanço mandibular são eleitos para o tratamento e correção desta má oclusão. Um destes aparelhos é o Herbst, que apresenta várias formas de ancoragens na sua confecção10. Tradicionalmente, as bandas eram o sistema de ancoragem mais usado, no entanto, pela alta frequência de quebras as mesmas foram substituídas por esplinte metálico12. Esse aparelho quando confeccionado de cromo cobalto pelo método da prótese parcial removível, apresenta como desvantagens a quantidade de passos laboratoriais e a possível contração do metal, podendo ocasionar a má adaptação da estrutura metálica à boca do paciente. Dessa forma, este artigo apresenta um novo método de confecção do aparelho de Herbst esplinte metálico fundido com uso da Duralay e liga níquel cromo. Esse método diminui os passos laboratoriais, proporciona maior resistência à tração e minimiza a contração da estrutura metálica, pois a resina química Duralay proporciona menor expansão do que a cera2.