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Sample records for ferramenta tipo aisi

  1. Estudio de los tipos de cráteres obtenidos en el impacto de proyectiles 5,56 SS109, sobre blancos de acero AISI-SAE 1045

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    Castro, Álvaro

    2000-02-01

    Full Text Available The present work describes the morphology and formation of the types of craters obtained with the impact of projectiles 5,56 SS109 over seven steel plates AISI-SAE 1045 that received different cycles of heat treatment. A comparison between the type of deformation and fracture structures and the ones generated by the impact of this projectile over one steel armor plate was made. Each one of the craters was characterized by visual and metallography observation. The influence of the plate microstructure on the efficiency for stopping the projectile and the mechanism of craters formation was evaluated.

    En el presente trabajo se describe la morfología y formación de los tipos de cráteres obtenidos, en el impacto de proyectiles 5,56 SS109, sobre siete chapas de acero AISI-SAE 1045 que fueron sometidas a diferentes tratamientos térmicos, comparando el tipo de estructuras de deformación y fractura obtenidas con las formadas por el impacto de uno de estos proyectiles sobre una chapa comercial para blindaje. Cada uno de los cráteres se caracterizó mediante ensayos de inspección visual y metalografía evaluándose, a partir de los resultados, el papel que ejerce la microestructura obtenida sobre el nivel de eficiencia en la detención del proyectil por parte de la chapa y el mecanismo de formación de los cráteres.

  2. Machining tools in AISI M2 high-speed steel obtained by spray forming process; Ferramentas de usinagem em aco rapido AISI M2 obtido por conformacao por 'spray'

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Edilson Rosa Barbosa de. E-mail: erbjesus@usp.br

    2004-07-01

    The aim of the present work was the obtention of AISI M2 high-speed steel by spray forming technique and the material evaluation when used as machining tool. The obtained material was hot rolled at 50% and 72% reduction ratios, and from which it was manufactured inserts for machining tests. The performance of inserts made of the spray formed material was compared to inserts obtained from conventional and powder metallurgy (MP) processed materials. The spray formed material was chemical, physical, mechanical and microstructural characterised. For further characterisation, the materials were submitted to machining tests for performance evaluation under real work condition. The results of material characterisation highlight the potential of the spray forming technique, in the obtention of materials with good characteristics and properties. Under the current processing, hot rolling and heat treatments condition, the analysis of the results of the machining tests revealed a very similar behaviour among the tested materials. Proceeding a criterious analysis of the machining results tests, it was verified that the performance presented by the powder metallurgy material (MP) was slight superior, followed by conventional obtained material (MConv), which presented a insignificant advantage over the spray formed and hot rolled (72% reduction ratio) material. The worst result was encountered for the spray forming and hot rolled (50% reduction ratio) material that presented the highest wear values. (author)

  3. Comportamento reológico de dispersões de argilas bentoníticas: efeitos do tipo de ferramenta, velocidade e tempo de agitação

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    Amorim L. V.

    2002-01-01

    Full Text Available Este trabalho teve como objetivo estudar a influência do tipo de ferramenta, da velocidade e do tempo de agitação nas propriedades reológicas de dispersões de quatro amostras de argilas bentoníticas sódicas industrializadas no Estado da Paraíba, Brasil. Foi realizado um planejamento fatorial do tipo 2³ para avaliar os fatores de entrada (tipo de ferramenta, velocidade e tempo de agitação sobre as viscosidades aparente e plástica e o volume de filtrado. As dispersões foram preparadas na concentração de 4,86% em massa de argila (24,3 g de argila em 500 mL de água deionizada utilizando ferramentas do tipo palheta corrugada e em forma de borboleta, duas velocidades (10.000 rpm e 17.000 rpm e dois tempos de agitação (10 e 20 min. As viscosidades aparente e plástica foram determinadas em viscosímetro Fann 35A, e o volume de filtrado, em filtro prensa Fann. Através da regressão dos dados experimentais, verificou-se que as variáveis de entrada não apresentam influências estatisticamente significativas nas propriedades reológicas das dispersões estudadas, bem como, que dentre as quatro argilas estudadas apenas uma apresenta comportamento reológico de acordo com as normas vigentes para uso como agente tixotrópico para fluidos de perfuração à base de água doce.

  4. Relaciones cuantitativas entre los contenidos de azufre y de sulfuros en los aceros inoxidables tipo AISI 303: influencia de la composición química de los sulfuros

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    Botella, J.

    1999-06-01

    Full Text Available The work has been done with ten AISI 303 stainless steel rods which have similar chemical compositions, except for sulphur which varies between 0.25 and 0.36%. These steels are studied by Scanning Electron Microscopy (SEM and Energy Dispersive X-Ray Spectrometry (EDX. The sulphides are chemically microanalysed and the occupied volume determined by automatic image analysis. It can be inferred that the chemical composition of sulphides in AISI 303 steels is variable to some extent even though the steel chemistry is almost invariable. This could mean that solidification conditions and thermomechanical transformations are able to affect resulting in variations of sulphide compositions. Quantitative relations between sulphur and sulphide contents are established and the influence of sulphide chemical compositions on those relations is studied. The experimental results are compared with those obtained from theoretical calculations. A good approach is obtained when the difference between chemical compositions of real sulphides and the theoretical one, MnS, is taken into account.

    Se trabaja con una serie de diez redondos de aceros inoxidables tipo AISI 303 de composiciones químicas prácticamente iguales a excepción del azufre que varía entre 0,25 y 0,36%. Se examinan los aceros mediante Microscopía Electrónica de Barrido (MEB y Espectrometría de Dispersión de Energías de Rayos X (EDX acoplada al MEB, analizándose químicamente los sulfuros y determinando, mediante análisis automático de imágenes, los volúmenes ocupados por los sulfuros. Parece deducible que la composición química de los sulfuros en el AISI 303 puede ser discretamente variable aún siendo prácticamente invariable la composición química del acero. Ello podría significar que las condiciones de solidificación y las transformaciones termomecánicas pueden influir, dando como resultado variaciones en la composición química de los sulfuros. Se establecen

  5. Estudo de algoritmo evolutivo com codificação real na geração de dados de teste estrutural e implementação de protótipo de ferramenta de apoio

    OpenAIRE

    André Vinicius Buzzo

    2011-01-01

    Resumo: A geração automática de dados de teste pode ser abordada como um problema de otimização e algoritmos evolutivos se tornaram um foco de muita pesquisa nesta área. Recentemente um novo tipo de algoritmo evolutivo chamado GEO (GEO - Generalized Extremal Optimization) tem sido explorado em uma grande classe de problemas de otimização. Neste trabalho é apresentado o uso do algoritmo evolutivo GEO com codificação real - GEOreal - na geração de dados de teste. O desempenho deste algoritmo é ...

  6. Química combinatória: moderna ferramenta para a obtenção de candidatos a protótipos de novos fármacos Combinatorial chemistry: advanced tool for drug leads discovery

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    Patrícia de Aguiar Amaral

    2003-12-01

    Full Text Available A Química Combinatória (QC é atualmente uma das mais promissoras ferramentas para a descoberta e o desenvolvimento de novas moléculas com potencialidades terapêuticas. Nesta metodologia de síntese os produtos são formados simultaneamente e podem ser testados biologicamente em uma só vez, seja em forma de misturas ou separadamente. A principal meta desta nova metodologia é reduzir o tempo necessário para a obtenção de um novo fármaco. A síntese de quimiotecas pode ser realizada através da utilização de polímeros insolúveis, solúveis ou pela tradicional síntese em solução, sendo que cada uma delas apresenta características que podem ser vantajosas ou não, dependendo da metodologia utilizada. O desenvolvimento de técnicas de high throughput screening (HTS devido às suas características peculiares necessita de tempo, razão pela qual a síntese de quimiotecas pequenas e racionais é enfatizada.Nowadays, Combinatorial Chemistry is one of the most promising tools used in the design and discovery of new molecules potentially useful in the therapeutics. In this methodology, the reaction products are synthesized simultaneously and can be evaluated once, either in a complex mixture or as isolated compounds. The main aim of this new approach is the time for the development of new drugs. The synthesis of combinatorial libraries can be performed using either insoluble or soluble polymers and also by the traditional organic synthesis in solution. Each one of these approaches presents features that may be advantageous depending on the final objective of the synthetic process. The development of high throughput screening (HTS assays takes much time, which makes the synthesis of small and well designed combinatorial libraries the most recommended strategy.

  7. Uma ferramenta para planejamento de estudos para concursos

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    Leonardo Pimentel

    2015-11-01

    Full Text Available De acordo com a constituição brasileira, a única forma de se tornar um empregado do governo é passar em um concurso público. O exame de conhecimento do cargo é um dos componentes mais importantes de um concurso. Estudar para esse exame é uma tarefa que requer planejamento. Um meio de obter um bom planejamento é construir uma grade de horários que relacione as matérias a serem estudadas com os respectivos horários disponíveis para o estudo. Esse tipo de problema se assemelha bastante à gerência de projetos, em que se procura estabelecer a distribuição das atividades ao longo do tempo disponível. Assim, torna-se interessante explorar a dinâmica de estudos para concursos como um projeto. O presente trabalho apresenta a ferramenta de apoio ao estudos - Passe-me, baseada no ciclo PDCA (do inglês, Plan-Do-Check-Act. Por se tratar de uma ferramenta web, o tempo de resposta para produzir uma grade de estudos é fundamental. A ferramenta faz uso de algoritmo genético para calcular a grade de horários priorizando a velocidade de resposta. A ferramenta foi avaliada em diferentes cenários de uso e obteve desempenho satisfatório durante a produção da grade de estudos.

  8. FRICTION WELDING OF DISSIMILAR AISI 304 AND AISI 8640 STEELS

    OpenAIRE

    BATI, Serkan; KILIÇ, Musa; KIRIK, İhsan

    2016-01-01

    This study investigates the joinability of AISI 8640 heat treatable steel and AISI 304 austenitic stainless steel combined with friction welding. These steels have completely different properties and widely used in industrial applications. Welding is applied on steels with the parameters of 1800 rev/min turning speed, 50 MPa friction pressure and 2, 4, 6, 8 and 10 sec friction time by using continuously driven friction welding machine. After the welding process, tensile and hardness testing a...

  9. Cyclic oxidation of stainless steel ferritic AISI 409, AISI 439 and AISI 441; Oxidacao ciclica dos acos inoxidaveis ferriticos AISI 409, AISI 439 e AISI 441

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Maria de Fatima; Santos, Diego Machado dos; Oliveira, Givanilson Brito de, E-mail: fatima.salgado@pq.cnpq.br [Universidade Estadual do Maranhao (CESC/UEMA), Caxias, MA (Brazil). Centro de Estudos Superiores; Rodrigues, Samara Clotildes Saraiva; Brandim, Ayrton de Sa [Instituto Federal do Piaui (PPGEM/IFPI), PI (Brazil); Lins, Vanessa de Freitas Cunha [Universidade Federal de Minas Gerais (IFMG), MG (Brazil)

    2014-07-01

    Stainless steels have many industrial applications. The cyclic oxidation of ferritic stainless steels technical and scientific importance presents, because they are less susceptible to peeling the austenitic alloys. For the purpose of investigating the behavior of these steels under thermal cycling, cyclic oxidation of AISI 409, AISI 441 and AISI 439 was carried out in a tubular furnace under two different conditions: oxidation by dipping the steel in the synthetic condensate for 10h and without oxidation immersion in the condensate, for up to 1500h at 300° C temperature. Using techniques: SEM, EDS and XRD revealed a microstructure with increased oxidation in the samples were immersed in the condensate. The oxide film remained intact during oxidation for steels 439 and 441 409 The Steel immersed in the condensate was rupture of the film after the 20th cycle of oxidation. The chemical characterization of the films allowed the identification of elements: Chromium, Iron, Aluminium and Silicon To a great extent, Cr{sub 2}O{sub 3}. (author)

  10. Parâmetros de conformação para a estampagem incremental de chapas de aço inoxidável AISI 304L

    OpenAIRE

    Luiz Carlos de Cesaro Cavaler

    2010-01-01

    O presente trabalho tem como objetivo conhecer o comportamento do aço inoxidável austenítico AISI 304L para o processo de Estampagem Incremental de Chapas (ISF - Incremental Sheet Forming), baseado nos parâmetros: raio da ferramenta RT, ângulo de parede a e passo vertical dz. Os experimentos baseiam-se na variante da Estampagem Incremental denominada Estampagem Incremental com Ponto Simples (SPIF - Single Point Incremental Forming). Foram realizados 29 ensaios, em três ferramentas com raios d...

  11. Estudo do encruamento dos aços AISI 304 e AISI 409 com uso da técnica de cisalhamento planar simples

    OpenAIRE

    Wellington Lopes

    2009-01-01

    Este trabalho analisou os efeitos de mudanças sucessivas na trajetória de deformação no encruamento de dois tipos de aços inoxidáveis: o aço inoxidável austenítico AISI 304 (tipo 304N) e o aço inoxidável ferrítico AISI 409, ambos, na forma de chapas. Para o estudo do encruamento desses aços inoxidáveis foram usadas técnicas de ensaios mecânicos de cisalhamento planar simples e de tração uniaxial para aplicação dos esforços de cisalhamento e de tração, respectivamente, além do uso de um lamina...

  12. STUDIO DELLA CORROSIONE INTERSTIZIALE DEGLI ACCIAI INOSSIDABILI AISI 316L, AISI 304L E AISI 444

    OpenAIRE

    Bellezze, T.; Quaranta, A.; Roventi, G.; Fratesi, R.

    2008-01-01

    Nel presente lavoro è stata studiata la suscettibilità alla corrosione interstiziale degli acciai inossidabili austenitici AISI 316L e 304L e dell’acciaio inossidabile ferritico AISI 444. Sono stati effettuati test di immersione a 40 °C in soluzione di FeCl3 1% in peso, utilizzando formatori artificiali d’interstizio (“crevice former”); sono stati poi eseguiti test elettrochimici di polarizzazione anodica a 80 °C in una soluzione contenente 1000 mg dm-3 di Cl-, sia in presenza che in assenza ...

  13. Surface fatigue and failure characteristics of hot-forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    Science.gov (United States)

    Townsend, Dennis P.

    1987-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground AISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  14. High temperature oxidation behavior of AISI 304 and AISI 430 stainless steels

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    Carlos Eduardo Reis de Carvalho

    2006-12-01

    Full Text Available The oxidation behavior of AISI 304 and AISI 430 stainless steels was investigated from 1100 °C up to 1200 °C. Mössbauer spectroscopy and x ray diffraction were used to access the phase composition of the formed scales. The main crystalline phases found in the oxidized materials at temperatures above 1100 °C were hematite and magnetite for AISI 430 steel, and hematite and a spinel-like phase for AISI 304 steel. Hematite was found to be the dominant oxide at lower temperatures, whereas magnetite preferentially forms at higher temperatures. The activation energy for oxidation is smaller for AISI 430 steel in relation to AISI 304 steel in the range of studied temperatures, and therefore the AISI 430 steel is less resistant towards oxidation at high temperatures.

  15. Surface fatigue and failure characteristics of hot forged powder metal AISI 4620, AISI 4640, and machined AISI 4340 steel spur gears

    Science.gov (United States)

    Townsend, D. P.

    1986-01-01

    Spur gear surface fatigue endurance tests were conducted to investigate hot forged powder metal AISI 4620 and 4640 steel for use as a gear material, to determine endurance characteristics and to compare the results with machined AISI 4340 and 9310 steel gear materials. The as-forged and unground SISI 4620 gear exhibited a 10 percent fatigue life that was approximately one-fourth of that for AISI 9310 and less than one-half that for the AISI 4340 gears. The forged and finish ground AISI 4620 gears exhibited a 10 percent life, approximately 70 percent that of AISI 9310 and slightly better than that of AISI 4340. The AISI 4640 hot forged gears had less fracture toughness and slightly less fatigue life than the AISI 4620 test gears.

  16. High temperature oxidation behavior of AISI 304 and AISI 430 stainless steels

    OpenAIRE

    Carvalho,Carlos Eduardo Reis de; Costa,Geraldo Magela da; Cota,André Barros; Rossi,Edson Hugo

    2006-01-01

    The oxidation behavior of AISI 304 and AISI 430 stainless steels was investigated from 1100 °C up to 1200 °C. Mössbauer spectroscopy and x ray diffraction were used to access the phase composition of the formed scales. The main crystalline phases found in the oxidized materials at temperatures above 1100 °C were hematite and magnetite for AISI 430 steel, and hematite and a spinel-like phase for AISI 304 steel. Hematite was found to be the dominant oxide at lower temperatures, wher...

  17. Comparing the Formability of AISI 304 and AISI 202 Stainless Steels

    Science.gov (United States)

    du Toit, M.; Steyn, H. G.

    2012-07-01

    The formability of AISI 202 austenitic stainless steel was compared with that of type AISI 304 stainless steel. Type 202 is a low-nickel austenitic stainless steel alloyed with manganese and nitrogen. In this study, the formability of the two grades was examined using Erichsen cupping tests and room temperature uniaxial tensile tests performed at various angles to the rolling direction. AISI 202 appears to work-harden at a slightly higher rate than AISI 304, even though the austenite in type 202 is more stable than that in 304 with respect to the formation of deformation-induced α' martensite. Although both grades are predicted to be susceptible to earing during deep drawing, AISI 202 displays a higher work-hardening exponent, higher average normal anisotropy, and a higher limiting drawing ratio than AISI 304. Similar cup heights were measured during Erichsen cupping tests, confirming that the two grades have very similar deep drawing properties. The results of this investigation therefore suggest that AISI 202 is a suitable alternative for AISI 304 in applications requiring good deep drawing properties.

  18. Comparative study of high temperature oxidation behaviour in AISI 304 and AISI 439 stainless steels

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    Antônio Claret Soares Sabioni

    2003-06-01

    Full Text Available This work deals with a comparison of high temperature oxidation behaviour in AISI 304 austenitic and AISI 439 ferritic stainless steels. The oxidation experiments were performed between 850 and 950 °C, in oxygen and Ar (100 vpm H2. In most cases, it was formed a Cr2O3 protective scale, whose growth kinetics follows a parabolic law. The exception was for the the AISI 304 steel, at 950 °C, in oxygen atmosphere, which forms an iron oxide external layer. The oxidation resistance of the AISI 439 does not depend on the atmosphere. The AISI 304 has the same oxidation resistance in both atmospheres, at 850 °C, but at higher temperatures, its oxidation rate strongly increases in oxygen atmosphere. Concerning the performance of these steels under oxidation, our results show that the AISI 439 steel has higher oxidation resistance in oxidizing atmosphere, above 850 °C, while, in low pO2 atmosphere, the AISI 304 steel has higher oxidation resistance than the AISI 439, in all the temperature range investigated.

  19. Comparative study of high temperature oxidation behaviour in AISI 304 and AISI 439 stainless steels

    OpenAIRE

    Sabioni,Antônio Claret Soares; Huntz,Anne-Marie; Luz,Elizete Conceição da; Mantel,Marc; Haut,Christian

    2003-01-01

    This work deals with a comparison of high temperature oxidation behaviour in AISI 304 austenitic and AISI 439 ferritic stainless steels. The oxidation experiments were performed between 850 and 950 °C, in oxygen and Ar (100 vpm H2). In most cases, it was formed a Cr2O3 protective scale, whose growth kinetics follows a parabolic law. The exception was for the the AISI 304 steel, at 950 °C, in oxygen atmosphere, which forms an iron oxide external layer. The oxidation resistance of the A...

  20. Comportamiento termomecánico de aceros AISI 304

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    El Wahabi, M.

    2001-04-01

    Full Text Available The hot deformation behaviour of three AISI 304 (H, L and HP austenitic stainless steel with different carbon contents has been studied. An analysis of the parameters describing their hot flow curves was carried out. No heavy effect of the carbon content was found on most of the latter parameters. However, the work hardening and dynamic recovery behaviour showed clear differences depending on the given alloy, especially at high temperatures and low strain rates where the high carbon steel displayed larger work hardening and dynamic recovery rates than the other steels. The high purity steel (interstitial free displayed the lower stress levels as its hardening rate was slower than in the other two steels.

    Se llevó a cabo un estudio del comportamiento termomecánico de tres aceros inoxidables austeníticos tipo AISI 304 (H, L y HP con diferentes contenido en carbono, mediante la determinación de los parámetros que describen las etapas de deformación en caliente. No se notó un fuerte efecto del carbono en dichos parámetros, excepto en los que describen los procesos de endurecimiento y de restauración dinámica que muestran una cierta dependencia con la composición química, especialmente a bajos valores del parámetro de Zener-Hollomon, donde el acero de alto carbono (304H endurece y restaura más rápido que el de bajo carbono (304L, alcanzándose valores de tensión de pico similares en ambos casos. El material de alta pureza (libre de intersticiales toma valores de tensión de pico más bajos que los otros aceros, endureciendo más lentamente y con una velocidad de restauración similar a la del 304H.

  1. Mechanical properties of martensitic alloy AISI 422

    International Nuclear Information System (INIS)

    Huang, F.H.; Hu, W.L.; Hamilton, M.L.

    1992-09-01

    HT9 is a martensitic stainless steel that has been considered for structural applications in liquid metal reactors (LMRs) as well as in fusion reactors. AISI 422 is a commercially available martensitic stainless steel that closely resembles HT9, and was studied briefly under the auspices of the US LMR program. Previously unpublished tensile, fracture toughness and charpy impact data on AISI 422 were reexamined for potential insights into the consequences of the compositional differences between the two alloys, particularly with respect to current questions concerning the origin of the radiation-induced embrittlement observed in HT9. 8 refs, 8 figs

  2. Investigação do desgaste de ferramentas de PCBN e metal duro no fresamento de topo de aços endurecidos

    OpenAIRE

    Aldo Braghini Junior

    1998-01-01

    O fresamento de topo de aços ferramenta, no estado endurecido, pode ser uma alternativa para a fabricação de moldes e matrizes, com alta taxa de remoção. Este trabalho estuda os tipos e mecanismos de desgaste presentes nesta operação de usinagem, bem como o comportamento da emissão acústica. São realizados experimentos com ferramentas de PCBN e Metal Duro usinando os aços H13 (49-51 HRc), VMO (54-57 HRc) e VC131 (57-59 HRc). O desgaste das ferramentas de PCBN é significativamente menor que o ...

  3. Generalidade da Aprendizagem em Situações de Uso de Ferramentas por um Macaco-Prego, Cebus Apella

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    Paulo Elias Gotardelo Audebert Delage

    Full Text Available Estudos sobre o uso de ferramentas em primatas do gênero Cebus divergem sobre se esta habilidade seria do tipo associativa ou "por compreensão". Estudos mostraram que o uso de ferramentas aprendido em um contexto pode se transferir para outros contextos, indicando que algo além da aprendizagem "estímulo-e-resposta" estaria envolvido. Neste estudo um macaco-prego foi exposto a duas situações problema, uma em que o animal precisava encaixar duas varetas para alcançar um pedaço de alimento e outra em que o animal precisava encaixar outro modelo de varetas para golpear um equipamento. Os resultados mostraram que a resolução do primeiro problema facilitou a resolução do segundo, indicando que em novas situações respostas anteriormente bem sucedidas se tornam mais prováveis.

  4. New tools for steel catenary risers inspection; Novas ferramentas para inspecao de risers tipo SCR

    Energy Technology Data Exchange (ETDEWEB)

    Camerini, Claudio Soligo; Marinho, Carla Alves; Raphael, Fabiana N.; Maia, Carlos [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Freitas, Miguel [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil); Lopes, Ricardo Tadeu; Rocha, Henrique [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    2005-07-01

    The Research Center of PETROBRAS and two of the Federal Brazilian Universities, PUC-Rio and UFRJ, have been developing two new projects in order to inspect risers of petroleum production. The first tool is an instrumented pig for profiling internal corrosion, having flexibility under diameter variations and independence related to thickness wall pipeline. The second one is a gammagraphy system remotely operated by ROVs, to be employed in alveoli corrosion and fatigue cracks detection in underwater pipelines. This work shows the trajectory of these two tools, describing laboratory and field tests and the future activities. (author)

  5. Links Patrocinados como Ferramenta para Captação de Clientes na Hotelaria

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    Tiago Savi Mondo

    2011-05-01

    Full Text Available Os links patrocinados desempenham a função de aumentar a velocidade e a qualidade das respostas de buscas realizadas em sites de pesquisa na internet. Nesse contexto, os meios de hospedagem, se enquadram como integrantes do processo, já que muitas das buscas de informações sobre destinos e empreendimentos turísticos são feitas por meio da internet. Assim, o objetivo central desse artigo é identificar a ocorrência de links patrocinados de meios de hospedagem de Santa Catarina nos buscadores Google, Terra e Uol. Esta pesquisa caracteriza-se por ser exploratória,descritiva, de caráter quantitativo e do tipo documental. A amostra foi composta por 2713 links patrocinados, provenientes de buscas realizadas com os termos “hotéis” e “pousadas” e ainda os termos geográficos “Florianópolis”, “Joinville”, “Blumenau”, “Bombinhas” e “ Balneário Camboriú”. As buscas foram realizadas do dia 10 ao dia 15 de Março de 2010, resultando em 450 buscas. Os principais resultados demonstram que os meios de hospedagem poderiam utilizar melhor a ferramenta e que boa parte da sua utilização de links patrocinados é feita por classificados, conglomerados de sites hoteleiros e agências de viagem online. Além disso, levantou-se que a ferramenta é mais utilizada nos fins de semana e durante os períodos vespertino e noturno. Conclui-se que a ferramenta é indispensável atualmente para o segmento turístico, servindo como auxilio à distribuição dos serviços do hotel e, consequentemente, ao aumento da ocupação hoteleira. DOI: 10.5585/remark.v10i1.2185

  6. State on AISI 304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    A. Fattah-alhosseini

    2011-01-01

    Full Text Available The passivity and protective nature of the passive films are essentially related to ionic and electronic transport processes, which are controlled by the optical and electronic properties of passive films. In this study, the electrochemical behavior of passive films anodically formed on AISI 304 stainless steel in sulfuric acid solution has been examined using electrochemical impedance spectroscopy. AISI 304 in sulphuric acid solution is characterized by high interfacial impedance, thereby illustrating its high corrosion resistance. Results showed that the interfacial impedance and the polarization resistance (pol initially increase with applied potential, within the low potential passive. However, at a sufficiently high potential passive (>0.4 V, the interfacial impedance and the polarization resistance decrease with increasing potential. An electrical equivalent circuit based on the impedance analysis, which describes the behavior of the passive film on stainless steel more satisfactorily than the proposed models, is presented.

  7. Characterization of AISI 4140 borided steels

    Science.gov (United States)

    Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martínez-Trinidad, J.

    2010-02-01

    The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form KC( π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

  8. Comparando anotações linguísticas na Gramateca: filosofia, ferramentas e exemplos

    Directory of Open Access Journals (Sweden)

    Diana Santos

    2015-12-01

    Full Text Available Neste artigo apresentamos a filosofia geral da Gramateca – um ambiente para fazera gramática da língua portuguesa baseada em corpos – e alguns estudos no seu âmbito, nomeadamente o estudo (1 dos conetores condicionais, (2 das palavras referentes ao corpo humano, e (3 das emoções na língua. A ênfase é na metodologia, e apresentamos detalhadamente o sistema Rêve para rever e partilhar anotações linguísticas. Ao descrever os vários estudos, indicamos também as metamorfoses e melhorias por que essa ferramenta passou, assim como o tipo de perguntas e de resultados que já conseguimos obter em áreas muito diversas.

  9. Análise de Projetos Mecânico utilizando ferramenta de simulação CAE

    Directory of Open Access Journals (Sweden)

    Washington Bueno de Oliveira

    2016-06-01

    Full Text Available Este estudo visa analisar a frequente quebra do eixo de uma ferramenta utilizada para operações mecânicas de fresagem, para o aumento de sua vida útil e confiabilidade. Será utilizado um software para simulação de CAE, para análise das propriedades mecânicas do material da peça, seus pontos frágeis e os esforços aplicados. Para a viabilidade do estudo houve alterações na geometria da ferramenta e mudança do material utilizado, buscando melhores resultados nas simulações. Serão utilizados quatro materiais para as simulações aço SAE 4340, alumínio 7075, aço SAE 1045 e aço ferramenta tipo A2. A primeira simulação detectou um ponto de fragilidade na estrutura da peça, após a realização das alterações na estrutura e do material, os resultados obtidos apresentaram uma melhora de aproximadamente de 18% na deformação plástica no local de cisalhamento.[1] Computer Aided Engineerring (CAE Engenharia assistida por computador é um Software para simulação.[2] Aço SAE (Society of Automotive Engineers – EUA: classificação normativa dos aços carbono.

  10. O podcast como ferramenta de educação inclusiva para deficientes visuais e auditivos

    Directory of Open Access Journals (Sweden)

    Eugênio Paccelli Freire

    2011-10-01

    Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}  Neste artigo buscamos apresentar a tecnologia podcast para, em seguida, sustentar sua relevância como ferramenta educativa inclusiva por meio da exposição de algumas de suas atuais aplicações nesse campo. Observamos a tecnologia por meio de um olhar freireano, para o qual mais importante que as possibilidades técnicas são as efetividades educativas. Considerando a natureza da atual utilização do podcast fora do contexto escolar, destacamos algumas de suas características específicas, sintonizadas com a cooperação de Célestin Freinet, para sustentar o caráter de adequação do uso dessa ferramenta às demandas educativas típicas dos portadores de deficiências visuais e auditivas. Para esses últimos, uma formulação de podcast atenta a um critério educativo inclusivo permite a ampliação dessa ferramenta para o acesso a conteúdos de oralidade mesmo para quem não possui qualquer tipo de audição. Ao final, apontamos a necessidade, por parte da escola, da apropriação do podcast como ferramenta de educação inclusiva.Palavras-chave: Podcast para surdos. Podcast e educação. Podcast e inclusão. 

  11. Microstructural characteristics on bead on plate welding of AISI 904 ...

    African Journals Online (AJOL)

    In the present work, bead-on -plate welds were carried out on AISI 904 L super austenitic stainless steel sheets using Gas Metal Arc Welding (GMAW) process. In this present investigation AISI 904 L solid wire having 1.2 mm diameter was used as an electrode with direct current electrode positive polarity. Argon was ...

  12. Experimental study of mechanical properties of friction welded AISI ...

    Indian Academy of Sciences (India)

    Friction welding is widely used as a mass production method in various industries. In the present study, an experimental set-up was designed in order to achieve friction welding of plastically deformed AISI 1021 steels. In this study, low alloy steel (AISI 1021) was welded under different welding parameters and afterwards ...

  13. Marine Shaft Steels (AISI 4140 and AISI 5120 Predicted Fracture Toughness by FE Simulation

    Directory of Open Access Journals (Sweden)

    Goran VUKELIC

    2017-02-01

    Full Text Available Optimal selection of material can be considered as one of the most critical steps in engineering design process. That is especially emphasized when dealing with constructions that operate in marine environment; high stresses and harsh operating conditions assert the importance of proper material characterization before its selection. This paper presents comparison of two types of steel usually used in marine shaft manufacturing, chromium-molybdenum steel AISI 4140 and chromium low-alloy steel AISI 5120. Comparison was made using numerically determined J-integral, an important fracture mechanics parameter. J-integral values are determined numerically using finite element (FE stress analysis results of compact tensile (CT and single-edge notched bend (SENB type specimens usually used in standardized J-integral experimental procedures. Obtained J values are plotted versus specimen crack growth values (Δa for different specimen geometries (a/W. Higher resulting values of J-integral for AISI 5120 than AISI 4140 can be noticed. Also, higher a/W ratios correspond to lower J-integral values of materials and vice versa. In addition to that, J-integral values obtained by using FE model of CT specimen give somewhat conservative results when compared with ones obtained by FE model of SENB specimen. Although this procedure differs from experimental analysis, results can be used a suitable fracture parameter value in fracture toughness assessment.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.13823

  14. AISI: A New Disease Severity Assessment Tool for Hidradenitis Suppurativa.

    Science.gov (United States)

    Chiricozzi, Andrea; Faleri, Sara; Franceschini, Chiara; Caro, Raffaele Dante Caposiena; Chimenti, Sergio; Bianchi, Luca

    2015-10-01

    Hidradenitis suppurativa (HS) is a chronic, disabling, skin disorder. Because of renewed scientific interest in HS, different aspects of the condition, such as disease severity assessment, are being investigated and better defined. The aim of this study is to provide a novel tool for the assessment of disease severity. An HS-tailored, composite, dynamic score, named the Acne Inversa Severity Index (AISI) was designed to include a physician-rated assessment that considers the type of lesions occurring and the affected body sites. Additionally, a 0-10 visual analog scale (VAS), named Illness-VAS, was created to assess a patient's pain, discomfort, and disability due to HS. The authors compared AISI with other validated measurements, namely the Hurley staging classification, modified Sartorius score, and the Dermatology Life Quality Index (DLQI). The AISI was tested in 46 patients with HS, demonstrating a significant correlation with Hurley staging (r: 0.70856; P = 0.0021), modified Sartorius score (r: 0.9730; P = less than 0.00001), and DLQI (r: 0.8257; P = 0.0221). According to AISI cut-offs, HS may be defined as mild (AISI less than 10), moderate (AISI 10 > 18), and severe (AISI > 18). Additionally, comparing the 2 dynamic scores, AISI and Sartorius, AISI proved significantly faster than the Sartorius score (46.44 ± 19.24 seconds vs 83.2 ± 19.04 seconds; P =1.31 x 10-6). Being simple, fast, dynamic, and accurate, the AISI could represent the ideal measurement for HS severity in both real-life and clinical trial settings.

  15. Hot hardness characteristics of ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C, and Super Nitralloy

    Science.gov (United States)

    Chevalier, J. L.; Dietrich, M. W.; Zaretsky, E. V.

    1973-01-01

    Short-term hot hardness studies were performed with ausformed AISI M-50, Matrix 2, WD-65, modified AISI 440-C (14-4-1) and case hardened Super Nitralloy. Hardness levels of each material were measured at elevated temperatures in an electric furnace with a low oxygen environment. Test temperatures ranged from 294 to 877 K. The hot hardness characteristics of the ausformed AISI-M-50, Matrix 2 WD-65, and modified AISI 440-C were the same as those determined for high-speed tool steels. Hot hardness for these steels can be predicted within one point Rockwell C. The hot hardness characteristics of both the case and core of Super Nitralloy were superior to AISI 52100 but inferior to the high-speed tool steels. The short-term Rockwell C hardness at temperature for the Super Nitralloy material between 294 and 769 K can be predicted within one point Rockwell C hardness.

  16. Microstructure and mechanical properties of friction welded AISI 1040/AISI 304L steels before and after electrochemical corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Sarsilmaz, Furkan [Firat Univ., Elazig (Turkey). Dept. of Mechatronics Engineering; Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi [Firat Univ., Elazig (Turkey)

    2018-03-01

    The aim of the present study is to investigate the effect of welding parameters both on the electrochemical corrosion behavior and tensile strength of pre- and post-electrochemical corrosion of friction welded dissimilar steels. The microstructural changes of AISI 1040/AISI 304L friction welded couples and also parent materials were analyzed by using scanning electron microscopy. The electrochemical behaviors of AISI1040/AISI304L joints were comparatively investigated by potentiodynamic polarization curve test and by electrochemical impedance spectra. Moreover, tensile strength experiments were carried out determining the behavior of friction welded joints of pre- and post-electrochemical corrosion and results indicated that the maximum tensile test value of the dissimilar welded pre-electrochemical corrosion was higher than those of post-electrochemical corrosion and was also very close to AISI 1040 parent material value.

  17. Avaliação da tecnologia Wiki: ferramenta para acesso à informação sobre ventilação mecânica em Terapia Intensiva

    Directory of Open Access Journals (Sweden)

    Daniela Couto Carvalho Barra

    2012-06-01

    Full Text Available O desenvolvimento e a aplicabilidade da informática influenciam todas as áreas do conhecimento, possibilitando novas formas de aprendizagem. O Wiki é uma ferramenta da informação e comunicação disponibilizada pela tecnologia da WEB 2.0 que pode ser explorada e utilizada no ensino, aprendizagem, cuidado e na pesquisa na área da Enfermagem. Assim, este estudo, de natureza quantitativa, do tipo descritivo e exploratório, objetivou avaliar com os acadêmicos de enfermagem os critérios de Ergonomia e Usabilidade da ferramenta Wiki como tecnologia de acesso à informação sobre os cuidados de enfermagem em ventilação mecânica na Unidade de Terapia Intensiva. A ferramenta foi avaliada como "excelente" quanto aos critérios de Ergonomia e Usabilidade, sendo considerada uma nova tecnologia emergente apropriada para o uso educacional.

  18. Mechanical and Microstructural Properties of Friction Welded AISI 304 Stainless Steel to AISI 1060 Steel AISI 1060

    Directory of Open Access Journals (Sweden)

    Ates H.

    2014-10-01

    Full Text Available Rotary Friction welding is one of the most popular methods of joining similar and dissimilar materials. It is widely used with metals and thermoplastics in a wide variety of aviation, transport and aerospace industrial component designs. This study investigates the influence of friction and upsetting pressures on the hardness, tensile properties and microstructure of the welds. The experimental results showed that as the friction and upsetting pressures increased, the hardness and tensile strength values increased, as well. The tensile fracture of welded joint occurred in the AISI 1060 side. The friction processed joints were evaluated for their integrity and quality aspects by optical and scanning electron microscopy. For the perfect interfacial bonding, sufficient upsetting and friction pressures are necessary to reach the optimal temperature and severe plastic deformation to bring these materials within the attraction range.

  19. A Comparati ve Study of Mechanical and Tribological Properties of AISI-304 and AISI-316 Submitted to Glow Discharge Nitriding

    OpenAIRE

    Nascimento, Fabiana Cristina; Foerster, Carlos Eugênio; Silva, Silvio Luiz Rutz da; Lepienski, Carlos Mauricio; Siqueira, Carlos José de Mesquita; Alves Jr, Clodomiro

    2009-01-01

    Mechanical and tribological properties of AISI 304 and AISI 316 stainless steels submitted to glow discharge ion nitriding are reported. The atmosphere was 20:80 - N2:H2 with substrate temperatures ranging from 300 to 500 °C. Treatment at 300 °C produced expanded austenite (γN) in both steels. Increasing the temperature, the phases γ′-Fe4N and ε- Fe2+xN were present and the latter is the major phase for AISI 304. At 500 °C, the CrN phase was also identified in both steels. Hardnesses of about...

  20. On dissimilar metal welding of AISI4140 and AISI410 by GTAW

    Science.gov (United States)

    Velu, M.; Dixit, Shantanu; Choure, Shubham

    2017-11-01

    This paper presents the results of metallurgical and mechanical examinations of Gas Tungsten Arc Welding of dissimilar steels AISI4140 and AISI410. Two different filler materials viz., ERNiCr3 and SS410 were used. The various properties of the weldments made using the fillers were compared to select the most appropriate one to get the sound joint. The ultimate tensile and yield strengths of the weldments of SS410 were greater than those of ERNiCr3. The fracture occurred at the weld in weldments made with ERNiCr3, whereas, in the base metal of AISI410 for weldments made with SS410. Microstructure of fusion zone of ERNiCr3 was fully austenitic. Microhardness values in the weld of SS410 were higher and fluctuating compared to those in the weld of ERNiCr3. From this research work, it shall be concluded that SS410 is the best filler material to weld these base materials.

  1. ESTUDO DE CAD LIVRE PARA IMPLEMENTAÇÃO DE FERRAMENTA DE PROJETO

    Directory of Open Access Journals (Sweden)

    Sergio Adriano Bizello

    2011-05-01

    Full Text Available O setor de projetos de Arquitetura Engenharia e Construção (AEC têm sua principal ferramenta de desenvolvimento sistemas de projeto auxiliado por computador (sistemas CAD, baseado em software proprietários, com custos elevados e necessários em várias estações de trabalho. Entretanto, atualmente os usuários de sistemas CAD no Brasil e no mundo carecem de um programa do tipo software livre ou open source que possa ser equiparado ao software proprietário padrão e líder de mercado, o AutoCAD®, da Autodesk, viabilizando redução de custos com Tecnologia da Informaçã. O estudo apresentado procura um sistema CAD alternativo que possa abrigar a metodologia de projeto automatizada. Esta pesquisa caracteriza-se como descritiva de sistemas CAD livre sendo desenvolvida nas seguintes etapas: levantamento, categorização, triagem, definição do sistema CAD de controle, definição de elementos e critérios de avaliação, aplicação da avaliação e análise. Os sistemas avaliados são apresentados e comentados. É possível dizer que ainda não há um sistema CAD livre que possa abrigar o desenvolvimento de uma ferramenta de projeto com características conjuntas de recursos em 2D, 3D e extensibilidade. Como contribuição apresenta-se um roteiro para escolha de um sistema CAD alternativo ao software proprietário para o desenvolvimento de projeto de AEC. Palavras-chave: CAD, software livre, open source, modelagem, projeto arquitetônico.

  2. A ANÁLISE DA UTILIZAÇÃO DO ORÇAMENTO EMPRESARIAL COMO FERRAMENTA DE GESTÃO INDUSTRIAL

    Directory of Open Access Journals (Sweden)

    Eduardo Lenz

    2016-12-01

    Full Text Available O orçamento empresarial é uma ferramenta importante no processo de gestão das empresas, diante da necessidade de planejar suas receitas, seus gastos, seus investimentos e suas despesas, possibilitando assim projetar seus fluxos de caixa e antecipar-se nas tomadas de decisão. Este estudo tem como objetivo analisar a utilização do orçamento empresarial como ferramenta de gestão, o tipo de orçamento mais utilizado, as principais técnicas de elaboração e a visão dos gestores. Quanto à metodologia, a pesquisa caracteriza-se como descritiva, pelo fato de buscar identificar quais situações, eventos, atitudes ou opiniões estão presentes em uma determinada população, e utiliza-se da técnica de pesquisa survey aplicada em 18 indústrias das cidades de Arroio do Meio, Estrela e Lajeado, no Estado do Rio Grande do Sul, por intermédio de um questionário fechado. A pesquisa revela que o orçamento empresarial é considerado pelas empresas uma ferramenta essencial para auxiliar na tomada de decisões e possibilita o estabelecimento de metas e responsabilidades a serem cumpridas. A maior parte das organizações o utiliza como ferramenta de controle de gastos, optando pelo tipo de orçamento flexível, e a grande maioria delas apresenta falhas na etapa do planejamento. Palavras-chave: Orçamento. Planejamento. Gestão.

  3. Swelling behavior of manganese-bearing AISI 216 steel

    International Nuclear Information System (INIS)

    Gelles, D.S.; Garner, F.A.

    1984-01-01

    The inclusion of 8.5 wt % manganese in AISI 216 does not appear to alter the swelling behavior from that found to be typical of austenitic alloys with comparable levels of other austentite-stabilizing elements. The swelling in AISI 216 in EBR-II is quite insensitive to irradiation temperature in the range 400-650 0 C. Microscopy reveals that this may arise from the low level of precipitation that occurs in the alloy

  4. Swelling behavior of titanium-modified AISI 316 alloys

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.; Puigh, R.J.

    1984-01-01

    It appears that titanium additions to stainless steels covering a wide compositional range around the specifications of AISI 316 result only in an increased delay period before neutron-induced void swelling proceeds. Once swelling is initiated the post transient behavior of both annealed and cold-worked titanium-modified steels is quite consistent with that of AISI 316, approaching a relatively temperature-independent swelling rate of approx. 1% per dpa

  5. Thermomechanical behaviour of AISI 304 steels

    International Nuclear Information System (INIS)

    El Wahabi, M.; Garcia, V. G.; Cabrera, J. M.; Prado, J. M.

    2001-01-01

    The hot deformation behaviour of three AISI 304 (H, L and HP) austenitic stainless steel with different carbon contents has been studied. An analysis of the parameters describing their hot flow curves was carried out. No heavy effect of the carbon content was found on most of the latter parameters. However, the work hardening and dynamic recovery behaviour showed clear differences depending on the given alloy, especially at high temperatures and low strain rates where the high carbon steel displayed larger work hardening and dynamic recovery rates than the other steels. The high purity steel (interstitial free) displayed the lower stress levels as its hardening rate was slower than in the other two steels. (Author) 16 refs

  6. Amostragem de terra para fins de fertilidade em função da ferramenta de amostragem

    Directory of Open Access Journals (Sweden)

    Ciro Antonio Rosolem

    2010-06-01

    Full Text Available Embora existam indicações de que a pá de corte proporcione melhor qualidade de amostragem de terra para fins de análise de fertilidade, seu manuseio demanda muito tempo. No presente trabalho foram comparados os resultados da análise química de terra proveniente de 15 áreas distintas, cujas amostras foram obtidas com cinco tipos de trado e com pá de corte. Também foram comparados o tempo demandado para a realização do trabalho e o volume de terra coletado com as diferentes ferramentas, em dois solos de texturas distintas. O tempo médio de amostragem foi estimado, avaliando-se o tempo gasto por seis pessoas para tomar dez amostras. Para o estudo de qualidade de resultados foram amostradas 15 áreas, com solos, manejos e níveis de fertilidade distintos, de modo a se obter grande variação entre os valores das características avaliadas. As amostragens constaram da estratificação por profundidades e amostras de 0 a 20 cm de profundidade no teste de tempo. A amostragem com a pá de corte demora de 1,3 a 2,3 vezes mais do que com os trados. Para os valores de pH, matéria orgânica, acidez do solo, Al trocável e P disponível, os resultados foram equivalentes para todas as ferramentas empregadas. Entretanto, para as bases do solo (Ca, Mg e K, as ferramentas empregadas resultaram, na maioria das vezes, em resultados diferentes dos obtidos pela pá de corte.

  7. A Controladoria como ferramenta de gestão no custeio de uma empresa de construção civil

    Directory of Open Access Journals (Sweden)

    Osmildo Sobral Santos

    2012-06-01

    de então, sistemas de gestão integrados de forma que a expressão controladoria passasse a envolver e apresentar-se como elo que agrega e confronta os aspectos positivos e negativos das organizações, convergindo-as para a busca de uma maior produtividade. As empresas que participaram do questionário foram analisadas com o objetivo de identificar quais os tipos ferramentas são utilizadas por elas para fazer o controle interno.

  8. Aplicação de uma ferramenta objetiva para previsão de tempo severo em ambiente operacional

    Directory of Open Access Journals (Sweden)

    Henri Rossi Pinheiro

    2014-06-01

    Full Text Available Este estudo discute a viabilidade de se empregar uma ferramenta objetiva para previsão de tempo severo em ambiente operacional, com o propósito principal de auxiliar a rotina do meteorologista previsor. O método baseia-se na combinação de parâmetros convectivos amplamente conhecidos na literatura, como os índices de instabilidade K, Total Totals e SWEAT. Para ajudar a identificação rápida das áreas com alto potencial para gerar tempestades foram produzidas cartas de visualização, definidas a partir de critérios específicos para convecção severa. Uma alternativa para detectar áreas favoráveis à ocorrência de granizo também foi apresentada, essencialmente para aqueles eventos originados pela ação de mecanismos dinâmicos. Os limiares mostraram-se importantes para caracterização do tipo de precipitação, permitindo através deles estabelecer diferentes padrões convectivos. Os resultados mostraram que a ferramenta proposta pode representar uma alternativa eficiente para a previsão de tempo na América do Sul, permitindo em alguns casos suprir limitações corriqueiras dos modelos numéricos, principalmente no que se refere à variável precipitação.

  9. Sistema diagnóstico: uma ferramenta para a construção de sistemas especialistas

    OpenAIRE

    Sandra Aparecida Sandri

    1985-01-01

    Este trabalho apresenta o sistema DIAGNÓSTICO, uma ferramenta para a construção de sistemas especialistas. A representação de conhecimento adotada e a de regra de decisão do tipo SE premissa ENTÃO (x) conclusão, onde x atesta a crença de que a conclusão é verdadeira se a premissa o for. O sistema consiste em quatro módulos: INICIALIZAÇÃO, AQUISIÇÃO,CONSULTA e EXPLANAÇÃO. O módulo de INICIALIZAÇÃO inicia lisa os arquivos do sistema e adquire palavras-chave. O módulo de AQUISIÇÃO interage com o...

  10. O telejornalismo como ferramenta para a comunicação pública

    Directory of Open Access Journals (Sweden)

    Fernanda Ribeiro

    2012-12-01

    Full Text Available Este artigo discute a função social do jornalismo, a abrangência e credibilidade do telejornalismo e a possibilidade do uso deste gênero televisivo enquanto ferramenta para a comunicação pública. Para isso faz-se necessário relembrar detalhes da implantação e desenvolvimento do telejornalismo no Brasil, conceituar o que é comunicação pública e cidadania, e também uma análise dos canais que o indivíduo utiliza para se informar, das características da comunicação de massa e, principalmente, da televisão e da necessidade da existência da comunicação pública para exercício da cidadania. Este estudo apresenta, ainda, uma análise de conteúdo do telejornal Bom Dia Goiás da TV Anhanguera – afiliada da Rede Globo em Goiás, revelando a abordagem do programa e o tipo de informação repassada à população sobre um grave problema social, a violência contra a mulher.

  11. O TELEJORNALISMO COMO FERRAMENTA PARA A COMUNICAÇÃO PÚBLICA

    Directory of Open Access Journals (Sweden)

    Tiago Mainieri

    2012-12-01

    Full Text Available Este artigo discute a função social do jornalismo, a abrangência e credibilidade do telejornalismo e a possibilidade do uso deste gênero televisivo enquanto ferramenta para a comunicação pública. Para isso faz-se necessário relembrar detalhes da implantação e desenvolvimento do telejornalismo no Brasil, conceituar o que é comunicação pública e cidadania, e também uma análise dos canais que o indivíduo utiliza para se informar, das características da comunicação de massa e, principalmente, da televisão e da necessidade da existência da comunicação pública para exercício da cidadania. Este estudo apresenta, ainda, uma análise de conteúdo do telejornal Bom Dia Goiás da TV Anhanguera – afiliada da Rede Globo em Goiás, revelando a abordagem do programa e o tipo de informação repassada à população sobre um grave problema social, a violência contra a mulher.

  12. Triangulação: uma ferramenta de validade e confiabilidade

    Directory of Open Access Journals (Sweden)

    Ademor Fábio Basso Júnior

    2016-05-01

    Full Text Available A subjetividade de estudos em ciências humanas e sociais aumenta as discussões sobre a aplicação de métodos qualitativos e/ou quantitativos e associa ao aumento da necessidade de validar e garantir a credibilidade de pesquisas qualitativas. Uma das ferramentas utilizadas para amenizar possíveis questionamentos referentes à credibilidade é a triangulação, que consiste na utilização diversificada de fontes de dados, tipos de dados e de métodos. O objetivo do presente artigo foi analisar o emprego da triangulação nos métodos de coleta de dados nos artigos publicados na RAE Eletrônica, de janeiro de 2004 a dezembro de 2010. Verificou-se que 63,37% dos artigos publicados não utilizaram a triangulação dos métodos de coleta de dados e 33,63% dos artigos utilizaram a triangulação, ou seja, foram utilizados 2 ou 3 métodos distintos para a obtenção dos dados utilizados na pesquisa. O que demonstra uma oportunidade existente para elevar a credibilidade das pesquisas qualitativas.

  13. Pulsed Nd:YAG laser welding of AISI 304 to AISI 420 stainless steels

    Science.gov (United States)

    Berretta, José Roberto; de Rossi, Wagner; David Martins das Neves, Maurício; Alves de Almeida, Ivan; Dias Vieira Junior, Nilson

    2007-09-01

    The technique to weld AISI 304 stainless steel to AISI 420 stainless steel with a pulsed Nd:YAG laser has been investigated. The main objective of this study was to determine the influence of the laser beam position, with respect to the joint, on weld characteristics. Specimens were welded with the laser beam incident on the joint and moved 0.1 and 0.2 mm on either side of the joint. The joints were examined in an optical microscope for cracks, pores and to determine the weld geometry. The microstructure of the weld and the heat affected zones were observed in a scanning electron microscope. An energy dispersive spectrometer, coupled to the scanning electron microscope, was used to determine variations in (weight %) the main chemical elements across the fillet weld. Vickers microhardness testing and tensile testing were carried out to determine the mechanical properties of the weld. The results of the various tests and examinations enabled definition of the best position for the incident laser beam with respect to the joint, for welding together the two stainless steels.

  14. Optimization of tensile strength of friction welded AISI 1040 and AISI 304L steels according to statistics analysis (ANOVA)

    Energy Technology Data Exchange (ETDEWEB)

    Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi; Firat, Emrah Hanifi; Caligulu, Ugur [Firat Univ., Elazig (Turkey)

    2013-06-01

    Materials difficult to weld by fusion welding processes can be successfully welded by friction welding. The strength of the friction welded joints is extremely affected by process parameters (rotation speed, friction time, friction pressure, forging time, and forging pressure). In this study, statistical values of tensile strength were investigated in terms of rotation speed, friction time, and friction pressure on the strength behaviours of friction welded AISI 1040 and AISI 304L alloys. Then, the tensile test results were analyzed by analysis of variance (ANOVA) with a confidence level of 95 % to find out whether a statistically significant difference occurs. As a result of this study, the maximum tensile strength is very close, which that of AISI 1040 parent metal of 637 MPa to could be obtained for the joints fabricated under the welding conditions of rotation speed of 1700 rpm, friction pressure of 50 MPa, forging pressure of 100 MPa, friction time of 4 s, and forging time of 2 s. Rotation speed, friction time, and friction pressure on the friction welding of AISI 1040 and AISI 304L alloys were statistically significant regarding tensile strength test values. (orig.)

  15. Physical properties of the AISI 348 L* austenitic stainless steel

    International Nuclear Information System (INIS)

    Teodoro, Celso Antonio; Lucki, Georgi; Silva, Jose Eduardo Rosa da; Terremoto, Luis Antanio Albiac; Castanheira, Myrthes; Damy, Margaret de Almeida

    2005-01-01

    The study of radiation damage in metals and alloys, used as structural materials of nuclear reactors has a strategic meaning in nuclear technology, because it allows the performance evaluation of these materials in working conditions of PWR. For this sake it is necessary to know the detrimental structural changes that occur during fast neutron irradiation. The aim of the present work is to show some strain-stress results of the AISI 348 L * stainless steel utilized as a structural material of the fuel elements of PWR, in comparison with the AISI 304. (author)

  16. Gangliosidosis generalizada tipo 1

    Directory of Open Access Journals (Sweden)

    Iván Hernández García

    Full Text Available La gangliosidosis generalizada tipo 1 es una enfermedad de acúmulo lisosomal producida por mutaciones en el gen de la enzima b-galactosidasa, caracterizada fundamentalmente por toma del sistema nervioso central, la visceromegalia, disostosis ósea y dimorfismo facial. Se presenta el caso de un lactante varón, hijo de padres no consanguíneos, de 5 meses de edad, Apgar 6/8 debido a hipoxia neonatal, con historia de múltiples ingresos por enfermedad diarreica e infecciones respiratorias. Es remitido a la Consulta de Genética Clínica por retardo del desarrollo psicomotor, macrocráneo y hepatomegalia, además de máculas hipercrómicas en piel. En el examen físico se encontraron evidencias de una posible afectación por enfermedad metabólica lisosomal. Entre las enfermedades a descartar estaban la galactosialidosis, de características clínicas similares, y la enfermedad de Morquio, con diferente presentación clínica pero idéntico defecto enzimático.

  17. Breakdown and Evolution of the Protective Oxide Scales of AISI 304 and AISI 316 Stainless Steels under High-Temperature Oxidation

    Directory of Open Access Journals (Sweden)

    K. A. Habib

    2011-01-01

    Full Text Available The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3 scale totally disappeared and exclusively Fe2O3 was formed, in AISI 316 stainless steel some Cr2O3 persisted and Fe3O4 was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown.

  18. mellitus tipo 2

    Directory of Open Access Journals (Sweden)

    Margarita Lazcano-Ortiz

    2008-01-01

    Full Text Available Objetivo: valorar las propiedades psicométricas de la escala de afrontamiento y proceso de adaptación de Roy en población mexicana. Materiales y métodos: la escala se aplicó a 200 participantes con diabetes mellitus tipo 2. Para validar el constructo se realizó la extracción de factores con componentes principales y rotación Varimax, con Eigenvalores por arriba de 1 y cargas de factor mayores a ,30. Resultados: seis reactivos fueron eliminados del análisis por mostrar correlación negativa con la correlación total de la escala. El análisis de componentes principales inicial reveló nueve factores con una variación explicada de 65,29%. Sin embargo, no se consideraron tres factores por contener cada uno de ellos solamente un reactivo. Por tanto, la escala final se acepta con 38 reactivos. El coeficiente de confiabilidad Alfa de Cronbach fue de, 93. Discusión: el análisis reveló seis factores, uno más de lo reportado por Roy, y con mayor variación explicada. Algunos reactivos parecen no ser bien comprendidos por los participantes. Conclusiones: este artículo aporta una aproximación metodológica para explorar la adecuación de un instrumento a una población diferente para la que originalmente fue diseñado. Se concluye que la escala tiene consistencia interna y validez de constructo incipiente, los datos reportados en este estudio deben tomarse en cuenta con cautela. Es conveniente revisar de nuevo los reactivos y adecuarlos a la cultura particular, y probar la escala de nuevo con pacientes con enfermedades crónicas degenerativas a fin de contar con instrumentos culturalmente equivalentes.

  19. Investigation of residual stress in laser welding between carbon steel AISI 1010 and stainless AISI 304

    International Nuclear Information System (INIS)

    Mirim, Denilson de Camargo

    2011-01-01

    The dissimilar materials union has the residual stress formation as one of the most critical problems, which occurs mainly because these materials have both different thermal expansion coefficients and thermal conductivities. In this study, it was investigated the laser welding technique between steels, AISI 1010 and AISI 304. The materials were joined by butt autogenous welding with a continuous Nd:YAG laser. The main objective was to identify the welding parameters influence by the residual stresses analysis in the heat affected zone (HAZ). It was executed a factorial design with three-factor at two levels with a replica, which were varied power, welding speed and focal position of the laser beam. Residual stress measurements by the diffraction of X-rays were performed on the sample surface, to study their variation as a function of the parameters investigated. The blind hole method was also used to evaluate the residual stress along the samples depth, up to depth of 1mm. Besides residual stress measurement, weld seams were evaluated by optical and scanned electron microscopy, which were aimed to determine the weld geometry and changes in the microstructure. It was also made Vickers hardness measurements to evaluate the extent of HAZ. To evaluate the mechanical properties of the union were performed tensile and fatigue test. The MINITAB 15 software was used to analyze the residual stresses obtained by the blind hole method at different depths of the HAZ. It was also used statistical regression based on both the influences different and the combination of this input factors, in the residual stress of union. The results indicate that the models can satisfactorily predict the responses and provide users a guide to better define the welding parameters. (author)

  20. pitting corrosion susceptibility pitting corrosion susceptibility of aisi ...

    African Journals Online (AJOL)

    eobe

    The susceptibility of austenitic (AISI 301) stainless steel to pitting corrosion was evaluated in sodium chloride ... halides, the most aggressive and thus, the most frequently investigated is the chloride ions, particularly its effect on pit formation in 18/8 stainless steel [1 - 3]. ... in sea water), and moderately high temperatures.

  1. Mössbauer studies on an AISI 1137 type steel

    Indian Academy of Sciences (India)

    An AISI 1137 type medium carbon steel was studied by means of scanning electron microscopy and Mössbauer spectroscopy. This steel in as received state at room temperature was ferritic. Different heat treatments on related steel exhibited different microstructures such as pearlite and bainite. Also magnetism of these ...

  2. Comparing creep in two stainless steels AISI 316

    International Nuclear Information System (INIS)

    Silveira, T.L. da; Monteiro, S.N.

    1976-07-01

    Two AISI 316 stainless steels, one of Brazilian fabrication (Villares), the other of foreign fabrication (Uddeholm) were submitted to creep tests with temperature ranging from 600 to 800 0 C. Some important differences in the mechanical behaviour of the two steels are pointed out. These differences are due to the particular thermomechanical history of the materials under consideration. (Author) [pt

  3. Stress corrosion cracking of AISI 321 stainless steel in acidic ...

    Indian Academy of Sciences (India)

    Unknown

    The stress corrosion cracking (SCC) of AISI 321 stainless steel in acidic chloride solution was studied by slow strain rate (SSR) ... Stress corrosion cracking; chloride; stainless steel; inhibitor. 1. Introduction. Stress corrosion cracking (SCC) ..... Xi'an Jiaotong University Press) (in Chinese). Huang Y L, Cao C N, Lu M and Lin ...

  4. Effect of Adenine Concentration on the Corrosion Inhibition of Aisi ...

    African Journals Online (AJOL)

    This gave a surface coverage of 0.8956 and corrosion penetration rate of 0.022132mm/yr. Hence, the best adenine concentration for the corrosion inhibition of alloys 304L in 1.0M sulphuric acid solution to obtain optimum inhibition efficiency is 0.011M. Keywords: Corrosion, AISI 304L Steel, Inhibition efficiency, Degree of ...

  5. Colloquium on Large Scale Improvement: Implications for AISI

    Science.gov (United States)

    McEwen, Nelly, Ed.

    2008-01-01

    The Alberta Initiative for School Improvement (AISI) is a province-wide partnership program whose goal is to improve student learning and performance by fostering initiatives that reflect the unique needs and circumstances of each school authority. It is currently ending its third cycle and ninth year of implementation. "The Colloquium on…

  6. Mössbauer studies on an AISI 1137 type steel

    Indian Academy of Sciences (India)

    Unknown

    Abstract. An AISI 1137 type medium carbon steel was studied by means of scanning electron microscopy and Mössbauer spectroscopy. This steel in as received state at room temperature was ferritic. Different heat treatments on related steel exhibited different microstructures such as pearlite and bainite. Also magnetism of.

  7. Investigation of the influential parameters of machining of AISI 304 ...

    Indian Academy of Sciences (India)

    Abstract. Austenitic stainless steels are hard materials to machine, due to their high strength, high ductility and low thermal conductivity. The last characteristic results in heat concentration at the tool cutting edge. This paper aims to optimize turning parameters of AISI 304 stainless steel. Turning tests have been performed in ...

  8. Investigation of the influential parameters of machining of AISI 304 ...

    Indian Academy of Sciences (India)

    parameters for turning of AISI 304 stainless steel by considering the process sound and observed that cutting sound pressure levels decreased parallel to positive results occurred in chip removal. Korkut et al (2004) tried to determine the effects of cutting speed on flank wear and surface roughness in the machining of ...

  9. Caracterización microestructural de uniones soldadas de acero AISI 316L en tuberías

    Directory of Open Access Journals (Sweden)

    Tomás H. Fernández-Columbié

    2016-03-01

    Full Text Available Se analizó el comportamiento microestructural de uniones soldadas de acero AISI 316L empleado en la fabricación de tuberías, las cuales se ven afectadas por agrietamiento en el cordón de soldadura. Se emplearon electrodos revestidos de acero inoxidables de los tipos E 309–16; 310–16 y E 316L–16, según norma de la AWS, los que fueron evaluados por su depósito en uniones a tope preparadas con biseles en V, soldadas por un solo lado del material de la tubería, así como la selección y preparación de muestra en zonas donde la tubería presenta daños mecánicos, fisuras y corrosión severa con pérdida del espesor de pared crítica para soportar las presiones de trabajo. Se caracterizó la microestructura de la zona fundida y la zona de influencia térmica de cada cordón luego de realizado el proceso de soldadura. Se concluye que la soldadura con electrodos del tipo E 309-16 y del tipo E 316-16 no son recomendables debido a que se obtiene una microestructura sensible al agrietamiento.

  10. Uso da rugoscopia palatina como ferramenta biométrica: um estudo populacional em Niterói-RJ, Brasil

    Directory of Open Access Journals (Sweden)

    Igor Iuco CASTRO-SILVA

    Full Text Available Introdução: Pesquisas por métodos biométricos auxiliares em perícias têm crescido na Odontologia Legal. Objetivo: Este estudo avaliou a eficácia da rugoscopia palatina na identificação humana. Material e método: Foram utilizados 184 modelos de gesso de estudantes voluntários em Niterói-RJ, para delineamento de suas rugosidades palatinas, sendo classificadas segundo quantidade, direção (sistema de Carrea e formato individual (sistema de Silva, e comparadas às variáveis demográficas sexo, cor da pele e idade. A análise estatística foi realizada com o teste qui-quadrado para amostras independentes, considerando-se p<0,05. Resultado: Houve maior prevalência de 2-7 rugas em homens. O tipo IV de Carrea e o tipo 1 de Silva foram mais evidentes, porém sem diferenças intergrupos significativas, de acordo com as variáveis propostas. Conclusão: A rugoscopia palatina é uma ferramenta biométrica viável e fornece informações morfológicas individuais relevantes, embora sua análise cega e em tempo único não exiba acurácia na estratificação populacional.

  11. Incubadora de Aprendizagem: ferramenta indutora do empreendedorismo na Enfermagem

    Directory of Open Access Journals (Sweden)

    Dirce Stein Backes

    2015-12-01

    Full Text Available RESUMO Objetivo: conhecer as contribuições da Incubadora de Aprendizagem no processo de educação permanente em saúde. Método: pesquisa de caráter qualitativo, cujos dados foram coletados entre agosto e dezembro de 2014, pela técnica de grupo focal, com 34 colaboradores de um hospital de ensino da região central do Rio Grande do Sul que, a priori, participaram do processo de incubação. Resultados: dos dados codificados pela análise de conteúdo resultaram em três categorias temáticas: Incubadora de Aprendizagem - espaço de acolhida e integração; Ferramenta instigadora e ampliadora de possibilidades; Estratégia de educação continuada e permanente. Conclusão: a Incubadora de Aprendizagem constitui uma importante ferramenta indutora do empreendedorismo na enfermagem e na saúde, pela capacidade de repensar as práticas mecanizadas, pela contingência de instigar novos modos de ser e agir e pela possibilidade de criar e desenvolver novas idéias, alicerçadas nas necessidades individuais e institucionais.

  12. A comparative study of mechanical and tribological properties of AISI-304 and AISI-316 submitted to glow discharge nitriding

    Directory of Open Access Journals (Sweden)

    Fabiana Cristina Nascimento

    2009-06-01

    Full Text Available Mechanical and tribological properties os AISI 304 and AISI 316 stainless steels submited to glow discharge ion nitriding are reported.The atmosphere was 20:80 - N2:H2 with substrate temperatures ranging from 300 to 500 °C. Treatment at 300 °C produced expanded austenite (γN in both steels. Increasing the temperature, the phases γ´-Fe4N and - Fe2+xN were present and the latter is the major phase for AISI 304. At 500 °C, the CrN phase was also identified in both steels. Hardnesses of about 13-14 GPa at near surface regions were obtained in both steels. Moreover, AISI 316 nitrided at 500 °C has the deepest hard layer. Tribological tests showed that wear can be reduced by up to a factor of six after the nitriding processes, even for a working temperature of 300 °C. The profiles during and after nanoscratch tests did not reveal significant differences after nitriding processes in both steels.

  13. Monitoramento de revistas científicas na web com a ferramenta Google Analytics: reflexões a partir da Revista Comunicação & Informação

    Directory of Open Access Journals (Sweden)

    João de Melo Maricato

    2015-04-01

    Com a web surgem os indicadores webométricos, análogos aos tradicionais indicadores bibliométricos e cientométricos. Estes podem ser úteis para compreender a popularidade e visibilidade de revistas científicas, subsidiando reflexões gerenciais. Objetiva-se apresentar a ferramenta Google Analytics aplicando-a a Revista Comunicação & Informação, com intuito de compreender sua potencialidade para a obtenção de informações e indicadores. A ferramenta Google Analytics proporcionou a elaboração e visualização de diversos indicadores baseados em visitas realizadas no site da revista e suas inúmeras variáveis (demográficas, tipo de tecnologia, assuntos, temporais, apontando grande potencial para o apoio à gestão e planejamento editorial de revistas científicas.

  14. Uso da análise de clusters como ferramenta de apoio à gestão no SUS

    Directory of Open Access Journals (Sweden)

    Oswaldo YoshimiTanaka

    2015-03-01

    Full Text Available A institucionalização de ferramentas de avaliação de serviços de saúde é um desafio estratégico para o desenvolvimento do Sistema Único de Saúde (SUS. O objetivo do estudo realizado foi explorar o potencial da análise de clusters (análise por conglomerados enquanto ferramenta de apoio à gestão do SUS. São apresentadas e discutidas as etapas do processo de construção dos clusters aplicadas a uma realidade concreta, por meio da análise de serviços de saúde de tipo pronto atendimento (AMA, do município de São Paulo. A estratégia metodológica baseou-se na utilização de dados secundários para a construção de agrupamentos homogêneos, o que permite análise de múltiplas variáveis potencializando a interpretação da relação entre as mesmas. Os achados do estudo indicam que essa técnica tem potencialidade para ser utilizada por atores institucionais da gestão do SUS na avaliação e monitoramento de serviços de saúde, em municípios de grande porte ou em regiões de saúde.

  15. Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding

    Science.gov (United States)

    2013-05-01

    REPORT Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding 14. ABSTRACT 16. SECURITY...NAMES AND ADDRESSES U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS AISI 1005, finite-element...Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding Report Title ABSTRACT A fully coupled (two-way

  16. Brincar de aprender: ferramentas interdisciplinares no ensino da ortografia

    Directory of Open Access Journals (Sweden)

    Jamylle Rebouças Ouverney-King

    2016-09-01

    Full Text Available Discutimos as ramificações do m-learning por meio da gamificação em uma aula de Português para uma turma de Ciências da Computação, com foco em ortografia por meio do aplicativo SoletrandoMob. As novas tecnologias têm se tornado uma prática frequente para dinamizar e tornar mais eficiente a metodologia de ensino contemporânea. Os jogos educativos e os recursos midiáticos possibilitam ao aluno aprender com mobilidade. O corpus é composto por parágrafos produzidos pelos alunos sobre o grau de satisfação em relação ao uso do aplicativo. A análise está fundamentada nas discussões sobre a Gamificação, o Software educacional e o M-learning. Concluímos que o uso da tecnologia, que se apoia no m-learning e na gamificação faz com que os alunos utilizem o smartphone de uma maneira inteligente para consolidarem o conhecimento ou ainda aprenderem novos conteúdos. Além disso, o SoletrandoMob, quando associado ao ensino do ensino da Língua Portuguesa, representa uma rica contribuição para aproximação entre a aprendizagem e o entretenimento de forma interdisciplinar. Ao contrário do que pode ser pensado, o uso das ferramentas tecnológicas em sala de aula deixou a esfera da ousadia e tem se tornado uma ferramenta natural.

  17. Weldability of AISI 304 to copper by friction welding

    Energy Technology Data Exchange (ETDEWEB)

    Kirik, Ihsan [Batman Univ. (Turkey); Balalan, Zulkuf [Firat Univ., Elazig (Turkey)

    2013-06-01

    Friction welding is a solid-state welding method, which can join different materials smoothly and is excessively used in manufacturing industry. Friction welding method is commonly used in welding applications of especially cylindrical components, pipes and materials with different properties, for which other welding methods remain incapable. AISI 304 stainless steel and a copper alloy of 99.6 % purity were used in this study. This couple was welded in the friction welding machine. After the welding process, samples were analyzed macroscopically and microscopically, and their microhardness was measured. Tensile test was used to determine the bond strength of materials that were joined using the friction welding method. At the end of the study, it was observed that AISI 304 stainless steel and copper could be welded smoothly using the friction welding method and the bond strength is close to the tensile strength of copper. (orig.)

  18. Surface hardening of AISI 4340 steel by electron beam treatment

    International Nuclear Information System (INIS)

    Wang Chienchun; Hwang Jiunren

    1994-01-01

    This paper investigates the effect of electron beam (EB) surface hardening on the abrasive wear property of AISI 4340 steel. The heat treatment conditions were varied so that the influence of microstructures on the wear resistance could be evaluated. A dry sand/rubber wheel abrasion test was selected to evaluate the high stress wear properties. The results show that the weight loss decreases with increasing hardness of surface layer or base material. The EB surface hardening can improve the abrasive wear resistance by about 10%. The best heat treatment process for AISI 4340 steel against abrasive wear is oil quenching from 840 C, tempering at 370 C, the EB surface hardening under heat input of 135-150 J mm -1 . The width and depth of the wear tracks are reduced after the EB surface hardening treatment. (orig.)

  19. Experimental evaluation of mechanical properties of friction welded AISI steels

    Directory of Open Access Journals (Sweden)

    Amit Handa

    2014-12-01

    Full Text Available In the present study, an experimental setup was designed and fabricated in order to accomplish friction welded joints between austenitic stainless steel and low-alloy steel. Thereafter, the effect of axial pressures on the mechanical properties of friction welded AISI 304 with AISI 1021 steels, produced by mechanical joining, have been investigated. Samples were welded under different axial pressures ranging from 75 to 135 MPa, at constant speed of 1250 rpm. The tensile strength, impact strength, and micro-hardness values of the weldments were determined and evaluated. Simultaneously, the fractrography of the tensile-tested specimens were carried out, so as to understand the failure analysis.

  20. Investigation of diffusion kinetics of plasma paste borided AISI 8620 ...

    Indian Academy of Sciences (India)

    X-ray diffraction analysis of boride layers on the surface of the steel revealed FeB and Fe2B phases. Depending on temperature and layer thickness, the activation energies of boron in steel were found to be 124.7 kJ/mol for 100% B2O3. Keywords. Plasma paste boriding; AISI 8620; B2O3 paste; kinetics; activation energy. 1.

  1. Metallographic observations of AISI 304 - copper dissimular joints

    International Nuclear Information System (INIS)

    Medeiros, R.C. de; Carvalho Perdigao, S. de

    1982-01-01

    The current work informs on the SMAW dissimilar joints embrittled by molten Copper. Bead on plate of that metal were deposited on four different base metals to evaluate the phenomena. Conventional and non conventional welding methods were employed to obtain dissimilar joints of AISI 304-Cu. The latter were observed metallographically. These results are to be complemented by mechanical testing actually being performed. (Author) [pt

  2. The aluminizing in powder technology of AISI 304 steel

    Science.gov (United States)

    Băitanu, D. B.; Găluşcă, D. G.; Achiţei, D. C.; Minciună, M. G.; Bakri Abdullah, Mohd Mustafa Al

    2016-06-01

    The paper presents a study about the aluminizing treatments applied to AISI 304 stainless steel, with the purpose to improve the corrosion resistance. The aluminizing is realized in a powder medium, composed by aluminium powder (with 99.95% purity), aluminium oxide Al2O3 and ammonium chloride NH4Cl. The structural characterization was made by scanning electronic microscopy to highlight the structure of layer after aluminizing, at different magnitudes.

  3. Corrosion under stress of AISI 304 steel in thiocyanate solutions

    International Nuclear Information System (INIS)

    Perillo, P.M.; Duffo, G.S.

    1989-01-01

    Corrosion susceptibility under stress of AISI 304 steel sensitized in a sodium thiocyanate solution has been studied and results were compared with those obtained with solutions of thiosulfate and tetrathionate. Sensitized steel type 304 is highly susceptible to corrosion when under intergranular stress (IGSCC) in thiocyanate solutions but the aggressiveness of this anion is less than that of the other sulphur anions studied (thiosulfate and tetrathionate). This work has been partly carried out in the Chemistry Department. (Author) [es

  4. Pitting Corrosion Susceptibility of AISI 301 Stainless Steel in ...

    African Journals Online (AJOL)

    The susceptibility of austenitic (AISI 301) stainless steel to pitting corrosion was evaluated in sodium chloride (NaCl) solutions - 0.1M, 0.2M, 0.3M, 0.5M and 0.7M and 1.0M. Tensile tests and microscopic examinations were performed on samples prepared from the steel after exposure in the various environments.

  5. Wear behavior of niobium carbide coated AISI 52100 steel

    International Nuclear Information System (INIS)

    Fernandes, Frederico Augusto Pires; Casteletti, Luiz Carlos; Oliveira, Carlos Kleber Nascimento de; Lombardi Neto, Amadeu; Totten, George Edward

    2010-01-01

    Bearing steels must have high hardness, good wear resistance and dimensional stability. The aim of this work was to study the effect of NbC coating, produced using the thermo-reactive deposition (TRD) process, on the wear resistance of the AISI 52100 steel. Untreated AISI 52100 samples were ground up to 600 mesh emery paper. The bath was composed of 5wt.% ferroniobium (65 wt.% Nb), 3wt.% aluminum and (Na2B4O7) to 100%. Samples were treated at 1000 deg C for 4h and quenched in oil directly from the bath. The resulting layer was characterized by X-ray diffraction, scanning electron microscopy and a micro-abrasive wear testing. The thermo-reactive deposition process in molten borax produced a hard and homogeneous layer composed by NbC, which was confirmed by X-ray diffraction. The NbC coating produced a great increase in the wear resistance of the AISI 52100 steel, decreasing the wear rate by an order of magnitude in relation to the substrate. For coated and uncoated samples the worn volume and wear rate increases with the load. (author)

  6. Crescimento de genótipos de frangos tipo caipira

    Directory of Open Access Journals (Sweden)

    R. C. Veloso

    2015-10-01

    Full Text Available RESUMOObjetivou-se com este trabalho comparar o padrão de crescimento, mediante ajustes das respectivas curvas de crescimento por modelos não lineares, bem como estudar o desenvolvimento de cortes de carcaça em relação ao peso da carcaça em diferentes genótipos de frangos tipo caipira. Foram utilizados 840 pintos de um dia, machos, distribuídos em delineamento inteiramente ao acaso, dos seguintes genótipos da linhagem Redbro: Caboclo, Carijó, Colorpak, Gigante Negro, Pesadão Vermelho, Pescoço Pelado e Tricolor. As aves foram alojadas em 28 boxes, sendo 30 aves/boxe, em galpão de alvenaria com acesso a um piquete de 45m², com quatro repetições. O peso corporal individual dos frangos foi medido ao nascer, aos 14, 28, 42, 56, 70 e 84 dias de idade. Para a determinação das curvas de crescimento do peso corporal das aves, os dados coletados foram avaliados por meio dos modelos não lineares: Brody, Gompertz, Logístico, Richards e von Bertalanffy. Foi empregado o PROC NLIN do SAS, utilizando-se o método interativo de Gauss-Newton. Os critérios usados para escolha do modelo de melhor ajuste da curva de crescimento foram o coeficiente de determinação, o desvio padrão assintótico, o desvio médio absoluto dos resíduos e o índice assintótico. As análises para obtenção dos coeficientes alométricos foram realizadas por meio do PROC GLM do SAS para os genótipos Carijó, Colorpak, Pesadão Vermelho, Pescoço Pelado e Tricolor. Foram avaliados os pesos da carcaça, do peito, das coxas, das sobrecoxas, das pernas e das asas das aves abatidas aos 85 dias de idade. Apenas as equações propostas por Gompertz, von Bertalanffy e Logístico atingiram a convergência, e o modelo proposto por von Bertalanffy foi o mais adequado para descrever o crescimento dos genótipos de frangos caipiras. Todos os cortes avaliados apresentaram crescimento tardio em relação ao peso da carcaça em genótipos de frangos tipo caipira.

  7. Comparison of pitting fatigue life of ausforged and standard forged AISI M-50 and AISI 9310 spur gears

    Science.gov (United States)

    Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

    1975-01-01

    Standard forged and ausforged spur gears made of vacuum-induction-melted, consumable-electrode, vacuum-arc-remelted AISI M-50 steel were tested under conditions that produced fatigue pitting. The gears were 8.89 cm (3.5 in.) in pitch diameter and had tip relief. The M-50 standard forged and ausforged test results were compared with each other. They were then compared with results for machined vacuum-arc-remelted AISI 9310 gears tested under identical conditions. Both types of M-50 gears had lives approximately five times that of the 9310 gears. The life at which 10 percent of the M-50 ausforged gears failed was slightly less than that at which the M-50 standard forged gears failed. The ausforged gears had a slightly greater tendency to fail by tooth fracture than did the standard forged gears, most likely because of the better forging and grain flow pattern of standard forged gears.

  8. Effect of temperature on the level of corrosion caused by heavy petroleum on AISI 304 and AISI 444 stainless steel

    Directory of Open Access Journals (Sweden)

    João Paulo Sampaio Eufrásio Machado

    2006-06-01

    Full Text Available This work presents a study on the influence of national heavy petroleum in the corrosion of the AISI 444 and AISI 304 stainless steels in simulated refining operation conditions. The petroleum was first characterized through physicochemical analysis (density, fluidity point, viscosity, sulfur concentration. In an attempt to understand the corrosion effect of temperature and of the type of heating the referred types of steel thermal treatments were carried out at three levels of temperature (200, 300 and 400 °C. The procedure was done in conditions close to those in the distillation column. Heat was gradually increased from room temperature, and directly heated to working temperature. Each treatment took 4 hours to be completed. Scanning electronic microscopy (SEM and the analysis of X rays dispersive energy (EDX were used after the trials to characterize the samples. The results show that treatment temperature, as well as the type of heating, has distinct influences on each type of steel.

  9. Validity and reliability of the attachment insecurity screening inventory (AISI) 2-5 years

    NARCIS (Netherlands)

    Wissink, I.B.|info:eu-repo/dai/nl/293037817; Stams, G.J.J.M.; Colonnesi, C.; Asscher, J.J.|info:eu-repo/dai/nl/288661834; Hoeve, M.; Noom, M.J.; Polderman, Nelleke; Kellaert-Knol, Marijke G.

    2016-01-01

    The Attachment Insecurity Screening Inventory (AISI) 2–5 years is a parent-report questionnaire for assessing attachment insecurity in preschoolers. Validity and reliability of the AISI 2–5 years were examined in a general sample (n = 429) and in a clinical sample (n = 71). Confirmatory factor

  10. Validity and reliability of the Attachment Insecurity Screening Inventory (AISI) 2-5 years

    NARCIS (Netherlands)

    Wissink, I.B.; Colonnesi, C.; Stams, G.J.J.M.; Hoeve, M.; Asscher, J.J.; Noom, M.J.; Polderman, N.; Kellaert-Knol, M.G.

    2016-01-01

    The Attachment Insecurity Screening Inventory (AISI) 2-5 years is a parent-report questionnaire for assessing attachment insecurity in preschoolers. Validity and reliability of the AISI 2-5 years were examined in a general sample (n = 429) and in a clinical sample (n = 71). Confirmatory factor

  11. Pengaruh Nitridasi Plasma Terhadap Kekerasan Aisi 304 Dan Baja Karbon Rendah

    OpenAIRE

    Suprapto, Suprapto; Sudjatmoko, Sudjatmoko; Sujitno, Tjipto

    2010-01-01

    PENGARUH NITRIDASI PLASMA TERHADAP KEKERASAN AISI 304 DAN BAJA KARBON RENDAH. Telahdilakukan nitridasi dengan teknik nitridasi plasma/ion untuk perlakuan permukaan AISI 304 dan baja karbon rendahsebagai material komponen mesin. Perlakuan permukaan dimaksudkan untuk meningkatkan kualitas permukaankhususnya kekerasan. Untuk mencapai kondisi optimum dilakukan dengan memvariasi tekanan gas saat prosesnitridasi, sedangkan untuk mengetahui hasilnya dilakukan uji kekerasan, struktur mikro dan kandun...

  12. Squeeze Casting Method Of AI-Si Alloy For Piston Material

    International Nuclear Information System (INIS)

    Wagiyo, H.; Dani, Muhammad; Sulistioso, G.S.; Pardede, Elman; Handayani, Ari; Teguh, Yulius S.P.P.

    2001-01-01

    The AI-Si alloy is an alloy used as piston material. This alloys could be as AI-Si hypereutectic alloy (Si content more than 12.5 % wt.), as AI-Si eutectic alloy (Si cuntent 12.5 % wt, and as AI-Si hypoeutectic alloy (Si content less than 12.5 % wt.). The synthesize of AI-Si alloy piston generally using the technique of gravity casting in a dies. This method is causing high porousity. By using the squeeze technique, amount ofporousity in AI-Si alloy is possibly reduced and the density of this alloy should be higher. The other factors such as alloying elements of AI-Si alloy (Mg. Cu, Zn) would increase the mechanical properties especially the hardness. The focuses of this research are the microstructure and the maximum hardness during the heat treatment of AI-Si alloy which was added by alloying elments. The result of hardness at test shows the maximum hardness at 94.7 kg/mm 2 obtained at aging temperature of 210 o C for hours with homogenous dendritic microstructure

  13. Jogos digitais como ferramenta de ensino: reflexões iniciais

    Directory of Open Access Journals (Sweden)

    Sandro Brincher

    2012-09-01

    Full Text Available http://dx.doi.org/10.5007/2176-8552.2011nesp1p42 O presente artigo visa a apresentar algumas considerações iniciais a respeito do uso de jogos como ferramenta na educação, mostrando como essa prática pode auxiliar na consolidação de práticas pedagógicas significativas. Para tanto, tratará do jogo como elemento de significação, associando essa característica a algumas teorias correntes sobre jogo e ludicidade, e discutirá formas de incorporação de jogos digitais em planejamentos curriculares. Ao final, apresentará uma lista com vários recursos - jogos de diversas plataformas; produtoras; instituições de pesquisa; portais agregadores de material para disciplinas e finalidades específicas; softwares de criação facilitada de jogos; etc. úteis para a efetiva implementação dessa proposta.

  14. As ferramentas da gestão social utilizada pelas organizações que prestam serviços sociais à comunidade e pertencem à microrregião do extremo Oeste do Estado de Santa Catarina

    Directory of Open Access Journals (Sweden)

    Wieczynski, Marineide

    2005-01-01

    Full Text Available O presente artigo aborda resultados de uma pesquisa de iniciação científica que teve como objetivo identificar e relatar quais são as ferramentas da gestão social utilizada pelas organizações que prestam serviços sociais e pertencem à microrregião do extremo oeste do Estado de Santa Catarina. O tipo de pesquisa foi de natureza quali-quantitativa, com o uso de questionários semi-estrutrados, amostragem por acessibilidade e um universo de 30 ONGs, cujos sujeitos foram os gestores dessas organizações. Constatou-se que nenhuma das organizações pesquisada utiliza plenamente as ferramentas da gestão social. O não uso das ferramentas – planejamento, organização, direção e controle/avaliação – comprometem a eficiência, a eficácia e a efetividade dos programas e projetos que vem sendo desenvolvidos por elas. Sugere-se a elaboração de um projeto de extensão e/ou de filantropia, no qual o Curso de Serviço Social da UNOESC – São Miguel do Oeste possa prestar assessoria e consultoria no que tange à gestão social de ONGs

  15. Microstructural Characteristic of Dissimilar Welded Components (AISI 430 Ferritic-AISI 304 Austenitic Stainless Steels) by CO2 Laser Beam Welding (LBW)

    OpenAIRE

    CALIGULU, Ugur; DIKBAS, Halil; TASKIN, Mustafa

    2012-01-01

    In this study, microstructural characteristic of dissimilar welded components (AISI 430 ferritic-AISI 304 austenitic stainless steels) by CO2 laser beam welding (LBW) was investigated. Laser beam welding experiments were carried out under argon and helium atmospheres at 2000 and 2500 W heat inputs and 100-200-300 cm/min. welding speeds. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and XRD analysis. The tensile strengt...

  16. Microstructural Characteristic of Dissimilar Welded Components (AISI 430 Ferritic-AISI 304 Austenitic Stainless Steels) by CO2 Laser Beam Welding (LBW)

    OpenAIRE

    ÇALIGÜLÜ, Uğur; CALIGULU, Ugur; DIKBAS, Halil; TASKIN, Mustafa

    2010-01-01

    In this study, microstructural characteristic of dissimilar welded components (AISI 430 ferritic-AISI 304 austenitic stainless steels) by CO2 laser beam welding (LBW) was investigated. Laser beam welding experiments were carried out under argon and helium atmospheres at 2000 and 2500 W heat inputs and 100-200-300 cm/min. welding speeds. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and XRD analysis. The tensile strengt...

  17. Influence of process parameters on torsional strength, impact toughness and hardness of dissimilar AISI 304 and AISI 1021 friction welded steels

    OpenAIRE

    Amit Handa; Vikas Chawla

    2014-01-01

    In this present study an attempt was made to join austenitic stainless steel (AISI 304) with low alloy steel (AISI 1021) at different rotational speeds and at different axial pressures and then determining the strength of the joint by means of mechanical properties such as torsional strength, impact strength and micro hardness. The experimental results indicate that the rotational speed and the axial pressure have a significant effect on the mechanical properties of the joint and it is possib...

  18. Analysis of the Enameled AISI 316LVM Stainless Steel

    Science.gov (United States)

    Bukovec, Mitja; Xhanari, Klodian; Lešer, Tadej; Petovar, Barbara; Finšgar, Matjaž

    2018-03-01

    In this work, four different enamels were coated on AISI 316LVM stainless steel and the corrosion resistance of these samples was tested in 5 wt.% NaCl solution at room temperature. The preparation procedure of the enamels was optimized in terms of firing temperature, time and composition. First the thermal expansion was measured using dilatometry followed by electrochemical analysis using chronopotentiometry, electrochemical impedance spectroscopy and cyclic polarization. The topography of the most resistant sample was obtained by 3D-profilometry. All samples coated with enamel showed significantly higher corrosion and dilatation resistance compared with the uncoated stainless steel material.

  19. Irradiation-induced swelling in solution annealed AISI 316

    International Nuclear Information System (INIS)

    Bates, J.F.; Weiner, R.A.; Korenko, M.K.

    1978-11-01

    Swelling in solution annealed AISI 316 has been empirically described as a function of temperature and fluence. An equation, suitable for design purposes, has been developed from an analysis of all of the available swelling data and complementary investigations. The equation is bi-linear in nature and incorporates different temperature dependent functions for both the maximum linear swelling rate parameter and the incubation parameter. The equation describing the swelling rate parameter differs from previous functions in that a constant swelling rate occurs from around 450 to 500 0 C followed by a peak swelling rate at around 570 0 C

  20. Analysis of the Enameled AISI 316LVM Stainless Steel

    Science.gov (United States)

    Bukovec, Mitja; Xhanari, Klodian; Lešer, Tadej; Petovar, Barbara; Finšgar, Matjaž

    2018-01-01

    In this work, four different enamels were coated on AISI 316LVM stainless steel and the corrosion resistance of these samples was tested in 5 wt.% NaCl solution at room temperature. The preparation procedure of the enamels was optimized in terms of firing temperature, time and composition. First the thermal expansion was measured using dilatometry followed by electrochemical analysis using chronopotentiometry, electrochemical impedance spectroscopy and cyclic polarization. The topography of the most resistant sample was obtained by 3D-profilometry. All samples coated with enamel showed significantly higher corrosion and dilatation resistance compared with the uncoated stainless steel material.

  1. INFLUENCE OF SHOT PEENING ON AISI 316Ti FATIGUE PROPERTIES

    Directory of Open Access Journals (Sweden)

    Mario Guagliano

    2012-05-01

    Full Text Available This paper deals with examination of fatigue properties of AISI 316Ti stainless steel before and after shot peening including analysis of residual stress relaxation during rotating bending fatigue tests (f = 50 Hz, T = 20 ± 3 °C, R = - 1 with use of X - ray diffractometer. Obtained experimental results show increase of fatigue properties in the high – cycle region including fatigue limit and show the behavior of residual stress, decrease, at given cyclic loading amplitude in the region from N = 103 cycles to N = 107 cycles of loading.

  2. A study of cumulative fatigue damage in AISI 4130 steel

    Science.gov (United States)

    Jeelani, S.; Musial, M.

    1986-01-01

    Experimental data were obtained using AISI 4130 steel under stress ratios of -1 and 0. A study of cumulative fatigue damage using Miner's and Kramer's equations for stress ratios of -1 and 0 for low-high, low-high-mixed, high-low, and high-low-mixed stress sequences has revealed that there is a close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than the popularly used Miner's rule does.

  3. On femtosecond laser shock peening of stainless steel AISI 316

    Science.gov (United States)

    Hoppius, Jan S.; Kukreja, Lalit M.; Knyazeva, Marina; Pöhl, Fabian; Walther, Frank; Ostendorf, Andreas; Gurevich, Evgeny L.

    2018-03-01

    In this paper we report on the competition in metal surface hardening between the femtosecond shock peening on the one hand, and formation of laser-induced periodic surface structures (LIPSS) and surface oxidation on the other hand. Peening of the stainless steel AISI 316 due to shock loading induced by femtosecond laser ablation was successfully demonstrated. However, for some range of processing parameters, surface erosion due to LIPSS and oxidation seems to dominate over the peening effect. Strategies to increase the peening efficiency are discussed.

  4. High-temperature strength of AISI 316 steel

    International Nuclear Information System (INIS)

    Antunes, A.E.B.; Monteiro, S.N.

    1975-01-01

    The mechanical properties, especially elastic limit and strain hardening of AISI-316 austenitic stainless steel were investigated within the temperature range 150-800 0 C for two strain rates. The results showed anomalous behaviour between 200 and 650 0 C, over which range there was an increase in maximum strenght and hardening, with a tendency to show peaks. These apparentley three in number, may be connected with the effects of interaction between point defects and dislocations leading to dinamic aging phenomena. The mechanisms responsible for this anomalous behaviour produce a negative dependence on strain rate [pt

  5. A DESCRIÇÃO COMO FERRAMENTA FUNDAMENTAL PARA UMA BOA COMUNICAÇÃO

    Directory of Open Access Journals (Sweden)

    Sérgio Brasil Fernandes

    2012-07-01

    Full Text Available A descrição é um dos principais modos de organização do discurso, pois é por intermédio dela que se adquire a base fundamental para bem utilizar outras formas de organizar a redação de um texto. A descrição viabiliza a possibilidade de as pessoas terem a noção particular e individual sobre si mesmas e sobre tudo o que as envolve. Enfatiza-se que a construção das imagens que constituem o mundo em que vivemos ocorre através dos cinco sentidos (visão, audição, olfato, paladar e tato e da imaginação criadora do ser humano. Explicitar todos esses aspectos fomentou a elaboração deste estudo que tem por objetivo demonstrar a importância da descrição como ferramenta fundamental para uma boa comunicação. Para isso, utilizou-se a pesquisa bibliográfica de natureza qualitativa como metodologia neste trabalho que se caracteriza como um estudo exploratório. Do referencial teórico que embasou o trabalho, cabe ressaltar que a descrição é a forma mais natural no ser humano de produzir um texto porque os instrumentos do descrever, ou seja, os sentidos humanos, já estão em nós e constituem os elementos vitais da nossa sensibilidade (AMARAL; ANTÔNIO; PATROCÍNIO, 2001. Neste estudo, por meio da análise de diversos tipos de texto, são identificadas técnicas descritivas e formas de influência exercidas pela descrição nos modos de organização do discurso narrativo e argumentativo. Em síntese, é preciso priorizar o estudo da descrição como modo de organização do discurso essencial para a obtenção de conhecimento de mundo e para a realização de uma comunicação precisa e eficaz.

  6. TURISMO: FERRAMENTA DE DESENVOLVIMENTO DE REGIÕES

    Directory of Open Access Journals (Sweden)

    Michele Vasconcellos Chiattone

    2015-08-01

    Full Text Available Esse artigo tem como foco a Mesorregião Metade Sul do estado do Rio Grande do Sul com suas regiões e microrregiões, descrevendo as cidades que as compõe com alguns de seus dados demográficos, econômicos e culturais; a estrutura de serviços para o turismo, os atrativos turísticos; e algumas rotas turísticas. Também enfoca o desenvolvimento do turismo na Metade Sul com os benefícios econômicos da atividade, o turismo rural e o enoturismo. O objetivo do estudo é discutir a importância do turismo como ferramenta de desenvolvimento econômico e social da metade sul do Rio Grande do Sul do Brasil. O procedimento metodológico utilizado no estudo foi a pesquisa exploratória descritiva através de uma revisão bibliográfica em publicações físicas e digitais. O estado do Rio Grande do Sul encontra-se dividido em duas mesorregiões, Sul e Norte, sendo que há grande disparidade econômica e demografica entre elas. Nesse sentido, o turismo surge como alternativa visando minimizar essas desigualdades regionais, criando a união de municípios para promover o desenvolvimento regional dos territórios demarcados pelas rotas. Palavras-chave: Turismo. Metade Sul. Roteiro turístico. Desenvolvimento.

  7. Aluminum coating by fluidized bed chemical vapor deposition on austenitic stainless steels AISI 304 and AISI 316

    Directory of Open Access Journals (Sweden)

    Jose Luddey Marulanda-Arevalo

    2015-01-01

    Full Text Available Los revestimientos de aluminio f ueron depositados sobre aceros inoxidables AISI 304 y AISI 316 en el rango de temperatura de 5 60 a 600 °C por deposición química de vapor en lecho fluidizado(CVD – FBR. Se utilizó un lecho que consistía en 10 % de aluminio en polvo y 90 % de lecho inerte (alúmina, el cual fue fluidizado con Ar y como ga ses activadores se utilizó una mezcla de ácido clorhídrico con hidrógeno (HCl/H 2 . En el recubrimiento si n tratamiento térmico están las siguiente s especies: Al 13 Fe 4 , Fe 2 Al 5 , FeAl 2 y Al 5 FeNi, las cuales están presentes para ambos aceros. Además, el tratamiento térmico provoca la difusa de alu minio hacia el sustrato y la difusa de hierro del sustrato haci a la superficie del recubrimiento, haciendo la trans formación de los compuestos ant eriores a FeAl, Fe 2 Al 5 , FeAl 2 , Al 0.99 Fe 0.99 Ni 0.02 , AlNi y el Fe 2 AlCr. Se realizó la simulación termodinámica con el s oftware Thermo Calc para obt ener información de la posible composición y la cantidad de mat erial depositado, para condiciones seleccionadas. Las muestras recubi ertas y sin recubrir, se expus ieron a 750 ºC en una atmósfera d onde el vapor agua se transporta a las muestras usando un flujo de N 2 de 40 ml/min, más 100 % vapor de agua (H 2 O. Los dos sustratos sin revestir se comportaron de manera diferente, ya que el acero AISI 304 soportó bien el a taque y ganó poco peso (0.49 mg/cm 2 , en comparación con el acero AISI 316 que perdió mucho peso (25.4 mg/cm 2 . Los aceros recubiertos ganaron poco de peso durante las mil horas de exposición (0.26 mg/cm 2 y soportaron muy bien el ataque corrosivo en c omparación con sustratos sin r ecubrimiento.

  8. SMART INTERFACE: FERRAMENTA DE AUXÍLIO AO DESENVOLVIMENTO DE APLICAÇÕES JAVA CARD

    Directory of Open Access Journals (Sweden)

    Leonardo Ataíde Minora

    2008-05-01

    Full Text Available Com a evolução da tecnologia de microprocessadores, hoje é possível colocar um minúsculo chip em um cartão de plástico, nas dimensões de um cartão de crédito convencional. Chip este com capacidade de armazenamento de informação e processamento. Esse tipo de cartão é chamado de Smart Card. É possível desenvolver aplicações para esses cartões utilizando um subconjunto da plataforma Java – Java Card. O subconjunto da plataforma Java para o desenvolvimento de aplicações próprias para executar em Smart Cards é bastante limitado, em virtude das limitações do hardware envolvido. O desenvolvimento deste tipo de aplicação implica invariavelmente em se trabalhar no nível de bytes, pois toda a comunicação com o cartão acontece através de APDUs (Applicaion Protocol Data Unit montadas como uma sequência de bytes. Para auxiliar nesse trabalho, foi desenvolvido o SMART SHELL: ferramenta, modo texto, que interpreta comandos para a interação com a aplicação gerente do cartão – card manager. Os objetivos deste trabalho são: aperfeiçoar as funcionalidades do SMART SHELL e desenvolver uma interface gráfica para o mesmo, denominada de SMART INTERFACE. A aplicação em questão visa oferecer ao desenvolvedor de aplicações Java Card um mecanismo simples e ágil para a realização de atividades comuns de manipulação de um cartão, tais como: (1 realizar o processo de autenticação para operar com o card manager, (2 listar as aplicações – applets Java Card – instalados em um cartão, (3 preparar uma aplicação para ser instalada em um cartão, (4 instalação de uma aplicação no cartão, (5 remoção de uma aplicação instalada no cartão, entre outras. Para a realização do trabalho serão seguida a seguinte metodologia: levantamento bibliográfico sobre o tema; definição dos aperfeiçoamentos necessários ao SMART SHELL; implementação dos aperfeiçoamentos propostos; e implementação da interface gr

  9. APLICAÇÃO DA FERRAMENTA FMEA: ESTUDO DE CASO EM UMA EMPRESA DO SETOR DE

    Directory of Open Access Journals (Sweden)

    Leandro Cantorski da Rosa

    2007-06-01

    Full Text Available Este trabalho apresenta um estudo de caso em que se implantou a ferramenta Failure Modes and Effects Analysis (FMEA emuma empresa atuante no segmento de transporte terrestre e aéreo de passageiros e cargas. O objetivo deste estudo de caso foideterminar, com a ferramenta FMEA, ações que minimizem ou eliminem modos de falha em potencial em um dos desdobramentos deserviços prestados pela empresa. O ponto específico onde se implantou a ferramenta foi na gestão dos pneus dos veículos de transporteterrestre de passageiros, pois falhas relacionadas a este componente aumentam os custos de manutenção da empresa e tendem a gerarinsatisfações aos clientes. Também foram utilizadas, incorporadas à ferramenta FMEA, outras ferramentas da qualidade como oBrainstorming, Diagrama de Ishikawa e Gráfico de Pareto. Os resultados do trabalho foram alcançados ao se determinar ações quetrazem consigo o objetivo principal deste estudo, isto é, o aumento de confiabilidade e qualidade do serviço prestado. Deste modo, arealização do presente estudo de caso proporcionou um maior entendimento acerca da temática proposta, além de mostrar aimportância da gestão da qualidade nos dias atuais e frente as crescentes exigências dos clientes.

  10. Pengaruh Ball Peening terhadap Kekerasan Baja Tahan Karat AISI 316L

    Directory of Open Access Journals (Sweden)

    Teguh Dwi Widodo

    2017-03-01

    Full Text Available In this work, ball peening was performed in order to evaluate its effect on the AISI 316L hardness. The process was conducted by employing AISI E52100 Chrome Steel ball which has hardness 752 HVN as bomber. In this research ball peening process was performed at three different nozzle pressure (6, 7, and 8 bar for 5 minutes. Vickers Micro Hardness Tester and Digital Optical Microscope was used to characterize the samples hardness and grains structure respectively. The results showed that the hardness of AISI 316L was improved. It may due to plastic deformation which toke places on its grains.

  11. Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy

    Science.gov (United States)

    Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

    2011-01-01

    Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction). PMID:28817030

  12. Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy.

    Science.gov (United States)

    Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

    2011-12-23

    Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction).

  13. PERFORMANCE STUDY ON AISI316 AND AISI410 USING DIFFERENT LAYERED COATED CUTTING TOOLS IN CNC TURNING

    Directory of Open Access Journals (Sweden)

    K. RAJA

    2015-01-01

    Full Text Available Stainless steel (SS is used for many commercial and industrial applications owing to its high resistance to corrosion. It is too hard to machine due to its high strength and high work hardening property. A surface property such as surface roughness (SR is critical to the function-ability of machined components. SS is generally regarded as more difficult to machine material and poor SR is obtained during machining. In this paper an attempt has been made to investigate the SR produced by CNC turning on austenitic stainless steel (AISI316 and martensitic stainless steel (AISI410 by different cases of coated cutting tool used at dry conditions. Multilayered coated with TiCN/Al2O3, multilayered coated with Ti(C, N, B and single layered coated with TiAlN coated cutting tools are used. Experiments were carried out by using Taguchi’s L27 orthogonal array. The effect of cutting parameters on SR is evaluated and optimum cutting conditions for minimizing the SR are determined. Analysis of variance (ANOVA is used for identifying the significant parameters affecting the responses. Confirmation experiments are conducted to validate the results obtained from optimization.

  14. Tig welding of stainless steel AISI 316 tubes for fuel rods

    International Nuclear Information System (INIS)

    Siqueira Queiroz Bittencourt, M. de.

    1985-01-01

    Sealing of austenitic stainless steel AISI 316 tubes (20% cold worked). By welding end-caps material was studied, aiming their utilization as fuel rods for nuclear reactors. It was used the autogenous TIG welding process. (author)

  15. Hardness of AISI type 410 martensitic steels after high temperature irradiation via nanoindentation

    Science.gov (United States)

    Waseem, Owais Ahmed; Jeong, Jong-Ryul; Park, Byong-Guk; Maeng, Cheol-Soo; Lee, Myoung-Goo; Ryu, Ho Jin

    2017-11-01

    The hardness of irradiated AISI type 410 martensitic steel, which is utilized in structural and magnetic components of nuclear power plants, is investigated in this study. Proton irradiation of AISI type 410 martensitic steel samples was carried out by exposing the samples to 3 MeV protons up to a 1.0 × 1017 p/cm2 fluence level at a representative nuclear reactor coolant temperature of 350 °C. The assessment of deleterious effects of irradiation on the micro-structure and mechanical behavior of the AISI type 410 martensitic steel samples via transmission electron microscopy-energy dispersive spectroscopy and cross-sectional nano-indentation showed no significant variation in the microscopic or mechanical characteristics. These results ensure the integrity of the structural and magnetic components of nuclear reactors made of AISI type 410 martensitic steel under high-temperature irradiation damage levels up to approximately 5.2 × 10-3 dpa.

  16. Effect of tip relief on endurance characteristics of super nitralloy and AISI M-50 spur gears

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.

    1974-01-01

    Tests were conducted with two groups of 8.89-centimeter (3.5-in.) pitch diameter spur gears with standard 20 deg involute profile with tip relief made of CVM Super-Nitralloy (5Ni-2Al) and CVM AISI M-50 at a temperature of 350 K (170 F). Super-Nitralloy gears with tip relief had a life 150 percent that of gears without tip relief. An increased scoring phenomenon was noted with the Super-Nitralloy gears with tip relief. Through-hardened AISI M-50 gears with tip relief failed due to tooth fracture. AISI M-50 gears without tip relief had a life approximately 40 times greater than the AISI M-50 gears with tip relief.

  17. Aplicação de ferramentas Lean na indústria cerâmica

    OpenAIRE

    Silva, Tiago Gomes

    2014-01-01

    O presente trabalho expõe o estudo e melhoria do processo de enchimento de peças a alta pressão na Vista Alegre, através da aplicação de ferramentas Lean. É apresentada uma revisão de literatura, visando o desenvolvimento da metodologia apropriada à aplicação ao projeto. Por meio da utilização de ferramentas Lean, tais como o mapeamento de fluxo de valor e balanceamento de linhas, foi possível aumentar em 25% a eficiência do processo e melhorar os índices de produtividade. Ainda que cer...

  18. Governamentalidade como ferramenta conceitual na pesquisa de políticas educacionais

    OpenAIRE

    Fimyar, Olena; Veiga-Neto, Alfredo José da

    2009-01-01

    Este artigo trata da governamentalidade, como ferramenta conceitual, na pesquisa em Ciências Humanas; particularmente, em estudos sobre políticas educacionais. Examinam-se as principais definições de governamentalidade apresentada por Foucault (1991). Argumento que a governamentalidade não constitui um enquadramento teórico fechado, mas é operacionalizada como ferramenta analítica genérica. A percepção desigual de governamentalidade nos estudos educacionais é discutida na segunda parte do ens...

  19. Texture evolution in thin-sheets on AISI 301 metastable stainless steel under dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.Y. [Posco Steels, Pohan, South Korea (Korea, Republic of); Kozaczek, K. [Oak Ridge National Lab., TN (United States); Kulkarni, S.M. [TRW Vehicle Safety Systems, Mesa, AZ (United States); Bastias, P.C.; Hahn, G.T. [Vanderbilt Univ., Nashville, TN (United States)

    1995-05-08

    The evolution of texture in thin sheets of metastable austenitic stainless steel AISI 301 is affected by external conditions such as loading rate and temperature, by inhomogeneous deformation phenomena such as twinning and shear band formation, and by the concurent strain induced phase transformation of the retained austenitc ({gamma}) into martensite ({alpha}). The present paper describes texture measurements on different gauges of AISI 301 prior and after uniaxial stretching under different conditions.

  20. Friction welding of Al-Cu-SiC composite to AISI 304 austenitic stainless steel

    OpenAIRE

    Özdemir, Niyazi; Balaban, Zülküf

    2017-01-01

    The present study investigates thefeasibility of joining an aluminium matrix composite reinforced with 5, 10 and15 vol. % of SiCp particles to AISI 304 austenitic stainless steel by usingfriction welding technique. In the present study, optical and electronmicroscopy as well as lap shear strength test and microhardness measurementswere used to evaluate the quality of bonding of Al-Cu-SiC and AISI 304austenitic stainless steel joints produced by friction welding

  1. Nitriding Process Characterization of Cold Worked AISI 304 and 316 Austenitic Stainless Steels

    OpenAIRE

    Monteiro, Waldemar Alfredo; Pereira, Silvio Andre Lima; Vatavuk, Jan

    2017-01-01

    The nitriding behavior of austenitic stainless steels (AISI 304 and 316) was studied by different cold work degree (0% (after heat treated), 10%, 20%, 30%, and 40%) before nitride processing. The microstructure, layer thickness, hardness, and chemical microcomposition were evaluated employing optical microscopy, Vickers hardness, and scanning electron microscopy techniques (WDS microanalysis). The initial cold work (previous plastic deformations) in both AISI 304 and 306 austenitic stainless ...

  2. Hardness evolution on annealing in AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Lopez, A.; Alvarez de Sotomayor, A.; Herrera, E. J.

    2001-01-01

    The evolution of the microstructure and hardness of commercial AISI 304 stainless-steel samples with the heat treatment has been studied. Steel specimens in the as-received condition, and after 50% cold rolling, were soaked for 1 hour at various temperatures between 650 and 1200 degree centigree Samples maintain their grain size and hardness until about 900 degree centigree, thereafter, size increases with temperature, while hardness lightly diminishes. Recrystallization of cold-rolled specimens begins at 650 degree centigree, and finishes around 850 degree centigree. Recrystallized grain-size reaches the value found in the as received materials after the treatment at 900 degree centigree. For high her annealing temperatures both grain growth and hardness decrease following the same trend in cold-worked and non-deformed materials. (Author) 10 refs

  3. Study of discordancy mobility in the AISI 304 steel

    International Nuclear Information System (INIS)

    Lima, L.F.C.P. de; Miranda, P.E.V. de; Monteiro, S.N.

    1987-01-01

    Internal Friction (IF), measurements were carried out in a type AISI 304 austenitic stainless steels at approximately 1HZ of frequency in the temperature interval from 120 to 573K. The IF spectra and the vibration frequency were obtained in samples were submitted to specific heat treatments. The results showed IF spectra with a well defined peak at 260K. The intensity dependes on the amount of plastic deformation previously introduced in the sample. Another broad peak was detected between 300 and 400K. Both peaks could only be detected after plastic deformation in uniaxial tension or torsion. In torsionably deformed samples at liquid nitrogen temperature, 77 K, the IF spectrum is observed only after linear annealing at 400K. This apparently results from a high damping due to a possible phase transformation which occurs around room temperature. The broad peak at higher temperature is sensitive to recovery induced by linear annealings. (Author) [pt

  4. Radiation-induced phase development in AISI 316

    International Nuclear Information System (INIS)

    Yang, W.J.S.; Brager, H.R.; Garner, F.A.

    1980-09-01

    During irradiation at temperatures between 460 and 650 0 C, the alloy AISI 316 decomposes into an austenite matrix of altered composition and some mixture of six possible precipitate phases. These phases are γ', G, eta-silicide, M 23 C 6 , M 6 C, and Laves. The balance of phases developed is exceptionally sensitive to a large number of material and environmental variables and frequently varies within a single grain. All of these phases are found to be either naturally rich in nickel and silicon or to become progressively enriched in these elements as the irradiation proceeds. The precipitates can be considered to be classified as thermally stable but modified, irradiation-enhanced, irradiation-induced, and irradiation-transformed

  5. Corrosion of AISI 304 stainless steel in polluted seawater

    International Nuclear Information System (INIS)

    Brankevich, G.; Guiamet, P.; Videla, H.A.

    1987-01-01

    The sequence of microbiofouling settlement on AISI 304 stain steel samples exposed to polluted harbor sea water of a power cooling water intake is studied. The firts sates of bacterial colonization are followed by means of scanning electron microscopy during two weeks of exposure. The relation between microbiofouling and corrosion is also followed by scanning electron microscopy and evaluated through electrochemical polarization experiments. The results obtained show that microbial colonization and extracellular polimeric substances forming the biofilms have a marked influence on the electrochemical behaviour of stainless steel in sea water. Laboratory experiments using inorganic chloride solutions or artificial sea water show a considerably lesser attack of the metal than those performed 'in situ' with natural sea water. Passivity breadown is highly facilitated when complex biological and inorganic deposits (fouling) have settled on the metal surface. (Author) [pt

  6. Fretting of AISI 9310 and selected fretting resistant surface treatments

    Science.gov (United States)

    Bill, R. C.

    1977-01-01

    Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, alumimum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a self-lubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

  7. Sputtering of the 1020 AISI steel in abnormal glow discharge

    Science.gov (United States)

    García Zúñiga, J. A.; Sarmiento Santos, A.; Álvarez Luna, B.

    2017-12-01

    In all material treated in Sbnormal Glow Discharge (AGD) the phenomenon of sputtering occurs. In this work we study the sputtering suffered at different temperatures by AISI 1020 steel subjected to a DC discharge in two types of atmospheres. The steel samples were previously sanded until obtaining mirror brightness and subjected to the AGD plasma in the gaseous atmospheres of H2 and Ar. The temperature for each sputtering process was set in the range of 420°C to 600°C. In these samples the mass variation was measured and the yield sputtering processes was determined. Next, the simulation of the sputtering process was performed in the SRIM/TRIM 2008 software, by adjusting sputtering yield computational computations to those experimentally measured, in order to determine the energy with which the responsible ions of the sputtering collide with studied target.

  8. Validity and Reliability of the Attachment Insecurity Screening Inventory (AISI) 2-5 Years.

    Science.gov (United States)

    Wissink, I B; Colonnesi, C; Stams, G J J M; Hoeve, M; Asscher, J J; Noom, M J; Polderman, N; Kellaert-Knol, M G

    The Attachment Insecurity Screening Inventory (AISI) 2-5 years is a parent-report questionnaire for assessing attachment insecurity in preschoolers. Validity and reliability of the AISI 2-5 years were examined in a general sample ( n  = 429) and in a clinical sample ( n  = 71). Confirmatory factor analysis (CFA) confirmed a three-factor model of avoidant, ambivalent/resistant and disorganized attachment, and one higher-order factor of total attachment insecurity. Multi-group CFA indicated measurement invariance across mothers and fathers, and across the general and clinical population sample. Reliability coefficients were generally found to be good. We found partial support for convergent validity in associations between AISI-scores and observed attachment (AQS). Concurrent validity was supported by associations between AISI-scores and observed parental sensitivity (MBQS) and parent-reported psychopathology (SDQ). Finally, the AISI discriminated well between children from the general and from the clinical sample. We argue that both research and practice could benefit from the AISI as there is now a prospect of quickly, reliably and validly screening for attachment insecurity in pre-school aged children. Based on this information, help can be offered timely and, subsequently, the prevention of attachment related problems of children can be strengthened.

  9. A life study of ausforged, standard forged, and standard machined AISI M-50 spur gears

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.; Bamberger, E. N.

    1975-01-01

    Tests were conducted at 350 K with three groups of 8.9 cm pitch diameter spur gears made of vacuum-induction melted (VIM), vacuum-arc remelted (VAR), AISI M-50 steel and one group of vacuum-arc remelted (VAR) AISI 9310 steel. The pitting fatigue life of the standard forged and ausforged gears was approximately five times that of the VAR AISI 9310 gears and ten times that of the bending fatigue life of the standard machined VIM-VAR AISI M-50 gears run under identical conditions. There was a slight decrease in the 10-percent life of the ausforged gears from that for the standard forged gears. However, the difference is not statistically significant. The standard machined gears failed primarily by gear tooth fracture while the forged and ausforged VIM-VAR AISI M-50 and the VAR AISI 9310 gears failed primarily by surface pitting fatigue. The ausforged gears had a slightly greater tendency to fail by tooth fracture than the standard forged gears.

  10. Physical properties of the AISI 348 L{sup *} austenitic stainless steel; Propriedades fisicas do aco inoxidavel austenitico AISI 348 L{sup *}

    Energy Technology Data Exchange (ETDEWEB)

    Teodoro, Celso Antonio; Lucki, Georgi; Silva, Jose Eduardo Rosa da; Terremoto, Luis Antanio Albiac; Castanheira, Myrthes; Damy, Margaret de Almeida [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: cteodoro@ipen.br

    2005-07-01

    The study of radiation damage in metals and alloys, used as structural materials of nuclear reactors has a strategic meaning in nuclear technology, because it allows the performance evaluation of these materials in working conditions of PWR. For this sake it is necessary to know the detrimental structural changes that occur during fast neutron irradiation. The aim of the present work is to show some strain-stress results of the AISI 348 L{sup *} stainless steel utilized as a structural material of the fuel elements of PWR, in comparison with the AISI 304. (author)

  11. Study of residual stresses generated in machining of AISI 4340 steel; Estudo das tensoes residuais geradas na usinagem de aco AISI 4340

    Energy Technology Data Exchange (ETDEWEB)

    Reis, W.P. dos; Fonseca, M.P. Cindra; Serrao, L.F.; Chuvas, T.C.; Oliveira, L.C., E-mail: mcindra@vm.uff.b [Universidade Federal Fluminense (PGMEC/UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    Among the mechanical construction steels, AISI 4340 has good harden ability, while combining high strength with toughness and good fatigue strength, making it excellent for application in the metalworking industry, where it can work at different levels and types of requests. Residual stresses are generated in almost all processes of mechanical manufacturing. In this study, the residual stresses generated in different machining processes and heat treatment hardening of AISI 4340 were analyzed by X-ray diffraction, by the sen{sup 2} {psi} method, using Cr{kappa}{beta} radiation and compared. All samples, except for turned and cut by EDM, presented compressive residual stresses in the surface with various magnitudes. (author)

  12. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment.

    Science.gov (United States)

    Ruiz, A; Timke, T; van de Sande, A; Heftrich, T; Novotny, R; Austin, T

    2016-06-01

    This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C) with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure.

  13. Effects of X-rays Radiation on AISI 304 Stainless Steel Weldings with AISI 316L Filler Material: A Study of Resistance and Pitting Corrosion Behavior

    Directory of Open Access Journals (Sweden)

    Francisco Javier Cárcel-Carrasco

    2016-04-01

    Full Text Available This article investigates the effect of low-level ionizing radiation, namely X-rays, on the micro structural characteristics, resistance, and corrosion resistance of TIG-welded joints of AISI 304 austenitic stainless steel made using AISI 316L filler rods. The welds were made in two different environments: natural atmospheric conditions and a closed chamber filled with inert argon gas. The influence of different doses of radiation on the resistance and corrosion characteristics of the welds is analyzed. Welded material from inert Ar gas chamber TIG showed better characteristics and lesser irradiation damage effects.

  14. Influence of process parameters on torsional strength, impact toughness and hardness of dissimilar AISI 304 and AISI 1021 friction welded steels

    Directory of Open Access Journals (Sweden)

    Amit Handa

    2014-06-01

    Full Text Available In this present study an attempt was made to join austenitic stainless steel (AISI 304 with low alloy steel (AISI 1021 at different rotational speeds and at different axial pressures and then determining the strength of the joint by means of mechanical properties such as torsional strength, impact strength and micro hardness. The experimental results indicate that the rotational speed and the axial pressure have a significant effect on the mechanical properties of the joint and it is possible to improve the quality of the joint by selecting the optimum parameters.

  15. Corrosion and microstructural analysis data for AISI 316L and AISI 347H stainless steels after exposure to a supercritical water environment

    Directory of Open Access Journals (Sweden)

    A. Ruiz

    2016-06-01

    Full Text Available This article presents corrosion data and microstructural analysis data of austenitic stainless steels AISI 316L and AISI 347H exposed to supercritical water (25 MPa, 550 °C with 2000 ppb of dissolved oxygen. The corrosion tests lasted a total of 1200 h but were interrupted at 600 h to allow measurements to be made. The microstructural data have been collected in the grain interior and at grain boundaries of the bulk of the materials and at the superficial oxide layer developed during the corrosion exposure.

  16. Comparative study of pulsed Nd:YAG laser welding of AISI 304 and AISI 316 stainless steels

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-02-01

    Laser welding is a potentially useful technique for joining two pieces of similar or dissimilar materials with high precision. In the present work, comparative studies on laser welding of similar metal of AISI 304SS and AISI 316SS have been conducted forming butt joints. A robotic control 600 W pulsed Nd:YAG laser source has been used for welding purpose. The effects of laser power, scanning speed and pulse width on the ultimate tensile strength and weld width have been investigated using the empirical models developed by RSM. The results of ANOVA indicate that the developed models predict the responses adequately within the limits of input parameters. 3-D response surface and contour plots have been developed to find out the combined effects of input parameters on responses. Furthermore, microstructural analysis as well as hardness and tensile behavior of the selected weld of 304SS and 316SS have been carried out to understand the metallurgical and mechanical behavior of the weld. The selection criteria are based on the maximum and minimum strength achieved by the respective weld. It has been observed that the current pulsation, base metal composition and variation in heat input have significant influence on controlling the microstructural constituents (i.e. phase fraction, grain size etc.). The result suggests that the low energy input pulsation generally produce fine grain structure and improved mechanical properties than the high energy input pulsation irrespective of base material composition. However, among the base materials, 304SS depict better microstructural and mechanical properties than the 316SS for a given parametric condition. Finally, desirability function analysis has been applied for multi-objective optimization for maximization of ultimate tensile strength and minimization of weld width simultaneously. Confirmatory tests have been conducted at optimum parametric conditions to validate the optimization techniques.

  17. EDUCAÇÃO AMBIENTAL COMO FERRAMENTA PARA PROMOVER MUDANÇAS ORGANIZACIONAIS

    Directory of Open Access Journals (Sweden)

    Tatiane Barbosa Trindade

    2015-09-01

    Full Text Available Este artigo tem como objetivo mostrar a importância de se investir em programas intensivos de educaçãoambiental, para que a mesma seja uma ferramenta no contexto de mudanças cultural, social e ética dentrodas organizações.

  18. ANÁLISE DAS SETE FERRAMENTAS ESTATÍSTICAS DA QUALIDADE UTILIZADAS NOS SISTEMAS PRODUTIVOS

    Directory of Open Access Journals (Sweden)

    Valéria Vasconcelos Perez

    2017-04-01

    Full Text Available Com o acelerado crescimento industrial, a competitividade pela eficiência da produtividade e pela disputa de clientes, fez que com as organizações tomassem a qualidade como sinônimo de sua sobrevivência ou fracasso. Com isso, a busca por métodos que auxiliem na detecção de anomalias e melhoria dos processos produtivos. As principais ferramentas estatísticas da qualidade são muito utilizadas para o auxílio na identificação de anomalias, tal como a eliminação das mesmas e ainda proporcionam ao gerente de produção a tomar decisões para a melhoria do processo. Este artigo objetiva buscar conhecimento das ferramentas estatísticas a partir da revisão da literatura. A partir da abordagem da revisão da literatura, foi feita uma pesquisa descritiva, sendo abordado dois estudos de casos que utilizaram as ferramentas da qualidade enfatizando qual ferramenta fora utilizada, sendo estas o Diagrama de Causa e Efeito, Diagrama de Dispersão, Gráfico de Pareto, Histograma, Folha de Verificação, Gráfico de Controle e qual foi a principal função das mesmas. Por fim, de acordo com os resultados analisados é possível afirmar que as ferramentas estatísticas da qualidade foram utilizadas corretamente e ainda as mesmas foram aptas para a análise do processo, tal como indicar possíveis oportunidades de melhorias do processo.

  19. Microstructural characterization of an AISI-SAE 4140 steel without nitridation and nitrided; Caracterizacion microestructural de un acero AISI-SAE 4140 sin nitrurar y nitrurado

    Energy Technology Data Exchange (ETDEWEB)

    Medina F, A.; Naquid G, C. [Gerencia de Ciencia de Materiales, Depto. de Sintesis y Caracterizacion de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2000-07-01

    It was micro structurally characterized an AISI-SAE 4140 steel before and after of nitridation through the nitridation process by plasma post-unloading microwaves through Optical microscopy (OM), Scanning electron microscopy (SEM) by means of secondary electrons and retrodispersed, X-ray diffraction (XRD), Energy dispersion spectra (EDS) and mapping of elements. (Author)

  20. Modelo paramétrico de pórticos em concreto armado com dimensionamento otimizado: uma proposta de ferramenta de projeto para as fases iniciais de concepção estrutural

    Directory of Open Access Journals (Sweden)

    Felipe Tavares da Silva

    Full Text Available Resumo Comumente, a concepção de sistema estrutural e seu projeto preliminar deveriam estar nos estágios iniciais do desenvolvimento do projeto da forma arquitetônica. Tradicionalmente, estudos sugerem regras de pré-dimensionamento dadas por relações entre a dimensão transversal e o comprimento de vãos. Para ajudar nesse processo, este artigo propõe um protótipo de ferramenta de projeto paramétrico estrutural para uma estrutura tridimensional de pórticos rígidos em concreto armado com vigas, colunas e lajes maciças. Os dados de entrada manipuláveis pelo usuário dessa ferramenta são as dimensões globais da estrutura, a resistência característica do concreto, a taxa de armadura dos pilares, o limite admissível do deslocamento do sistema de piso, o valor de cargas sobre lajes e vigas e as dimensões das seções transversais das peças. A obtenção das soluções desse sistema foi realizada utilizando um algoritmo genético acoplado ao algoritmo proposto. Como produto, obtém-se um modelo geométrico da estrutura com as espessuras visualizadas em tempo real na janela do sistema CAD, atualizado de acordo com as mudanças nos dados de entrada. Foram realizadas comparações do desempenho dessa ferramenta em relação a outras propostas anteriores e análises críticas sobre sua possibilidade de uso corrente para o auxílio do trabalho transdisciplinar em projeto de edificações.

  1. The Surface Fatigue Life of Contour Induction Hardened AISI 1552 Gears

    Science.gov (United States)

    Townsend, Dennis P.; Turza, Alan; Chaplin, Mike

    1995-01-01

    Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for surface fatigue life. One group was manufactured from AISI 1552 and was finished ground to a 0.4 micron (16 micro-in.) rms surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 micron (16 micro-in.) rms surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 GPa (248 ksi), a bulk gear temperature of approximately 350 K (170 F) and a speed of 10,000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent surface fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AISI 1552 gears by bending fatigue.

  2. Nitriding Process Characterization of Cold Worked AISI 304 and 316 Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Waldemar Alfredo Monteiro

    2017-01-01

    Full Text Available The nitriding behavior of austenitic stainless steels (AISI 304 and 316 was studied by different cold work degree (0% (after heat treated, 10%, 20%, 30%, and 40% before nitride processing. The microstructure, layer thickness, hardness, and chemical microcomposition were evaluated employing optical microscopy, Vickers hardness, and scanning electron microscopy techniques (WDS microanalysis. The initial cold work (previous plastic deformations in both AISI 304 and 306 austenitic stainless steels does not show special influence in all applied nitriding kinetics (in layer thicknesses. The nitriding processes have formed two layers, one external layer formed by expanded austenite with high nitrogen content, followed by another thinner layer just below formed by expanded austenite with a high presence of carbon (back diffusion. An enhanced diffusion can be observed on AISI 304 steel comparing with AISI 316 steel (a nitrided layer thicker can be noticed in the AISI 304 steel. The mechanical strength of both steels after nitriding processes reveals significant hardness values, almost 1100 HV, on the nitrided layers.

  3. The Forming of AISI 409 sheets for fan blade manufacturing

    International Nuclear Information System (INIS)

    Foroni, F. D.; Menezes, M. A.; Moreira Filho, L. A.

    2007-01-01

    The necessity of adapting the standardized fan models to conditions of higher temperature has emerged due to the growth of concern referring to the consequences of the gas expelling after the Mont Blanc tunnel accident in Italy and France, where even though, with 100 fans in operation, 41 people died. The objective of this work is to present an alternative to the market standard fans considering a new technology in constructing blades. This new technology introduces the use of the stainless steel AISI 409 due to its good to temperatures of gas exhaust from tunnels in fire situation. The innovation is centered in the process of a deep drawing of metallic sheets in order to keep the ideal aerodynamic superficies for the fan ideal performance. Through the impression of circles on the sheet plane it is shown, experimentally, that, during the pressing process, the more deformed regions on the sheet plane of the blade can not reach the deformation limits of the utilized sheet material

  4. High-temperature thermal fatigue of AISI 316L steel

    International Nuclear Information System (INIS)

    Petersen, C.; Rubiolo, G.H.

    1991-01-01

    A test method for performing uniaxial low-cycle thermal fatigue tests on metals is described. The test facility consists of an ohmic heating system built in a closed loop material testing maschine. The used hollow, hourglass-shaped, tubular specimens are subjected to constant linear heating and cooling rates in a temperature range of a fixed minimum temperature (200deg C) and a variable maximum temperature (550 to 750deg C) in air atmosphere. The specimens are constrained at mean temperature and the test starts tension going towards the minimum temperature. Total mechanical strain amplitudes between 0.4 and 1.4% are evaluated by applying a strain measuring system that allows direct recording of mechanical strain by eliminatingthe thermal component from the measurable net strain. Thermal fatigue life of AISI 316 L steel is found to be shorter than isothermal, strain controlled fatigue life at a temperature equal to the mean temperature of thermal cycling and in some cases even shorter than the maximum temperature of thermal cycling. As scanning electron microscopy of failed specimens shows, crack initiation occurs in most cases on nonmetallic inclusions or impurities and the fracture topology has a typical striation appearance. (orig.)

  5. Environment-tensile property relationship in AISI 1018 steel

    International Nuclear Information System (INIS)

    Srivatsan, T.S.; Hanigofsky, M.; Auradkar, R.; Hoff, T.

    1990-01-01

    Environment-material interaction depends on several concurrent and mutually competitive variables ranging from nature of the environment to composition of the steel and including: the test temperature; the time of exposure of the material to the environment; the deformation rate; and intrinsic microstructural effects; The present work is a characterization of strain rate and environment influences on the tensile properties of a steel, AISI 1018, having a fully spheroidized microstructure. Tensile tests were performed at ambient temperature (300 K) in environments which are mildly aggressive (moist laboratory air-relative humidity 50%) and inert (dry gaseous nitrogen). The specimens were deformed to failure at strain rates of 10 -4 sec -1 and 10 -5 sec -1 . No appreciable increase in yield and tensile strengths was observed at the strain rate of 10 -4 sec -1 . However, the increase in both was of the order of 10 to 12% at the strain rate of 10 -5 sec -1 . Ductility showed no variation with strain rate, but increased in the inert environment at both strain rates. Both environment and strain rate were found to have little to no influence on reduction in area of the test specimens. The true fracture stress followed a similar trend to the yield strength and ultimate tensile strength. (author)

  6. UMA REVISÃO SISTEMÁTICA DE FERRAMENTAS DE CONSTRUÇÃO DE OBJETOS DE APRENDIZAGEM

    Directory of Open Access Journals (Sweden)

    Marcelo Werneck Barbosa

    2012-12-01

    Full Text Available Este trabalho realizou uma revisão sistemática de ferramentas de criação de objetos de aprendizagem. O intuito foi encontrar ferramentas de construção de OAs que possam ser usadas por educadores ainda que estes tenham apenas conhecimentos básicos de informática. Para isso, as ferramentas levantadas foram categorizadas seguindo critérios de relevância, usabilidade e facilidade para o usuário, instaladas e testadas. Os resultados mostraram que poucas são as ferramentas acessíveis ao professor e, consequentemente, a quantidade de objetos de aprendizagem também é insuficiente para apoiar a educação.

  7. Estimating the Contact Endurance of the AISI 321 Stainless Steel Under Contact Gigacycle Fatigue Tests

    Science.gov (United States)

    Savrai, R. A.; Makarov, A. V.; Osintseva, A. L.; Malygina, I. Yu.

    2018-02-01

    Mechanical testing of the AISI 321 corrosion resistant austenitic steel for contact gigacycle fatigue has been conducted with the application of a new method of contact fatigue testing with ultrasonic frequency of loading according to a pulsing impact "plane-to-plane" contact scheme. It has been found that the contact endurance (the ability to resist the fatigue spalling) of the AISI 321 steel under contact gigacycle fatigue loading is determined by its plasticity margin and the possibility of additional hardening under contact loading. It is demonstrated that the appearance of localized deep and long areas of spalling on a material surface can serve as a qualitative characteristic for the loss of the fatigue strength of the AISI 321 steel under impact contact fatigue loading. The value of surface microhardness measured within contact spots and the maximum depth of contact damages in the peripheral zone of contact spots can serve as quantitative criteria for that purpose.

  8. Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

  9. Surface fatigue life of CBN and vitreous ground carburized and hardened AISI 9310 spur gears

    Science.gov (United States)

    Townsend, Dennis P.; Patel, P. R.

    1988-01-01

    Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9310 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temeprature of 320 K (116 F), an outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.

  10. The engineering of soft ferromagnetic plane by AISI 304 hardening process

    Science.gov (United States)

    Mubarok, Naila; Notonegoro, Hamdan Akbar; Thosin, Kemas Ahmad Zaini; Manaf, Azwar

    2017-01-01

    Austenitic stainless steels AISI 304 are widely used in engineering applications for various industrial applications. In basic condition, AISI 304 is non-magnetic. Shifting the structure through the hardening process will affect the magnetic properties. This technique makes it possible to produce soft ferromagnetic material through mechanical processes. A percentage of thinning rate correlated linearly with the thickness of the sample. Sizeable changing occurred at 21-30 HVC. The hysteresis curve shows the soft ferromagnetic property with small coercivity. The magnetic value significantly increased found at 344 HVC to 371 HVC and maximum when reaching 425 HVC. We suggest a 60% of thinning as a better hardening process for manufacturing soft ferromagnetic material from AISI 304.

  11. Corrosion resistance of the AISI 304, 316 and 321 stainless steel surfaces modified by laser

    Science.gov (United States)

    Szubzda, B.; Antończak, A.; Kozioł, P.; Łazarek, Ł.; Stępak, B.; Łęcka, K.; Szmaja, A.; Ozimek, M.

    2016-02-01

    The article presents the analysis results of the influence of laser fluence on physical and chemical structure and corrosion resistance of stainless steel surfaces modified by irradiating with nanosecond-pulsed laser. The study was carried out for AISI 304, AISI 316 and AISI 321 substrates using Yb:glass fiber laser. All measurements were made for samples irradiated in a broad range of accumulated fluence (10÷400 J/cm2). The electrochemical composition (by EDX) and surface morphology (by SEM) of the prepared surfaces were carried out. Finally, corrosion resistance was analyzed by a potentiodynamic electrochemical test. The obtained results showed very high corrosion resistance for samples made by fluency of values lower than 100 J/cm2. In this case, higher values of corrosion potentials and breakdown potentials were observed. A correlation between corrosion phenomena, the range of laser power (fluence) and the results of chemical and structural tests were also found.

  12. Evaluation of AISI 316L stainless steel welded plates in heavy petroleum environment

    International Nuclear Information System (INIS)

    Carvalho Silva, Cleiton; Pereira Farias, Jesualdo; Batista de Sant'Ana, Hosiberto

    2009-01-01

    This work presents the study done on the effect of welding heating cycle on AISI 316L austenitic stainless steel corrosion resistance in a medium containing Brazilian heavy petroleum. AISI 316L stainless steel plates were welded using three levels of welding heat input. Thermal treatments were carried out at two levels of temperatures (200 and 300 deg. C). The period of treatment in all the trials was 30 h. Scanning electronic microscopy (SEM) and analysis of X-rays dispersive energy (EDX) were used to characterize the samples. Weight loss was evaluated to determine the corrosion rate. The results show that welding heating cycle is sufficient to cause susceptibility to corrosion caused by heavy petroleum to the heat affected zone (HAZ) of the AISI 316L austenitic stainless steel

  13. Evolution of sensitization in stainless steel AISI 304; Evaluacion del grado de sensibilizacion en el acero ionxidable AISI 304

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, O.; Santos, G.

    2003-07-01

    Austenitic stainless steel, when heat-treated at 550-850 degree centigree became susceptible to intergranular corrosion in acids. this phenomenon, know as sensitization, it is result from the precipitation of chrome carbides in the grain boundary, making these areas less resistant to corrosion. Two different electrochemical reactivation tests are compared with a destructive test and related to the classification of its respective microstructures. It was established a quantitative methodology to evaluate the degree of sensitization in AISI 304and also to compare the correspondence of the results with the data of the automatic and portable EPR device for non-destructive field measurement of the degree of sensitization. The used electrochemical techniques were the EPR (Electrochemical Potentiokinetic Reactivation) or single loop test and the PRP (Pasivation Reactivation Potentiokinetic) or double loop test. The destructive test used was boiling, 120 h ferric sulfate-50% sulfuric acid, according to the standard practices ASTM A-262 practices B. The classifications of etch structures were according to the standard practices ASTM A-262 practices B. (Author)

  14. The Influence of The Temperature on Dry Friction of AISI 3315 Steel Sliding Against AISI 3150 Steel

    Science.gov (United States)

    Odabas, D.

    2018-01-01

    In this paper, the effects the influence of frictional heating on the wear of AISI 3315 Steel were investigated experimentally using a pin-on-ring geometry. All the tests were carried out in air without any lubricant. In order to understand the variation in frictional coefficient and temperature with load and speed, the friction tests were carried out at a speed of 1 m/s and loads in the range 115-250 N, and at a speed range 1-4 m/s, a load of 115 N. The sliding distance was 1500 m. The bulk temperature of the specimen was measured from the interface surface at a distance of 1 mm from the contact surface by using type K thermocouples (Ni-Cr-Ni). The coefficient of friction was determined as a function of test load and speed. The steady state coefficient of friction of the test material decreases with increasing load and speed due to the oxide formation. But the unsteady state coefficient of friction increases with an increase in load and speed.

  15. Uma ferramenta didática para o dimensionamento e detalhamento de pilares de concreto armado

    Directory of Open Access Journals (Sweden)

    A. B. Colombo

    Full Text Available Este texto apresenta uma ferramenta didática desenvolvida para o dimensionamento e detalhamento de pilares de concreto armado. São apresentadas as funcionalidades básicas do aplicativo e o processo de validação dos resultados obtidos. Um exemplo de dimensionamento de um pilar utilizando as expressões da norma brasileira de projeto de estruturas de concreto, NBR6118:2003, também é apresentado.

  16. Estudio de microestructura y composición de la oxidación en vapor a 700 y 750oC de los aceros austeníticos AISI 304, 316 y 317

    Directory of Open Access Journals (Sweden)

    José Luddey Marulanda

    2013-01-01

    Full Text Available Se ha investigado la oxidación de los aceros inoxidables austeníticos AISI SAE: 304, 316 y 317; a temperaturas de 700 y 750oC, en una atmósfera próxima al 100% de vapor de agua, y de 10 a 1000h de exposición. La finalidad es comprobar la calidad de los aceros austeníticos y estudiar la morfología, composición y estructura de la fases de las capas formadas en la cascarilla del óxido de las muestras por Microscopía Electrónica de Barrido (SEM, Análisis de Rayos X por Dispersión de Energía (EDAX y Difracción de Rayos X (XRD, respectivamente. Así como también, se ha realizado a diferentes tiempos un estudio sistemático de termogravimetría de las muestras oxidadas, donde se ha observado que el acero AISI 304 presentó la menor ganancia de masa y el acero AISI 316 fue el de mayor de masa respecto a los tres aceros del trabajo. Adicionalmente fue realizado un estudio teórico de simulación termodinámica de oxidación en vapor de los tres aceros, en las mismas condiciones experimentales y mediante el programa Thermo-calc. En estos aceros oxidados se han comprobado la presencia de estructuras de fases de óxidos como: Fe2O3, espinelas protectoras Fe3O4 y Cr2NiO4, y óxidos mixtos de tipo (CrxFey2O3, (Fe,Cr,Mn3O4 y Ni6MnO8. Finalmente, se discute un posible mecanismo de la formación de las capas de óxidos de las muestras ensayadas.

  17. Damage Mechanisms in AISI 304 Borided Steel: Scratch and Daimler-Benz Adhesion Tests

    OpenAIRE

    Rodríguez-Castro, German Anibal; Jiménez-Tinoco, Luis Fernando; Méndez-Méndez, Juan Vicente; Arzate-Vázquez, Israel; Meneses-Amador, Alfonso; Martínez-Gutiérrez, Hugo; Campos-Silva, Iván

    2015-01-01

    In this study, damage mechanisms in the FeB/Fe2B coatings formed on the surface of AISI 304 steel are determined by adhesion tests. First, the boriding of the AISI 304 steel was carried out through the powder-pack method at 1223 K in the range from 2-10 h of exposure time. After treatment, Berkovich depth-sensing indentation test were conducted; the result showed tensil and compressive residual stresses in the FeB and Fe2B, respectively. The adhesion of borided steels was evaluated by the Dai...

  18. Effect of cold working on nitriding process of AISI 304 and 316 austenitic stainless steel

    International Nuclear Information System (INIS)

    Pereira, Silvio Andre de Lima

    2012-01-01

    The nitriding behavior of AISI 304 and 316 austenitic stainless steel was studied by different cold work degree before nitriding processes. The microstructure, thickness, microhardness and chemical micro-composition were evaluated through optical microscopy, microhardness, scanner electronic microscopy and x ray diffraction techniques. Through them, it was observed that previous plastic deformations do not have influence on layer thickness. However, a nitrided layer thicker can be noticed in the AISI 304 steel. In addition, two different layers can be identified as resulted of the nitriding, composed for austenitic matrix expanded by nitrogen atoms and another thinner immediately below expanded by Carbon atoms. (author)

  19. Study of residual stresses generated in machining of AISI 4340 steel

    International Nuclear Information System (INIS)

    Reis, W.P. dos; Fonseca, M.P. Cindra; Serrao, L.F.; Chuvas, T.C.; Oliveira, L.C.

    2010-01-01

    Among the mechanical construction steels, AISI 4340 has good harden ability, while combining high strength with toughness and good fatigue strength, making it excellent for application in the metalworking industry, where it can work at different levels and types of requests. Residual stresses are generated in almost all processes of mechanical manufacturing. In this study, the residual stresses generated in different machining processes and heat treatment hardening of AISI 4340 were analyzed by X-ray diffraction, by the sen 2 ψ method, using Crκβ radiation and compared. All samples, except for turned and cut by EDM, presented compressive residual stresses in the surface with various magnitudes. (author)

  20. Characterization of Tungsten Carbide coatings deposited on AISI 1020 steel

    International Nuclear Information System (INIS)

    Santos, A; Gonzalez, C; Ramirez, Z Y

    2017-01-01

    In order to determine the variation in the mechanical properties of AISI 1020 standardized steel, heat treated by a quenching and tempering process and with a Tungsten Carbide coating, was performed a microstructural and chemical characterization of the coating material through electron microscopy scanning and X-ray energy dispersive spectroscopy. The steel received a heat treatment of quenching performed by heating to 850°C, followed by cooling in water and tempering at a temperature of 450°C with air cooling. Tests of a) microhardness with a Wilson-Wolpert Tukon 2100B micro durometer and b) resistance to adhesive and abrasive wear following the ASTM G99-05 “Standard test method for wear testing with a pin-on-disk machine” and ASTM G65-04 “standard test method for measuring abrasion using dry sand and rubber Wheel” standards respectively. The results show that the microhardness of the steel do not vary with the load used to perform the test; in addition, the heat treatment of quenching and tempering improves by 5.5% the property while the coating increase it by 124.2%. Regarding the abrasive wear resistance, it is observed that the amount of material lost increases linearly with the distance covered. It was determined that the heat treatment decreased on average by 17.5% the volume of released material during the tests while the coating recued it by 66.7%. The amount volume of material lost during the adhesive wear tests increases linearly with the distance covered while the heat treatment decreased on average by 10.5% the volume of released material during the trial and the coating reduced it by 66.5%. (paper)

  1. Biomaterial Studies on AISI 316L Stainless Steel after Magnetoelectropolishing

    Science.gov (United States)

    Hryniewicz, Tadeusz; Rokosz, Krzysztof; Filippi, Massimiliano

    2009-01-01

    The polarisation characteristics of the electropolishing process in a magnetic field (MEP – magnetoelectropolishing), in comparison with those obtained under standard/conventional process (EP) conditions, have been obtained. The occurrence of an EP plateau has been observed in view of the optimization of MEP process. Up-to-date stainless steel surface studies always indicated some amount of free-metal atoms apart from the detected oxides and hydroxides. Such a morphology of the surface film usually affects the thermodynamic stability and corrosion resistance of surface oxide layer and is one of the most important features of stainless steels. With this new MEP process we can improve metal surface properties by making the stainless steel more resistant to halides encountered in a variety of environments. Furthermore, in this paper the stainless steel surface film study results have been presented. The results of the corrosion research carried out by the authors on the behaviour of the most commonly used material − medical grade AISI 316L stainless steel both in Ringer’s body fluid and in aqueous 3% NaCl solution have been investigated and presented earlier elsewhere, though some of these results, concerning the EIS Nyquist plots and polarization curves are also revealed herein. In this paper an attempt to explain this peculiar performance of 316L stainless steel has been undertaken. The SEM studies, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on 316L samples after three treatments: MP – abrasive polishing (800 grit size), EP – conventional electrolytic polishing, and MEP – magnetoelectropolishing. It has been found that the proposed magnetoelectropolishing (MEP) process considerably modifies the morphology and the composition of the surface film, thus leading to improved corrosion resistance of the studied 316L SS.

  2. Study of radiation damages in AISI 316 and 347 steels

    International Nuclear Information System (INIS)

    Santos, G.R. dos.

    1993-03-01

    The CV-28 cyclotron at IEN (Nuclear Engineering Institute) has been used to simulated, in a short time scale, uniform He concentrations produced during neutron irradiation of metals by (n, α) reactions. Helium was implanted at concentrations of 1 to 300 ppm in 100 μm thick sheet samples of AISI 316 and 347 S S by degrading a 28 MeV alpha particle beam with a rotating energy degrader. The effects of He on the mechanical properties of the steels were studied by both non-destructive (positron annihilation) and destructive tests (tensile, creep, TEM and SEM). The positron lifetime measurements of irradiated and annealed samples were used as the base to discuss the He diffusion mechanism. Activation energies of 0.34±0.04 eV for 316 S S and 0.57±0.06 eV for 347 S S, characterized a dissociative process above 650 0 C. TEM analyses have suggested the Ostwald ripening process for bubble growth over the full range of He concentrations studied. It was shown, in agreement with theoretical calculations that, by themselves the displacements produced during the helium implantation, at rate of 1.8 x 10 -3 d pa/ppm, were not sufficient to cause significant changes in ductility. However, a strong ductility loss with increasing He concentration was observed for both types of steel for tensile tests at 25 0 C, as well as in creep at 750 0 C over the range of strain (100 to 200 MPa). Finally, it was shown that charged particle simulation associated with positron annihilation techniques provides a fast, relatively low cost, and useful method to study different kinds of neutron damage in materials. (author)

  3. A biorremediação como ferramenta para a descontaminação de ambientes terrestres e aquáticos

    Directory of Open Access Journals (Sweden)

    Danielle Arruda Carneiro

    2011-04-01

    Full Text Available A biorremediação é um processo do qual se utilizam micro-organismos na remoção de contaminantes tóxicos do meio ambiente. Essa técnica é bastante promissora, pois visa à minimização dos impactos antrópicos e à reestruturação dos habitats naturais. Relativamente nova, essa tecnologia tem sido alvo de inúmeras pesquisas, pois oferece uma maior segurança, uma menor perturbação ao meio ambiente e também é uma ferramenta eficiente a custos baixos. A biorremediação possui grande aplicabilidade e a otimização do seu processo depende das condições ambientais, do tipo de contaminante e da técnica empregada. Os tratamentos se diferenciam por ser “in situ” (quando é realizado no próprio local ou “ex situ” (quando há remoção do contaminante para tratamento em outro ambiente. A biorremediação é uma técnica inovadora que merece atenção e incentivo nos processos de recuperação ambiental. O objetivo dessa revisão é conhecer o processo de biorremediação, suas técnicas e aplicabilidades.

  4. Sistema de Informação Ambiental: proposta de adequações ao módulo de fauna para sua utilização como uma ferramenta de apoio à aprendizagem

    Directory of Open Access Journals (Sweden)

    Vania Elisabete Schneider

    2017-12-01

    Full Text Available A sociedade tem se transformado em um ritmo crescente e de forma acelerada, demandando a reinvenção das metodologias e ferramentas de ensino, visando uma aprendizagem mais significativa. Uma tendência que vem sendo utilizada como ferramenta de apoio à educação é a Tecnologia da Informação e Comunicação, permitindo aos alunos que interajam com o professor, apesar de restrições de tempo e local, fornecendo acesso a diferentes fontes de conhecimento a qualquer momento. O Instituto de Saneamento Ambiental da Universidade de Caxias do Sul (ISAM/UCS vem desenvolvendo, ao longo de oito anos, um Sistema de Informação Ambiental (SIA, no qual são armazenadas informações relativas as temáticas: água, fauna, clima e geografia da Bacia Hidrográfica Taquari-Antas, monitorados por empreendimentos hidrelétricos ali instalados. A partir do cruzamento dos dados armazenados no SIA, é possível obter diferentes resultados e avaliações. Nesse contexto, esse trabalho objetiva propor adequações (de interface e de interação para integrar ao SIA, com vistas a utilização do módulo específico de fauna como um Objeto de Aprendizagem (OA, como funcionalidades que permitem algum tipo de interatividade entre o usuário e a informação disponibilizada, tornando-o mais atrativo e eficiente do ponto de vista educacional. As alterações propostas foram baseadas na revisão de sistemas semelhantes e ferramentas educativas visando a inserção de novas funcionalidades no módulo de fauna. Desta forma, foram propostas quatro adequações: abordagem sobre o risco de extinção, compartilhamento de informações entre usuários, desenvolvimento e integração de um jogo educativo e a avaliação de usabilidade do sistema. A partir da implementação das adequações propostas, espera-se que esta ferramenta seja explorada no ambiente escolar, principalmente na região da Bacia Hidrográfica Taquari-Antas, visto que as informações disponibilizadas no

  5. Comparative evaluation of laser-assisted micro-milling for AISI 316, AISI 422, TI-6AL-4V and Inconel 718 in a side-cutting configuration

    International Nuclear Information System (INIS)

    Shelton, Jonathan A; Shin, Yung C

    2010-01-01

    This paper is focused on numerical modeling and experimental evaluation of laser-assisted micro-milling (LAMM). An experimental setup consisting of a 25 W CO 2 laser, three-axis CNC linear stages and a high-speed spindle was used to implement the LAMM process. Micro-endmills between 100 and 300 µm in diameter were used to perform side-cutting operations with and without laser preheat on four materials: AISI 316, AISI 422, Ti-6Al-4V and Inconel 718. A three-dimensional transient finite-volume-based thermal model was used to analytically predict appropriate process parameters on the basis of material-removal temperatures. The effects of LAMM on the machined surface finish, edge burrs, tool wear and workpiece microstructure were evaluated experimentally.

  6. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars

    International Nuclear Information System (INIS)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-01-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

  7. Study of carbonitriding thermochemical treatment by plasma screen in active with pressures main austenitic stainless steels AISI 409 and AISI 316L

    International Nuclear Information System (INIS)

    Melo, M.S.; Oliveira, A.M.; Leal, V.S.; Sousa, R.R.M. de; Alves Junior, C.; Centro Federal de Educacao Tecnologica do Piaui; Universidade Federal do Rio Grande do Norte

    2010-01-01

    The technique called Active Screen Plasma Nitriding (ASPN) is being used as an alternative once it offers several advantages with respect to conventional DC plasma. In this method, the plasma does not form directly in the sample's surface but on a screen, in such a way that undesired effects such as the edge effect is minimized. Stainless steels present not very satisfactory wearing characteristics. However, plasma carbonitriding has been used as to improve its resistance to wearing due to the formation of a fine surface layer with good properties. In this work, samples of stainless steel AISI 316L and AISI 409 were treated at pressures of 2.5 and 5 mbar. After the treatments they were characterized by microhardness, microscopy and Xray diffraction. Microscopy and hardness analysis showed satisfactory layers and toughness in those steels. (author)

  8. Investigation of Nd:YAG pulsed laser dissimilar welding of AISI 4340 and AISI 316L stainless steels on weld geometry and mechanical properties

    Science.gov (United States)

    Sufizadeh, A. R.; Akbari Mousavi, S. A. A.

    2017-12-01

    In this paper, laser welding of 316L and AISI 4340 steel is studied. Studies are focused on the effects of laser parameters on the depth and width of the welds. The results show that increasing in pulse energy and frequency will increase the weld depth and the weld width. The calculation of effective peak power density related to the welded joints results in optimum operating welding parameters with full penetration and proper dimensions and strengths. The tensile strength values of the full penetrated weldments are greater than the tensile strength values of AISI 316 base metal. The effects of laser parameters on weld grain size and HAZ size were investigated. The results show that the weld grain size and HAZ size increase with pulse energy and frequency.

  9. Structure and properties of the Stainless steel AISI 316 nitrided with microwave plasma; Estructura y propiedades del acero inoxidable AISI 316 nitrurado con plasmas de microondas

    Energy Technology Data Exchange (ETDEWEB)

    Becerril R, F

    1999-07-01

    In this work were presented the results obtained by nitridation on stainless steel AISI 316 using a plasma generated through a microwave discharge with an external magnetic field using several moistures hydrogen / nitrogen to form a plasma. The purpose of nitridation was to increase the surface hardness of stainless steel through a phase formation knew as {gamma}N which has been reported that produces such effect without affect the corrosion resistance proper of this material. (Author)

  10. Effect of Cl on the corrosive wear of AISI 321 stainless steel in ...

    Indian Academy of Sciences (India)

    Unknown

    2002-07-25

    Jul 25, 2002 ... 1994). It was found that the accelerating effect of Cl– on corrosive wear was caused by the Cl– assisted surface film cracking. In addition, there are controversies about the role of surface film in corrosive wear. In this work, the effect of Cl– on the corrosive wear behaviour of AISI. 321 stainless steel in H2SO4 ...

  11. Effect of microstructure on KCl corrosion attack of modified AISI 310 steel

    DEFF Research Database (Denmark)

    Malede, Yohanes Chekol; Montgomery, Melanie; Dahl, Kristian Vinter

    2018-01-01

    The effect of microstructure on KCl corrosion attack was studied using a specifically chosen modified AISI 310 austenitic steel in a 15% (v/v) H2O (g)+ 5%(v/v) O2 (g) + N2 (g) (balance) atmosphere at 600°C for 168 h. The material was a targeted choice as it allows investigation of different...

  12. Evaluation of the TIG welding mechanical behavior in AISI 316 tubes for fuel rods

    International Nuclear Information System (INIS)

    Bittencourt, M.S.Q.; Carvalho Perdigao, S. de

    1985-10-01

    The effect of service temperature, the mechanical resistance and the creep behaviour of a steel which is intendend to be used as fuel rods in Nuclear Reactors was investigated. The tests were performed in seamless tubes of austenitic stainless steel, AISI 316, 20% cold worked, TIG welded. (Author) [pt

  13. Determination tensile mechanical properties of AISI316 stainless steel implanted with different helium concentrations

    International Nuclear Information System (INIS)

    Abreu, A.S. de; Santos, G.R. dos; Goncalves, Z.C.

    1986-01-01

    Tensile tests in AISI 316 stainless steel samples steel samples implanted with different helium concentration were carried out. The samples were irradiated in Brazilian-CNEN cyclotron. The irradiated samples were submitted to annealing at the temperature of 1000 sup(0)C during 10 minutes. The results are presented. (M.C.K.)

  14. Taguchi optimization of machining parameters in drilling of AISI D2 ...

    Indian Academy of Sciences (India)

    This study focused on using the Taguchi technique to optimize the process parameters in drilling of AISI D2 steel with carbide drills to minimize the surface roughness (Ra) and thrust forces (Ff). The drilling experiments were conducted on a CNC vertical machining centre according to the L18 experimental design. Uncoated ...

  15. On the oxide formation on stainless steels AISI 304 and incoloy 800H investigated with XPS

    NARCIS (Netherlands)

    Langevoort, J.C.; Sutherland, I.; Hanekamp, L.J.; Gellings, P.J.

    1987-01-01

    The influence of cold work on the initially formed oxide layer on the stainless steels AISI 304 and Incology 800H has been studied by XPS. Oxidations were performed at pressures of 10-6-10-4 Pa and temperatures of 300–800 K. All samples showed a similar oxidation behaviour. The oxidation rates of

  16. Surface characterization and wear behaviour of laser surface melted AISI 316L stainless steel

    CSIR Research Space (South Africa)

    Kumar, A

    2010-01-01

    Full Text Available The present study concerns an in depth investigation of the influence of laser surface melting of AISI 316L stainless steel using Ar and N2 as shrouding atmosphere. Laser surface melting has been carried out using a 5 kW continuous wave (CW) fibre...

  17. Neutron fluence effect on the IASCC susceptibility of AISI 304 stainless steel under simulated BWR conditions

    International Nuclear Information System (INIS)

    Navas, M.; Castano, M.L; Gomez-Briceno, D.; Karlsen, T.

    2004-01-01

    Full text: Neutron irradiation modifies the stress corrosion cracking (SCC) resistance of AISI 304 stainless steel in high temperature water. The microstructure and the microchemistry of materials change with the increasing of dose, inducing Radiation Hardening and Radiation Induced Segregation (RIS). SCC behaviour of irradiated material is influenced by these changes, leading to a value of threshold neutron fluence which could depend on different variables. Therefore, fully understanding of the IASCC material susceptibility implies the study of the effect of critical parameters like accumulated neutron fluence, material composition and water chemistry. Experimental work is being carried out in collaboration with the Halden Reactor Project and it includes the performance of Constant Extension Rate Tests (CERT) at CIEMAT laboratories in out-of-pile loops that simulate BWR operating conditions. The main objective is to determine the influence of neutron fluence on the SCC susceptibility of austenitic steels. A test matrix was defined to test unirradiated and irradiated specimens fabricated from tubes used previously in the Crack Initiation Test (IFA 618) performed at the Halden Reactor Project. According to the irradiation periods of IFA 618, three materials (Annealed and thermally-sensitised AISI 304 and AISI 316L) with three different accumulated neutron fluences are available. This paper presents the results obtained with annealed and thermally sensitised AISI 304 SS tested in different environments. (Author)

  18. Influence of plasma nitriding on the hardness of AISI 304 and low carbon steel

    International Nuclear Information System (INIS)

    Suprapto; Sudjatmoko; Tjipto Sujitno

    2010-01-01

    Nitriding with plasma/ion nitriding technique for surface treatment of AISI 304 and low carbon steel as a machine component material has been done. Surface treatment is meant to improve the surface quality of metal especially its hardness. To reach the optimum condition it has been done a variation of nitriding pressure, while to analyse the result it has been done the hardness and microstructure test, and the nitrogen content. Result of the test indicates that: the optimum hardness obtained at 1.8 mbar of pressure that is 624.9 VHN or 2.98 times while the initial hardness is 210.3 VHN for AISI 304 and 581.6 VHN or 3.07 times compare with initial hardness 142.9 VHN for low carbon steel. The thickness of nitride layer for AISI 304 and low carbon steel is around 30 µm. Nitrogen contents after nitriding are 10.74% mass or 30.32% atom for AISI 304 and 6.81% mass or 21.76% atom for low carbon steel. (author)

  19. Microstructural characterization of an AISI-SAE 4140 steel without nitridation and nitrided

    International Nuclear Information System (INIS)

    Medina F, A.; Naquid G, C.

    2000-01-01

    It was micro structurally characterized an AISI-SAE 4140 steel before and after of nitridation through the nitridation process by plasma post-unloading microwaves through Optical microscopy (OM), Scanning electron microscopy (SEM) by means of secondary electrons and retrodispersed, X-ray diffraction (XRD), Energy dispersion spectra (EDS) and mapping of elements. (Author)

  20. A comprehensive review on cold work of AISI D2 tool steel

    Science.gov (United States)

    Abdul Rahim, Mohd Aidil Shah bin; Minhat, Mohamad bin; Hussein, Nur Izan Syahriah Binti; Salleh, Mohd Shukor bin

    2017-11-01

    As a common material in mould and die application, AISI D2 cold work tool steel has proven to be a promising chosen material in the industries. However, challenges remain in using AISI D2 through a modified version with a considerable progress having been made in recent years. This paper provides a critical review of the original as-cast AISI D2 cold work tool steel up to the modified version. The main purpose is to develop an understanding of current modified tool steel trend; the machinability of AISI D2 (drilling, milling, turning, grinding and EDM/WEDM; and the microstructure evolution and mechanical properties of these cold work tool steels due to the presence of alloy materials in the steel matrix. The doping of rare earth alloy element, new steel fabrication processes, significant process parameter in machinability and surface treatment shows that there have been few empirical investigations into these cold work tool steel alloys. This study has discovered that cold work tool steel will remain to be explored in order to survive in the steel industries.

  1. Treatment of nitridation by microwave post discharge plasma in an AISI 4140 steel

    International Nuclear Information System (INIS)

    Medina F, A.; Rodriguez L, V.; Zamora R, L.; Oseguera P, J.

    1998-01-01

    The objective of this work is to determine through X-ray diffraction, microhardness measurement and scanning electron microscopy those main operation parameters of the microwave post discharge treatment (temperature of treatment, gas mixture and permanence time) nitriding an AISI 4140 steel and to characterize the compact layer of nitrides formed during the treatment. (Author)

  2. Plasma nitriding of AISI 52100 ball bearing steel and effect of heat ...

    Indian Academy of Sciences (India)

    Abstract. In this paper an effort has been made to plasma nitride the ball bearing steel AISI 52100. The difficulty with this specific steel is that its tempering temperature (∼170–200◦C) is much lower than the standard processing temperature (∼460–580◦C) needed for the plasma nitriding treatment. To understand the ...

  3. Numerical simulation of laser bending of AISI 304 plate with a ...

    African Journals Online (AJOL)

    This paper presents investigation of laser bending of AISI 304 plate having a rectangular cut out at its middle via process modeling by finite element method and statistical techniques. The objective is to study the effects of process and geometric parameters on thermal and deformation fields. Correlations are developed, with ...

  4. Sub-surface Fatigue Crack Growth at Alumina Inclusions in AISI 52100 Roller Bearings

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    Sub-surface fatigue crack growth at non metallic inclusions is studied in AISI 52100 bearing steel under typical rolling contact loads. A first 2D plane strain finite element analysis is carried out to compute the stress history in the innner race at a characteristic depth, where the Dang Van...

  5. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Czech Academy of Sciences Publication Activity Database

    Dundeková, S.; Hadzima, B.; Fintová, Stanislava

    2015-01-01

    Roč. 22, č. 2 (2015), s. 77-84 ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * EIS * Corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/167/278

  6. Tipos de tricomas em genótipos de Lycopersicon Types of trichomes in Lycopersicon genotypes

    Directory of Open Access Journals (Sweden)

    Luciana C. Toscano

    2001-11-01

    Full Text Available Foram identificados os tipos de tricomas em alguns genótipos de Lycopersicon, utilizando microscópio eletrônico de varredura. Foram utilizados os genótipos L. hirsutum (PI 127826 e PI 127827, L. hirsutum var. glabratum (PI 134417, L. pennellii (LA 716 e L. esculentum (híbrido Bruna VFN e Santa Clara. Os tricomas glandulares encontrados foram tipo IV em LA 716, PI 127826, PI 127827 e PI 134417; tipo VIc em PI 127826, PI 127827, PI 134417 e Santa Clara; tipo VII em PI 127826, PI 127827 e PI 134417; tipo I em PI 127826, PI 127827, PI 134417, híbrido Bruna VFN e Santa Clara; tipo VIa em híbrido Bruna VFN. Os tricomas não glandulares observados foram: tipo Va em PI 127826, PI 127827, PI 134417, híbrido Bruna VFN e Santa Clara; VIII em híbrido Bruna VNF e os tipos III e Vb em Santa Clara.The types of trichomes in some Lycopersicon genotypes were identified using the scanning electron microscope. The tomato genotypes observed were L. hirsutum (PI 127826 and PI 127827, L. hirsutum f. glabratum (PI 134417, L. pennellii (LA 716 and L. esculentum (Bruna VFN hybrid and Santa Clara. The following glandular trichomes were found: type IV in LA 716, PI 127826, PI 127827 and PI 134417; type VIc in PI 127826, PI 127827, PI 134417 and Santa Clara; type VII in PI 127826, PI 127827 and PI 134417; type I in PI 127826, PI 127827, PI 134417 , Bruna VFN hybrid and Santa Clara; type VIa in Bruna VFN hybrid. The following nonglandular trichomes were observed: type Va in PI 127826, PI 127827, PI 134417, Bruna VFN Hybrid and Santa Clara; type VIII in Bruna VNF hybrid and types III and Vb in Santa Clara.

  7. Preparation of high-performance ultrafine-grained AISI 304L stainless steel under high temperature and pressure

    OpenAIRE

    Peng Wang; Jinzan Zhang; Yang Zhang; Haitao Wang; Wentao Hu; Dongli Yu

    2016-01-01

    Bulk ultra-fine grained (UFG) AISI 304L stainless steel with excellent mechanical properties was prepared by a high-temperature and high-pressure (HTHP) method using nanocrystalline AISI 304L stainless steel powders obtained from ball milling. Samples were sintered in high-pressure conditions using the highest martensite content of AISI 304L stainless steel powders milled for 25 h. Analyses of phase composition and grain size were accomplished by X-ray diffraction and Rietveld refinement. By ...

  8. Catarata e diabetes mellitus tipo 1

    OpenAIRE

    Pizzol,Melissa Manfroi Dal; Esteves,Jorge Freita; Sccoco,Caio Augusto; Roggia,Murilo Felix; Rosa,Carolina Maurente da; Lambert,José Humberto Franco; Canani,Luís Henrique

    2008-01-01

    OBJETIVO: Avaliar a prevalência de catarata e seus fatores de risco em uma população portadora de diabetes mellitus tipo 1 (DM1). MÉTODOS: Estudo de casos e controles de um banco de dados de 181 pacientes (362 olhos) com diagnóstico de diabetes mellitus tipo 1. Os pacientes foram classificados como casos quando apresentavam diagnóstico de catarata. As variáveis estudadas foram a presença ou não de retinopatia diabética, tratamento com panfotocoagulação, presença de hipertensão arterial sistêm...

  9. Algunos tipos de preferencias no transitivas

    OpenAIRE

    Carmen Vázquez

    2010-01-01

    Este trabajo ofrece una visión sobre la modelación de las relaciones de preferencias del consumidor diferente a la clásica, pues prescindimos de la hipótesis de transitividad. Concretamente, analizamos dos tipos de relaciones de preferencias no transitivas, las acíclicas y las asimétricas, que bajo ciertas condiciones, admiten tipos de representación numérica distintos. Justificamos la aceptación de las mismas mediante ejemplos prácticos y vemos también resultados que garantizan la existencia...

  10. FERRAMENTA DE GESTÃO - UM ESTUDO DE CASO NO PROJETO FORMAÇÃO GESAC DO MINISTÉRIO DAS COMUNICAÇ

    Directory of Open Access Journals (Sweden)

    Leonardo Barroso da Silva

    2011-01-01

    Full Text Available Este artigo apresenta o desenvolvimento e a utilização de uma ferramenta de gestão de código aberto. A ferramenta tem como objetivo principal automatizar os processos de gestão gerando maior produtividade e qualidade no controle dos processos de um projeto e da organização. A ferramenta foi amplamente utilizada na gestão do Projeto de Formação GESAC do Ministério das Comunicações (MC. O artigo relata de que forma a ferramenta foi utilizada neste projeto e os benefícios gerados.

  11. Análise do rendimento dos alunos com o uso do AVA Moodle como ferramenta de apoio na disciplina Música Brasileira.

    Directory of Open Access Journals (Sweden)

    Rivaldo José de Souza Silva

    2017-04-01

    Full Text Available O presente artigo tem como objetivo apresentar os resultados sobre a utilização do AVA Moodle - UFAL como ferramenta de apoio às aulas presenciais na disciplina Música Brasileira ministrada no Curso de Música da Universidade Federal de Alagoas - UFAL. Na Introdução, há uma fundamentação sobre o uso das TIC para a renovação pedagógica. Os autores citados criticam o ensino tradicional centrado no professor e defendem a junção entre educação presencial e a distância, numa combinação de recursos. A pesquisa vem discutir a seguinte pergunta: de que maneira o uso do Moodle e os recursos das TIC se traduzem em resultado expressivo na disciplina presencial Música Brasileira? Na seção Materiais e Métodos, foram utilizadas aulas no AVA Moodle - UFAL com apostilas para leitura, questionários (dos tipos ensaio, múltipla escolha, respostas embutidas, verdadeiro ou falso, fórum, vídeos-documentários, podcasts, wikis, um grupo para a turma no WhatsApp, e um questionário semiestruturado de pesquisa para os alunos. Na seção Resultados e Discussões, são disponibilizadas e analisadas as respostas dos alunos ao questionário de pesquisa, e a participação nas aulas propostas no AVA Moodle – UFAL no primeiro e segundo bimestres em forma de gráficos e porcentagem. Nas Considerações Finais, concluímos que o uso do AVA Moodle – UFAL transformou-se num lugar de encontro e discussão dos alunos e do professor, principalmente no segundo bimestre quando foram ampliados os recursos virtuais utilizados. Dessa forma, o Moodle mostrou-se uma ferramenta poderosa para o ensino, aprendizagem e interação.

  12. Entrevista de desligamento como ferramenta de Gestão de Conhecimento

    Directory of Open Access Journals (Sweden)

    Juarez Domingos Frasson Vidotto

    2013-07-01

    Full Text Available A gestão de pessoas exerce um papel estratégico nas organizações, uma vez que a capacidade mental dos trabalhadores é um dos principais ativos organizacionais; entretanto, a rotatividade faz com que conhecimentos sejam perdidos quando um funcionário deixa a organização. Este estudo tem como objetivo analisar a prática da Entrevista de Desligamento como ferramenta de Gestão do Conhecimento e como ela pode minimizar os efeitos do turnover. Para tanto, foi realizada uma pesquisa em uma empresa industrial da região de Florianópolis, que utiliza a Entrevista de Desligamento como uma ferramenta de Gestão do Conhecimento. A metodologia utilizada foi da pesquisa qualitativa, estudo de caso, e os dados foram coletados por meio de entrevista semiestruturada. Os resultados indicam que a entrevista de desligamento é uma ferramenta de gestão que tem trazido benefícios para ambas as partes na relação empregador x empregado, pois, por um lado, à organização ela fornece um diagnóstico sobre o que está ocorrendo no seu ambiente permitindo capturar conhecimentos, implementar eventuais medidas corretivas e de melhorias na execução das atividades que podem evitar outras demissões e, por outro, ao funcionário entrevistado permite uma última oportunidade para manifestar-se livremente sobre sua história na organização. Ao final, o estudo apresenta uma série de evidências que justificam a utilização da entrevista de desligamento para preservar a parte do conhecimento organizacional que seria perdida pela rotatividade do pessoal.

  13. Entrevista de desligamento como ferramenta de Gestão de Conhecimento

    Directory of Open Access Journals (Sweden)

    Juarez Domingos Frasson Vidotto

    2013-11-01

    Full Text Available A gestão de pessoas exerce um papel estratégico nas organizações, uma vez que a capacidade mental dos trabalhadores é um dos principais ativos organizacionais; entretanto, a rotatividade faz com que conhecimentos sejam perdidos quando um funcionário deixa a organização. Este estudo tem como objetivo analisar a prática da Entrevista de Desligamento como ferramenta de Gestão do Conhecimento e como ela pode minimizar os efeitos do turnover. Para tanto, foi realizada uma pesquisa em uma empresa industrial da região de Florianópolis, que utiliza a Entrevista de Desligamento como uma ferramenta de Gestão do Conhecimento. A metodologia utilizada foi da pesquisa qualitativa, estudo de caso, e os dados foram coletados por meio de entrevista semiestruturada. Os resultados indicam que a entrevista de desligamento é uma ferramenta de gestão que tem trazido benefícios para ambas as partes na relação empregador x empregado, pois, por um lado, à organização ela fornece um diagnóstico sobre o que está ocorrendo no seu ambiente  permitindo capturar conhecimentos, implementar eventuais medidas corretivas e de melhorias na execução das atividades que podem evitar outras demissões e, por outro, ao funcionário entrevistado permite uma última oportunidade para manifestar-se livremente sobre sua história na organização. Ao final, o estudo apresenta uma série de evidências que justificam a utilização da entrevista de desligamento para preservar a parte do conhecimento organizacional que seria perdida pela rotatividade do pessoal. 

  14. INFUZZY: Ferramenta para desenvolvimento de aplicações de sistemas difusos

    Directory of Open Access Journals (Sweden)

    Ederson Luis Posselt

    2015-04-01

    Full Text Available A ferramenta de modelagem de sistemas difusos, InFuzzy, foi desenvolvida com o intuito de agir como um facilitador do uso da técnica por parte de estudantes e de profissionais interessados nessa subárea da Inteligência Artificial (IA. A lógica difusa é uma excelente técnica para a solução de problemas que envolvam o uso de dados imprecisos, porém, a sua implementação e o seu entendimento não são fatos triviais. As seguintes etapas foram contempladas: estudo dos conceitos da lógica difusa, softwares existentes no mercado, ergonomia e usabilidade de interfaces, modelagem e desenvolvimento da ferramenta InFuzzy e homologação das suas funcionalidades. Como resultado, apresenta-se a ferramenta desenvolvida, uma interface gráfica para modelagem de aplicações de sistemas difusos, dotada de recursos de simulação e integração com outros softwares por meio do protocolo UDP/IP. Até o momento, muitos usuários instalaram o software InFuzzy, dentre ao quais pesquisadores e alunos de programas de mestrado e de doutorado dos seguintes estados brasileiros: Amazonas, Bahia, Ceará, Espírito Santo, Goiás, Maranhão, Minas Gerais, Pará, Paraíba, Pernambuco, Piauí, Paraná, Rio de Janeiro, Rio Grande do Norte, Rondônia, Rio Grande do Sul, Santa Catarina, São Paulo e Distrito Federal.

  15. Ferramenta de autoria web e repositório para objetos de aprendizagem

    Directory of Open Access Journals (Sweden)

    Costa, Lucas Ferrari da

    2013-12-01

    Full Text Available Objeto de aprendizagem (OA é um conjunto de conteúdos educacionais com um arquivo de metadados responsável pela descrijao técnica e educacional destes conteúdos, a partir da qual é possível compartilhar OAs em repositorios educacionais, desde que ambos metadados e repositorio fajam uso do mesmo padrao, como o IEEE LOM, o CanCore ou o OBAA - sendo este último o padrao de referencia brasileiro. Assim, propoe-se o desenvolvimento de uma ferramenta cuja origem dá-se na deficiencia de ferramentas de criajao de OA em apresentar as características nesta empregadas, tais como ser grátis, fácil de usar e nao requerer instalajao, bem como utilizar a especificajao OBAA e o modelo SCORM. Objetiva-se com seu uso facilitar, para o professor, a criajao de conteúdos didáticos e incentivar os alunos a inventarem seus próprios materiais, bem como disseminar a utilizajao do modelo OBAA. Para tanto, realizou-se, através de websites, artigos académicos e da leitura dos trabalhos de Wiley e Silva, estudo dos objetos de aprendizagem, seus metadados, especificajoes e ferramentas relacionadas, bem como das tecnologias necessárias para a criajao do sistema proposto. Com as funcionalidades principais já operantes, é tangível que a aplicajao aqui apresentada, mesmo em estágio inicial de desenvolvimento, atende ao perfil destacado.

  16. APLICAÇÃO DA FERRAMENTA FMEA: ESTUDO DE CASO EM UMA EMPRESA DO SETOR DE TRANSPORTE DE PASSAGEIROS

    Directory of Open Access Journals (Sweden)

    Cristiano Roos

    2007-12-01

    Full Text Available Este trabalho apresenta um estudo de caso em que se implantou a ferramenta Failure Modes and Effects Analysis (FMEA em uma empresa atuante no segmento de transporte terrestre e aéreo de passageiros e cargas. O objetivo deste estudo de caso foi determinar, com a ferramenta FMEA, ações que minimizem ou eliminem modos de falha em potencial em um dos desdobramentos de serviços prestados pela empresa. O ponto específico onde se implantou a ferramenta foi na gestão dos pneus dos veículos de transporte terrestre de passageiros, pois falhas relacionadas a este componente aumentam os custos de manutenção da empresa e tendem a gerar insatisfações aos clientes. Também foram utilizadas, incorporadas à ferramenta FMEA, outras ferramentas da qualidade como o Brainstorming, Diagrama de Ishikawa e Gráfico de Pareto. Os resultados do trabalho foram alcançados ao se determinar ações que trazem consigo o objetivo principal deste estudo, isto é, o aumento de confiabilidade e qualidade do serviço prestado. Deste modo, a realização do presente estudo de caso proporcionou um maior entendimento acerca da temática proposta, além de mostrar a importância da gestão da qualidade nos dias atuais e frente as crescentes exigências dos clientes.

  17. REJUVENESCIMENTO DE SISTEMAS LEGADOS - UMA FERRAMENTA PARA APOIAR A EVOLUÇÃO DO SOFTWARE

    OpenAIRE

    Vasconcelos, Maria das Graças da Silva

    2011-01-01

    A engenharia de software como geradora de solução dedica pouco dos seus recursos para criação de ferramentas, que possam auxiliar no aumento da produtividade dos projetos de Tecnologia de Informação, voltadas para a área de manutenção evolutiva de software. Os projetos de evolução do software necessários ao rejuvenescimento das aplicações apresentam características de grandes projetos, com nível crescente de complexidade pela idade das aplicações e pelo número de usuários e ...

  18. ESPAÇOS DE SOCIABILIDADE A Música como ferramenta de identidade dos imigrantes brasileiros

    OpenAIRE

    Mota, Cristóvão Cunha Simões da

    2016-01-01

    MOTA, Cristóvão Cunha Simões da - Espaços de sociabilidade : a música como ferramenta de identidade dos imigrantes brasileiros. Coimbra : [s.n.], 2016. Dissertação de Mestrado em Antropologia Social e Cultural O contexto que a visão deste trabalho habita é o da modernidade líquida e do capitalismo tardio, que proporciona através do desencaixe das instituições, da grande flexibilização de algumas fronteiras, as atividades de trabalho descoladas de um local, o sistema monetário internacional...

  19. INTEROPERABILIDADE DE FERRAMENTAS DE MODELAGEM PARAMÉTRICA EM PROJETOS INDUSTRIAIS

    Directory of Open Access Journals (Sweden)

    Ezequiel Rosa Dias

    2015-11-01

    Full Text Available Este trabalho resulta de uma pesquisa de mestrado que investigou a troca de dados entre diferentes ferramentas BIM utilizadas por um grupo de empresas de Belo Horizonte na elaboração de projetos industriais. As principais fontes da pesquisa exploratória foram entrevistas não estruturadas e análises de documentações. Verificou-se que as empresas utilizam a modelagem 3D principalmente para visualização e verificação de interferências construtivas. As mesmas se encontram focadas na resolução de problemas de interoperabilidade em função da utilização simultânea de ferramentas BIM e de modelagem paramétrica industrial, mescla que pode induzir o uso de novas tecnologias pelo setor AEC à medida que projetos mais complexos são desenvolvidos pelo setor. A interoperabilidade entre os softwares utilizados ocorre preferencialmente por links diretos e padrões proprietários, em virtude de inexistência de definições normativas, fato que requer iniciativas de harmonizações entre padrões como IFC, CIS/2 e ISO-15926. Este estudo mostra que as disciplinas de projeto compõem um modelo digital 3D integrado. Contudo, o modelo integrado não dispõe de características paramétricas suficientes para o emprego de simulações do empreendimento como um todo. Para a gestão da modelagem, as empresas adotam uma ferramenta própria para criação de objetos paramétricos, tradução de modelos entre ferramentas não interoperáveis e gestão de listas de materiais. A pesquisa possibilitou a compilação do fluxo da troca de dados entre softwares, com a discriminação das linguagens utilizadas, das fases de projetos e das equipes envolvidas.

  20. Effect of Continuous and Pulsed Current on the Metallurgical and Mechanical Properties of Gas Tungsten Arc Welded AISI 4340 Aeronautical and AISI 304 L Austenitic Stainless Steel Dissimilar Joints

    OpenAIRE

    Arivarasu, Moganraj; Ramkumar Kasinath, Devendranath; Natarajan, Arivazhagan

    2015-01-01

    In this research work, the weldability of low alloyed AISI 4340 aeronautical steel and AISI 304L austenitic stainless steel joined by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) techniques, using ER309L and ERNiCr-3 filler metals was investigated. The main focus of the study involves the investigation on the effect of continuous and pulsed current mode of GTA welding process on the metallurgical and mechanical properties of these dissimilar weldments. Micro...

  1. Strength Comparison of Flawed Single-Layer and Multilayer AISI 301 Stainless Steel Pressure Vessels at Cryogenic Temperatures

    National Research Council Canada - National Science Library

    Pierce, William

    1965-01-01

    An experimental investigation was conducted to determine the strengths of single-layer and multilayer scale model tanks of AISI 301 stainless steel containing sharp notches and having the same total wall thickness...

  2. Microstructural changes of AISI 316L due to structural sensitization and its influence on the fatigue properties

    Czech Academy of Sciences Publication Activity Database

    Dundeková, S.; Nový, F.; Fintová, Stanislava

    2014-01-01

    Roč. 21, č. 4 (2014), s. 172-177 ISSN 1335-0803 Institutional support: RVO:68081723 Keywords : AISI 316L * Structural sensitization * Rotating bending fatigue test Subject RIV: JL - Materials Fatigue, Friction Mechanics

  3. Effect of heat treatment on an AISI 304 austenitic stainless steel evaluated by the ultrasonic attenuation coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Moghanizadeh, Abbas; Farzi, Abolfazl [Islamic Azad Univ., Esfarayen (Iran, Islamic Republic of). Dept. of Civil Engineering

    2016-07-01

    The properties of metals can be substantially changed by various methods, one of them is using heat treatment processes. Moreover, ultrasonic testing is the most preferred and effective, nondestructive testing technique for characterization of mechanical material properties. Austenitic stainless steel AISI 304 serves in many applications due to high strength and corrosion resistance. In certain applications, it is important to evaluate the mechanical properties of AISI 304 stainless steel. In this study, the ultrasonic method (attenuation measurement technique) is used to evaluate the hardness of AISI 304 stainless steel samples which were heat treated at different levels. Due to the heat treatment process, each sample has its specific microstructure and hardness which attenuate ultrasonic waves appropriately. The ultrasonic and hardness test show that it is possible to evaluate the hardness of AISI 304 stainless steel by ultrasonic attenuation coefficient. In addition, the relationship between ultrasonic attenuation coefficients and time of heat treatment is investigated.

  4. Solidificação da zona de fusão na soldagem do AISI 304 com inconel 600 por laser de Nd: YAG Microstructure development in Nd: YAG laser welding of AISI 304 and Inconel 600

    Directory of Open Access Journals (Sweden)

    Maurício David M. das Neves

    2009-06-01

    Full Text Available Neste trabalho estudou-se a morfologia de solidificação da zona de fusão, numa junta formada a partir de materiais dissimilares, composta por aço inoxidável austenítico AISI 304 e por liga de níquel Inconel 600, soldada com laser pulsado de Nd:YAG. Os parâmetros do feixe laser e do sistema óptico foram selecionados, visando obter uma solda com penetração total e bom acabamento superficial. A caracterização microestrutural foi realizada por microscopia ótica, onde se observou uma zona de fusão com penetração total do tipo keyhole, a presença de pequenos poros e a ausência de trincas. As juntas soldadas foram caracterizadas também, por meio de microscopia eletrônica de varredura (MEV. Medidas realizadas por espectrometria de raios X por dispersão de energia na zona de fusão indicaram uma distribuição levemente heterogênea de níquel e ferro. Observou-se que o início de solidificação da zona de fusão ocorreu por meio de crescimento epitaxial. A morfologia de solidificação da ZF foi basicamente dendrítica e celular sendo, influenciada pelo gradiente de temperatura, velocidade de solidificação e composição química. As variações de composição química e da morfologia de solidificação não alteraram significativamente os valores de microdureza Vickers na zona de fusão. Resultados obtidos nos ensaios de tração indicaram valores de eficiência de soldagem adequados.An autogenous laser welding of dissimilar materials involving AISI 304 austenitic stainless steels and Inconel 600 nickel alloy was investigated in this study. Hence, the aim of this investigation was to study the solidification and microstructure of fusion zone when using a pulsed Nd:YAG laser. The laser and optical beam parameters were chosen to achieve a good weld with total penetration. Optical microscopy pictures showed a typical keyhole weld with total penetration, small pores and free of cracks. The x-ray spectrometry by energy dispersion

  5. Uma análise do Twitter como ferramenta de apoio à aprendizagem

    Directory of Open Access Journals (Sweden)

    Guilherme M. Torres

    2013-11-01

    Full Text Available A Web 2.0 impulsionou um aumento significativo do uso de aplicações relacionadas às redes sociais. Nesse quesito, o Twitter tem se destacado por ser um meio eletrônico de colaboração, comunicação e troca de ideias entre usuários que possuem interesses em comum. Dentro do contexto de aprendizagem pode-se observar uma crescente adoção das redes sociais como recurso de apoio às aulas presenciais. Elas podem ser empregadas como extensões da sala de aula, provendo mecanismos para compartilhamento de ideias e discussão dos temas de estudo. Contudo, não há um consenso na literatura se essas ferramentas são, de fato, eficientemente utilizadas pelos usuários para esse fim. Sendo assim, este artigo apresenta um experimento realizado com alunos de graduação, onde o Twitter foi utilizado como ferramenta de apoio extra sala de aula. Os resultados empíricos obtidos no experimento apresentam o comportamento dos alunos diante da utilização do ambiente.

  6. Avaliação da Sustentabilidade da Madeira por Meio da Ferramenta ISMAS

    Directory of Open Access Journals (Sweden)

    Márcia Bissoli-Dalvi

    2017-10-01

    Full Text Available RESUMO Esta pesquisa objetivou avaliar o índice de sustentabilidade da madeira usada na construção civil a partir dos critérios previamente estabelecidos na ferramenta ISMAS – Instrumento para Seleção de Materiais Mais Sustentáveis, cuja metodologia considera especificamente os aspectos relacionados à “economia de matérias-primas” e “geração e gestão de resíduos” nos procedimentos de avaliação. A ferramenta apresenta a seguinte escala de graduação para os possíveis resultados: muito baixo, baixo, médio, alto e elevado. A metodologia adotada para a obtenção dos resultados foi estabelecida a partir de testes com o instrumento, envolvendo arquitetos sediados no Estado do Espírito Santo, Brasil. O resultado demonstrou que a madeira obteve o índice “alto” de sustentabilidade, contrariando a hipótese inicial de que o material alcançaria o nível “elevado”. Esse resultado sugere o amadurecimento do conceito sustentável da madeira, que atualmente relaciona-se somente com o critério renovável. A avaliação pelo ISMAS demonstrou a necessidade do uso de outros critérios.

  7. Assessment of XM-19 as a Substitute for AISI 348 in ATR Service

    Energy Technology Data Exchange (ETDEWEB)

    F. A. Garner; L. R. Greenwood; R. E. Mizia; C. R. Tyler

    2007-11-01

    It has been proposed that XM-19 alloy be considered as a possible replacement steel for AISI 348 in the construction of Advanced Test Reactor (ATR) capsules. AISI 348 works well, but is currently very difficult to obtain commercially. The superior and desirable mechanical properties of XM-19 alloy have been proven in non-nuclear applications, but no data are available regarding its use in radiation environments. While most 300 series alloys will meet the conditions required in ATR , it cannot be confidently assumed that XM-19 can be substituted without prior qualification in a radiation test. Compared to AISI 348, XM-19 will have an enhanced tendency for phase instabilities due to its higher levels of Ni and, especially, Si. However, transmutation of important elemental components in the highly thermalized ATR spectrum may have a very pronounced effect on its performance during irradiation. Not only will strong transmutation of Mn to Fe reduce the ductility and strength advantages provided by the higher initial Mn content of XM-19, but the extensive loss of Mn will also release from solution much of the N upon which the higher strength of XM-19 depends. In addition, the combined influence of transmutation and Inverse Kirkendall processes may lead to gas-bubble-covered grain boundaries, producing a very fragile alloy after significant irradiation has accumulated. At present, there are no radiation data available to substantiate this possible scenario. An alternate proposal is therefore advanced. Since the response of AISI 348 and 347 to radiation are expected to be relatively indistinguishable, the AISI 347 might serve as an acceptable replacement. While AISI 348 is usually chosen for nuclear service in order to reduce the overall radioactivity arising from relatively small amounts of highly transmutable elements such as cobalt, these elements have very little effect on the radiation performance of the steel. In the proposed application, however, the activity

  8. Neodesarrollismo y el tipo de cambio competitivo

    Directory of Open Access Journals (Sweden)

    Alejandro Fiorito

    2015-01-01

    Full Text Available En este trabajo se intenta mostrar que las modificaciones en los tipos de cambio tienen efectos limitados en el aumento del producto, mientras que, inversamente, esos cambios impactan especialmente en la distribución del ingreso al incidir en los precios domésticos. Se analizan y muestran múltiples referencias de la literatura internacional que cuestionan este "consenso de tipos de cambio competitivos". Se realizan correlaciones que muestran resultados distintos de los obtenidos en Rodrik (2008 con los mismos datos utilizados, aunque simplemente cambiando la metodología de datos de panel y usando en cambio una más convencional de series de tiempo.

  9. Tipos e mitos do pensamento brasileiro

    Directory of Open Access Journals (Sweden)

    Ianni Octavio

    2002-01-01

    Full Text Available No pensamento brasileiro são freqüentes os "tipos ideais" elaborados por diferentes autores e que se tornam emblemáticos, notáveis ou mesmo definitivos, podendo, às vezes, figurar como mitos. Esse é o caso do bandeirante, do gaúcho, do Jeca Tatu, do Macunaíma, do homem cordial e outros. Vale a pena refletir sobre este aspecto da cultura e do pensamento brasileiros.

  10. An AES investigation of brushed AISI 304 stainless steel after corrosion testing: AES-preiskave krtačenega nerjavnega jekla AISI 304 po korozijskem preskusu:

    OpenAIRE

    Lamut, Martin; Mandrino, Djordje; Torkar, Matjaž

    2008-01-01

    During a test in a wet salt (NaCl) chamber rusty spots and elongated pits appeared on the brushed surface of a prototype casing for a household device made from AISI 304 stainless steel. The corrosion pits only formed on the brushed surface and on the deformed edges. Metallography revealed deformation-induced martensite and delta ferrite in the microstructure. In the wet salt environment the brushed surface showed a lower corrosion resistance than the non-brushed surface. The corrosion was ex...

  11. Toolpath strategy for cutter life improvement in plunge milling of AISI H13 tool steel

    Science.gov (United States)

    Adesta, E. Y. T.; Avicenna; hilmy, I.; Daud, M. R. H. C.

    2018-01-01

    Machinability of AISI H13 tool steel is a prominent issue since the material has the characteristics of high hardenability, excellent wear resistance, and hot toughness. A method of improving cutter life of AISI H13 tool steel plunge milling by alternating the toolpath and cutting conditions is proposed. Taguchi orthogonal array with L9 (3^4) resolution will be employed with one categorical factor of toolpath strategy (TS) and three numeric factors of cutting speed (Vc), radial depth of cut (ae ), and chip load (fz ). It is expected that there are significant differences for each application of toolpath strategy and each cutting condition factor toward the cutting force and tool wear mechanism of the machining process, and medial axis transform toolpath could provide a better tool life improvement by a reduction of cutting force during machining.

  12. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars; Evaluacion del comportamiento estructural y de resistencia a la corrosion de armaduras de acero inoxidable austenitico AISI 304 y duplex AISI 2304 embebidas en morteros de cemento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-07-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

  13. Research of AISI 321 steel microrelief after ultrasonic impact treatment with marker applying

    Science.gov (United States)

    Fedorov, A. A.; Polonyankin, D. A.; Blesman, A. I.; Postnikov, D. V.

    2018-01-01

    The paper consideres the influence of AISI 321 steel microstructure formed by ultrasonic impact treatment on the microrelief regularity of preliminary prepared by turning (Ra=2.15 μm) and grinding (Ra=0.36 μm) austenitic stainless steel samples. The developed technique application for exploration the microstructure influence on the microrelief local irregularity of AISI 321 steel made it possible to establish the absence of a significant effect of twins and grain boundaries on the regular microrelief formation. The most probable reasons for irregular microrelief domain’s formation could be considered the design features of dynamic technological module and the quality of initial surface preparation before the ultrasonic impact treatment.

  14. Martensitic transformation on AISI 304 stainless steel produced by a coaxial plasma gun

    International Nuclear Information System (INIS)

    Kelly, H.; Lepone, Alejandro; Marquez, Adriana

    1997-01-01

    Full text: In a previous paper, a surface treatment of AISI 304 stainless steel irradiated by a Nitrogen ion beam generated in a coaxial plasma gun has been reported. The device is operated with a Titanium insert at the end of the inner electrode, producing a TiN coating on the surface of the sample. Because of the ion and plasma energy deposition, the sample surface is strongly heated during the treatment resulting in titanium diffusion. Preliminary X-ray diffraction (XRD) studies have shown the presence of a martensitic transformation on AISI 304 samples, probably induced by Ti atoms. In this work, the transformation depth is studied with grazing-incidence XRD on samples subjected to several superimposed shots. For this purpose, multiple low angles of incidence are used, allowing the analysis at different depths of the substrate

  15. Study of carbonitriding thermochemical treatment by plasma screen in active with pressures main austenitic stainless steels AISI 409 and AISI 316L; Estudo do tratamento termoquimico de carbonitretacao por plasma em tela ativa com pressoes variaveis nos acos inoxidaveis austenitico AISI 316L e ferririco AISI 409

    Energy Technology Data Exchange (ETDEWEB)

    Melo, M.S.; Oliveira, A.M.; Leal, V.S.; Sousa, R.R.M. de; Alves Junior, C. [Centro Federal de Educacao Tecnologica do Maranhao (CEFET/MA), Sao Luis, MA (Brazil); Centro Federal de Educacao Tecnologica do Piaui (CEFET/PI), Teresina, PI (Brazil); Universidade Federal do Rio Grande do Norte (DF/UFRN), Natal, RN (Brazil). Dept. de Fisica. Labplasma

    2010-07-01

    The technique called Active Screen Plasma Nitriding (ASPN) is being used as an alternative once it offers several advantages with respect to conventional DC plasma. In this method, the plasma does not form directly in the sample's surface but on a screen, in such a way that undesired effects such as the edge effect is minimized. Stainless steels present not very satisfactory wearing characteristics. However, plasma carbonitriding has been used as to improve its resistance to wearing due to the formation of a fine surface layer with good properties. In this work, samples of stainless steel AISI 316L and AISI 409 were treated at pressures of 2.5 and 5 mbar. After the treatments they were characterized by microhardness, microscopy and Xray diffraction. Microscopy and hardness analysis showed satisfactory layers and toughness in those steels. (author)

  16. Wear resistance of AISI 304 stainless steel submitted to low temperature plasma carburizing

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Barcelos

    Full Text Available Abstract Despite the AISI 304 stainless steel has high corrosion/oxidation resistance, its tribological properties are poor, being one of the barriers for use in severe wear applications. Thus, there is a wide field for studying technologies that aim to increase the surface hardness and wear resistance of this material. In this work, hardness and wear resistance for AISI 304 stainless steel submitted to the thermochemical treatment by low temperature plasma carburizing (LTPC in a fixed gas mixture composition of 93% H2 and 7% CH4 are presented. Through the evaluation of the carburizing layers, it was possible to observe a substantial improvement in tribological properties after all temperature and time of treatment. This improvement is directly related to the increase of the process variables; among them temperature has a stronger influence on the wear resistance obtained using LTPC process.

  17. Effect of temperature changes on swelling and creep of AISI 316

    International Nuclear Information System (INIS)

    Garner, F.A.; Gilbert, E.R.; Gelles, D.S.; Foster, J.P.

    1980-04-01

    A number of previous publications have shown that the swelling of cold-worked AISI 316 is quite sensitive to changes in temperature which occur during irradiation. In this report those data are expanded and reanalyzed to show that the concurrent irradiation creep is also quite sensitive to changes in irradiation temperature. An explanation is advanced to explain this behavior in terms of the sensitivity to temperture history of the radiation-induced microchemical evolution of this steel. In particular, the sensitivity to temperature history of the radiation-stabilized gamma prime phase is invoked to explain the enhanced creep and swelling behavior of AISI 316 components which experienced either gradual or abrupt decreases in temperature. The phase development observed in this steel in response to temperature changes during irradiation is also compared to the similar behavior found in aged specimens subjected to isothermal irradiation

  18. INFLUENCE OF AISI 316Ti STAINLESS STELL SURFACE TREATMENT ON PITTING CORROSION IN VARIOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    Pavol Fajnor

    2010-12-01

    Full Text Available Investigation of the surface treatment effect on the resistance of AISI 316Ti stainless steel to pitting corrosion is presented in this paper. The grinded surfaces without additional chemical treatment, grinded and pickled, grinded, pickled and passivated surfaces are tested. The corrosion tests are carried out by exposition in solution which evoke pitting and by electrochemical cyclic potential - sweep method. According to the results the surface treatment has a great influence on the resistance of the tested material to pitting. It is not possible to estimate the best surface treatment because behavior of AISI 316Ti stainless steel with different surface state depends on the mechanism of corrosion processes which vary in the used experimental methods.

  19. Boriding kinetics of Fe2B layers formed on AISI 1045 steel

    Directory of Open Access Journals (Sweden)

    Zuno-Silva J.

    2014-01-01

    Full Text Available In the present work, a diffusion model was suggested to study the growth kinetics of Fe2B layers grown on the AISI 1045 steel by the pack-boriding treatment. The generated boride layers were analyzed by optical microscopy and X-ray diffraction analysis. The applied diffusion model is based on the principle of mass conservation at the (Fe2B/ substrate interface. It was used to estimate the boron diffusion coefficients of Fe2B in the temperature range of 1123-1273 K. A validation of the model was also made by comparing the experimental Fe2B layer thickness obtained at 1253 K for 5 h of treatment with the predicted value. Basing on our experimental results, the boron activation energy was estimated as 180 kJ mol-1 for the AISI 1045 steel.

  20. Radiation-induced evolution of austenite matrix in silicon-modified AISI 316 alloys

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.

    1980-01-01

    The microstructures of a series of silicon-modified AISI 316 alloys irradiated to fast neutron fluences of about 2-3 and 10 x 10 22 n/cm 2 (E > 0.1 MeV at temperatures ranging from 400 0 C to 600 0 C have been examined. The irradiation of AISI 316 leads to an extensive repartition of several elements, particularly nickel and silicon, between the matrix and various precipitate phases. The segregation of nickel at void and grain boundary surfaces at the expense of other faster-diffusing elements is a clear indication that one of the mechanisms driving the microchemical evolution is the Inverse Kirkendall effect. There is evidence that at one sink this mechanism is in competition with the solute drag process associated with interstitial gradients

  1. Corrosion resistance of the welded AISI 316L after various surface treatments

    Directory of Open Access Journals (Sweden)

    Tatiana Liptáková

    2014-01-01

    Full Text Available The main aim of this work is to monitor the surface treatment impact on the corrosion resistance of the welded stainless steel AISI 316L to local corrosion forms. The excellent corrosion resistance of austenitic stainless steel is caused by the existence of stable, thin and well adhering passive layer which quality is strongly influenced by welding. Therefore surface treatment of stainless steel is very important with regard to its local corrosion susceptibility Surfaces of welded stainless steel were treated by various mechanical methods (grinding, garnet blasting. Surface properties were studied by SEM, corrosion resistance was evaluated after exposition tests in chlorides environment using weight and metalographic analysis. The experimental outcomes confirmed that the mechanical finishing has a significant effect on the corrosion behavior of welded stainless steel AISI 316L.

  2. Ataxia espinocerebelar tipo 6: relato de caso

    Directory of Open Access Journals (Sweden)

    Bianca Simone Zeigelboim

    2014-10-01

    Full Text Available O objetivo deste estudo foi verificar as alterações vestibulococleares observadas em um caso de ataxia espinocerebelar tipo 6. O caso foi encaminhado do Hospital de Clínicas para o Laboratório de Otoneurologia de uma Instituição de Ensino e foi submetido aos seguintes procedimentos: anamnese, inspeção otológica, avaliações audiológica e vestibular. O caso retrata uma paciente com diagnóstico genético de ataxia espinocerebelar tipo 6, do sexo feminino, com 57 anos de idade, que referiu desequilíbrio à marcha com tendência a queda para a esquerda, disartria e disfonia. Na avaliação audiológica apresentou configuração audiométrica descendente a partir da frequência de 4kHz e curva timpanométrica do tipo "A" com presença dos reflexos estapedianos bilateralmente. No exame vestibular observou-se na pesquisa da vertigem posicional presença de nistagmo vertical inferior e oblíquo, espontâneo e semiespontâneo múltiplo com características centrais (ausência de latência, paroxismo, fatigabilidade e vertigem, nistagmooptocinético abolido e hiporreflexia à prova calórica. Constataram-se alterações labirínticas que indicaram afecção do sistema vestibular central evidenciando-se a importância dessa avaliação. A existência da possível relação entre os achados com os sintomas vestibulares apresentados pela paciente apontou a relevância do exame labiríntico neste tipo de ataxia uma vez que a presença do nistagmo vertical inferior demonstrou ser frequente neste tipo de patologia.

  3. Martensitic transformation during fatigue testing of an AISI 301LN steel

    OpenAIRE

    Mateo García, Antonio Manuel; Fargas Ribas, Gemma; Zapata Dederle, Ana Cristina

    2012-01-01

    The plastic deformation accumulated during fatigue testing can induce the transformation of austenite to martensite in metastable austenitic stainless steels. To analyze this issue, a metastable austenitic stainless steel grade AISI 301 LN was studied in two different conditions, i.e. annealed and cold rolled. In the first case, the steel was fully austenitic, whereas cold rolled material had almost 30% of martensite. High cycle fatigue tests at a stress ratio of 0.8 were carried out on flat ...

  4. Study of corrosion resistance of AISI 444 ferritic stainless steel for application as a biomaterial

    International Nuclear Information System (INIS)

    Marques, Rogerio Albuquerque

    2014-01-01

    Ferritic stainless steels are ferromagnetic materials. This property does not allow their use in orthopedic prosthesis. Nevertheless, in some specific applications, this characteristic is very useful, such as, for fixing dental and facial prostheses by using magnetic attachments. In this study, the corrosion resistance and cytotoxicity of the AISI 444 ferritic stainless steel, with low nickel content, extra-low interstitial levels (C and N) and Ti and Nb stabilizers, were investigated for magnetic dental attachments application. The ISO 5832-1 (ASTM F-139) austenitic stainless steel and a commercial universal keeper for dental attachment (Neo-magnet System) were evaluated for comparison reasons. The first stainless steel is the most used metallic material for prostheses, and the second one, is a ferromagnetic keeper for dental prostheses (NeoM). In vitro cytotoxicity analysis was performed by the red neutral incorporation method. The results showed that the AISI 444 stainless steel is non cytotoxic. The corrosion resistance was studied by anodic polarization methods and electrochemical impedance spectroscopy (EIS), in a saline phosphate buffered solution (PBS) at 37 °C. The electronic properties of the passive film formed on AISI 444 SS were evaluated by the Mott-Schottky approach. All tested materials showed passivity in the PBS medium and the passive oxide film presented a duplex nature. The highest susceptibility to pitting corrosion was associated to the NeoM SS. This steel was also associated to the highest dopant concentration. The comparatively low levels of chromium (nearly 12.5%) and molybdenum (0.3%) of NeoM relatively to the other studied stainless steels are the probable cause of its lower corrosion resistance. The NeoM chemical composition does not match that of the SUS444 standards. The AISI 444 SS pitting resistance was equivalent to the ISO 5832-1 pointing out that it is a potential candidate for replacement of commercial ferromagnetic alloys used

  5. Influence of the surface finishing on the corrosion behaviour of AISI 316L stainless steel

    Czech Academy of Sciences Publication Activity Database

    Dundeková, S.; Zatkalíková, V.; Fintová, Stanislava; Hadzima, B.; Škorík, Viktor

    2015-01-01

    Roč. 22, č. 1 (2015), s. 48-53 ISSN 1335-0803 R&D Projects: GA MŠk(CZ) EE2.3.30.0063 Institutional support: RVO:68081723 Keywords : AISI 316L stainless steel * Corrosion * Immersion test * Corrosion rate Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://ojs.mateng.sk/index.php/Mateng/article/view/166/251

  6. Potentiodynamic corrosion studies on laser beam welded austenitic stainless steel AISI 321

    Science.gov (United States)

    Nair, Adithya R.; Niranjhan, P.; Abijith, M. N.; Arivarasu, M.; Manikandan, M.; Padmanaban, R.; Arivazhagan, N.

    2017-11-01

    In this study, the microstructure and corrosion characteristics of laser beam welded austenitic stainless plates has been studied. CO2 Laser beam produced defect free weldments in AISI 321 with no trace of heat affected zone. The microstructural studies revealed distributed ferrites in the weld zone. Potentio-dynamic polarization studies were carried out on the weldments in 5% NaCl environment in order to understand corrosion current, potential and rate.

  7. Corrosion behaviour of AISI 316L stainless-steel alloys in diabetic serum.

    Science.gov (United States)

    Moura e Silva, T; Monteiro, J M; Ferreira, M G; Vieira, J M

    1993-01-01

    The present study investigates the pitting-corrosion behaviour of AISI 316L stainless steel in human physiological fluids. The emphasis is on the effect of diabetic serum with glucose and proteins, but reference solutions of isotonic saline solution with and without antibiotics were also used. Polarization experiments were carried out, and the results point to the innocuity of those fluids on the performance of the alloy as far as pitting corrosion is concerned.

  8. Use of Direct Current Resistivity Measurements to Assess AISI 304 Austenitic Stainless Steel Sensitization

    OpenAIRE

    Mesquita, Ramaiany Carneiro; Mecury, José Manoel Rivas; Tanaka, Auro Atsumi; Sousa, Regina Célia de

    2015-01-01

    This paper describes the feasibility of using direct current electrical resistivity measurements to evaluate AISI 304 austenitic stainless steel sensitization. ASTM A262 – Practice A and double loop electrochemical potentiodynamic reactivation (DL-EPR) tests were performed to assess the degree of sensitization (DoS) qualitatively and quantitatively, and electrical resistivity (ER) was measured by the four-point direct-current potential drop method. The results indicate that the DoS incr...

  9. Improvement of Surface Properties of AISI 304 Stainless Steel by Laser Melting

    Science.gov (United States)

    Carbucicchio, M.; Palombarini, G.; Rateo, M.; Sambogna, G.

    1998-12-01

    The microstructures and properties of deep laser melted and rapidly solidified zones produced by a cw power laser on thick plates of AISI 304 stainless steel were studied. Both chemical and mechanical properties of the solidified regions were found to be comparable or better than those characterizing the original material, thus allowing the melting process to be used for technological purposes, in particular for welding.

  10. Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

    OpenAIRE

    Chen Ying An; Francisco Piorino Neto; Eder Paduan Alves

    2010-01-01

    Abstract: The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW), which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The ...

  11. Structure and properties of the Stainless steel AISI 316 nitrided with microwave plasma

    International Nuclear Information System (INIS)

    Becerril R, F.

    1999-01-01

    In this work were presented the results obtained by nitridation on stainless steel AISI 316 using a plasma generated through a microwave discharge with an external magnetic field using several moistures hydrogen / nitrogen to form a plasma. The purpose of nitridation was to increase the surface hardness of stainless steel through a phase formation knew as γN which has been reported that produces such effect without affect the corrosion resistance proper of this material. (Author)

  12. Martensitic Transformation in Ultrafine-Grained Stainless Steel AISI 304L Under Monotonic and Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Heinz Werner Höppel

    2012-02-01

    Full Text Available The monotonic and cyclic deformation behavior of ultrafine-grained metastable austenitic steel AISI 304L, produced by severe plastic deformation, was investigated. Under monotonic loading, the martensitic phase transformation in the ultrafine-grained state is strongly favored. Under cyclic loading, the martensitic transformation behavior is similar to the coarse-grained condition, but the cyclic stress response is three times larger for the ultrafine-grained condition.

  13. Effect of Austempering and Martempering on the Properties of AISI 52100 Steel

    OpenAIRE

    Krishna, P. Vamsi; Srikant, R. R.; Iqbal, Mustafa; Sriram, N.

    2013-01-01

    The mechanical properties of steel decide its applicability for a particular condition. Heat treatment processes are commonly used to enhance the required properties of steel. The present work aims at experimentally investigating the effect of austempering and martempering on AISI 52100 steel. Different tests like microstructure analysis, hardness test, impact test, and wear test are carried out after heat treatment process. It was found that annealed steel was least hard and more wear prone,...

  14. Stoichiometric titanium dioxide ion implantation in AISI 304 stainless steel for corrosion protection

    Science.gov (United States)

    Hartwig, A.; Decker, M.; Klein, O.; Karl, H.

    2015-12-01

    The aim of this study is to evaluate the applicability of highly chemically inert titanium dioxide synthesized by ion beam implantation for corrosion protection of AISI 304 stainless steel in sodium chloride solution. More specifically, the prevention of galvanic corrosion between carbon-fiber reinforced plastic (CFRP) and AISI 304 was investigated. Corrosion performance of TiO2 implanted AISI 304 - examined for different implantation and annealing parameters - is strongly influenced by implantation fluence. Experimental results show that a fluence of 5 × 1016 cm-2 (Ti+) and 1 × 1017 cm-2 (O+) is sufficient to prevent pitting corrosion significantly, while galvanic corrosion with CFRP can already be noticeably reduced by an implantation fluence of 5 × 1015 cm-2 (Ti+) and 1 × 1016 cm-2 (O+). Surface roughness, implantation energy and annealing at 200 °C and 400 °C show only little influence on the corrosion behavior. TEM analysis indicates the existence of stoichiometric TiO2 inside the steel matrix for medium fluences and the formation of a separated metal oxide layer for high fluences.

  15. Stoichiometric titanium dioxide ion implantation in AISI 304 stainless steel for corrosion protection

    International Nuclear Information System (INIS)

    Hartwig, A.; Decker, M.; Klein, O.; Karl, H.

    2015-01-01

    The aim of this study is to evaluate the applicability of highly chemically inert titanium dioxide synthesized by ion beam implantation for corrosion protection of AISI 304 stainless steel in sodium chloride solution. More specifically, the prevention of galvanic corrosion between carbon-fiber reinforced plastic (CFRP) and AISI 304 was investigated. Corrosion performance of TiO 2 implanted AISI 304 – examined for different implantation and annealing parameters – is strongly influenced by implantation fluence. Experimental results show that a fluence of 5 × 10 16 cm −2 (Ti + ) and 1 × 10 17 cm −2 (O + ) is sufficient to prevent pitting corrosion significantly, while galvanic corrosion with CFRP can already be noticeably reduced by an implantation fluence of 5 × 10 15 cm −2 (Ti + ) and 1 × 10 16 cm −2 (O + ). Surface roughness, implantation energy and annealing at 200 °C and 400 °C show only little influence on the corrosion behavior. TEM analysis indicates the existence of stoichiometric TiO 2 inside the steel matrix for medium fluences and the formation of a separated metal oxide layer for high fluences.

  16. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Sylvia Dundeková

    2015-05-01

    Full Text Available Stainless steels from 316 group are very often and successfully uses for medical applications where the good mechanical and chemical properties in combination with non-toxicity of the material assure its safe and long term usage. Corrosion properties of AISI 361L stainless steel are strongly influenced by surface roughness and treatment of the engineering parts (specimens and testing temperature. Electrochemical characteristics of ground, mechanically polished and passivated AISI 316L stainless steel specimens were examined with the aim to identify the polarization resistance evolution due to the surface roughness decrease. Results obtained on mechanically prepared specimens where only natural oxide layer created due to the exposure of the material to the corrosion environment was protecting the materials were compared to the passivated specimens with artificial oxide layer. Also the influence of temperature and stabilization time before measurement were taken into account when discussing the obtained results. Positive influence of decreasing surface roughness was obtained as well as increase of polarization resistance due to the chemical passivation of the surface. Increase of the testing temperature and short stabilization time of the specimen in the corrosion environment were observed negatively influencing corrosion resistance of AISI 316L stainless steel.

  17. Effects of Ce on Inclusions, Microstructure, Mechanical Properties, and Corrosion Behavior of AISI 202 Stainless Steel

    Science.gov (United States)

    Cai, Guojun; Li, Changsheng

    2015-10-01

    The sizes and morphologies of nonmetallic inclusions, microhardness, tensile strength, and Charpy impact toughness in AISI 202 stainless steel with different Ce contents were synthetically analyzed by means of SEM, TEM, microhardness tester, and tensile and Charpy impact tests. Effects of Ce addition on the corrosion behavior were investigated in 5 wt.% H2SO4 solution for different periods of time through measuring AC impedance. The EIS measurements indicate that the steels with Ce addition exhibit higher R p values than those without Ce, which illustrates the relative resistance to uniform corrosion is accompanied by an increasing Ce addition. Ce addition to AISI 202 stainless steel improves its uniform corrosion resistance owing to metamorphic inclusions and the improvement of electrode potential in matrix. Upon increasing Ce addition, the indentation morphology of samples transfers from sink-in types to pile-up types, explaining good machinability of steels containing Ce. It is witnessed from the fracture mode that Ce refines the grain size of steels, significantly increasing the strength; in the meantime, its plasticity is improved, thereby solving the contradiction between the strength and the plasticity of steels. It is concluded that AISI 202 stainless steel with 0.016 wt.% Ce addition in the mass fraction has the best mechanical properties and the uniform corrosion resistance.

  18. Stoichiometric titanium dioxide ion implantation in AISI 304 stainless steel for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, A.; Decker, M.; Klein, O.; Karl, H., E-mail: helmut.karl@physik.uni-augsburg.de

    2015-12-15

    The aim of this study is to evaluate the applicability of highly chemically inert titanium dioxide synthesized by ion beam implantation for corrosion protection of AISI 304 stainless steel in sodium chloride solution. More specifically, the prevention of galvanic corrosion between carbon-fiber reinforced plastic (CFRP) and AISI 304 was investigated. Corrosion performance of TiO{sub 2} implanted AISI 304 – examined for different implantation and annealing parameters – is strongly influenced by implantation fluence. Experimental results show that a fluence of 5 × 10{sup 16} cm{sup −2} (Ti{sup +}) and 1 × 10{sup 17} cm{sup −2} (O{sup +}) is sufficient to prevent pitting corrosion significantly, while galvanic corrosion with CFRP can already be noticeably reduced by an implantation fluence of 5 × 10{sup 15} cm{sup −2} (Ti{sup +}) and 1 × 10{sup 16} cm{sup −2} (O{sup +}). Surface roughness, implantation energy and annealing at 200 °C and 400 °C show only little influence on the corrosion behavior. TEM analysis indicates the existence of stoichiometric TiO{sub 2} inside the steel matrix for medium fluences and the formation of a separated metal oxide layer for high fluences.

  19. Experimental study on the stress corrosion cracking behavior of AISI347 in acid chloride ion solution

    Directory of Open Access Journals (Sweden)

    Yanpeng Qu

    2016-01-01

    Full Text Available The stress corrosion cracking (SCC behavior of AISI347 austenitic stainless steel exposed to acid solution containing chloride ion at different temperature and pressure is studied through slow strain rate testing (SSRT at different test condition. The result of SSRT shows, with the pressure increasing, the SCC resistance is getting worse and the trend of brittle fracture presented by the fracture surface is more obvious. With the temperature rising, the mechanical properties of AISI347 getting worse first and then getting better, it gets to be the worst when the temperature is 260 °C. The result of significance effect analysis of temperature and pressure on SCC shows that the temperature has a greater effect on the resistance to SCC of AISI347 austenitic stainless steel than the pressure. The main component of passive film is analyzed and the mechanism of SCC is discussed. Chromium oxides soluble in the acidic chloride solution results in the forming of corrosion pits and the cracking of the passive film under stress.

  20. Influence of the ion nitriding temperature in the wear resistance of AISI H13 tool steel

    International Nuclear Information System (INIS)

    Heck, Stenio Cristaldo; Fernandes, Frederico Augusto Pires; Pereira, Ricardo Gomes; Casteletti, Luiz Carlos; Totten, George Edward

    2010-01-01

    The AISI H13 tool steel for hot work is the most used in its category. This steel was developed for injection molds and extrusion of hot metals as well as for conformation in hot presses and hammers. Plasma nitriding can improve significantly the surface properties of these steels, but the treatments conditions, such as temperature, must be optimized. In this work the influence of nitriding treatment temperature on the wear behavior of this steel is investigated. Samples of AISI H13 steel were quenched and tempered and then ion nitrided in the temperatures of 450, 550 and 650 deg C, at 4mbar pressure, during 5 hours. Samples of the treated material were characterized by optical microscopy, Vickers microhardness, x-ray analysis and wear tests. Plasma nitriding formed hard diffusion zones in all the treated samples. White layers were formed in samples treated at 550 deg C and 650 deg C. The treatment temperature of 450 deg C produced the highest hardness. Treatment temperature showed great influence in the diffusion layer thickness. X-ray analysis indicated the formation of the Fe 3 N, Fe 4 N and CrN phases for all temperatures, but with different concentrations. Nitriding increased significantly the AISI H13 wear resistance. (author)

  1. Wear resistance of Fe-Nb-Cr-W, Nb, AISI 1020 and AISI 420 coatings produced by thermal spray wire arc; Resistencia al desgaste de recubrimientos Fe-Nb-Cr-W, Nb, AISI 1020 y AISI 420 producidos por proyeccion termica por arco electrico

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Covaleda, E. A.; Mercado-Veladia, J. L.; Olaya-Florez, J. J.

    2013-07-01

    The commercial materials 140MXC (with iron, tungsten, chrome, niobium), 530AS (AISI 1015 steel) and 560AS (AISI 420 steel) on AISI 4340 steel were deposited using thermal spray with arc. The aim of work was to evaluate the best strategy abrasive wear resistance of the system coating-substrate using the following combinations: (1) homogeneous coatings and (2) coatings depositing simultaneously 140MXC + 530AS and 140MXC + 560AS. The coatings microstructure was characterized using Optical microscopy, Scanning electron microscopy and Laser con focal microscopy. The wear resistance was evaluated through dry sand rubber wheel test (DSRW). We found that the wear resistance depends on the quantity of defects and the mechanical properties like hardness. For example, the softer coatings have the biggest wear rates and the failure mode was characterized by plastic deformation caused by particles indentation, and the other hand the failure mode at the harder materials was grooving. The details and wear mechanism of the coatings produced are described in this investigation. (Author)

  2. Divergência genética entre genótipos de frangos tipo caipira

    Directory of Open Access Journals (Sweden)

    R. C. Veloso

    2015-10-01

    Full Text Available RESUMOObjetivou-se com este trabalho verificar a divergência genética entre sete genótipos de frangos tipo caipira da linhagem Redbro utilizando as características de desempenho por meio de técnicas de análise multivariada. Foram utilizados 840 pintos de um dia, machos, distribuídos em delineamento inteiramente ao acaso, dos seguintes genótipos: Caboclo, Carijó, Colorpak, Gigante Negro, Pesadão Vermelho, Pescoço Pelado e Tricolor. Após a consistência dos dados, foram avaliadas as seguintes variáveis: ganho em peso médio diário, consumo de ração médio diário e conversão alimentar, para os períodos: 1 a 28, 1 a 56, 1 a 70 e 1 a 84 dias de idade; peso corporal ao nascimento, aos 28, 56, 70 e aos 84 dias de idade. O desempenho dos genótipos foi avaliado por meio da análise de variância multivariada e da função discriminante linear de Fisher, usando os testes do maior autovalor de Roy e da união-interseção de Roy para as comparações múltiplas. O estudo da divergência genética foi feito por meio da análise por variáveis canônicas e pelo método de otimização de Tocher. Os genótipos Caboclo e Gigante Negro apresentaram médias canônicas diferentes dos demais genótipos. As duas primeiras variáveis canônicas explicaram 97,41% da variação entre os genótipos. A divergência genética entre os genótipos avaliados permitiu a formação de quatro grupos com os seguintes genótipos: grupo 1 - Colorpak; grupo 2 - Pesadão Vermelho e Pescoço Pelado; grupo 3 - Carijó e Tricolor; e grupo 4 - Caboclo e Gigante Negro.

  3. Fatores que influenciam a adocao de ferramentas de TIC nos experimentos de bioinformatica de organizacoes biofarmaceuticas: um estudo de caso no Instituto Nacional do Cancer

    Directory of Open Access Journals (Sweden)

    Claudio Pitassi

    2014-01-01

    Full Text Available O objetivo deste artigo é identificar e analisar os fatores que influenciaram a adoção de ferramentas de Tecnologias de Informação e de Comunicação (TIC nos experimentos de Bioinformática do Instituto Nacional do Câncer (Inca. Trata-se de um estudo de campo único descritivo e exploratório, dentro da tradição qualitativa. As evidências foram coletadas principalmente em entrevistas de fundo com os gestores de áreas da Coordenação Geral Técnico-Científica e da Divisão de Tecnologia da Informação do Inca. As respostas foram tratadas pelo método de análise de conteúdo do tipo categorial. As categorias de análise foram definidas a partir da revisão da literatura e consolidadas nos sete fatores do Modelo Tecnologia-Organização-Ambiente (TOE adaptado para este estudo. O modelo proposto permitiu demonstrar como atuam no caso do Inca os fatores que impactam a adoção das complexas TIC usadas nos experimentos de Bioinformática, contribuindo para investigações em duas áreas de importância crescente para o Complexo Econômico-Industrial de Saúde brasileiro: a inovação tecnológica e a Biotecnologia. Com base nas evidências coletadas, uma questão é formulada: em que medida o alinhamento dos fatores pertinentes à adoção das TIC nos experimentos de Bioinformática pode aumentar a capacidade de inovar de uma organização biofarmacêutica brasileira?

  4. O uso do QFD como ferramenta para otimizar a usabilidade de produtos: um estudo exploratório

    Directory of Open Access Journals (Sweden)

    Joici Paloma Genro

    2015-05-01

    Full Text Available O Desdobramento da Função Qualidade (QFD é uma ferramenta que em síntese utiliza a voz do consumidor para priorizar os principais requisitos dos clientes durante o desenvolvimento de produtos. A usabilidade dos produtos por ter relação direta com os requisitos e muitas vezes necessidades dos clientes, pode ser alcançada através da utilização de ferramentas como o QFD, que captam a voz do consumidor e definem as características mais importes do projeto. Neste contexto o objetivo deste trabalho é realizar um estudo teórico sobre a relação da utilização do QFD como ferramenta para otimizar a usabilidade de produtos, com foco em produtos de tecnologia da informação. Para isto foi realizada uma pesquisa teórica em trabalhos acadêmicos e artigos científicos onde se analisou a utilização do QFD no desenvolvimento de produtos e serviços. A pesquisa demonstrou que o QFD é uma ferramenta adequada para a definição dos requisitos dos produtos e entretanto, adequada para definir requisitos de usabilidade.

  5. Estudo comparativo das ferramentas para mapeamento das atividades executadas pelos consumidores em processos de serviço

    Directory of Open Access Journals (Sweden)

    Gabriela Andre Jorge

    2015-01-01

    Full Text Available Resumo O objetivo deste artigo é explorar o potencial de aplicação das ferramentas de mapeamento na construção de mapas de processo que evidenciem as atividades executadas pelos consumidores em processos de serviço. O artigo aborda as ferramentas SIPOC, Fluxograma, Blueprint, Process-Chain-Network, Mapa do Consumo, SERVPRO e Carta de Atividades, exemplificando sua aplicação na construção de mapas que oferecem diferentes visões processuais para um processo de compra via internet adotando a abordagem de decomposição hierárquica na análise do fluxo de atividades do consumidor. Estas ferramentas são analisadas quanto à capacidade de representar os diferentes aspectos do processo mapeado, considerando características como a forma de representação gráfica e o enfoque, abrangência e granularidade da visualização que oferecem. Finalmente, é apresentada uma avaliação comparativa da capacidade informativa destas ferramentas, procurando-se evidenciar o diferencial de cada uma.

  6. Aplicação das ferramentas da Qualidade: estudo de caso em pequena empresa de pintura

    Directory of Open Access Journals (Sweden)

    Fabrício Pozzuto de Souza Coelho

    2016-10-01

    Full Text Available As sete ferramentas da qualidade mostram um conjunto de técnicas úteis para a melhoria da qualidade. Apesar do uso disseminado, poucos estudos avaliaram sua implantação no âmbito das pequenas empresas. Este artigo objetivou investigar o impacto da implantação dessas ferramentas em uma pequena empresa de pintura localizada no litoral do Estado de São Paulo. Utilizando o referencial da qualidade e o método do estudo de caso se verificou que a implantação de cinco ferramentas da qualidade: Fluxograma do processo; Folha de verificação; Gráfico de Pareto; Diagrama de causa e efeito e plano de ação; e, Gráfico de controle, apresentou resultados satisfatórios para a gerência da empresa. Partiu-se de um índice de produtos não-conformes de 12,5% para 4% ao final do sexto mês da implantação das ações de melhoria. Verificou-se neste artigo o potencial da implantação das ferramentas da qualidade no âmbito das pequenas empresas.

  7. O desenvolvimento de ferramentas de predição de balneabilidade baseadas em níveis de precipitação: estudo de caso da praia de Cachoeira das Emas (SP

    Directory of Open Access Journals (Sweden)

    Fabio Muller Hirai

    Full Text Available RESUMO Este artigo apresenta resultados de um estudo realizado na praia Cachoeira das Emas, Rio Mogi-Guaçu, Pirassununga (SP, onde foram desenvolvidos modelos estatísticos simples de regressão linear utilizando níveis de precipitação como variáveis explanatórias, por meio da correlação positiva observada entre concentração de indicadores fecais na água e precipitação acumulada em 24, 48 e 72 horas anteriores à amostragem no rio. Os dados aplicados na calibração (período de 2009 a 2011 e validação (período de 2012 das ferramentas obtidas são oriundos das redes de monitoramento pluviométrico do Departamento de Águas e Energia Elétrica (DAEE e de balneabilidade de água doce da Companhia Ambiental do Estado de São Paulo (Cetesb. Como essas redes possuem objetivos distintos, nem todos os eventos de precipitação que ocorreram durante o período de estudo foram relacionados com um valor de concentração de indicador fecal na água, e vice-versa. Logo, as equações de regressão obtidas ficaram baseadas em um baixo número de observações. Os resultados sugerem que há potencial de aplicação prática desse tipo de ferramenta, porém requer-se monitoramento específico e conjunto dos parâmetros do modelo a fim de obter uma quantidade significante de dados para a calibração e a validação da ferramenta. A aplicação desse recurso de gerenciamento de balneabilidade seria ideal para um período específico do ano com maior afluência de pessoas, em praias cuja principal fonte de poluição seja difusa e consequente do escoamento de drenagem. Teoricamente, seria possível empregar outras variáveis ambientais ao modelo além dos níveis de precipitação, tais como turbidez e vazão, desde que os parâmetros fossem monitorados com a qualidade da água.

  8. A técnica de cluster como ferramenta para a gestão ambiental

    Directory of Open Access Journals (Sweden)

    Núbia Cristina Bezerra da Silva

    2003-12-01

    Full Text Available No Brasil, os gestores ambientais tentam constantemente se adaptar aos novos tempos e, em conseqüência disso, buscam iniciativas capazes de facilitar a gestão de uma Unidade de Conservação. O sistema de parceria transformou-se em uma eficaz ferramenta utilizada pelos gestores de parques nacionais, e possibilitou aprimorar o conceito de gestão. Dos modelos de gestão utilizados pelos parques nacionais tem-se na gestão compartilhada o modelo contemporâneo. O Parque Nacional da Serra da Capivara constitui-se no único caso brasileiro a utilizar esse modelo, o que permitiu identificar os problemas existentes e atenuá-los por meio de uma série de medidas sustentáveis.

  9. Web Semântica: ontologias como ferramentas de representação do conhecimento

    Directory of Open Access Journals (Sweden)

    Maria Elisa Valentim Pickler

    Full Text Available A Web Semântica é uma extensão da Web que acrescenta semântica ao atual formato de representação de dados. Para isso foram propostas diversas tecnologias, dentre essas a criação de ontologias,visando atribuir sentido e significado ao conteúdo dos documentos, atuando como ferramenta de representaçãdo conhecimento. Na presente pesquisa, procurou-se verificar se as ontologias seriam utilizadas apenas para representar o assunto de uma página Web através de termos contextualizados ou se tentariam controlar o vocabulário da Web como um Tesauro.

  10. O mito como ferramenta de persuasão no Fedro de Platão

    OpenAIRE

    Botter, Barabra

    2015-01-01

    O artigo visa analisar o Fedro de Platão. Centraliza a importância do mito como ferramenta de persuasão para se alcançar a verdade no diálogo. Para isso, foi realizada uma reflexão, a partir do diálogo, sobre a estrutura do mito, sua simbologia e a possibilidade de Platão reconhecer os limites do conhecimento filosófico em pretender alcançar a verdade. O argumento filosófico utilizado por Sócrates se funda no mito como discurso erótico. Esse discurso, em seu percurso mítico, alcança os amante...

  11. O talento profissional com ênfase na ferramenta coaching no ambiente empresarial

    OpenAIRE

    Risso, Divino Lozetti; CENTRO UNIVERSITÁRIO UNINTER; Zanetti, Elizabeth

    2014-01-01

    RESUMO Tendo como objetivo discorrer sobre o talento profissional com ênfase na ferramenta coaching, este artigo foi elaborado a partir de uma revisão de literatura a respeito do tema. Em seu conteúdo, discorre-se sobre: o processo coaching; coaching e liderança; a importância do líder coach nas organizações e o desenvolvimento de talentos. Foi possível constatar que o coaching não é apenas uma técnica a ser aplicada em determinadas situações, mas também  uma forma de agir, de pensar e de ser...

  12. O USO DAS FERRAMENTAS VIRTUAIS NA EDUCAÇÃO A DISTÂNCIA: O PAPEL DO TUTOR

    Directory of Open Access Journals (Sweden)

    Francisca Auderlânia de Oliveira Dias

    2017-08-01

    Full Text Available Este artigo busca apresentar a importância do papel do professor-tutor na modalidade à distância e as ferramentas que a acompanha, considerando sua experiência vivida no decorrer de sua vida acadêmica. Através do surgimento das novas tecnologias a internet tornou-se um meio propício para a difusão do conhecimento, aumentando a oferta de cursos superiores à distância. Nesse contexto o tutor é responsável por manter uma comunicação ativa com seus alunos através das ferramentas, por isso propomos neste artigo reflexões que abordem a importância do professor-tutor nessa modalidade, destacando suas principais características, funções e as ferramentas utilizadas no ensino à distância. A metodologia utilizada foi á pesquisa bibliográfica, e teve como  objetivo descrever e analisar o sistema de tutoria na Educação a Distância bem como suas ferramentas, destacando o importante trabalho do professor-tutor, averiguando suas características e suas qualidades. Concluiu- se também que com esse estudo, contribuiu para repensar a função dos tutores presenciais e a distância atuantes na modalidade de ensino à distância, utilizando-se das ferramentas tecnológicas, tendo em vista que, acreditamos ser de fundamental importância á realização de formação inicial e continuada com esses profissionais, pois são eles que mantêm contato direto e diário com os alunos.

  13. ANÁLISE DA UTILIZAÇÃO DAS FERRAMENTAS CONTÁBEIS GERENCIAIS EM MICRO E PEQUENAS EMPRESAS

    Directory of Open Access Journals (Sweden)

    Jéssica Aline Stacke

    2017-03-01

    Full Text Available A importância das Micro e Pequenas Empresas (MPEs na economia global é inquestionável, porém sua taxa de mortalidade é elevada e relacionada, em especial, a problemas de gestão. Neste sentido, este estudo objetiva analisar a importância atribuída pelos gestores de MPEs em relação a utilização das ferramentas contábeis gerenciais para a gestão e tomada de decisão. A pesquisa é quantitativa, de levantamento ou survey e descritiva. A survey operacionalizou-se por meio de questionário fechado contendo 30 questões e 105 respondentes foram validados. Os resultados denotam que a maioria das MPEs - 74 a 93% - utilizam as ferramentas voltadas ao controle operacional, já as ferramentas gerenciais voltadas a tomada de decisão são utilizadas pela minoria de 43 a 63%. Quanto a tomada de decisão, na maioria das empresas (64% se dá através da consulta a controles gerenciais e os gestores consideram mais importante a consulta a controles gerenciais para as decisões relacionadas ao preço de venda. Conclui-se que as ferramentas gerenciais voltadas ao controle operacional possuem maior importância em relação as voltadas à tomada de decisões. Além disso, o desconhecimento acerca dessas ferramentas gerenciais é a principal causa pela não utilização e pela menor importância atribuída.

  14. Microestructura de una unión disímil AISI 321 y una aleación A 351 grado HK-40 obtenida mediante soldadura manual por arco eléctrico

    Directory of Open Access Journals (Sweden)

    Reilis Fuentes-Guilarte

    2016-05-01

    Full Text Available El objetivo fue establecer el comportamiento microestructural de una unión disímil de acero inoxidable austenítico AISI 321 y de la aleación A 351 grado HK 40 obtenida por fundición mediante soldadura manual por arco eléctrico y electrodos revestidos del tipo E 309 L-16. La estructura ferrita–austeníta que se forma en la unión del acero con la aleación es resultado del elevado contenido de carbono de la segunda. La baja velocidad de enfriamiento del cordón de soldadura revela ausencia de discontinuidades en el retículo cristalino de la zona afectada térmicamente y atenúa la formación de carburos de cromo del tipo Cr23C6, que puede formar la aleación A 351 grado HK 40 durante la difusión del volumen de fracción en masa del cromo.

  15. Glaucoma secundario a neurofibromatosis tipo-1

    Directory of Open Access Journals (Sweden)

    Anay Martínez Díaz

    2012-02-01

    Full Text Available Paciente de 59 años de edad, con antecedentes de neurofibromatosis tipo 1 y trauma contuso del ojo derecho desde hace años. Acudió a consulta de oftalmología refiriendo disminución lenta de la visión; al examen físico se constató una agudeza visual de 0.6 en ambos ojos, así como disminución concéntrica del campo visual en la perimetría por confrontación. El examen objetivo mostró en los anexos una pingüécula en ojo derecho y pterigion grado II en ojo izquierdo; en segmento anterior, múltiples nódulos de Lisch en el iris de ambos ojos, y en el ojo derecho, pupila ligeramente midriática, pero reactiva. Se le realizó gonoscopia, oftalmoscopia y perimetría Humphry; en esta última se halló un escotoma arqueado en ojo derecho, y un defecto superior arqueado en el ojo izquierdo. Se concluyó el caso con los diagnósticos de catarata presenil incipiente y glaucoma secundario a neurofibromatosis tipo 1.

  16. Evaluation of performance of AISI 444 steel for application in distillation towers; Avaliacao do desempenho do aco AISI 444 para aplicacao como 'lining' em torres de destilacao

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, R.F.; Miranda, H.C. de; Farias, J.P. [Universidade Federal do Ceara (DEMM/UFC), Fortaleza, CE (Brazil). Dept. de Engenharia Metalurgica e de Materiais. Lab. de Caracterizacao de Materiais], e-mail: rf.guimaraes@yahoo.com.br

    2008-07-01

    In this work, the behavior of the AISI 444 ferritic stainless steel submitted to thermal fatigue test and their corrosion resistance in heavy crude oil was evaluated. The AWS E309MoL-16 and E316L-17 weld metal was employed as filler metal. Plates of the AISI 444 were welded on ASTM A-516 Gr. 60 plates and submitted to fatigue thermal cycle. Samples were extracted from plates welded and heat treated immersed in heavy crude oil at 300 deg C. Optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive of X-ray analysis (EDX) were used to characterize the microstructure and the corroded surface. The results show that the AISI 444 stainless steels did not present cracks after the thermal fatigue cycle and the heat treated immerse in heavy crude oil. The electrode AWS E309MoL-16 show better corrosion resistance than the AWS E316L-17. (author)

  17. Os Sistemas de workflow em arquivística: a identificação dos modelos e a análise das ferramentas

    Directory of Open Access Journals (Sweden)

    Sérgio Renato Lampert

    Full Text Available Apresenta a tecnologia de workflow sob a ótica da arquivística, apontando os sistemas de workflow, bem como a identificação dos modelos e a análise das ferramentas. Com base nos critérios deste estudo, foi possível identificar uma gama de ferramentas que promovem funções arquivísticas. A análise deu-se apenas nas ferramentas identificadas como sendo Sistemas de Gestão Documental (DMS, as quais são: Agorum Core, Alfresco, ArchivistaBox, KnowledgeTree, Maarch e Owl Intranet.

  18. A ferramenta de análise fmea como suporte para a identificação dos aspectos e impactos ambientais em uma agroindústria de arroz

    Directory of Open Access Journals (Sweden)

    Franclin Ferreira Wenceslau

    2012-01-01

    Full Text Available O setor de beneficiamento de arroz, principalmente no Rio Grande do Sul, é um dos mais representativos no que diz respeito ao percentual de participação na economia do Estado. Até pouco tempo atrás, não correspondia da mesma forma nas questões ambientais. Porém, há alguns anos as empresas deste setor começaram a se preocupar com essa questão, iniciando o desenvolvimento deprogramas e ações para a redução de seus impactos ambientais. Levando-se em conta o panorama atual de degradação ambiental, foiproposta a avaliação dos aspectos e impactos ambientais em uma agroindústria de arroz, na cidade de Bagé/RS, considerando que essaé uma etapa fundamental para a implantação de um Sistema de Gestão Ambiental. Partindo desse princípio e utilizando a ferramentaFMEA (Failure Modes and Effect Analysis – Análise do Tipo e Efeito de Falha, foram apresentados os parâmetros para a análise ecorreção desses impactos. A utilização da ferramenta FMEA auxilia na identificação, classificação e no diagnóstico quanto ao tipo deimpacto ambiental gerado pelo processo produtivo de uma organização, auxiliando na operacionalização de um plano de ação paramitigação dos impactos ambientais mais significativos da empresa.Abstract Rice processing, especially in the Rio Grande doSul State, is very representative percentagewise in the economyof the State. Until not long ago the industry was not equally up toenvironmental standards. A few years ago, rice processingcompanies started to look into it and initiated programs andactions to reduce impact on the environment. Consideringtoday’s level of environmental degradation we chose to evaluatethe environmental impact of a rice processing plant in the city ofBagé/RS because this is a fundamental step for theimplementation of an environmental management system. Withthis in mind and using a FMEA (Failure Modes and EffectAnalysis tool, we defined the parameters for analysis andcorrection

  19. TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Pascual, M.; Salas, F.; Carcel, F.J.; Perales, M.; Sanchez, A.

    2010-07-01

    This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal. (Author). 12 refs.

  20. Preparation of high-performance ultrafine-grained AISI 304L stainless steel under high temperature and pressure

    Directory of Open Access Journals (Sweden)

    Peng Wang

    2016-08-01

    Full Text Available Bulk ultra-fine grained (UFG AISI 304L stainless steel with excellent mechanical properties was prepared by a high-temperature and high-pressure (HTHP method using nanocrystalline AISI 304L stainless steel powders obtained from ball milling. Samples were sintered in high-pressure conditions using the highest martensite content of AISI 304L stainless steel powders milled for 25 h. Analyses of phase composition and grain size were accomplished by X-ray diffraction and Rietveld refinement. By comparing the reverse martensite transformation under vacuum and HTHP treat, we consider that pressure can effectively promote the change in the process of transformation. Compared with the solid-solution-treated 304L, the hardness and yield strength of the samples sintered under HTHP are considerably higher. This method of preparation of UFG bulk stainless steel may be widely popularised and used to obtain UFG metallic materials with good comprehensive performance.

  1. Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears. [aircraft construction materials

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

  2. Effect of cold working on nitriding process of AISI 304 and 316 austenitic stainless steel; Estudo da influencia da deformacao plastica na cinetica de nitretacao em acos inoxidaveis AISI 304 e 316

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Silvio Andre de Lima

    2012-07-01

    The nitriding behavior of AISI 304 and 316 austenitic stainless steel was studied by different cold work degree before nitriding processes. The microstructure, thickness, microhardness and chemical micro-composition were evaluated through optical microscopy, microhardness, scanner electronic microscopy and x ray diffraction techniques. Through them, it was observed that previous plastic deformations do not have influence on layer thickness. However, a nitrided layer thicker can be noticed in the AISI 304 steel. In addition, two different layers can be identified as resulted of the nitriding, composed for austenitic matrix expanded by nitrogen atoms and another thinner immediately below expanded by Carbon atoms. (author)

  3. Study on the mechanical and radiation-shielding properties of borided AISI 304 stainless steels: Študija mehanskih lastnosti in zaščitnih sposobnosti nerjavnega jekla AISI 304 pred sevanjem:

    OpenAIRE

    Akkurt, Iskender; Çalik, Adnan; Karakaş, Serdar; Turhan, Adem; Uçar, Nazim

    2013-01-01

    The boriding effect on the tensile properties, microhardness and radiation shielding has been studied. While boriding increased the hardness of the AISI 304 steel from 240 HV0.1 to the maximum value of 1 740 HV0.1, the elongation and the maximum stress clearly showed decreasing values. Borided specimens were more capable at stopping the high-energy photons and boriding improved the radiation-shielding properties of the AISI 304 steel. From the obtained results, it has been concluded that the ...

  4. Effect of temperature and pressure on wear properties of ion nitrided AISI 316 and 409 stainless steels

    International Nuclear Information System (INIS)

    Fernandes, Frederico Augusto Pires; Heck, Stenio Cristaldo; Pereira, Ricardo Gomes; Casteletti, Luiz Carlos; Nascente, Pedro Augusto de Paula

    2010-01-01

    Stainless steels are widely used in chemical and other industries due to their corrosion resistance property. However, because of their low hardness and wear properties, their applications are limited. Many attempts have been made to increase the surface hardness of these materials by using plasma techniques. Plasma nitriding is distinguished by its effectiveness, and for presenting a relatively low cost and being a clean process, producing hard surface layers on stainless steels. Aiming to verify the influence of the temperature and pressure on the modified resultant layers, samples of AISI 316 and 409 stainless steels were plasma nitrided in two different temperatures (450 and 500°C) and pressures of 400, 500, and 600Pa for 5h. After the nitriding treatment, the layers were analyzed by means of optical microscopy and wear tests. Wear tests were conducted in a fixed-ball micro-wear machine without lubrication. After the plasma nitriding treatment on AISI 316 and 409 samples, homogeneous and continuous layers were produced and their thicknesses increased as the temperature increased, and as the pressure decreased. The nitriding treatment on the AISI 316 steel sample resulted on the formation of expanded austenite layers at 450°C, and chromium nitrides (CrN and Cr 2 N) phases at 500°C. The nitriding treatment on AISI 409 sample yielded the formation of similar layers for both treatment temperatures; these layers constituted mainly by chromium (Cr 2 N) and iron (Fe 2 N, Fe3 N , and Fe 4 N) nitrides. After the nitriding treatment, the AISI 316 steel sample presented higher wear resistance for lower temperature and pressure values. The increase on layer fragility, for higher temperature and pressure values can be responsible for this inverse tendency. The wear resistance of the nitrided AISI 409 sample followed a logic tendency: the harder the layer the better the performance, i.e. the performance was improved with the increase in both the temperature and pressure

  5. TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

    Directory of Open Access Journals (Sweden)

    Sánchez, A.

    2010-12-01

    Full Text Available This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal.

    En este estudio se analiza la influencia que el uso de una cámara de soldadura de gas inerte tiene sobre la microestructura y las propiedades mecánicas de las soldaduras TIG en el acero inoxidable austenítico AISI-316L cuando se emplean AISI ER316L, AISI 308L e Inconel 625 como materiales de aporte. Cuando se compara con el típico proceso de TIG, el uso de una cámara de gas inerte induce cambios en la microestructura, incrementando la presencia de ferrita vermicular y de laminillas de ferrita, resultando en un aumento del límite elástico y una pérdida de dureza. Su influencia sobre otras características de las soldaduras como la carga de rotura depende de la composición del material de aporte. La mejor combinación de propiedades mecánicas se obtuvo usando el Inconel 625 como material de aporte y soldando en la cámara de gas inerte.

  6. Numerical-experimental analysis of a rin AISI{sub 7}Mg Alloy; Analisis numerico experimental de un rin de aleacion AISi{sub 7}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Sauceda Mesa, Israel; Mata Lucero, Omar; Tirado Delgado, Luis; Ocampo Diaz, Juan de Dios [Universidad Autonoma de Baja California, Mexicali, Baja California (Mexico)

    2005-10-15

    The present work shows the results obtained from an investigation mode on the behaviour of a rin of alloy AISi{sub 7}Mg, which is used in compact Volkswagen's cars. Due to two kind of analysis were realized, firstly an experimental and numerical analysis was done, using a special machine for test the flexionante torque and material fatigue, besides was used an equipment of laser to scanner zone with strength concentrations and the maximum displacement amplitudes. The second analysis was done with the finite element technique, using the software ANSYS and CATIA. The difference between life fatigue cycles obtained from the two analyses was 0.6%. While the time optimize by MEF, was of 85% less than experimental analysis. [Spanish] En el presente trabajo se hicieron investigaciones del comportamiento de un rin de aleacion AISi{sub 7}Mg, el cual es usado en automoviles compactos de volkswagen (VW). Para esto, se realizo analisis experimental y numerico. En el primero se utilizo una maquina para prueba de fatiga de momento flexionante, un equipo de medicion de laser escaner donde se detectaron las zonas de concentraciones de esfuerzos y la maxima amplitud de desplazamiento en el rin. Mientras que en el segundo se obtuvieron los esfuerzos que ocasionaban la fatiga por el elemento finito, utilizando los paquetes de computo Ansys y Catia. La diferencia de los ciclos de vida de fatiga obtenidos entre ambos analisis fue del 0.6%. Mientras que el tiempo que se optimizo por el MEF, fue de un 85% menos que el analisis experimental.

  7. Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Aadhavan, R.; Suresh Babu, K., E-mail: sureshbabu.nst@pondiuni.edu.in

    2017-07-31

    Highlights: • Ceria coating reduced the oxidation kinetics of AISI304 by 3–4 orders. • Lower deposition rate (0.1 Å/s) resulted in dense and uniform coating. • Substrate temperature of 100 °C provided coating with smaller crystallite size. • Surface morphology of the coating has strong influence in oxidation protection. - Abstract: Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50–300 °C) and deposition rate (0.1–50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7–18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10{sup −3} kg{sup 2} m{sup −4} s{sup −1} while ceria coating lowered the kinetics by 3–4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

  8. Characterization Of Oxide Layers Produced On The AISI 321 Stainless Steel After Annealing

    Directory of Open Access Journals (Sweden)

    Bochnowski W.

    2015-09-01

    Full Text Available In this study, the structure, chemical composition and topography of oxide layers produced on the surface of the AISI 321 austenitic steel in the annealing process were analyzed. Heat treatment was done at 980°C temperature for 1 hour time in different conditions. The annealing was done in a ceramic furnace in oxidation atmosphere and in vacuum furnaces with cylindrical molybdenum and graphite chambers. The analysis was carried out using the following methods: a scanning electron microscope (SEM equipped with an energy-dispersive X-ray spectrometer (EDX, a transmission electron microscope (TEM equipped with an energy-dispersive X-ray spectrometer (EDX, an X-ray diffractometer (XRD, a secondary ion mass spectrometer with time-of-flight mass analyzer (TOF SIMS and an atomic force microscope (AFM. The oxide layer formed during annealing of the AISI 321 steel at 980°C consisted of sub-layers, diversified in the chemical composition. The thickness of the oxidized layer is depended on the annealing conditions. In a ceramic furnace in oxidation atmosphere, the thickness of the oxide layer was of 300-500 nm, in a vacuum furnace with molybdenum and graphite heating chambers, it ranged from 40 to 300 nm and from a few to 50 nm, respectively. TOF SIMS method allows to get average (for the surface of 100 μm × 100 μm depth profiles of concentration of particular elements and elements combined with oxygen. In oxide layers formed in vacuum furnaces there are no iron oxides. Titanium, apart from being bounded with carbon in carbides, is a component of the oxide layer formed on the surface of the AISI 321 steel.

  9. Electrochemical Study of AISI C1018 Steel in Methanesulfonic Acid Containing an Acetylenic Alcohol-Based Corrosion Inhibitor Formulation.

    Science.gov (United States)

    Finšgar, Matjaž; Jackson, Jennifer

    2016-10-01

    In this work, the electrochemical potentiodynamic behavior of AISI C1018 lower-grade steel material was investigated in 20 wt.% methanesulfonic acid (MSA) solutions with or without different components to design corrosion inhibitor formulations based on acetylenic alcohol, cinnamaldehyde, 1-dodecylpyridinium chloride, and methanol. MSA has recently been considered as a new potential acid to be used in the matrix stimulation procedure and in well cleaning. It is demonstrated that AISI C1018 steel MSA needs to be inhibited. Inhibition type is determined for single components as well as for formulations. © 2015 Society for Laboratory Automation and Screening.

  10. Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

    OpenAIRE

    Richárd Székely; Réka Répánszki; András Somogyi; Ákos Horváth; János Dobránszki

    2010-01-01

    This is a comparative study of the corrosion behaviour of welds in AISI 304 and AISI 904L stainless steels carried out in seawater model solution in the temperature range 5-35°C and the standard of corrosion testing of welds was followed. The corrosion rate and corrosion attack characteristics were determined for welds of the examined steels with several type of treatment. The aim of this work was to compare the steels based on their resistance against the corrosion in terms of pitting potent...

  11. Anodic behaviour of the stainless steel AISI 430 in aqueous solutions of chloride and sulphate ions

    International Nuclear Information System (INIS)

    Sebrao, M.Z.

    1982-01-01

    The kinetics of the dissolution of stainless steel AISI 430 in the presence of chloride and sulphate ions has been studied in terms of the ion concentration, the pH variation, and the velocity of the working electrode. The experimental method utilized was the potentiostatic anodic polarization, and the reactants used were NaCl and Na 2 SO 4 at room temperature. Atomic Absorption spectrophotometry and Auger Electrons spectroscopy (AES) analyses were made in order to support the interpretation of results obtained by means of the potentiostatic polarization method. (author)

  12. Low cycle fatigue life improvement of AISI 304 by initial and intermittent wire brush hammering

    OpenAIRE

    MAKHLOUF, Kamel; SIDHOM, Naziha; KHLIFI, Ammar; SIDHOM, Habib; BRAHAM, Chedly

    2013-01-01

    The effects of hammering by wire brush as a method of improving low cycle fatigue life of highly ductile austenitic stainless steel AISI 304 have been investigated through an experimental study combining imposed strain fatigue tests and assessment of surface characteristic changes under cyclic loading by SEM examinations and XRD analysis. It has been shown that the fatigue life of wire brush hammered surface was increased by 307% at an imposed strain rate of 0.2% and only 17% at an imposed st...

  13. The structural characterization of some biomaterials, type AISI 310, used in medicine

    Science.gov (United States)

    Minciuna, M. G.; Vizureanu, P.; Hanganu, C.; Achitei, D. C.; Popescu, D. C.; Focsaneanu, S. C.

    2016-06-01

    Orthopedics biomaterials are intended for implantation in the human body and substituted or help to repair of bones, cartilage or organ transplant, and tendons. At the end of the 20th century, the availability of materials for the manufacture implants used in medicine has been the same as for other industrial applications. The most used metals for manufacturing the orthopedics implants are: stainless steels, cobalt-chrome-molybdenum alloys, titanium and his alloys. The structural researches which are made in this paper, offer a complete analysis of AISI310 stainless steels, using: optical spectrometry, X-ray diffraction and scanning electronic microscopy.

  14. Effect of cold working and annealing on stress corrosion cracking of AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Yeon, Y.M.; Kwun, S.I.

    1983-01-01

    A study was made of the effects of cold working and annealing on the stress corrosion cracking of AISI 304 stainless steel in boiling 42% MgCl 2 solution. When the 60% or 76% of yield stress was applied, the resistance to SCC showed maximum at 30% of cold work. However, when the same load was applied to the annealed specimens after cold working, the resistance to SCC decreased abruptly at 675degC annealing. The fracture mode changed mode change mixed → intergranular → transgranular as the amount of cold work increased. (Author)

  15. Comparative study of the microbiological corrosion among an AISI 304L and an API X65

    International Nuclear Information System (INIS)

    Diaz S, A.; Arganis J, C.; Luna C, P.; Carapia M, L.; Gonzalez F, E.

    2004-01-01

    Metallic samples of AISI 304L sensitized and API X65, were subjected to the action of an inoculated media with reductive sulphate microorganisms (SBR), carrying out electrochemical evaluations by means of the techniques of Polarization Resistance (RP), Tafel extrapolation (ET) and Electrochemical Noise (RE). The generated information was complemented with the analysis and diagnostic of the present damage in the surfaces exposed in both metals. The used electrochemical techniques allow to determine the corrosion velocities associated to each system, establishing that the uniform corrosion is not affected by the effect of the microorganisms; however, electrochemical noise, evidenced the formation of stings associated to the presence of bacteria. (Author)

  16. Behaviour under fatigue of AISI 304-L stainless steel welded joints

    International Nuclear Information System (INIS)

    Scal, M.W.; Joia, C.J.B.M.; Sousa e Silva, A.S. de

    1979-01-01

    The fatigue behaviour at room temperature of AISI-304-L stainless steel welded joints obtained by two distinct welding methods was studied. The results obtained were compared to those characteristic of the base metal. The welded joint fatigue samples were rectified in order to eliminate the effect of the welded seam geometry. It was concluded that the mechanisms of fatigue crack start in this case is commanded by the austenitic matrix, there being no influence of the delta ferrite rate and distribution present at the melted zone. (Author) [pt

  17. Experimental Design and Data collection of a finishing end milling operation of AISI 1045 steel.

    Science.gov (United States)

    Dias Lopes, Luiz Gustavo; de Brito, Tarcísio Gonçalves; de Paiva, Anderson Paulo; Peruchi, Rogério Santana; Balestrassi, Pedro Paulo

    2016-03-01

    In this Data in Brief paper, a central composite experimental design was planned to collect the surface roughness of an end milling operation of AISI 1045 steel. The surface roughness values are supposed to suffer some kind of variation due to the action of several factors. The main objective here was to present a multivariate experimental design and data collection including control factors, noise factors, and two correlated responses, capable of achieving a reduced surface roughness with minimal variance. Lopes et al. (2016) [1], for example, explores the influence of noise factors on the process performance.

  18. PITTING CORROSION OF AISI 316Ti STAINLESS STEEL WITH POLISHED SURFACE

    Directory of Open Access Journals (Sweden)

    Viera Zatkalíková

    2010-05-01

    Full Text Available AISI 316Ti is Cr–Ni–Mo austenitic stainless steel with the high Pitting Resistance Equivalent Number (PREN. The effect of the surface finishing by polishing on the pitting corrosion resistance was tested in aggressive 5% FeCl3 solution. The immersion tests were curried out at the temperature 30, 50, 80 °C. The electrochemical cyclic potentiodynamic tests were carried out in the same solution at temperature 30 and 50 °C. The evaluation of the corrosion resistance arose from the comparison of the results of the immersion and the cyclic potentiodynamic tests.

  19. Dynamic testing of large AISI-316L steel specimens behaviour using LDTF

    International Nuclear Information System (INIS)

    Casadei, F.; Delzano, C.; Magonette, G.; Halleux, J.P.; Verzeletti, G.

    1987-01-01

    The paper presents the results of a series of dynamic experiments on AISI-316L steel specimens having a cross section of 2000 mm 2 and a gauge length of 350 mm subject to dynamic traction up to rupture. Results for dynamic tests at a nominal strain rate up to 50 s -1 are compared to quasi-static ones, showing an important increase in both yield stress and flow stress. The experimental techniques are described, with special emphasis on full-field optical strain measurements based on Moire interferometry. A 1-D numerical analysis of the experiments is presented. (orig.)

  20. Dynamics testing of large AISI 316L steel specimens behaviour using L.D.T.F

    International Nuclear Information System (INIS)

    Casadei, F.; Delzano, C.; Magonette, G.; Halleux, J.P.; Verzeletti, G.

    1986-01-01

    The paper presents the results of a series of dynamic experiments on AISI-316L steel specimens having a cross section of 2000 mm 2 and a gauge length of 350 mm subject to dynamic traction up to rupture. Results for dynamic tests at a nominal strain rate up to 50 s -1 are compared to quasi-static ones, showing an important increase in both yield stress and flow stress. The experimental techniques are described, with special emphasis on full-field optical strain measurements based on Moire interferometry. A 1-D numerical analysis of the experiments is presented. (orig.)

  1. Active flux tungsten inert gas welding of austenitic stainless steel AISI 304

    OpenAIRE

    Klobčar, D.; Tušek; Bizjak, M.; Simončič, S.; Lešer, V.

    2016-01-01

    The paper presents the effects of flux assisted tungsten inert gas (A-TIG) welding of 4 (10) mm thick austenitic stainless steel EN X5CrNi1810 (AISI 304) in the butt joint. The sample dimensions were 300 ´ 50 mm, and commercially available active flux QuickTIG was used for testing. In the planned study the influence of welding position and weld groove shape was analysed based on the penetration depth. A comparison of microstructure formation, grain size and ferrit number between TIG welding a...

  2. Pengaruh Variasi Arus Pengelasan dan Variasi Diameter Elektroda Terhadap Kekuatan Tarik Pada Stainless Steel AISI 304

    OpenAIRE

    Manurung, Erwin Makmur

    2016-01-01

    The usage of electric current will affect the outcome of welding result for powering weldingarc. Determination of the welding current for connecting the metal in the welding arc will affect the efficiency of work and welding materials. In this study using austenitic stainless steel AISI 304 Stainless Steel with Welding Shield Metal Arc Welding (SMAW), large of welding current 85 A, 95 A and 105 A, and the type of electrode E 308 L diameter of 2.6 mm, 3.2 mm , and 4.0 mm. The purpose of this s...

  3. Corrosion behaviour of iron and AISI 304 stainless steel in tungstate aqueous solutions containing chloride

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    Azambuja Denise S.

    2003-01-01

    Full Text Available The corrosion behavior of iron and AISI 304 stainless steel in aqueous tungstate solutions containing chloride ion was investigated by cyclic voltammetry, open circuit measurements and impedance spectroscopy. The obtained results point out that the inhibitive performance of tungstate depends on the presence of dissolved oxygen, being strongly related to the adsorption of this anion on the surface of the electrode. Under anodic polarization, at low sweep rate and electrode rotation the passive film is more stable and the corrosion rate decreases. At the open circuit potential, the EIS data have clearly demonstrated that for longer immersion times the tungstate inhibitive action is considerably improved.

  4. Service experience with AISI type 316 steel components in CEGB Midlands Region power plant

    International Nuclear Information System (INIS)

    Plastow, B.; Bagnall, B.I.; Yeldham, D.E.

    1979-01-01

    The service performance of AISI Type 316 steel components in sections up to 100 mm thick in Power Plant of the Midlands Region of the C.E.G.B. is reviewed. A comparison is drawn between the satisfactory performance of components whose dimensional stability is not critical and the difficulties experienced when rapid rates of change of temperature cause distortion in thick section components. Weldment manufacture and performance are reviewed and both are considered to be satisfactory. In general the material has performed well and the difficulties due to distortion have been overcome by imposing operating regimes which limit rates of temperature change. (author)

  5. Aspects of plasma arc cutting process in the AISI 321 type stainless steel

    International Nuclear Information System (INIS)

    Souza Barros, I. de.

    1985-01-01

    Some aspects of plasma arc cutting process in the AISI321 stainless steel, used in nuclear industry, are analysed. The maximum values of the velocity of cutting and, the minimum quantity of energy per unit of length necesary for the plasma were determined. The localization of irregularities in the cut surface in function of the velocity of cutting was investigated. The cut surfaces were evaluated by surface roughness, using as measurement parameter, the distance between the sharpest salience and the deepest reentrance of the sample profile. The width of layer from thermal action of the plasma was influenced by the velocity of cutting. (Author) [pt

  6. Neutron diffraction study of residual strains across electron beam welds in AISI 316L stainless steel

    International Nuclear Information System (INIS)

    Braham, C.; Ceretti, M.; Coppola, R.; Lodini, A.; Rustichelli, F.; Tosto, S.

    1995-01-01

    The results of neutron diffraction investigation of the strains produced across an electron-beam (EB) weld in SA AISI 316L reference steel for NET are presented. The sample size was 10 x 5 x 3 cm 3 and the measurements have been carried out at different distances from the weld plane with a spatial resolution of approximately 8 mm 3 in the bulk of the material. Grain size and crystallographic texture effects were investigated, on the same sample, by means of X-ray diffraction and metallography. A method to determine the stress field from the neutron diffraction data even in the presence of strong texture is discussed. (orig.)

  7. Two-scale approach to dynamic localization failure of AISI 316H stainless steel sheets

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    Gambin W.

    2008-01-01

    Full Text Available Dynamic localization failure of a thin sheet made of AISI 316H steel is considered on the macroscopic and mesoscopic level for proportional and nonproportional stress paths. On the macroscopic level, we propose: (1 the replacement of time as independent variable by a function of plastic dissipation and (2 dependence of the initial equivalent yield stress on stress rate. On the mesoscopic level - the regularized Schmid model for description of the single grain behavior is used and the polycrystalline yield surface generated by the texture development enables to improve the Forming Limit Diagrams for the sheet element.

  8. Microstructural changes due to laser surface melting of an AISI 304 stainless steel

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    d?Oliveira A.S.C.M.

    2001-01-01

    Full Text Available Several techniques can be used to improve surface properties. These can involve changes on the surface chemical composition (such as alloying and surface welding processes or on the surface microstructure, such as hardening and melting. In the present work surface melting with a 3kW CO2 cw laser was done to alter surface features of an AISI 304 stainless steel. Microstructure characterisation was done by optical and scanning electron microscopy. Vickers and Knoop microhardness tests evaluated mechanical features after surface melting. Phase transformation during rapid solidification is analysed and discussed.

  9. Microstructure and corrosion behaviour of pulsed plasma-nitrided AISI H13 tool steel

    International Nuclear Information System (INIS)

    Basso, Rodrigo L.O.; Pastore, Heloise O.; Schmidt, Vanessa; Baumvol, Israel J.R.; Abarca, Silvia A.C.; Souza, Fernando S. de; Spinelli, Almir; Figueroa, Carlos A.; Giacomelli, Cristiano

    2010-01-01

    The effect of pulsed plasma nitriding temperature and time on the pitting corrosion behaviour of AISI H13 tool steel in 0.9% NaCl solutions was investigated by cyclic polarization. The pitting potential (E pit ) was found to be dependent on the composition, microstructure and morphology of the surface layers, whose properties were determined by X-ray diffraction and scanning electron microscopy techniques. The best corrosion protection was observed for samples nitrided at 480 o C and 520 o C. Under such experimental conditions the E pit -values shifted up to 1.25 V in the positive direction.

  10. Mechanical Properties of Stellite-6 coated AISI 316L Stainless Steel

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    Pushpinderjit Singh

    2016-01-01

    Full Text Available Present paper describes the mechanical properties of Stellite-6 coated AISI 316 L stainless steel. Specimens were coated using Detonation Gun thermal spray process, with different coating thicknesses of Stellite-6 ranging from 50 µm to 150 µm. Afterwards their properties like tensile strength, impact strength and micro hardness were evaluated on the basis of the results obtained from the experimentation. For comparison of substrate and coated material the graphs were plotted. The coated specimens exhibited superior impact strength and microhardness than that of the bare specimens, whereas the tensile strength of coated specimens decreased marginally with the increase in coating thickness.

  11. Microstructural origins of yield-strength changes in AISI 316 during fission or fusion irradiation

    International Nuclear Information System (INIS)

    Garner, F.A.; Hamilton, M.L.; Panayotou, N.F.; Johnson, G.D.

    1981-08-01

    The changes in yield strength of AISI 316 irradiated in breeder reactors have been successfully modeled in terms of concurrent changes in microstructural components. Two new insights involving the strength contributions of voids and Frank loops have been incorporated into the hardening models. Both the radiation-induced microstructure and the yield strength exhibit transients which are then followed by saturation at a level dependent on the irradiation temperature. Extrapolation to anticipated fusion behavior based on microstructural comparisons leads to the conclusion that the primary influence of transmutational differences is only to alter the transient behavior and not the saturation level of yield strength

  12. 1020 AISI-SAE steel Austenitic Nitrocarburising with alcohol and triethanolamine

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    Álvaro Castro P

    2005-01-01

    Full Text Available The present work shows AISI-SAE 1020 steel's nitrocarbide layer's microstructure and micro-hardness profile following 4 hours at 700ºC using methanol, isopropanol and triethanolamine. The steel was then hardened by quenching it in water and then tempered at 350ºC for 1 hour. Its surface had been partially oxidised by heating it at 400ºC for 1 hour. An example is given of other researchers analysing microstructure and propierties in steel having 0,5% C, using endothermic gas and different amounts of ammoniac.

  13. Monitoring of focusing tube wear during abrasive waterjet (AWJ cutting of AISI 309

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    P. Hreha

    2014-10-01

    Full Text Available The paper deals with the investigating the possibility of using vibrations as a potential source of information for the detection of the malfunctions during the abrasive supplying and focusing tube wear in the process of AWJ. The tested material was the stainless steel AISI 309. Variable factors in the experiment were the abrasive mass flow ma and the focusing tube diameter df. The scanned vibration signal of the material was subjected to frequency analysis. With the increase of the abrasive mass flow, the shift of the amplitudes will follow the opposite direction and decrease. Frequency spectra of all assessed signals are similar by shape in the high-frequency area.

  14. Gestão Ambiental Empresarial: Estudo de Caso da Ferramenta de Teste de Estresse por Sequência

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    Isabella Mesquita

    2017-12-01

    Full Text Available A consciência ambiental é uma tarefa precípua da sociedade humana. É imperativo aplicar uma abordagem multidisciplinar e atuar em todas as instâncias, público e privado, para desenvolver soluções sustentáveis. Nesta seara, o artigo busca estudar a gestão ambiental inserida na trajetória empresarial, tendo em vista que exerce influência nos resultados e na concorrência corporativa. Com relação às ferramentas de gestão ambiental, deu-se atenção à ferramenta de Teste de Estresse por Sequência, que foi criada com o objetivo de avaliar os eventuais riscos da seca.

  15. Ejemplares tipo de Asteraceae (= Compositae de A. L. Cabrera

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    Susana E. Freire

    2000-01-01

    Full Text Available Freire, S. E. & Iharlegui, L. 2000. Ejemplares tipo de Asteraceae (= Compositae de A. L.Cabrera. Darwiniana 38(3-4: 307-364.El presente trabajo representa un catálogo de los ejemplares tipo de 426 especies y 82 variedades deAsteraceae descriptas por A. L. Cabrera entre los años 1931 y 1999. Los taxones se presentan en ordenalfabético. Para cada taxón se indica: diagnosis original, tipo nomenclatural, categoría del tipo, herbario,etiqueta original y nombre actualizado

  16. Avaliação da suscetibilidade à corrosão sob tensão da ZAC do aço inoxidável AISI 316L em ambiente de reator nuclear PWR Stress corrosion cracking of stainless steel AISI 316L HAZ in PWR Nuclear reactor environment

    Directory of Open Access Journals (Sweden)

    Mônica Maria de Abreu Mendonça Schvartzman

    2009-09-01

    Full Text Available Aços carbono de baixa liga e aços inoxidáveis são amplamente utilizados nos circuitos primários de reatores nucleares do tipo PWR (Pressurized Water Reactor. Ligas de níquel são empregadas na soldagem destes materiais devido a características como elevadas resistências mecânica e à corrosão, coeficiente de expansão térmica adequado, etc. Nos últimos 30 anos, a corrosão sob tensão (CST tem sido observada principalmente nas regiões das soldas entre materiais dissimilares existentes nestes reatores. Este trabalho teve como objetivo avaliar, por comparação, a suscetibilidade à corrosão sob tensão da zona afetada pelo calor (ZAC do aço inoxidável austenítico AISI 316L quando submetida a um ambiente similar ao do circuito primário de um reator nuclear PWR nas temperaturas de 303ºC e 325ºC. Para esta avaliação empregou-se o ensaio de taxa de deformação lenta - SSRT (Slow Strain Rate Test. Os resultados indicaram que a CST é ativada termicamente e que a 325ºC pode-se observar a presença mais significativa de fratura frágil decorrente do processo de corrosão sob tensão.In pressurized water reactors (PWRs, low alloy carbon steels and stainless steel are widely used in the primary water circuits. In most cases, Ni alloys are used to joint these materials and form dissimilar welds. These alloys are known to accommodate the differences in composition and thermal expansion of the two materials. Stress corrosion cracking of metals and alloys is caused by synergistic effects of environment, material condition and stress. Over the last thirty years, CST has been observed in dissimilar metal welds. This study presents a comparative work between the CST in the HAZ (Heat Affected Zone of the AISI 316L in two different temperatures (303ºC and 325ºC. The susceptibility to stress corrosion cracking was assessed using the slow strain rate tensile (SSRT test. The results of the SSRT tests indicated that CST is a thermally

  17. El lenguaje verbal como instrumento matemático A linguagem verbal como ferramenta matemática Verbal Language as a Mathematical Tool

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    Héctor Hernando Díaz

    2009-12-01

    Full Text Available La investigación analiza la forma como se manifiesta la comprensión del concepto de función en estudiantes de ingeniería, tomando como instrumento de comunicación el lenguaje verbal, y haciendo transferencia de este concepto a los otros tres lenguajes con que cuenta la matemática: algebraico, aritmético y geométrico. El análisis de la información recogida nos permitió concluir que no es prudente utilizar solo el lenguaje verbal para evaluar la comprensión, porque se estarían evaluando dos saberes en forma simultánea: los conocimientos matemáticos y la capacidad de redactar correctamente; esto haría que las deficiencias del estudiante en el segundo saber, que no es matemático, alteraran los resultados. Por ello se recomienda: primero, que se utilice el lenguaje oral, que le daría al estudiante la oportunidad de aclarar sus explicaciones y replicar objeciones, pero que se combine con otros lenguajes. Segundo, conviene involucrar un uso abundante del lenguaje verbal en el aula de matemáticas, como una poderosa herramienta para mejorar la comprensión, tanto matemática como lingüística.Esta pesquisa analisa a maneira como expressa o entendimento do conceito de função em estudantes de engenharia, tendo a linguagem verbal como ferramenta de comunicação, e transferindo esse conceito para as outras três línguas disponíveis para a matemática: algébrica, aritmética e geométrica. A análise da informação recolhida permitiu-nos concluir que não é prudente a utilizar apenas a linguagem verbal para avaliar a compreensão, porque se estariam avaliando dois tipos de conhecimento, simultaneamente: o conhecimento matemático e a capacidade de escrever corretamente. Assim, as deficiências do aluno no segundo saber-que não é matemático-alterarão os resultados. Portanto, recomenda-se empregar a linguagem oral, o que daria ao estudante a oportunidade de esclarecer suas explicações e replicar objeções, mas combinada com

  18. O Twitter como Ferramenta Estratégica para a Comunicação Audiovisual: Estudos de Casos

    Directory of Open Access Journals (Sweden)

    Raul Parreira Maciel

    2012-12-01

    Full Text Available No contexto atual das comunicações, e particularmente da internet, em que a visibilidade, a conquista da atenção do consumidor e consequentemente a prescrição social possuem enorme valor comercial, o twitter pode ser considerado mais uma rede social entre tantas outras. Todavia, dadas suas especificidades, ele mostra-se uma poderosa ferramenta estratégica de comunicação e marketing. É assim que ele se impõe, essencialmente por meio das formas como gere as trocas de informações entre os usuários. São essas formas e o próprio twitter como ferramenta que devem ser analisadas aqui do ponto de vista da estratégia de comunicação para o audiovisual. A intenção deste estudo não é defender as capacidades do twitter como ferramenta estratégica, mas analisar casos específicos para demonstrar as possibilidades de ação na rede social.

  19. O Controle Interno e a Auditoria como Ferramenta de Desenvolvimento nas Micro e Pequenas Empresas

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    Rafaela Lorenzoni

    2013-10-01

    Full Text Available Geralmente, nas pequenas empresas, os procedimentos operacionais e as rotinas administrativas são mais passíveis de falhas. Isso pode acontecer por múltiplos motivos, como por exemplo: falha no registro das operações, falta de capacitação dos funcionários, etc. O que os pequenos empresários não notam é que muitas técnicas de auditoria interna podem ser propagadas sem altos investimentos e gerenciadas pelo proprietário ou administrador. São, por exemplo, as rotinas que permitem a conferência de saldos, estoques e pagamentos. Muitos empresários pecam, também, por não fazer uso da contabilidade como ferramenta de controle interno. Utilizando-a como instrumento fiscal, perdem a chance de lidar com um lado ainda pouco explorado do contador: o de auditor. A contabilidade gera dados de forma ordenada, cria rotinas e garante o registro de toda a movimentação do patrimônio da empresa. Esse ambiente de informação cria oportunidades únicas para o planejamento de um sistema de controle interno.

  20. Troca rápida de ferramentas: proposta metodológica e estudo de caso

    Directory of Open Access Journals (Sweden)

    Fogliatto Flávio Sanson

    2003-01-01

    Full Text Available A troca rápida de ferramentas (TRF tem por objetivo reduzir o tempo de preparação (ou setup de equipamentos, minimizando períodos não-produtivos no chão-de-fábrica. Como conseqüência, é possível a redução do tamanho dos lotes de produção na manufatura. A TRF fundamenta-se em técnicas que enfatizam o trabalho cooperativo em equipe e a proposição de formas criativas de melhoria de processos. Este artigo apresenta uma proposta metodológica para a TRF, constituída dos seguintes passos: definição do projeto, planejamento das atividades, treinamento da equipe de implantação, implantação propriamente dita, acompanhamento e consolidação. Um estudo de caso desenvolvido na indústria moveleira ilustra a metodologia proposta.

  1. Filosofia da ciência como ferramenta microeconômica

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    Fabio Barbieri

    2009-06-01

    Full Text Available A teoria neoclássica pressupõe conhecimento perfeito. A crítica hayekiana a essa teoria, por sua vez, afirma que esse conhecimento é resultado do processo competitivo e, portanto, não pode ser considerado como dado. O “Problema de Hayek” investiga sob que condições o conhecimento do agente se aproxima dos reais fundamentos de uma economia. A fim de solucionar o “Problema de Hayek”, o nosso artigo utiliza algumas idéias da literatura de metodologia da Ciência, conhecida como teoria do “crescimento do conhecimento” (Popper, Kuhn, Lakatos e outros. Essas idéias são utilizadas para se compreender como evolui o conhecimento dos agentes econômicos, em especial o dos empresários. Estes são vistos como ativos formuladores de teorias empresariais conjecturais criticadas no processo competitivo, não como agentes passivos que maximizam funções já conhecidas da teoria convencional. Utiliza-se a Filosofia da Ciência não para analisar metodologicamente a microeconomia, mas, sim, como ferramenta analítica pertencente à própria teoria econômica.

  2. Aplicabilidade de ferramentas de geotecnologia para estudos e perícias ambientais

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    Victor Wilson Botteon

    2016-04-01

    Full Text Available Impactos ambientais se tornam frequentes preocupações nos dias atuais. Dentre os vários meios produtores de prova na esfera judicial, a perícia ambiental se destaca e ocupa um espaço importante no esclarecimento de questões destinadas a apurar determinado fato relacionado a litígios ambientais. Em virtude da importância e da grande complexidade de ilícitos contra o meio ambiente, é fundamental que se desenvolvam tecnologias para auxiliar os exames pericias no desempenho de suas atividades. Dessa forma, as geotecnologias apresentam vantagens e se tornam primordiais para lidar com a complexidade da avaliação ambiental e áreas de grande extensão. O uso de geotecnologias é amplo e se dá principalmente pela disponibilidade de equipamentos adequados ao processamento de informações e à facilidade de acesso a dados, otimizando custos operacionais e agilizando processos de tomadas de decisão. Esse quadro pode oferecer suporte ao perito na realização de exames de forma mais eficiente e permitindo acessibilidade de recursos tecnológicos a baixos custos para melhor instruir um laudo pericial ambiental. O presente trabalho objetivou apresentar exemplos de alguns estudos e a importância de ferramentas de geotecnologias, com ênfase na perspectiva de aplicabilidade nas atividades de perícia ambiental.

  3. Componentes da teoria social de aprendizagem numa ferramenta para ensino na Enfermagem

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    Marcia Regina Cubas

    2015-10-01

    Full Text Available RESUMOObjetivo:identificar componentes fundamentais da teoria social de aprendizagem numa ferramenta computacional para auxílio ao ensino do processo de raciocínio para elaboração do diagnóstico de enfermagem.Método:estudo qualitativo que analisou o discurso, coletado por meio de grupo focal, de 18 professores e estudantes de duas escolas de enfermagem brasileiras.Resultados:os temas foram agrupados em quatro categorias relacionadas aos componentes da teoria e em 13 subcategorias.Conclusão: o significado da aprendizagem pode ser ampliado pela didática do professor e evidenciado pela relação entre a sistematização e o raciocínio; para aprender fazendo são necessários pré-requisitos e um processo de motivação e capacitação, que também é inerente à aprendizagem pela formação de identidade no grupo; no sentimento de pertencimento a um determinado grupo tornaram-se visíveis aspectos relacionados à profissão em detrimento do pertencimento a uma comunidade de prática de aprendizagem.

  4. Dependence of corrosion properties of AISI 304L stainless steel on the austenite grain size

    Energy Technology Data Exchange (ETDEWEB)

    Sabooni, Soheil; Rashtchi, Hamed; Eslami, Abdoulmajid; Karimzadeh, Fathallah; Enayati, Mohammad Hossein; Raeissi, Keyvan; Imani, Reihane Faghih [Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of). Dept. of Materials Engineering; Ngan, Alfonso Hing Wan [The Univ. of Hong Kong (China). Dept. of Mechanical Engineering

    2017-07-15

    The corrosion resistance of austenitic stainless steels is known to be hampered by the loss of chromium available for passive surface layer formation as a result of chromium carbide precipitation at austenite grain boundaries during annealing treatments. Although high-temperature annealing can promote carbide dissolution leading to better corrosion resistance, grain coarsening also results, which would lead to poorer mechanical properties. Processing methods to achieve both good corrosion resistance and mechanical properties are thus highly desirable for austenitic stainless steels. In the present study, we show that the corrosion resistance of AISI 304L stainless steel can be improved by grain refinement into the ultrafine-grained regime. Specifically, samples with different austenite grain sizes in the range of 0.65-12 μm were studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests in a 3.5 wt.% NaCl solution. All samples showed a typical passive behavior with similar corrosion potential, but the corrosion current density decreased significantly with decreasing grain size. The results show that the sample with the finest grain size had the best corrosion resistance due to a higher resistance of the passive layer to pitting attacks. This study indicates that grain refinement which improves mechanical properties can also significantly improve the corrosion resistance of AISI 304L stainless steel.

  5. Physical and Tribological Properties of Nitrided AISI 316 Stainless Steel Balls

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    Yang Shicai

    2016-01-01

    Full Text Available AISI 316 austenitic stainless steel balls (diameters 5.0 and 12.0 mm, typical hardness 250 HV0.3 and flat samples (20×20×2.0 mm were nitrided by a pulsed glow discharge Ar/N2 plasma. Hardness of the ball surfaces was analysed using Vickers indentation. Thermal stability of the nitrided balls (diameter 12.0 mm was studied using a furnace to heat them in air for 8 hours at temperatures up to 700.0°C and then, after cooling to room temperature, the surface hardness of the heated balls was re-measured. Scanning electron microscopy and X-ray diffraction were used to study the microstructures, composition and phase formation of the nitrided sublayers. Unlubricated pin-on-disc wear testing was used to evaluate the wear resistance of nitrided stainless steel balls (5.0 mm diameter and the results were compared with similar testing on hardened Cr-Steel balls (5 mm diameter with hardness of about 650 HV0.3. All the test results indicated that the nitrided AISI 316 austenitic stainless steel balls have advantages over the hardened Cr-Steel balls in terms of retaining high hardness after heat treatment and high resistance to sliding wear at room temperature under higher counterpart stress. These properties are expected to be beneficial for wide range of bearing applications.

  6. Microstructure, Texture, and Mechanical Property Analysis of Gas Metal Arc Welded AISI 304 Austenitic Stainless Steel

    Science.gov (United States)

    Saha, Saptarshi; Mukherjee, Manidipto; Pal, Tapan Kumar

    2015-03-01

    The present study elaborately explains the effect of welding parameters on the microstructure, texture, and mechanical properties of gas metal arc welded AISI 304 austenitic stainless steel sheet (as received) of 4 mm thickness. The welded joints were prepared by varying welding speed (WS) and current simultaneously at a fixed heat input level using a 1.2-mm-diameter austenitic filler metal (AISI 316L). The overall purpose of this study is to investigate the effect of the variation of welding conditions on: (i) Microstructural constituents using optical microscope and transmission electron microscope; (ii) Micro-texture evolution, misorientation distributions, and grain boundaries at welded regions by measuring the orientation data from electron back scattered diffraction; and (iii) Mechanical properties such as hardness and tensile strength, and their correlation with the microstructure and texture. It has been observed that the higher WS along with the higher welding current (weld metal W1) can enhance weld metal mechanical properties through alternation in microstructure and texture of the weld metal. Higher δ-ferrite formation and high-angle boundaries along with the + grain growth direction of the weld metal W1 were responsible for dislocation pile-ups, SFs, deformation twinning, and the induced martensite with consequent strain hardening during tensile deformation. Also, fusion boundary being the weakest link in the welded structure, failure took place mainly at this region.

  7. Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

    Science.gov (United States)

    Aadhavan, R.; Suresh Babu, K.

    2017-07-01

    Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50-300 °C) and deposition rate (0.1-50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7-18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10-3 kg2 m-4 s-1 while ceria coating lowered the kinetics by 3-4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

  8. Variation in sessile microflora during biofilm formation on AISI-304 stainless steel coupons.

    Science.gov (United States)

    de França, F P; Lutterbach, M T

    1996-07-01

    Coupons of stainless steel type AISI-304 were exposed to the industrial cooling system of a petrochemical plant fed by seawater from the Guanabara Bay, Rio de Janeiro, Brazil, in order to study the in situ formation of biofilms. Bacteria, microalgae and fungi were detected on the coupons as soon as 48 h after exposure. Their respective numbers were determined at times 48, 96 and 192 h and over the following 8 weeks. Aerobic, anaerobic and sulfate-reducing bacteria were quantified according to the technique of the most probable number, and fungi by the pour plate technique. The number of microorganisms present in the forming biofilm varied over the experimental period, reaching maximal levels of 14 x 10(11) cells cm-2, 30 x 10(13) cells cm-2, 38 x 10(11) cells cm-2 and 63 x 10(5) cells cm-2, respectively, for aerobic bacteria, anaerobic bacteria, sulfate-reducing bacteria and fungi, and the dynamics of this variation depended on the group of microorganisms. Bacillus sp, Escherichia coli, Serratia sp and Pseudomonas putrefaciens were identified among the aerobic bacteria isolated. Additionally, microalgae and bacteria of the genus Gallionella were also detected. Nonetheless, no evidence of corrosion was found on the stainless steel type AISI-304 coupons over the experimental period.

  9. Corrosion behaviour of AISI 304 stainless steel with Cu coatings in H 2SO 4

    Science.gov (United States)

    Pardo, A.; Merino, M. C.; Coy, A. E.; Arrabal, R.; Viejo, F.; M'hich, A.

    2007-09-01

    The work addresses the influence of cementation and electrodeposition of copper coatings on the corrosion resistance of AISI 304 stainless steel immersed in 30 wt.% H 2SO 4 at temperatures of 25 and 50 °C. Corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The specimen surfaces were analysed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. The corrosion performance of AISI 304 stainless steel in sulphuric acid solution was greatly improved by copper coatings. The amount of copper deposited by the cementation process was sufficient to protect the stainless steel of corrosion. A greater amount of copper obtained by electrodeposition treatments does not supply further improvement in the corrosion behaviour. The improved corrosion resistance is related to copper dissolution at the initial stages of immersion tests and the presence of Cu 2+ in the solution, which makes the medium more oxidizing, increasing the stability of the passive layer. In addition, the presence of copper at the surface reduces the overpotential of cathodic reaction, enabling the transition from an active region to the passive one.

  10. Effects of processing on the transverse fatigue properties of low-sulfur AISI 4140 steel

    Energy Technology Data Exchange (ETDEWEB)

    Collins, S.R.; Michal, G.M. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering

    1993-12-01

    The effects of inclusions due to steelmaking processes on the fatigue life of AISI 4140 have been investigated. The test matrix consisted of three commercially produced heats of AISI 4140 of comparable cleanliness: one was conventionally cast (CC), and two were inert gas-shielded/bottom-poured (IGS). One of the IGS heats was calcium-treated to explore the effects of inclusion shape control (IGS/SC). All heats were hot-rolled and reduced over 95 pct to produce bar stock of 127 to 152 mm (5 to 6 in.) in diameter. Transverse axial specimens confirming to ASTM E466 were machined, quenched, and tempered to approximately 40 HRC, and they were fatigue tested in tension-tension cycling (R = 0.1). Test results and statistical analyses of the stress-life data show that the IGS grade has several times the fatigue strength of the CC grade at 10{sup 7} cycles. Lower-limit fatigue strengths calculated at a 99.9 pct probability were 518.5 MPa (75.2 ksi) for IGS vs 55.6 MPa (8.1 ksi) for the CC grade. The IGS/SC grad had the best performance at all stress and life levels. The results obtained indicate that fatigue performance can be improved by choosing a processing method that reduces the indigence of exogenous oxides and by controlling the shape of the sulfides.

  11. Effect of Friction Coefficient on the Small Punch Creep Behavior of AISI 316L Stainless Steel

    International Nuclear Information System (INIS)

    Kim, Bum-Joon; Cho, Nam-Hyuck; Kim, Moon-K; Lim, Byeong-Soo

    2011-01-01

    Small punch creep testing has received attention due to the convenience of using smaller specimens than those of conventional uniaxial creep tests, which enables creep testing on developing or currently operational components. However, precedent studies have shown that it is necessary to consider friction between the punch and specimen when computing uniaxial equivalent stress from a finite element model. In this study, small punch creep behaviors of AISI 316L stainless steel, which is widely used in high temperature-high pressure machineries, have been compared for the two different ceramic balls such as Si 3 N 4 and Al 2 O 3 . The optimal range of the friction coefficient is 0.4⁓0.5 at 650°C for the best fit between experimental and simulation data of AISI 316 L stainless steel. The higher the friction coefficient, the longer the creep rupture time is. Therefore, the type of ceramic ball used must be specified for standardization of small punch creep testing.

  12. A Computational Study of Plastic Deformation in AISI 304 Induced by Surface Mechanical Attrition Treatment

    Science.gov (United States)

    Zhang, X. C.; Lu, J.; Shi, S. Q.

    2010-05-01

    As a technique of grain refinement process by plastic deformation, surface mechanical attrition treatment (SMAT) has been developed to be one of the most effective ways to optimize the mechanical properties of various materials including pure metals and alloys. SMAT can significantly reduce grain size into nanometer regime in the surface layer of bulk materials, providing tremendous opportunities for improving physical, chemical and mechanical properties of the materials. In this work, a computational modeling of the surface mechanical attrition treatment (SMAT) process is presented, in which Johnson-Cook plasticity model and the finite element method were employed to study the high strain rate, elastic-plastic dynamic process of ball impact on a metallic target. AISI 304 steel with low stacking fault energy was chosen as the target material. First, a random impact model was used to analyze the statistic characteristics of ball impact, and then the plastic deformation behavior and residual stress distribution in AISI 304 stainless steel during SMAT were studied. The simulation results show that the compressive residual stress and vertical deformation of the surface structures were directly affected by ball impact frequency, incident impact angle and ball diameter used in SMAT process.

  13. Tribological Response of Heat Treated AISI 52100 Steels Against Steel and Ceramic Counterparts

    Directory of Open Access Journals (Sweden)

    Türedi E.

    2017-09-01

    Full Text Available AISI 52100 bearing steels are commonly used in applications requiring high hardness and abrasion resistance. The bearing steels are working under dynamic loads in service conditions and their toughness properties become important. In order to provide the desired mechanical properties, various heat treatments (austenizing, quenching and tempering are usually applied. In this study, AISI 52100 bearing steel samples were austenized at 900°C for ½ h and water quenched to room temperature. Then tempering was carried out at 795°C, 400°C and 200°C for ½ h. In order to investigate the effect of heat treatment conditions on wear behavior, dry friction tests were performed according to ASTM G99-05 Standard with a ‘ball-on-disk’ type tribometer. The samples were tested against steel and ceramic counterparts using the parameters of 100 m distance and 30 N load and 0.063 m/s rotational speed. After wear test, the surface characterization was carried out using microscopy. Wear loss values were calculated using a novel optical method on both flat and counterpart specimens.

  14. Factors Affecting Optimal Surface Roughness of AISI 4140 Steel in Turning Operation Using Taguchi Experiment

    Science.gov (United States)

    Novareza, O.; Sulistiyarini, D. H.; Wiradmoko, R.

    2018-02-01

    This paper presents the result of using Taguchi method in turning process of medium carbon steel of AISI 4140. The primary concern is to find the optimal surface roughness after turning process. The taguchi method is used to get a combination of factors and factor levels in order to get the optimum surface roughness level. Four important factors with three levels were used in experiment based on Taguchi method. A number of 27 experiments were carried out during the research and analysed using analysis of variance (ANOVA) method. The result of surface finish was determined in Ra type surface roughness. The depth of cut was found to be the most important factors for reducing the surface roughness of AISI 4140 steel. On the contrary, the other important factors i.e. spindle speed and rake side angle of the tool were proven to be less factors that affecting the surface finish. It is interesting to see the effect of coolant composition that gained the second important factors to reduce the roughness. It may need further research to explain this result.

  15. Micro-Abrasion Wear Resistance of Borided 316L Stainless Steel and AISI 1018 Steel

    Science.gov (United States)

    Reséndiz-Calderon, C. D.; Rodríguez-Castro, G. A.; Meneses-Amador, A.; Campos-Silva, I. E.; Andraca-Adame, J.; Palomar-Pardavé, M. E.; Gallardo-Hernández, E. A.

    2017-11-01

    The 316L stainless steel has high corrosion resistance but low tribological performance. In different industrial sectors (biomedical, chemical, petrochemical, and nuclear engineering), improvement upon wear resistance of 316L stainless steel components using accessible and inexpensive methods is critical. The AISI 1018 steel is widely used in industry, but its tribological performance is not the best among steels. Therefore, in this study the behavior of the borided 316L stainless steel and 1018 steel is evaluated under micro-abrasion wear. The boriding was carried out at 1223 K over 6 h of exposure time, resulting in a biphase layer composed of FeB/Fe2B phases. In order to evaluate Fe2B phase with no influence from FeB phase, AISI 1018 steel samples were borided at 1273 K for over 20 min and then diffusion annealed at 1273 K over 2 h to obtain a Fe2B mono-phase layer. Micro-abrasion wear resistance was evaluated by a commercial micro-abrasion testing rig using a mix of F-1200 SiC particles with deionized water as abrasive slurry. The obtained wear rates for FeB and Fe2B phases and for the 316L stainless steel were compared. Wear resistance of 316L stainless steel increases after boriding. The wear mechanisms for both phases and for the stainless steel were identified. Also, transient conditions for rolling and grooving abrasion were determined for the FeB and Fe2B phases.

  16. Low-temperature dependence of yielding in AISI 316 stainless steels

    International Nuclear Information System (INIS)

    Tobler, R.L.; Reed, R.P.

    1981-01-01

    Tensile tests at temperatures between 323 and 4 K were performed on one heat of AISI 316 austenitic stainless steel having the composition Fe-17.34Cr-12.17Ni-1.55Mn-2.16Mo-0.051C. The temperature dependences of the yield and flow strengths at plastic strain increments from 0.2 to 3.65% are analyzed. At the yield strain (0.2%), no body-centered cubic (bcc) martensite phase transformation is detected. At higher strains (approx.3.2 +- 0.6%), bcc martensite forms from the parent austenite phase at test temperatures below 190 K, but there are no discontinuities in the temperature dependence of flow strength. A review of data available for three heats of AISI 316 at temperatures between 973 and 4 K reveals that deviations from thermally activated plastic flow theory occur at temperatures below 175 K, apparently depending on heat-to-heat compositional variations. Grain size and magnetic transition effects on the yield strength are discussed

  17. Relationship between phase development and swelling of AISI 316 during temperature changes

    International Nuclear Information System (INIS)

    Yang, W.J.S.; Garner, F.A.

    1982-04-01

    The effect of temperature changes on radiation-induced swelling and phase development of AISI 316 has been examined for specimens irradiated in two different experiments. The formation of radiation-stable phases at low temperature appears to precede swelling but these phases tend to dissolve when subsequently subjected to higher temperature. Phases which develop at high temperature persist when the temperature is subsequently lowered. Once nucleated at low temperatures, voids tend to persist without reduction in density at higher temperatures. However, a new round of void nucleation occurs when the temperature is decreased during irradiation. If the swelling has entered the steady-state swelling regime prior to the temperature change, there is no effect on the subsequent swelling rate. For temperature changes that occur before the end of the transient swelling regime, substantial changes can occur in the swelling behavior, particularly if the changes occur in the range around 500 0 . The isothermal swelling behavior of AISI 316 is much less sensitive to irradiation temperature than previously envisioned

  18. Sintering, microstructure and properties of WC-AISI304 powder composites

    Energy Technology Data Exchange (ETDEWEB)

    Marques, B.J. [Department of Materials and Ceramic Engineering, CICECO University of Aveiro, 3810-193 Aveiro (Portugal); Fernandes, C.M., E-mail: cmfernandes@ua.pt [Department of Materials and Ceramic Engineering, CICECO University of Aveiro, 3810-193 Aveiro (Portugal); ISEC, Mechanical Department, Engineering Institute of Coimbra, Rua Pedro Nunes, 3030-199 Coimbra (Portugal); Senos, A.M.R. [Department of Materials and Ceramic Engineering, CICECO University of Aveiro, 3810-193 Aveiro (Portugal)

    2013-06-15

    Highlights: ► Total replacement of Co binder by stainless steel AISI 304 in WC based composites. ► Processing conditions for WC–stainless steel composites. ► Mechanical behavior and oxidation resistance of WC–stainless steel composites. -- Abstract: Tungsten carbide–stainless steel (AISI 304) based composites were successfully prepared by powder metallurgy routes using vacuum sintering at a maximum temperature of 1500 °C. The effects of the binder amount (between 6 and 15 wt.%) on the phase composition, microstructure and mechanical properties, namely hardness and fracture toughness, were investigated. Appreciable amount of (M,W){sub 6}C up to 12 wt.% was detected, especially for the higher SS contents. However, a good compromise between toughness and hardness was observed. Besides that, improved oxidation resistance was noticed in WC–SS based composites compared with WC–Co composites. The results are discussed having in mind the correlation between chemical composition, phase composition, microstructure and mechanical behavior.

  19. Microstructure, Mechanical and Corrosion Properties of Friction Stir-Processed AISI D2 Tool Steel

    Science.gov (United States)

    Yasavol, Noushin; Jafari, Hassan

    2015-05-01

    In this study, AISI D2 tool steel underwent friction stir processing (FSP). The microstructure, mechanical properties, and corrosion resistance of the FSPed materials were then evaluated. A flat WC-Co tool was used; the rotation rate of the tool varied from 400 to 800 rpm, and the travel speed was maintained constant at 385 mm/s during the process. FSP improved mechanical properties and produced ultrafine-grained surface layers in the tool steel. Mechanical properties improvement is attributed to the homogenous distribution of two types of fine (0.2-0.3 μm) and coarse (1.6 μm) carbides in duplex ferrite-martensite matrix. In addition to the refinement of the carbides, the homogenous dispersion of the particles was found to be more effective in enhancing mechanical properties at 500 rpm tool rotation rate. The improved corrosion resistance was observed and is attributed to the volume fraction of low-angle grain boundaries produced after friction stir process of the AISI D2 steel.

  20. UM DEBATE SOBRE A DESCRIMINALIZAÇÃO DA MACONHA SOB O ENFOQUE DA CRIMINOLOGIA CRÍTICA E A AUDIÊNCIA DE CUSTÓDIA COMO FERRAMENTA CONTRA A PRISÃO CAUTELAR

    Directory of Open Access Journals (Sweden)

    Yuri Anderson Pereira Jurubeba

    2017-02-01

    Full Text Available O objetivo deste artigo é expor um debate contextualizado sobre a descriminalização da maconha para uso próprio, sob o enfoque metodológico da Criminologia da Crítica (CARVALHO, 2013, pela consolidação das políticas criminais alternativas. Considera-se no debate a repercussão geral do Recurso Extraordinário n° 635.659/SP, que tramita no STF. Para além de uma análise jurídica, o tema abordado figura num contexto social com muitas contradições e diferentes aspectos que precarizam a vida e vulnerabilizam a juventude. Os dados divulgados pelo Infopen (2014 mostram que o sistema penal brasileiro e tocantinense é seletivo e recai sobre pobres, negros e desempregados com baixo nível escolar. Para evitar danos sociais maiores às pessoas, a Audiência de Custódia pode ser importante ferramenta contra a prisão cautelar. O problema que procuramos elucidar é que a criminalização do uso e porte da maconha se soma à expansão de outros tipos penais, mais graves e com alta periculosidade, contribuindo para o encarceramento massivo de pessoas num sistema penitenciário superlotado e em condições que desrespeitam os Direitos Humanos.

  1. A TRANSFORMAÇÃO SOCIAL DE UMA FERRAMENTA ESTRATÉGICA EM UMA ORGANIZAÇÃO FAMILIAR BRASILEIRA

    Directory of Open Access Journals (Sweden)

    Eros Renato Silva Cardoso

    Full Text Available RESUMO O objetivo deste artigo é compreender o fenômeno de transformação de um software, com potencial para ser uma ferramenta estratégica, pelas construções sociais dos atores inseridos em uma organização familiar brasileira. Defende-se que as ferramentas estratégicas podem ser transformadas pelas construções sociais de seus usuários articuladas nos contextos em que estão inseridos. Para compreender o fenômeno dessas transformações nas ferramentas estratégicas, discute-se a temática da construção social nas organizações, reconhecendo as implicações das especificidades sociais das organizações familiares. Esta pesquisa trouxe uma abordagem fenomenológica do mundo social de Schütz. O lócus do estudo foi uma organização familiar do setor de vendas de equipamentos comerciais no estado do Espírito Santo - Brasil. A coleta de dados se deu a partir de dezessete entrevistas semiestruturadas, observação participante e pesquisa documental. A análise dos dados foi inspirada no método fenomenológico. A justificativa deste trabalho está em contribuir para preencher lacunas de pesquisa sobre a transformação das ferramentas estratégicas no “fazer estratégia” em uma ótica socialmente construída, por meio de articulações teóricas e empíricas. Como resultados, questões como o despreparo, o feeling, as redes de motivos e interesses, as imposições, as heranças do contexto, as tentativas (de manutenção de práticas, a experiência de vida do indivíduo e interesses organizacionais, entre outras, evidenciaram que as transformações da ferramenta foram causadas pelas redes de motivos e interesses, tanto institucionais quanto específicos dos atores sociais, imersos em construções sociais no contexto.

  2. Comprometimento medular por linfoma tipo Burkitt: relato de um caso

    Directory of Open Access Journals (Sweden)

    Murillo Côrtes Drummond

    1985-06-01

    Full Text Available Registro de caso de linfoma tipo Burkitt com comprometimento intrarraqueano em criança de três anos de idade. Considerações sobre esse tipo de tumor são feitas em função do caso observado e de dados da literatura.

  3. Study of the M23C6 precipitation in AISI 304 stainless steel by small angle neutron scattering

    International Nuclear Information System (INIS)

    Boeuf, A.; Caciuffo, R.G.M.; Institut Max von Laue - Paul Langevin, 38 - Grenoble; Ancona Univ.; Melone, S.; Puliti, P.; Rustichelli, F.; Institut Max von Laue - Paul Langevin, 38 - Grenoble; Ancona Univ.; Coppola, R.

    1985-01-01

    The results of some small-angle neutron scattering (SANS) experiments on M 23 C 6 (M=Fe, Cr) carbide precipitation in AISI 304 stainless steel, aged at different temperatures during different times, are presented. The total volume fraction, the total surface of precipitates per unit sample volume and the size distribution functions of the M 23 C 6 carbides were determined. (orig.)

  4. The effect of cladding speed on phase constitution and properties of AISI 431 stainless steel laser deposited coatings

    NARCIS (Netherlands)

    Hemmati, I.; Ocelik, V.; De Hosson, J. Th. M.

    2011-01-01

    Shorter processing time has given impetus to laser cladding technology and therefore in this research the AISI 431 martensitic stainless steel coatings are laser deposited at high cladding speeds, i.e. up to 117 mm/s. The analysis of phase constitution and functional properties of the coatings are

  5. X-Ray diffraction application in studying the nitrogen fixing and aging in stainless steel AISI 304

    International Nuclear Information System (INIS)

    Ramos, L.F.V.

    1973-01-01

    Solid solutions of N in AISI-304 stainless steels were aged to different degrees. The aging was monitored through X-Ray difraction measurement of the lattice parameter 'a'. The increases in 'a', due to the increase of N in solid solution were determined experimentally

  6. Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials

    Science.gov (United States)

    Townsend, D. P.

    1985-01-01

    Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.

  7. Extended X-Ray Absorption Fine Structure Investigation of Carbon Stabilized Expanded Austenite and Carbides in Stainless Steel AISI 316

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny

    2011-01-01

    Low temperature carburized AISI 316 stainless steel - carbon expanded austenite - was investigated with EXAFS and synchrotron diffraction together with synthesized carbides of the type M3C2, M7C3 and M23C6. It was found that the chemical environment of carbon expanded austenite is not associated ...

  8. Effects of Ultrasonic Nanocrystal Surface Modification (UNSM) on Residual Stress State and Fatigue Strength of AISI 304

    Science.gov (United States)

    Cherif, A.; Pyoun, Y.; Scholtes, B.

    2010-03-01

    The effects of a new mechanical surface treatment method, called ultrasonic nanocrystal surface modification (UNSM), on near-surface microstructures and residual stress states as well as on the fatigue behavior of an austenitic steel AISI 304 are investigated and discussed. The results are compared with consequences of other mechanical surface treatment methods such as deep rolling or shot peening.

  9. Laser surface cladding of Ti-6Al-4V on AISI 316L stainless steel for bio-implant application

    CSIR Research Space (South Africa)

    Kumar, A

    2014-01-01

    Full Text Available The present study concerns an in-depth investigation of the influence of laser surface cladding of Ti-6Al-4V on the microstructure (both the top surface, cross-section and interface), wear resistance, corrosion resistance and bio-activity of AISI...

  10. In-situ investigation of martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature

    DEFF Research Database (Denmark)

    Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen

    2013-01-01

    Martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature was investigated with Vibrating Sample Magnetometry. The investigation reports the stabilization of retained austenite in quenched samples during storage at room temperature and reveals the thermally activated nature...

  11. Fogão solar: ferramenta viável para cozimento de alimentos a partir de materiais de baixo custo

    Directory of Open Access Journals (Sweden)

    Camila Vitorino dos Santos

    2016-04-01

    Full Text Available Na busca do desenvolvimento de projetos voltados à utilização de energia limpa e renovável, a energia solar vem ganhando destaque nos últimos anos. Esta configura-se como uma fonte de energia abundante e inesgotável, uma vez que é proveniente de fenômenos naturais e possibilita a captação e conversão em outras formas de energia. Estudos relatam a importância e viabilidade da utilização de muitos equipamentos, dentre estes, o fogão solar para cocção de vários alimentos. Deste modo, o presente estudo objetivou apresentar uma ferramenta viável e barata para fins de cozimento de alimentos e fervura (desinfecção da água, a construção de um fogão solar tipo caixa, contribuindo com as futuras operações do Projeto Rondon, as quais têm lugar em regiões com forte incidência de luz solar, norte e nordeste do Brasil. Durante o evento I Jornada de Pesquisa, Extensão e Cultura- I Mostra de Projetos, realizado nos dias 4 a 8 de maio de 2015 na Faculdade de Tecnologia de Jundiaí (FATEC- JD, pode-se compreender o princípio de funcionamento de um fogão solar construído pelos alunos do Curso de Tecnologia em Gestão Ambiental (GAM, sendo possível identificar sua eficiência e bom desempenho ao realizar o cozimento de alimentos. A partir da Mostra de Projetos pensou-se na viabilidade do seu uso em comunidades carentes, principalmente, as que utilizam fogão a lenha, e em regiões com grande potencial solar, caso do Nordeste, podendo ser substituído, parcialmente, para o cozimento de determinados alimentos como arroz, macarrão, além da fervura da água.

  12. Lesao óssea em leucemias agudas linfoblásticas tipo T e TIPO nao T / nao B

    OpenAIRE

    Martins, Fernando Lopes

    2013-01-01

    Resumo: O AUTOR APRESENTA OS RESULTADOS DO ESTUDO RADIOLÓGICO DE ESQUELETO DE 61 PACIENTES PORTADORES DE LEUCEMIA AGUDA LINFOBLÁSTICA, CORRELACIONANDO A PRESENÇA OU NÃO DE Lesões ÓSSEAS COM A CLASSIFICAÇÃO IMUNOLÓGICA DE LAL TIPO T E TIPO não T / não B

  13. Caracterização da movimentação de bovinos com o uso de um modelo tipo centro-periferia

    Directory of Open Access Journals (Sweden)

    H.O.D Gutierrez

    2010-12-01

    Full Text Available Verificou-se a influência da movimentação de bovinos na configuração de uma estrutura do tipo centro-periferia. Foram aplicadas técnicas das redes sociais - modelo centro/periferia (C/P contínuo - para inferir sobre a semelhança entre os padrões de movimentação registrados no estudo com uma estrutura C/P perfeita. Os resultados mostram alta correlação, e o poder discriminatório do algoritmo permite identificar a existência de uma estrutura tipo C/P. Este resultado perfila a metodologia proposta como uma ferramenta analítica nos processos de caracterização produtiva e a regionalização de medidas de intervenção sanitária. O trabalho considera a aplicação de conceitos intuitivos sobre a definição de estruturas C/P condizentes com os determinantes de circuitos pecuários

  14. Internal structure and reliability of the Attachment Insecurity Screening Inventory (AISI) for children age 6 to 12.

    Science.gov (United States)

    Spruit, Anouk; Wissink, Inge; Noom, Marc J; Colonnesi, Cristina; Polderman, Nelleke; Willems, Lucia; Barning, Charlotte; Stams, Geert Jan J M

    2018-02-05

    The aim of the present study was to examine the internal structure and reliability of the Attachment Insecurity Screening Inventory (AISI) 6-12. The AISI 6-12 years is a parent-report questionnaire for assessing the parents' perspective on the quality of the attachment relationship with their child aged between 6 and 12 years. The sample consisted of 681 mothers and fathers reporting on 372 children (72.3% adoption parents, 14.9% non-biological primary care takers including foster parents, and 12.8% biological parents). The internal structure was assessed with multilevel confirmatory factor analyses (CFA) and the reliability of the scores with Cronbach's and ordinal alphas. Multilevel CFA confirmed a three-factor model of avoidant, ambivalent/resistant and disorganized attachment. Multi-group CFA indicated full configural and metric measurement invariance, and partial scalar and strict measurement invariance across mothers and fathers. Reliability coefficients were found to be sufficient. This study showed the potential of using parental reports in the initial screening of attachment related problems, especially considering the practical approach of parental reports. However, further development of the AISI 6-12 years seems important to increase the validity of the AISI 6-12 years. In addition, future studies are necessary to replicate the current findings, and to strengthen the evidence that the AISI 6-12 years is appropriate for the use in middle childhood and validly assesses the parents' perspective on attachment insecurities in their child.

  15. Effect of the Ultrasonic Nanocrystalline Surface Modification (UNSM on Bulk and 3D-Printed AISI H13 Tool Steels

    Directory of Open Access Journals (Sweden)

    In-Sik Cho

    2017-11-01

    Full Text Available A comparative study of the microstructure, hardness, and tribological properties of two different AISI H13 tool steels—classified as the bulk with no heat treatment steel or the 3D-printed steel—was undertaken. Both samples were subjected to ultrasonic nanocrystalline surface modification (UNSM to further enhance their mechanical properties and improve their tribological behavior. The objective of this study was to compare the mechanical properties and tribological behavior of these tool steels since steel can exhibit a wide variety of mechanical properties depending on different manufacturing processes. The surface hardness of the samples was measured using a micro-Vickers hardness tester. The hardness of the 3D-printed AISI H13 tool steel was found to be much higher than that of the bulk one. The surface morphology of the samples was characterized by electron backscattered diffraction (EBSD in order to analyze the grain size and number of fractions with respect to the misorientation angle. The results revealed that the grain size of the 3D-printed AISI H13 tool steel was less than 0.5 μm, whereas that of the bulk tool steel was greater than 4 μm. The number of fractions of the bulk tool steel was about 0.5 μm at a low misorientation angle, and it decreased gradually with increasing misorientation angle. The low-angle grain boundary (LAGB and high-angle grain boundary (HAGB of the bulk sample were about 21% and 79%, respectively, and those of the 3D-printed sample were about 8% and 92%, respectively. Moreover, the friction and wear behavior of the UNSM-treated AISI H13 tool steel specimen was better than those of the untreated one. This study demonstrated the capability of 3D-printed AISI H13 tool steel to exhibit excellent mechanical and tribological properties for industrial applications.

  16. ANÁLISE DE MERCADO COMO FERRAMENTA PARA O TERCEIRO SETOR

    Directory of Open Access Journals (Sweden)

    Grazielle Rigotti da Silva

    2012-04-01

    Full Text Available O foco dessa pesquisa consiste em identificar, através do estudo de caso, como o processo de Análise de Mercado como ferramenta de escolha de canal de marketing, pode ser um instrumento estratégico também adequado para o êxito no desenvolvimento profissional de instituições do terceiro setor, particularmente àquelas voltadas à área educacional, tratadas especialmente aqui.  Sendo assim, partindo de uma minuciosa pesquisa de mercado em quatro cidades onde atua a Sagrado: Rede de educação, relacionando os temas Marketing, Sustentabilidade e técnicas de Análise de Mercado, e concluindo com o método da Pontuação Ponderada como facilitador da visualização e tomada de decisão, vislumbra-se que as conclusões alcançadas possam auxiliar no planejamento não só da organização apresentada, encontrando soluções que visem a superação dos obstáculos e dificuldades encontradas, mas que seja um impulso a todas as quais se revelam semelhantes à apontada. Parte-se da realidade de que entre os principais obstáculos ao desenvolvimento destas instituições, destacam-se: a carga histórica ligada à pura filantropia, a gerência por intuição, o desconhecimento de técnicas administrativas e a sobrecarga de trabalhos exercida pelos dirigentes, focados mais em atividades fins, do dia-a-dia da empresa. Estes, entre outros fatores, acabam por ocasionar uma elevada taxa de falência entre estas organizações.

  17. Perícia contábil: uma ferramenta de combate ao crime organizado

    Directory of Open Access Journals (Sweden)

    IDALBERTO JOSÉ DAS NEVES JÚNIOR

    2011-11-01

    Full Text Available No Brasil e no mundo, devido principalmente à ausência do Estado no cumprimento do seu papel de garantidor da lei e da ordem, as organizações criminosas cresceram significativamente, e as suas ações passaram a ocorrer de formas planejadas e estratégicas. Para combatê-las e reprimi-las, a Perícia Contábil, materializada nos laudos periciais elaborados pelos peritos criminalistas, surge como importante ferramenta de Inteligência. Nesse contexto, o objetivo desta pesquisa foi identificar a relevância da Perícia Contábil como meio de prova para a solução de controvérsias relativas ao crime organizado. Para tanto, houve a realização de pesquisa de campo por meio de questionário aplicado aos Delegados, Escrivães e Agentes de Polícia das divisões da Diretoria de Combate ao Crime organizado – DCOR do Departamento de Polícia Federal. Também, houve a utilização de técnicas de estatística multivariada de análise de cluster para o estudo dos registros (K-Means clusters do software SPSS, que resultou na formação de dois agrupamentos. Considerando a pesquisa de campo e o referencial teórico, verificou-se que a Perícia Contábil, no limite de suas atribuições, é um relevante meio de prova para a solução de controvérsias relativas ao crime organizado.

  18. O uso de Elisa como ferramenta complementar para o controle da tuberculose bovina no Brasil

    Directory of Open Access Journals (Sweden)

    Walter Lilenbaum

    2006-04-01

    Full Text Available A detecção de animais infectados é um dos mais importantes fatores envolvidos no controle da tuberculose e, com algumas variações, é realizado através de testes intradérmicos de tuberculinização. No entanto, animais negativos aos testes intradérmicos podem estar infectados e representam uma importante ameaça aos programas de erradicação da tuberculose. Apesar deste conhecido fenômeno, o uso de ELISA não é rotina nestes programas. Nosso objetivo foi o de descrever experiências do uso a campo de ELISA na detecção de animais anérgicos no Rio de Janeiro, Brasil. Dentre 18 rebanhos envolvidos em um programa de controle da tuberculose, dois apresentaram animais infectados negativos aos testes intradérmicos, o que atrasou e comprometeu o sucesso do programa, com severas perdas econômicas. A infecção nestes animais foi identificada através de ELISA e confirmada pelo isolamento de M.bovis nas lesões pulmonares. Desta forma foram considerados como a mais provável fonte de infecção e responsáveis pela manutenção da enfermidade nos rebanhos. Sem o uso de testes sorológicos como ELISA estes animais provavelmente permaneceriam nos rebanhos perpetuando a infecção e a erradicação da enfermidade seria impossível. Em conclusão, sugere-se o uso de ELISA como uma valiosa ferramenta complementar para identificar animais anérgicos que possam atuar como reservatórios do agente nos rebanhos.

  19. O ensino do design de moda: o uso da moulage como ferramenta pedagógica

    Directory of Open Access Journals (Sweden)

    Jonathan Gurgel de Lima

    2016-06-01

    Full Text Available Resumo O presente artigo discute questões referentes ao papel da educação formal no desenvolvimento do potencial criativo de jovens profissionais. Com enfoque na formação universitária em design de moda, aponta as possíveis causas para a desmotivação dos alunos quando deparados com as disciplinas que envolvem práticas de criatividade. É percebido que, além das dificuldades técnicas para expressar as ideias do projeto, há também entraves em relação à não exigência de resultados predefinidos. Tomando como base os estudos de pesquisadores que atribuem às causas do bloqueio criativo dos alunos a uma formação educacional formal estagnada e que pouco privilegia o desenvolvimento humano, o texto levanta a hipótese do uso de uma ferramenta que, embora comum ao cotidiano dos profissionais da área de moda, ainda é pouco explorada em seu pleno potencial. Trata-se do manequim de moulage, mais comumente usado para a concepção de moldes de vestuário em três dimensões. Este artigo defende que o processo criativo, fazendo uso das técnicas de moulage, possui potencialidades pouco exploradas que podem contribuir para o aprimoramento do ensino do design de moda, desenvolver o potencial criativo, motivar o aprendizado, bem como servir de alternativa para a expressão de ideias em vestuário. Apresentam-se neste trabalho o conteúdo e os resultados de uma atividade de criação em moulage desenvolvida com o intuito de experimentar e comprovar as hipóteses aqui levantadas.

  20. Biologia molecular como ferramenta no esporte de alto rendimento: possibilidades e perspectivas

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Bueno Júnior

    2010-05-01

    Full Text Available Várias estratégias têm sido pensadas com o propósito de se utilizar a biologia molecular como ferramenta na pré-seleção e na seleção de talentos esportivos, na manipulação genética visando ao aumento ou à diminuição da produção de determinadas substâncias pelo organismo, na prescrição do treinamento e na recuperação de lesões. Portanto, o objetivo desta revisão é apresentar o DNA como regulador do funcionamento do organismo e de que forma alterações no perfil genético, tanto espontâneas como induzidas artificialmente, podem modular respostas fisiológicas e morfológicas por alterar a expressão de determinadas proteínas. Será dada especial atenção à descrição dos procedimentos utilizados para a manipulação genética, nos baixos riscos associados e nas estratégias que têm sido desenvolvidas com o objetivo de detectá-la. Com base em conhecimentos científicos, coerência e bom senso, diversas visões devem ser expostas e amplamente discutidas para ser definido o que é permitido e o que é proibido nas competições esportivas.

  1. Tipos especiales de niños

    Directory of Open Access Journals (Sweden)

    Mercedes Rodrigo Bellido

    1946-09-01

    Full Text Available En las tres últimas lecciones han sido expuestas algunas consideraciones referentes a niños y adolescentes desde el nacimiento hasta el dintel de la juventud. En todas ellas hemos procurado poner de relieve la necesidad de individualizar el conocimiento de cada niño para obtener mejores resultados en su adaptación a su futura vida de adultos, En todas ellas  nos hemos referido al llamado niño normal. Nos corresponde en la lección de hoy ocuparnos can la superficialidad característica de estas charlas tipo-muestrario, de otras categorías de niños muy dignos de interés.. quienes unas por exceso, otros por defecto, otros por dificultades de adaptación por diferentes causas, se desvían de la línea media de la normalidad. Consideramos que no está fuera del lugar, aquí, el tema de los niños excepcionales y por el contrario que es necesario intensificar el estudio de los trastornos de la vida mental y emocional de los niños en la preparación de los estudiantes de Medicina. Y no es nuestra solo esta opinión; no hace mucho tiempo en la Medical School de Ia Universidad de Minnessota hemos sabido que se ha hecho un intento de considerar y evaluar factores emocionales ambientales sobre las mismas bases que los descubrimientos fisiológicos.

  2. GGraph: Uma ferramenta para aplicações que envolvem grafos

    OpenAIRE

    Luiz Carlos Lucca

    2012-01-01

    Diversas são as aplicações que podem ser expressas por meio de grafos [2]. Algoritmos [3] e modelos de visualização [15] podem ser encontrados amplamente na literatura. Todos os problemas de grafos possuem uma base em comum: um modelo genérico que nasce da própria natureza dos elementos e das relações que podem ser expressas entre eles, diferindo apenas pelo tipo de resposta que queremos obter desta complexa malha. Além disso, é natural que, para problemas que sejam de áreas distintas, mas qu...

  3. Fenótipo Rett em paciente com cariótipo XXY: relato de caso

    Directory of Open Access Journals (Sweden)

    SCHWARTZMAN JOSÉ SALOMÃO

    1998-01-01

    Full Text Available Relatamos o caso de um menino com cariótipo XXY que apresenta desordem neurológica progressiva com início por volta dos 11 meses de idade, com estagnação do desenvolvimento seguida de regressão. A criança apresenta, ainda, movimentos estereotipados de mãos, apraxia manual e microcefalia. Investigações não constataram presença de qualquer condição neurológica ou sistêmica definida que pudesse ser apontada como possível etiologia para o quadro descrito. Trata-se de menino com alterações fenotípicas muito similares àquelas consideradas típicas para a síndrome de Rett que, associadas com a alteração cromossômica constatada (cariótipo XXY, constituem quadro de evidente interesse científico.

  4. Nuevo tipo de apoyos y articulaciones

    Directory of Open Access Journals (Sweden)

    Andrä, Fritz Leonhardt

    1963-11-01

    of theoretical and technical difficulties inherent in these bearings: they also express acknowledgement to German individuals and institutions, for their contribution to this investigation.Las tendencias actuales son funciones que dependen directamente de la presencia creciente y mejorada de los materiales de construcción que se ofrecen al comercio. En el campo de los materiales cabe una marcada subdivisión en naturales y preparados o sintéticos; estos últimos constituyen la preocupación de los autores para su aprovechamiento y adecuada aplicación. De entre ellos, las resinas sintéticas o caucho artificial, dentro de las distintas especies de la extensa familia han gozado de un lugar preferente en este estudio de nuevos tipos de apoyos que presentan los notables ingenieros alemanes Wolfhart Andrä y Fritz Leonhardt. En los ensayos de laboratorio y a escala natural, las variedades comerciales de estas resinas, conocidas con los nombres de «neopreno» y «Teflon», han sido elegidas por presentar, por lo menos actualmente, características marcadamente apropiadas a la finalidad perseguida en este estudio, del que se confía ulterior desarrollo y mejor acogida, por las importantes aplicaciones que de él se derivan en el campo de la ingeniería y construcción. Los autores estudian con detenimiento y sobrado rigor para las aplicaciones prácticas las deformaciones que de estos materiales se espera al someterlos a fuerzas de gran concentración. En los apoyos juega particular interés la distribución de la carga siempre concentrada en superficies relativamente pequeñas, lo que exige elevadas cargas unitarias y, con ello, la utilización de materiales extremadamente nobles para resistirlas con la resistencia que las deformaciones instantáneas requieren para recobrar rápidamente la posición de estabilidad perdida momentáneamente. La fatiga en el ciclo de deformaciones relaja los materiales, y ha de tenerse presente al considerar las características que los

  5. Resistencia al desgaste de recubrimientos Fe-Nb-Cr-W, Nb, AISI 1020 y AISI 420 producidos por proyección térmica por arco eléctrico

    Directory of Open Access Journals (Sweden)

    López-Covaleda, E. A.

    2013-10-01

    Full Text Available The commercial materials 140MXC (with iron, tungsten, chrome, niobium, 530AS (AISI 1015 steel and 560AS (AISI 420 steel on AISI 4340 steel were deposited using thermal spray with arc. The aim of work was to evaluate the best strategy abrasive wear resistance of the system coating-substrate using the following combinations: (1 homogeneous coatings and (2 coatings depositing simultaneously 140MXC + 530AS and 140MXC + 560AS. The coatings microstructure was characterized using Optical microscopy, Scanning electron microscopy and Laser confocal microscopy. The wear resistance was evaluated through dry sand rubber wheel test (DSRW. We found that the wear resistance depends on the quantity of defects and the mechanical properties like hardness. For example, the softer coatings have the biggest wear rates and the failure mode was characterized by plastic deformation caused by particles indentation, and the other hand the failure mode at the harder materials was grooving. The details and wear mechanism of the coatings produced are described in this investigation.Mediante proyección térmica de arco eléctrico fueron depositados tres materiales comercialmente conocidos como: 140MXC (a base de hierro, wolframio, cromo y niobio, 530AS (acero AISI 1020 y 560AS (acero AISI 420, sobre acero AISI 4340. Con el objetivo de evaluar la mejor estrategia para incrementar la resistencia al desgaste abrasivo, los recubrimientos fueron depositados de dos formas: (1 monocapas homogéneas de cada material y (2 recubrimientos depositando con alambres disimiles de 140MXC + 530AS y 140MXC + 560AS. Los recubrimientos fueron caracterizados microestructuralmente mediante Difracción de rayos X, Microscopía óptica, Microscopía láser confocal y Microscopía electrónica de barrido. La evaluación de la resistencia al desgaste abrasivo se realizó mediante ensayo con arena seca y rueda de caucho (DSRW. Se encontró que la resistencia al desgaste depende entre otras de las

  6. The effect of internal hydrogen on surface slip localisation on polycrystalline AISI 316L stainless steel

    International Nuclear Information System (INIS)

    Aubert, Isabelle; Olive, Jean-Marc; Saintier, Nicolas

    2010-01-01

    A statistical analysis of the effect of internal hydrogen on the surface slip morphology of relatively high nickel content AISI 316L type austenitic stainless steel was carried out on high resolution data obtained by atomic force microscopy. Surface plastic strain localisation was studied for different hydrogen contents, two grain sizes, and two plastic strain levels. The height and spacing of approximately 8000 slip bands, observed on 12 specimens, are shown to follow log-normal distributions. Hydrogen increased the mean slip-band height and the mean slip-band spacing for the two macroscopic plastic strain levels considered, and for the two hydrogen concentrations in coarse-grained specimens. The hydrogen effect was also observed for fine-grained specimens, but only for the highest hydrogen concentration. In addition, the emerging dislocation velocity increased by a factor 3 for high hydrogen content.

  7. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser...... treated surface was investigated using a novel micro electrochemical technique with a tip resolution of ~1 mm. Results show that hybrid laser welding of 316L has increased corrosion susceptibility probably as a result of grain boundary carbide formation. However a suitable post laser treatment could...

  8. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent ...... regain the corrosion resistance by desensitization.......Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser...

  9. Microstructure Evolution During Continuous Cooling in AISI 5140 Steel Processed by Induction Heating Chromizing

    Science.gov (United States)

    Hu, Jianjun; Ma, Chaoping; Yang, Xian; Xu, Hongbin; Guo, Ning; Yu, Hongbing

    2017-11-01

    In this study, induction heating chromizing (IHC) and box-type furnace heating chromizing (BFHC) were conducted on commercial AISI 5140 steels, respectively. Microstructure, microhardness and wear resistance of the chromized samples were characterized. The results show that the IHC samples have thicker Cr coating layer and stronger interface bond due to pre-compressive stress among the packed powders. Three kinds of microstructures including alloyed cementite (AC-layer), fine pearlite zone (FP-zone) and carbon-poor zone (CP-zone) are formed near the interface in the IHC samples. The main reason given for this is that different contents of Cr and C have different effects on pearlite phase and morphology. The IHC sample shows better wear properties due to its stronger interface bonding strength than that of the BFHC sample. The formation mechanism of CP-zone and its influences on microhardness and wear resistance are also discussed.

  10. Adhesion of composite carbon/hydroxyapatite coatings on AISI 316L medical steel

    Directory of Open Access Journals (Sweden)

    J. Gawroński

    2009-07-01

    Full Text Available In this paper are contains the results of studies concerning the problems associated with increased of hydroxyapatite (HAp adhesion, manufactured by using Pulse Laser Deposition (PLD method, to the austenitic steel (AISI 316L through the coating of carbon interlayer on it. Carbon coating was deposited by Radio Frequency Plasma Assisted Chemical Vapour Deposition (RF PACVD method.Test results unequivocally showed that the intermediate carbon layer in a determined manner increase the adhesion of hydroxyapatite to the metallic substrate. Obtained results give rise to deal with issues of manufacturing composite bilayer – carbon film/HAp – on ready implants, casted from austenitic cast steel by lost-wax process method as well as in gypsum forms.

  11. The influence of machining condition and cutting tool wear on surface roughness of AISI 4340 steel

    Science.gov (United States)

    Natasha, A. R.; Ghani, J. A.; Che Haron, C. H.; Syarif, J.

    2018-01-01

    Sustainable machining by using cryogenic coolant as the cutting fluid has been proven to enhance some machining outputs. The main objective of the current work was to investigate the influence of machining conditions; dry and cryogenic, as well as the cutting tool wear on the machined surface roughness of AISI 4340 steel. The experimental tests were performed using chemical vapor deposition (CVD) coated carbide inserts. The value of machined surface roughness were measured at 3 cutting intervals; beginning, middle, and end of the cutting based on the readings of the tool flank wear. The results revealed that cryogenic turning had the greatest influence on surface roughness when machined at lower cutting speed and higher feed rate. Meanwhile, the cutting tool wear was also found to influence the surface roughness, either improving it or deteriorating it, based on the severity and the mechanism of the flank wear.

  12. Modification and characterization of the AISI 410 martensitic stainless steels surface

    International Nuclear Information System (INIS)

    Bincoleto, A.V.L.; Nascente, P.A.P.

    2010-01-01

    Steam turbines are used in the generation of more than half the electric energy produced in the world nowadays. It is important the study which aims to improve the efficiency by means of the optimization of leaks and of the aerodynamic profiles, as well as to maintain the integrity of the components. The martensitic stainless steels are widely employed due to the combination of their good mechanical properties with higher corrosion resistance. However, their lower wear resistance and their poor tribological behavior limit their use, since they decrease the component life time. In order to evaluate the improvement in the performance of the AISI 410 stainless steel, several process of surface modification were employed. Five samples were produced: the first one was not treated, the second one received liquid nitriding, the third, gas nitriding, the forth, thermal aspersion of tungsten carbide, and the fifth, boronizing. The samples were characterized by optical microscopy, surface microhardness, and X-ray diffractometry. (author)

  13. Evaluation of the sticky wearing down of the steel AISI – SAE 1020

    OpenAIRE

    Tristancho Reyes, José Luís; Higuera Cobos, Oscar Fabián; Flórez García, Luís Carlos; Grupo de Investigaciones en Materiales Avanzados -GIMAV-UTP

    2007-01-01

    En el momento en que se da inicio a la construcción de los primeros mecanismos mecánicos se presenta el desgaste de los materiales que los conforman; la tribología, que no es más que la evaluación del desgaste de los materiales, cobra importancia tanto a nivel industrial como académico. En esta investigación se evaluó el comportamiento del acero AISI –SAE 1020 al ser sometido a desgaste adhesivo en un tribómetro de cilindros cruzados, el ensayo se realizó bajo norma ASTM G83 – 96. At t...

  14. Fatigue assessment by energy approach during tensile tests on AISI 304 steel

    Directory of Open Access Journals (Sweden)

    A. Risitano

    2017-01-01

    Full Text Available Estimation of the fatigue limit for steel ductile materials using non-destructive methods is a topic of great interest to researchers today. In recent years, the method adopted has implemented infrared sensors to detect the surface temperature and correlate it with the fatigue limit. In previous paper, a new energy approach was proposed to investigate the fatigue limit during tensile test. The numerical procedure proposed by Chrysochoos is adopted to clean infrared images and applied to analyse the surface heat sources during tensile test. AISI 304 specimens with rectangular cross-sections are tested. Moreover fatigue tests at increasing loads were carried out on steel by a stepwise succession, applied to the same specimen, for applying the thermographic method. The predictions of the fatigue limit, obtained by the analysis of the energy evolution during the static tests, were compared with the predictions obtained applying the thermographic method during fatigue tests.

  15. Surface effects induced by cathodic hydrogenation in type AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Silva, T.C.V.

    1984-08-01

    Cathodic hydrogen charging of type AISI 304 stainless steel modified its austenitic structure, giving rise to the formation of two new martensitic phases and the appearance of cracks, in most cases delayed. As electrolyte a 1 N H 2 S O 4 solution containing As 2 O 3 was employed. The cathodic hydrogenation was carries out at room temperature. The transformed phases were identified with black and white and coloured metallographic techniques, as well as by X-ray diffraction. The effect of cathodic hydrogenation in samples uniaxially tensile tested with constant nominal strain rate was investigated. It was concluded that the number of cracks per unit surface area changes with hydrogenation conditions and that hydrogen should be present for the embrittlement to occur. (author)

  16. Quantifying Cutting and Wearing Behaviors of TiN- and CrNCoated AISI 1070 Steel.

    Science.gov (United States)

    Cakan, Ahmet; Ozkaner, Vedat; Yildirim, Mustafa M

    2008-11-05

    Hard coatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP) technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM), line scan analyses and X-ray diffraction (XRD). The wear properties of TiN- and CrNcoated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  17. Microstructural characterization of laser surface melted AISI M2 tool steel.

    Science.gov (United States)

    Arias, J; Cabeza, M; Castro, G; Feijoo, I; Merino, P; Pena, G

    2010-09-01

    We describe the microstructure of Nd:YAG continuous wave laser surface melted high-speed steel, namely AISI M2, treated with different laser scanning speeds and beam diameters on its surface. Microstructural characterization of the remelted surface layer was performed using light optical and scanning electron microscopy and X-ray diffraction. The combination of the three techniques provided new insights into the substantial changes induced by laser surface melting of the steel surface layer. The advantage of the method is that it avoids the difficult and tedious work of preparing samples of this hard material for transmission electron microscopy, which is the technique normally used to study these fine microstructures. A melted zone with a dendritic structure and a partially melted zone with a heterogeneous cellular structure were observed. M(2)C carbides with different morphologies were identified in the resolidified surface layer after laser melting.

  18. An investigation of the aseptic loosening of an AISI 316L stainless steel hip prosthesis.

    Science.gov (United States)

    Godec, Matjaz; Kocijan, Aleksandra; Dolinar, Drago; Mandrino, Djordje; Jenko, Monika; Antolic, Vane

    2010-08-01

    The total replacement of joints by the implantation of permanently indwelling prosthetic components has been one of the major successes of modern surgery in terms of relieving pain and correcting deformity. However, the aseptic loosening of a prosthetic-joint component is the most common reason for joint-revision surgery. Furthermore, it is thought that wear particles are one of the major contributors to the development and perpetuation of aseptic loosening. The aim of the present study was to identify the factors related to the aseptic loosening of an AISI 316L stainless steel total hip prosthesis. The stem was evaluated by x-ray photoelectron spectroscopy, with polished and rough regions being analyzed in order to establish the differences in the chemical compositions of both regions. Specific areas were examined using scanning electron microscopy with energy dispersive x-ray spectroscopy and light microscopy.

  19. Comparisons of modified Vasco X-2 and AISI 9310 gear steels

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Endurance tests were conducted with four groups of spur gears manufactured from three heats of consumable electrode vacuum melted (CVM) modified Vasco X-2. Endurance tests were also conducted with gears manufactured from CVM AISI 9310. Bench type rolling element fatigue tests were conducted with both materials. Hardness measurements were made to 811 K. There was no statistically significant life difference between the two materials. Life differences between the different heats of modified Vasco X-2 can be attributed to heat treat variation and resultant hardness. Carburization of gear flanks only can eliminate tooth fracture as a primary failure mode for modified Vasco X-2. However, a tooth surface fatigue spall can act as a nucleus of a tooth fracture failure for the modified Vasco X-2.

  20. Influence of Cryogenic Treatments on the Wear Behavior of AISI 420 Martensitic Stainless Steel

    Science.gov (United States)

    Prieto, G.; Tuckart, W. R.

    2017-11-01

    The objective of the present work is to characterize the wear behavior of a cryogenically treated low-carbon AISI 420 martensitic stainless steel, by means of ball-on-disk tribological tests. Wear tests were performed under a range of applied normal loads and in two different environments, namely a petrolatum bath and an argon atmosphere. Wear tracks were analyzed by both optical and scanning electron microscopy and Raman spectroscopy to evaluate wear volume, track geometry, surface features and the tribolayers generated after testing. This paper is an extension of the work originally reported in the VIII Iberian Conference of Tribology (Prieto and Tuckart, in: Ballest Jiménez, Rodríguez Espinosa, Serrano Saurín, Pardilla Arias, Olivares Bermúdez (eds) VIII Iberian conference of tribology, Cartagena, 2015). In this study, it has been experimentally demonstrated that cryogenically treated specimens showed a wear resistance improvement ranging from 35 to 90% compared to conventionally treated ones.

  1. Effect of five lubricants on life of AISI 9310 spur gears

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.

    1985-01-01

    Spur-gear surface fatigue tests were conducted with five lubricants using a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 spur gears. The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants are classified as either a synthetic hydrocarbon, mineral oil, or ester-based lubricant. All five lubricants have imilar viscosity and pressure-viscosity coefficients. A pentaerythritol base stock without sufficient antiwear additives produced a surface fatigue life pproximately 22 percent that of the same base stock with chlorine and phosphorus type additives. The presence of sulfur type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears tested. No statistical difference in the 10-percent surface fatigue life was produced with four of the five lubricants.

  2. Electrochemical behaviour of iron and AISI 304 stainless steel in simulated acid rain solution

    Energy Technology Data Exchange (ETDEWEB)

    Pilic, Zora; Martinovic, Ivana [Mostar Univ. (Bosnia and Herzegovina). Dept. of Chemistry

    2016-10-15

    The growth mechanism and properties of the oxide films on iron and AISI 304 stainless steel were studied in simulated acid rain (pH 4.5) by means of electrochemical techniques and atomic absorption spectrometry. The layer-pore resistance model was applied to explain a potentiodynamic formation of surface oxides. It was found that the growth of the oxide film on iron takes place by the low-field migration mechanism, while that on the stainless steel takes place by the high-field mechanism. Kinetic parameters were determined. Impedance measurements revealed that Fe surface film has no protective properties at the open circuit potential, while the resistance of stainless steel oxide film is very high. The concentration of the metallic ions released into solution and measured by atomic absorption spectroscopy was in accordance with the results obtained from the electrochemical techniques.

  3. The fracture toughness of Fe{sub 2}B formed on boronized AISI 304

    Energy Technology Data Exchange (ETDEWEB)

    Topuz, Polat; Guendogdu, Emine; Yilamz, Eren; Guemues, Emre [Gedik Univ., Pendik Istanbul (Turkey). Gedik Vocational School

    2014-10-01

    In this study, the fracture toughness of Fe{sub 2}B boride layer on boronized AISI 304 stainless steel was investigated. Samples were boronized in an indirect heated fluidized bed furnace with Ekabor 1 trademark boronizing agent at 1123 K, 1223 K, and 1323 K for 1 h, 2 h, and 4 h, respectively. The boride phases were investigated by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indentation. With increasing boriding temperature and time the fracture toughness values were reduced. The boride layer thickness formed on the boronized samples ranged between 12 μm and 176 μm. The hardness of the borides ranged between 1709 HV{sub 0.1} and 2119 HV{sub 0.1} and fracture toughness was in the range of 2.19-4.47 MPa x m{sup 1/2} depending on the layer thickness and hardness.

  4. AISI 304 Welding Fracture Resistance by a Charpy Impact Test with a High Speed Sampling Rate

    Directory of Open Access Journals (Sweden)

    Bambang Riyanta

    2017-12-01

    Full Text Available The purpose of this study was to evaluate fracture resistance in AISI 304. The J-R curve was constructed from data, which resulted from an impact test by Charpy Impact machine equipped with high-speed sampling rate data acquisition equipment. The critical values of fracture resistance in fusion zones (FZ, high temperature heat affected zones (HTHAZ, low temperature heat affected zones (LTHAZ and unaffected base metals (UBM were obtained by calculation methods using some formulas and by graphical methods. Laboratory experiments demonstrated the relationships among the values of energy absorption along the impact test with the obstruction of dislocation movement due to the presence of chromium interstitial solute in all zones and chromium rich carbide precipitates in fusion zones and heat affected zones.

  5. Laser welding of 3 mm thick laser-cut AISI 304 stainless steel sheet

    Science.gov (United States)

    Kumar, Harish; Ganesh, P.; Kaul, Rakesh; Rao, B. Tirumala; Tiwari, Pragya; Nath, A. K.; Brajpuriya, Ranjeet; Chaudhari, S. M.

    2006-02-01

    The objective of the present work was to study the laser weldability of laser-cut 3 mm thick AISI 304 austenitic stainless steel sheet (using oxygen as an assist gas). For minimizing heat input during laser cutting, which is an important factor influencing the thickness of the oxide layer on the cut surface, laser cutting was performed in pulsed mode. The results of the study demonstrated that although the laser welding of laser-cut specimens did not result in the formation of weld defects, the resultant laser weldments exhibited reduced ductility with respect to base metal and bead-on-plate laser weldments. Laser-cut and laser-welded specimens also displayed higher notch sensitivity than the base metal. However, laser-cut and laser-welded specimens still possessed enough ductility to pass guided bend tests.

  6. Plastic strain and residual stress distributions in an AISI 304 stainless steel BWR pipe weld

    Science.gov (United States)

    Saukkonen, Tapio; Aalto, Miikka; Virkkunen, Iikka; Ehrnstén, Ulla; Hänninen, Hannu

    In AISI 304 stainless steel pipe welds weld shrinkage causes large variations in residual plastic strain in different parts of the weld metal and heat-affected zone (HAZ). The amount of strain was analyzed by EBSD quantitatively by comparing the intra-grain misorientations to the calibration curve. Highest degrees of plastic strain (10...20%) were detected in the HAZ close to the root area of a prototypical BWR plant weld. Strain in the weld metal varies in the different directions of solidification, being high in the weld bead boundaries and near the fusion lines. Preliminary studies of the effects of mechanical and elastic anisotropy of the weld metal microstructure on the grain size level were performed by EBSD and nanoindentation. The residual stress distribution in the same weld cross-section was determined by a contour method. The residual strain and stress distributions are superimposed and EAC susceptibility of various areas of the pipe weld is evaluated and discussed.

  7. Corrosion Resistance Modification of AISI 304 Stainless Steel Using Argon Ion Bombardment

    Science.gov (United States)

    Ramezani, A. H.; Ghoranneviss, M.; Shokouhy, A.; Sari, A. H.

    2011-02-01

    Ion implantation has been widely used as a surface modification technique to improve surface properties. In this work, argon ions of 30 keV energy have been implanted into AISI 304 stainless steel at different fluences ranging from 3 × 1017 to 1 × 1018 Ar+/cm2. The surface bombardment with inert gases mainly produces structural changes and modify topography and morphology of the surface. The AFM analysis of implanted samples clearly shows significant change in surface. In order to evaluate the effect of the ion bombardment on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation fluences.

  8. Corrosion behavior of low energy, high temperature nitrogen ion-implanted AISI 304 stainless steel

    Science.gov (United States)

    Ghoranneviss, M.; Shokouhy, A.; Larijani, M. M.; Haji Hosseini, S. H.; Yari, M.; Anvari, A.; Gholipur Shahraki, M.; Sari, A. H.; Hantehzadeh, M. R.

    2007-01-01

    This work presents the results of a low-energy nitrogen ion implantation of AISI 304 type stainless steel (SS) at a moderate temperature of about 500°C. The nitrogen ions are extracted from a Kauffman-type ion source at an energy of 30 keV, and ion current density of 100 μA cm^{-2}. Nitrogen ion concentration of 6 × 10^{17}, 8 × 10^{17} and 10^{18} ions cm^{-2}, were selected for our study. The X-ray diffraction results show the formation of CrN polycrystalline phase after nitrogen bombardment and a change of crystallinity due to the change in nitrogen ion concentration. The secondary ion mass spectrometry (SIMS) results show the formation of CrN phases too. Corrosion test has shown that corrosion resistance is enhanced by increasing nitrogen ion concentration.

  9. Variación microestructural del acero AISI 1045 endurecido por rodadura

    Directory of Open Access Journals (Sweden)

    Esther Fernández-Guilarte

    2010-03-01

    Full Text Available En este trabajo se analiza el comportamiento microestructural del acero AISI 1045, endurecido mediante deformación plástica superficial por rodillo, empleando como variables en el proceso de endurecimiento el número de revoluciones, avance y fuerza del torno 16D20. Se empleó el análisis espectral para determinar la composición química del acero y el Nital como reactivo químico para resaltar la estructura metalográfica después de pulida. Se establecen los parámetros de los regímenes de la deformación plástica superficial por rodillo para evaluar la dureza de los pasadores utilizados en las esteras de los equipos de laboreo minero y se expone una metodología para determinar el tiempo de ejecución del corte de las muestras.

  10. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    Science.gov (United States)

    Santos, A.; Remolina, A.; Marulanda, J.

    2016-02-01

    This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.

  11. Microchemistry characterization by Auger electron spectroscopy of a cold-worked AISI-304L stainless steel

    International Nuclear Information System (INIS)

    Hernandez-Mayoral, M.; Diego, G. de; Garcia-Mazario, M.

    2000-01-01

    Auger electron spectroscopy (AES) has been performed on grain boundaries of an AISI-304L stainless steel. The aim of the work was to study microchemistry at grain boundaries by AES after simulating irradiation effects by cold work followed by heat treatments. The results show that phosphorus was present at interfaces in all material conditions. Sometimes, phosphorus was accompanied by molybdenum and by chromium enrichment. Those analyses were attributed to ferrite/austenite interfaces while those where phosphorus was found alone were thought to belong to austenite/austenite interfaces. Cold work when combined with heat treatment at low temperature was shown to affect phosphorus and chromium segregation in a similar way to radiation-induced segregation. In this respect, cold work enhanced non-equilibrium phosphorus segregation to interfaces, while it induced chromium diffusion away from grain boundaries. Finally, corrosion and stress corrosion tests were performed to study the influence of this particular microchemistry on 304L performance

  12. The Mechanism of Transpassive Dissolution of AISI 321 Stainless Steel in Sulphuric Acid Solution

    Directory of Open Access Journals (Sweden)

    A. Fattah-Alhosseini

    2011-01-01

    Full Text Available The transpassive dissolution mechanism of AISI 321 stainless steel in a 0.5 M sulphate solution was studied using electrochemical impedance spectroscopy (EIS. On the basis of the experimental results, surface charge approach, and point defect model, a kinetic model of the transpassive dissolution process is proposed. The transpassive film is modeled as a highly doped n-type semiconductor—insulator-p-type semiconductor structure. Injection of negative defects at the transpassive film/solution interface results in their accumulation as a negative surface charge. It alters the nonstationary transpassive film growth rate controlled by the transport of positive defects (oxygen vacancies. The model describes the process as dissolution of Cr as Cr (VI and Fe as Fe (III through the transpassive film via parallel reaction paths.

  13. Surface characteristics analysis of dry EDMed AISI D2 steel using modified tool design

    International Nuclear Information System (INIS)

    Pragadish, N.; Kumar, M. Pradeep

    2015-01-01

    A modified tool design is proposed which helps in drilling holes without any central core, and also enables the effective removal of the debris particles. Experiments were conducted on AISI D2 Steel using copper electrode as tool in both conventional EDM and dry EDM processes and the performance of both processes is compared. Experiments were designed using Taguchi's L27 orthogonal array. Discharge current (I), gap voltage (V), pulse on time (T ON ), gas pressure (P) and tool rotational speed (N) were chosen as the various input parameters, and their effect on the material removal rate (MRR), surface roughness (SR), surface morphology, microstructure and elemental composition of the machined surface is analyzed. The experimental results show better surface characteristics in the surface machined under dry EDM process.

  14. Carburizing plasma in a low temperature austenitic stainless steel AISI 304

    International Nuclear Information System (INIS)

    Mota, W.T.; Ramos, F.D.; Rocha, R.C.; Barcelos, M.V.; Barcelos, M.A.

    2014-01-01

    The industrial use of thermochemical treatment assisted by the cold plasma has been widely employed in recent years, mainly oriented to the excellent results obtained in the surface modification of engineering materials, when compared to more traditional methods. In this work, we studied the plasma carburizing low temperature steel AISI 304 mechanical parts used in construction. The thermochemical treatment was performed at a fixed gas atmosphere 7% CH 4 (g) and 93 % H 2 (g), 350 ° C and times of 1, 3 and 5 hours. Samples being tested for Vickers hardness, abrasive microwear, microstructure evaluation by optical microscopy and SEM and X-ray diffraction. The results show significant improvement in surface hardness, wear resistance and good formation of expanded austenite layer and no identifiers peaks of carbides. The results achieved are due to diffusion/adsorption of carbon present in the gaseous atmosphere to the evaluated samples. (author)

  15. Influence of Residual Stress on Fatigue Design of AISI 304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    L. Singh

    2011-06-01

    Full Text Available Austenitic stainless steel cannot be hardened by any form of heat treatment, in fact, quenching from 10000C merely softens them. They are usually cold worked to increase the hardness. Shot peening is a cold working process that changes micro-structure as well as residual stress in the surface layer. In the present work, the compressive residual stress and fatigue strength of AISI 304 austenitic stainless steel have been evaluated at various shot peening conditions. The improvement in various mechanical properties such as hardness, damping factors and fatigue strength was noticed. Compressive residual stress induced by shot peening varies with cyclic loading due to relaxation of compressive residual stress field. The consideration of relaxed compressive residual stress field instead of original compressive residual stress field provides reliable fatigue design of components. In this paper, the exact reductions in weight and control of mechanical properties due to shot peening process are discussed.

  16. Semiconducting properties of oxide and passive films formed on AISI 304 stainless steel and Alloy 600

    Directory of Open Access Journals (Sweden)

    Ferreira M. G. S.

    2002-01-01

    Full Text Available The semiconducting properties of passive films formed on AISI 304 stainless steel and Alloy 600 in borate buffer solution were studied by capacitance (Mott-Schottky approach and photocurrent measurements. Oxide films formed on 304 stainless steel in air at 350 ºC have also been studied. The results obtained show that, in all cases the electronic structure of the films is comparable to that of a p-n heterojunction in which the space charges developed at the metal-film and film-electrolyte interfaces have also to be considered. This is in accordance with analytical results showing that the oxide films are in all cases composed of an inner region rich in chromium oxide and an outer region rich in iron oxide.

  17. Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    Sang Hwan Bak

    2016-07-01

    Full Text Available Plastic deformation and strain-induced martensite (SIM, α′ transformation in metastable austenitic AISI 304 stainless steel were investigated through room temperature tensile tests at strain rates ranging from 2 × 10−6 to 2 × 10−2/s. The amount of SIM was measured on the fractured tensile specimens using a feritscope and magnetic force microscope. Elongation to fracture, tensile strength, hardness, and the amount of SIM increased with decreasing the strain rate. The strain-rate dependence of RT tensile properties was observed to be related to the amount of SIM. Specifically, SIM formed during tensile tests was beneficial in increasing the elongation to fracture, hardness, and tensile strength. Hydrogen suppressed the SIM formation, leading to hydrogen softening and localized brittle fracture.

  18. Evaluation of the corrosion resistance of AISI 316 stainless steel filters

    Directory of Open Access Journals (Sweden)

    Luzinete Pereira Barbosa

    2005-06-01

    Full Text Available In this investigation, the corrosion resistance of AISI 316 SS filters prepared with powders in the size ranges 74-44 µm and 210-105 µm and compacted with pressures of 300 MPa and 400 MPa has been evaluated in naturally aerated 0.5 M H2SO4 solution at 25 °C. Weight loss of filters manufactured with compacting pressure of 400 MPa were significantly higher than that of filters compacted at 300 MPa. The filter compacted at 400 MPa had higher carbon and nitrogen contents compared to those compacted at 300 MPa. The former also had chromium rich precipitates and oxides in the grain boundaries. The pores in filters compacted at 400 MPa were smaller than in filters compacted at 300 MPa. Smaller pores favor the formation of concentration cells and consequently, increased crevice corrosion.

  19. Optimization of process parameters of ECM by RSM on AISI 202 steel

    Directory of Open Access Journals (Sweden)

    P. Alex John Britto

    2015-12-01

    Full Text Available The machining of complex shaped designs was difficult earlier, but with the advent of the newer machining processes incorporating in it electrical, chemical & mechanical processes, manufacturing has redefined itself. Especially, the Electrochemical Machining (ECM process is used to machine the hard to cut materials without producing heat and friction. Hence, in this work, the ECM process has been chosen to machine SS AISI 202 steel. This study establishes the effect of process parameters such as voltage, current and concentration of electrolyte on the responses on material removal rate (MRR. In this work, second-order quadratic models were developed for MRR, considering the electrolyte concentration, voltage and current as the machining parameters, using central composite design. The developed models were used for Response Surface Methodology (RSM optimization by desirability function approach to determine the optimum machining parameters.

  20. Dynamic Recrystallization Behavior of AISI 420 Stainless Steel under Hot Compression

    Science.gov (United States)

    Cao, Y.; Di, H. S.; Misra, R. D. K.

    2015-04-01

    Hot deformation behavior of AISI 420 stainless steel was studied under hot compression tests in the temperature range of 950 to 1150 °C and strain rates of 0.01 s-1 and 0.1 s-1. The study indicates that higher deformation temperature makes the peak stress pronounced and the occurrence of DRX is detected by inflection point in the work hardening rate vs. flow stress (θ-σ) plot, irrespective of the shape of flow stress curve. Local misorientation (ML) was calculated to reveal the local change in the crystal orientation. The distribution of ML suggested that the process of DRX reduces the local misorientation during hot deformation. The critical stress for initiation of DRX under different deformation conditions was determined by setting the derivative of the third order polynomial to θ-σ plot. A good linear relationship between critical stress (σc) & critical strain (ɛc) and Zener-Hollomon parameter was established.

  1. Influence of nitrogen alloying on hydrogen embrittlement in AISI 304-type stainless steels

    Science.gov (United States)

    Hannula, Simo-Pekka; Hänninen, Hannu; Tähtinen, Seppo

    1984-12-01

    Hydrogen embrittlement of AISI 304-type austenitic stainless steels has been studied with special emphasis on the effects of the nitrogen content of the steels. Hydrogen charging was found to degrade the mechanical properties of all the steels studied, as measured by a tensile test. The fracture surfaces of hydrogen charged specimens were brittle cleavage-like whereas the uncharged specimens showed ductile, dimpled fracture. In sensitized materials transgranular cleavage mode of fracture was replaced by an intergranular mode of fracture and the losses of mechanical properties were higher. Nitrogen alloying decreased the hydrogen-induced losses of mechanical properties by increasing the stability of austenite. In sensitized steels the stability of austenite and nitrogen content were found to have only a minor effect on hydrogen embrittlement, except when sensitization had caused α'-martensite transformation at the grain boundaries.

  2. Comparison of experimental and theoretical results of nitrogen implantation in AISI 304 stainless steel

    Science.gov (United States)

    Gazestani, S. H. Haji Hosseini; Shahraki, M. Gholipour; Hantehzadeh, M. R.; Ghoranneviss, M.; Shokouhy, A.

    2004-10-01

    Depth and distribution of implanted ions play an important role in electrical and mechanical properties of implanted surfaces. In this study nitrogen implantation at 30 keV with different doses in the range of 1 × 10 17-1 × 10 18 ions/cm 2 on AISI 304 stainless steel samples has been performed. The experimental and theoretical depth profiles of nitrogen-implanted samples are investigated. Experimental depth profile using secondary ion mass spectrometry (SIMS) is compared with theoretical analysis (TRIM simulation). By considering the presence of N 2+ in the implanting ion beam and sputtering effects, the TRIM and SIMS results were modified to good agreement. The proper ratio of N 2+/N + is evaluated by a curve fitting procedure.

  3. Effect of the powder particle size on the wear behavior of boronized AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guenen, Ali [Mustafa Kemal Univ., Hatay (Turkey). Dept. of Metallurgy and Material Engineering; Kuecuek, Yilmaz; Oege, Mecit; Goek, M. Sabri [Bartin Univ. (Turkey). Dept. of Mechanical Engineering; Er, Yusuf [Firat Univ., Elazig (Turkey); Cay, V. Veli [Dicle Univ., Diyarbakir (Turkey). Civil Aviation Higher School

    2015-06-01

    In this study, the AISI 304 steel specimens were boronized with nanoboron of the size of 10 50 nm and commercial Ekabor 3 powders (<1400 μm) at 950 C to 1000 C for 2 h and 4 h. Boronized steel specimens were characterized via SEM, microhardness and XRD analyses. Abrasive wear behavior of the specimens, boronized at different temperatures and treatment durations, were examined. The fixed ball micro-abrasion tests were carried out using the abrasive slurry, prepared with different SiC powder particle sizes on the boronized specimens at different rotational speeds. The specimens boronized with nanoboron powders exhibited a higher hardness and abrasive wear resistance than the samples boronized with the Ekabor 3 powders.

  4. Nitrocarburizing of AISI-304 stainless steel using high-voltage plasma immersion ion implantation

    Science.gov (United States)

    Abd El-Rahman, A. M.; Mohamed, S. H.; Ahmed, M. R.; Richter, E.; Prokert, F.

    2009-05-01

    AISI-304 austenitic stainless steel has been nitrocarburized in N 2 and C 2H 2 ambient using high-voltage plasma immersion ion implantation (PIII) technology. The use of different PIII treatment times revealed important hints with respect to the microstructural, mechanical and corrosion properties of the nitrocarburized layer. Grazing incidence X-ray diffraction (GIXRD) shows the presence of nitride ( γN and CrN) and carbide ( γC and Fe 3C) phases. Glow discharge optical spectroscopy (GDOS) has been used to characterize the elemental depth profiles in which the thickness of the modified layers is derived. Dynamic microindentation method is used for the study of mechanical performance of the nitrocarburized layer as well as the untreated material. The microhardness has been increased to a maximum value of more than nine times compared to that of the untreated one. The corrosion performance is characterized by potentiodynamic polarization technique and was found to be treatment time dependent.

  5. Effect of Carbon and Nitrogen Content on Deformation and Fracture of AISI 304 Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    C. Menapace

    2008-04-01

    Full Text Available The effect of small differences in the content of carbon and nitrogen on the room temperature tensile deformation and fracture behaviour of an AISI 304 stainless steel was studied. In the steel containing the lower amount of carbon and nitrogen, a higher amount of strain induced alfa’ martensite is formed, which increases strain hardening rate and both uniform and total elongation at fracture. The presence of large martensitic areas in the cross section causes strain localization at the austenite/martensite interface, which promotes the nucleation of cracks and their propagation along the interface. This results in a decrease of Ultimate Tensile Strength. Strain induced transformation slightly reduces strain rate sensitivity, as well.

  6. 3DII implantation effect on corrosion properties of the AISI/SAE 1020 steel

    Energy Technology Data Exchange (ETDEWEB)

    Dulce M., H.J.; Rueda V., Alejandro [Universidad Francisco de Paula Santander, A.A. 1055, Cucuta (Colombia); Dougar-Jabon, Valeri [Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia)

    2005-08-01

    The three dimensional ion implantation technology (3DII) is one of the methods of improving the tribological characteristics and resistance to hydrogen embrittlement processes in metals. In this report, some results concerning the resistance effect of nitrogen ion implantation to oxidation of the sample, made of AISI/SAE 1020 steel, are given. The nitrogen ions were implanted in the discharge chamber of the JUPITER reactor. Both the treated and untreated samples were tested through potential-static measurements, which permitted to determine the corrosion current, the slopes that characterise the braking level of anode and cathode reactions. The polarization resistance near the corrosion potential is calculated. The results of the study encourage to consider the nitrogen ion implantation in high voltage and low pressure discharges as one of the methods of anticorrosive protection which do not change the geometric configuration of the treated steel pieces. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Welding with coated electrodes E 6010 and E 7018 in AISI 1025 steel

    Directory of Open Access Journals (Sweden)

    Dennis Reyes-Carcasés

    2018-01-01

    Full Text Available The welding of steel of low carbon content is a common practice in the nickel industry, where components with steels of these characteristics are manufactured. The objective of the paper was to establish the microstructural behavior of the AISI 1025 steel when it was welded with two types of electrodes (E 6010 and E 7018, the first one deposited as a mattress, and the second one to guarantee mechanical resistance; they were made in a 240 x 240 x 10 mm plate with simple bevel preparation. The microstructures obtained with the electrode E 6010 are of the ferrite type Widmanstátten, columnar ferrite and intergranular pearlite, with a hardness of 345 HV, while with the electrode E 7018 the microstructures are ferrite Widmanstátten, austenite and martensite, with hardness of 332 HV . The decrease in hardness in the latter case is associated with the thermal treatment of multipass annealing.

  8. Investigations on the creep-rupture behaviour of the austenitic stainless steel AISI 316 NET

    International Nuclear Information System (INIS)

    Schirra, M.; Heger, S.; Ritter, B.

    1991-08-01

    The report describes the creep-rupture tests carried out with a 17Cr-13Ni-2Mo-steel in the frame of the German-Spanish collaboration (KfK-CIEMAT). The material studied is the austenitic steel AISI 316(L) selected as potential first-wall material for NET (Next European Torus). The test program on base material with a NET specified batch comprises in the temperature range 500-750deg C the rupture-time-range till 40 000 h. The results permit statements on the creep- and creep-rupture behaviour and ductility. Metallographic examinations give informations about the fracture behaviour and demonstrate the complex precipitation behaviour. The results are compared with literature data and own results from two batches of the European Fast-Breeder-Program. (orig.) [de

  9. Effect of plasma nitriding time on surface properties of hard chromium electroplated AISI 1010 steel

    International Nuclear Information System (INIS)

    Kocabas, Mustafa; Uelker, Suekrue

    2015-01-01

    Properties of steel can be enhanced by surface treatments such as coating. In some cases, further treatments such as nitriding can also be used in order to get even better results. In order to investigate the properties of nitride layer on hard Cr coated AISI 1010 steel, substrates were electroplated to form hard Cr coatings. Then hard Cr coatings were plasma nitrided at 700 C for 3 h, 5 h and 7 h and nitride phases on the coatings were investigated by X-ray diffraction analysis. The layer thickness and surface properties of nitride films were investigated by scanning electron microscopy. The hardness and adhesion properties of Cr-N phases were examined using nano indentation and Daimler-Benz Rockwell C adhesion tests. The highest measured hardness was 24.1 GPa and all the three samples exhibited poor adhesion.

  10. Investigating Tribological Characteristics of HVOF Sprayed AISI 316 Stainless Steel Coating by Pulsed Plasma Nitriding

    Science.gov (United States)

    Mindivan, H.

    2018-01-01

    In this study, surface modification of aluminum alloy using High-Velocity Oxygen Fuel (HVOF) thermal spray and pulsed plasma nitriding processes was investigated. AISI 316 stainless steel coating on 1050 aluminum alloy substrate by HVOF process was pulsed plasma nitrided at 793 K under 0.00025 MPa pressure for 43200 s in a gas mixture of 75 % N2 and 25 % H2. The results showed that the pulse plasma nitriding process produced a surface layer with CrN, iron nitrides (Fe3N, Fe4N) and expanded austenite (γN). The pulsed plasma nitrided HVOF-sprayed coating showed higher surface hardness, lower wear rate and coefficient of friction than the untreated HVOF-sprayed one.

  11. Topological characterization of static strain aging of type AISI 304 austenitic stainless steel

    International Nuclear Information System (INIS)

    Monteiro, S.N.; Miranda, P.E.V. de

    1981-01-01

    Static strain aging of type AISI 304 austenitic stainless steel was studied from room temperature up to 623K by conducting tests in which the load was held approximately constant. The aging times varied between 10s and 100h, using a plastic pre-deformation of 9%. The static strain aging of 304 steel furnished an activation energy of 23.800 cal/mol. This implies that vacancies play an important role on the aging process. The curve of the variation of the discontinuous yielding with aging time presented different stages, to which specific mathematical expressions were developed. These facts permited the conclusion that Snock type mechanisms are responsible for the aging in such conditions. (Author) [pt

  12. Active flux tungsten inert gas welding of austenitic stainless steel AISI 304

    Directory of Open Access Journals (Sweden)

    D. Klobčar

    2016-10-01

    Full Text Available The paper presents the effects of flux assisted tungsten inert gas (A-TIG welding of 4 (10 mm thick austenitic stainless steel EN X5CrNi1810 (AISI 304 in the butt joint. The sample dimensions were 300 ´ 50 mm, and commercially available active flux QuickTIG was used for testing. In the planned study the influence of welding position and weld groove shape was analysed based on the penetration depth. A comparison of microstructure formation, grain size and ferrit number between TIG welding and A-TIG welding was done. The A-TIG welds were subjected to bending test. A comparative study of TIG and A-TIG welding shows that A-TIG welding increases the weld penetration depth.

  13. Quantifying Cutting and Wearing Behaviors of TiN- and CrNCoated AISI 1070 Steel

    Directory of Open Access Journals (Sweden)

    Ahmet Cakan

    2008-11-01

    Full Text Available Hard coatings such as titanium nitride (TiN and chromium nitride (CrN are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM, line scan analyses and X-ray diffraction (XRD. The wear properties of TiN- and CrNcoated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  14. A New Continuous Cooling Transformation Diagram for AISI M4 High-Speed Tool Steel

    Science.gov (United States)

    Briki, Jalel; Ben Slima, Souad

    2008-12-01

    The increasing evolution of dilatometric techniques now allows for the identification of structural transformations with very low signal. The use of dilatometric techniques coupled with more common techniques, such as metallographic, hardness testing, and x-ray diffraction allows to plot a new CCT diagram for AISI M4 high-speed tool steel. This diagram is useful for a better selection of alternate solutions, hardening, and tempering heat treatments. More accurate determination of the various fields of transformation of austenite during its cooling was made. The precipitation of carbides highlighted at high temperature is at the origin of the martrensitic transformation into two stages (splitting phenomena). For slow cooling rates, it was possible to highlight the ferritic, pearlitic, and bainitic transformation.

  15. Applications of the essay at slow deformation velocity in pipes of stainless steel AISI-304

    International Nuclear Information System (INIS)

    Zamora R, L.; Mora R, T. De la

    2004-01-01

    Nowadays is carried out research related with the degradation mechanisms of structures, systems and/or components in the nuclear power plants, since many of the involved processes are those responsible for the dependability of these, of the integrity of the components and of the aspects of safety. The purpose of this work, was to determine the grade of susceptibility to the corrosion of a pipe of Austenitic stainless steel AISI 304, in a solution of Na CI (3.5%) to the temperatures of 60 and 90 C, in two different thermal treatments - 1. - Sensitive 650 C by 4 hours and cooled in water. 2. Solubilized to 1050 C by 1 hour and cooled in water

  16. Corrosion behaviour of electropolished AISI 316L austenitic biomaterial in physiological solution

    Science.gov (United States)

    Zatkalíková, V.; Markovičová, L.; Škorvanová, M.

    2017-11-01

    Due to suitable mechanical properties, satisfactory corrosion resistance and relatively low cost, austenitic stainless steels are important biomaterials for manufacture of implants and various medical instruments and devices. Their corrosion properties and biocompatibility are significantly affected by protective passive surface film quality, which depends on used mechanical and chemical surface treatment. This article deals with corrosion resistance of AISI 316L stainless steel, which is the most widely used Cr-Ni-Mo austenitic biomaterial. Corrosion behaviour of five various surfaces (original, electropolished, three surfaces with combined treatment finished by electropolishing) is evaluated on the bases of cyclic potentiodynamic polarization tests performed in physiological solution at the temperature of 37± 0.5 °C.

  17. Effects of Austenitizing and Forging on Mechanical Properties of MIL A-12560/AISI 4340 Steel

    Science.gov (United States)

    Herbirowo, S.; Adjiantoro, B.; Romijarso, T. B.

    2017-05-01

    Laterite steels might be used for alternative armored steels. Their properties can be improved in various ways, such as by heat treatment. This paper reports the influences of tempering temperature on the hardness and microstructure of the modified MIL A-12560/AISI 4340 steels. Samples were austenitized at 1200, 1000, and 800°C and forged at 100, 75, and 50 tons. Mechanical properties consisted of Hardness measurement was conducted by Brinell indentation and metallographic observation was conducted by scanning electron microscopy (SEM). The results showed that increasing forging force until 100 tons can decrease hardness. The formation of the microstructure consists of tempered martensite containing ferrite and dual phase perlite. The presence of void and porous can also decrease hardness. Decreasing austenizing temperature from 1200 °C to 800°C can increase material strength and hardness.

  18. Thermal creep effects on 20% cold worked AISI 316 mechanical properties

    International Nuclear Information System (INIS)

    Duncan, D.R.

    1980-09-01

    The effects of thermal creep on subsequent mechanical properties of 20% cold worked AISI 316 pressurized tubes were investigated. Specimens were subjected to temperatures of 811 to 977 0 K and stresses of 86 MPa to 276 MPa. This resulted in strains up to 1.3%. Subsequent mechanical property tests included load change stress rupture tests (original test pressure increased or decreased), uniaxial tensile tests, and temperature ramp burst tests. Load change stress rupture tests were consistent with predictions from isobaric tests, and thus, consistent with the linear life fraction rule. Tests with large stress increases and tests at 866 0 K displayed a tendency for earlier than predicted failure. Tensile and temperature ramp burst tests had only slight effects on material properties (property changes were attributed to thermal recovery). The test results showed that, under the conditions of investigation, dislocation structure recovery was the most significant effect of creep. 9 figures, 5 tables

  19. Implementação de ferramentas Lean numa empresa de componentes para calçado

    OpenAIRE

    Ramos, Sandra Raquel Teixeira

    2015-01-01

    Dissertação de mestrado em Engenharia Industrial A presente dissertação retrata a implementação de ferramentas de Lean Manufacturing em ambiente industrial, mais concretamente no sistema produtivo da empresa Flexospuma, Lda., inserida na indústria de componentes para calçado. Os objetivos desta dissertação são reduzir em 20% o tempo gasto em atividades que não acrescentam valor no setor da produção e reduzir erros do planeamento e da produção em 50% até 30 de Junho de 2015. Este proj...

  20. Ambientes virtuais de aprendizagem como ferramentas de apoio em cursos presenciais e a distância.

    OpenAIRE

    Brito, Lélis Maia de; Giuberti Júnior, José Renato; Gomes, Silvane Guimarães Silva; Mota, João Batista

    2013-01-01

    As tecnologias vêm sendo incorporadas na educação presencial e a distância com o objetivo de enriquecer o processo de ensino-aprendizagem. Uma dessas inovações compreende-se nos ambientes virtuais de aprendizagem (AVAs), que são espaços virtuais nos quais os usuários, os educadores e os educandos podem interagir por meio de diversas ferramentas. A ideia é a de que esses ambientes criem novas possibilidades de aprendizagem ao aluno em face às mudanças tecnológicas que vêm ocorrendo na sociedad...

  1. Ferramenta informática para avaliação de políticas de stockagem

    OpenAIRE

    Almeida, Ana Marta Santos

    2014-01-01

    O presente documento relata o projeto desenvolvido na Nestlé Portugal – Fábrica de Avanca, em âmbito de estágio curricular. O projeto em causa vai ao encontro da filosofia Lean, a dar os primeiros passos nesta fábrica do Grupo Nestlé, visando eliminar o desperdício causado pelo excesso de stocks. O objetivo principal do projeto é a construção de uma ferramenta informática que permita avaliar decisões relativas à gestão de stocks e testar, comparativamente, algumas das políticas mais usadas...

  2. Action of an aerobic hydrogenotroph bacteria isolated from ultrapure water systems on AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Gales, Gregoire; Roy, Marc; Feron, Damien; Libert, Marie-Francoise; Sellier, Regine; Cournac, Laurent; Heulin, Thierry

    2004-01-01

    Several microbial studies have been recently performed in nuclear power stations. These studies concerned essentially the formation of bio-films on submerged metal coupons. Heterotrophic micro-organisms have been found in bulk water of nuclear fuel storage basins but the in situ nutrient sources for bacterial development in such highly oligo-trophic water was unknown. In nuclear environments, radiations lead to the production of molecular hydrogen, hydrogen peroxide and some radicals (OH, O 2 - ) by radiolysis of water or embedding matrices. Bacterial oxidation of molecular H 2 commonly occurs in nature, as molecular hydrogen represents a high-energy reductant. We investigated the microbiology of a ultra-pure water basin containing irradiating waste. The initial aim of this study was to determine if autotrophic bacterial growth was possible in this basin. A major bacteria was isolated (Ralstonia sp. GGLH002) which was able to grow autotrophically with hydrogen as the electron donor and oxygen as the electron acceptor, and heterotrophically with organic nutrients. Its hydrogenase activity has been characterized. We focused then our study on the effects of this strain on 304L AISI stainless steel depending on the nutrient source used for bacterial development, e.g hydrogen or organics. In conclusion, the mechanism of passivation enhanced by Ralstonia sp. GGLH002 on AISI 304L SS still remains unknown. Several techniques could give substantial information, including XPS and polarization curves. It seems for the moment that the major bacteria inhabiting an oxic environment containing hydrogen due to radiolysis is not aggressive to stainless steel in conditions near from its environment. Further investigations are needed to test this hypothesis, including a study of the molecular diversity of the bacteria using culture-independent techniques, as cultivatable bacterial populations represent in general only a fraction of the total bacteria. (authors)

  3. Action of an aerobic hydrogenotroph bacteria isolated from ultrapure water systems on AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Gales, Gregoire [DTN/SMTM/LMTE, CEA Cadarache, F-13108 Saint-Paul-lez-Durance (France)]|[DSV/DEVM/LEMIR, UMR 6191 CNRS-CEA-Universite Aix-Marseille II, CEA Cadarache, F- 13108 Saint-Paul-lez-Durance (France); Roy, Marc; Feron, Damien [DEN/DPC/SCCME/LECA, Bat 458, CEA Saclay F- 91191 Gif sur Yvette (France); Libert, Marie-Francoise; Sellier, Regine [DTN/SMTM/LMTE, CEA Cadarache, F-13108 Saint-Paul-lez-Durance (France); Cournac, Laurent [DSV/DEVM/LEP, UMR 6191 CNRS-CEA-Universite Aix-Marseille II, CEA Cadarache, F- 13108 Saint-Paul-lez-Durance (France); Heulin, Thierry [DSV/DEVM/LEMIR, UMR 6191 CNRS-CEA-Universite Aix-Marseille II, CEA Cadarache, F- 13108 Saint-Paul-lez-Durance (France)

    2004-07-01

    Several microbial studies have been recently performed in nuclear power stations. These studies concerned essentially the formation of bio-films on submerged metal coupons. Heterotrophic micro-organisms have been found in bulk water of nuclear fuel storage basins but the in situ nutrient sources for bacterial development in such highly oligo-trophic water was unknown. In nuclear environments, radiations lead to the production of molecular hydrogen, hydrogen peroxide and some radicals (OH, O{sub 2}{sup -}) by radiolysis of water or embedding matrices. Bacterial oxidation of molecular H{sub 2} commonly occurs in nature, as molecular hydrogen represents a high-energy reductant. We investigated the microbiology of a ultra-pure water basin containing irradiating waste. The initial aim of this study was to determine if autotrophic bacterial growth was possible in this basin. A major bacteria was isolated (Ralstonia sp. GGLH002) which was able to grow autotrophically with hydrogen as the electron donor and oxygen as the electron acceptor, and heterotrophically with organic nutrients. Its hydrogenase activity has been characterized. We focused then our study on the effects of this strain on 304L AISI stainless steel depending on the nutrient source used for bacterial development, e.g hydrogen or organics. In conclusion, the mechanism of passivation enhanced by Ralstonia sp. GGLH002 on AISI 304L SS still remains unknown. Several techniques could give substantial information, including XPS and polarization curves. It seems for the moment that the major bacteria inhabiting an oxic environment containing hydrogen due to radiolysis is not aggressive to stainless steel in conditions near from its environment. Further investigations are needed to test this hypothesis, including a study of the molecular diversity of the bacteria using culture-independent techniques, as cultivatable bacterial populations represent in general only a fraction of the total bacteria. (authors)

  4. Tribological Properties of Nanometric Atomic Layer Depositions Applied on AISI 420 Stainless Steel

    Directory of Open Access Journals (Sweden)

    E. Marin

    2013-09-01

    Full Text Available Atomic Layer Deposition ( ALD is a modern technique that Allows to deposit nanometric, conformal coatings on almost any kind of substrates, from plastics to ceramic, metals or even composites. ALD coatings are not dependent on the morphology of the substrate and are only regulated by the composition of the precursors, the chamber temperature and the number of cycles. In this work, mono- and bi -layer nanometric, protective low-temperature ALD Coatings, based on Al2O3 and TiO2 were applied on AISI 420 Stainless Steel in orderto enhance its relatively low corrosion resistance in chloride containing environments. Tribological testing were also performed on the ALD coated AISI 420 in order to evaluate the wear and scratch resistance of these nanometric layers and thus evaluate their durability. Scratch tests were performed using a standard Rockwell C indenter, under a variable load condition, in order to evaluate the critical loading condition for each coating. Wear testing were performed using a stainless steel counterpart, in ball-on-discconfiguration, in order to measure the friction coefficient and wear to confront the resistance. All scratch tests scars and wear tracks were then observed by means of Scanning Electron Microscopy (SEM in order to understand the wear mechanisms that occurred on the sample surfaces. Corrosion testing, performed under immersion in 0.2 M NaCl solutions, clearly showed that the ALD coatings have a strong effect in protecting the Stainless Steel Substrate against corrosion, reducing the corrosion current density by two orders of magnitude.Tribological The preliminary results showed that ALD depositions obtained at low Temperatures have a brittle behavior caused by the amorphous nature of their structure, and thus undergo delamination phenomena during Scratch Testing at relatively low applied loads. During ball-on-disc testing, the coatings were removed from the substrate, in particular for monolayer ALD configurations

  5. Effect of Deep Cryogenic Treatment on Hardness and Wear Behavior of 5120 AISI Steel

    Directory of Open Access Journals (Sweden)

    S. Torkian

    2016-12-01

    Full Text Available In this paper the effect of deep cryogenic treatment time on microstructure and tribological behavior of AISI 5120 case hardennig steel is studied. The disk shape samples were carburized at 920 ◦C for 6 hours and air cooled; after austenitizing, the samples were quenched in oil.Then immediately after quenching and sanding, the sample were kept in liquid nitrogen for 1, 24, 30 and 48 h and then tempered at 200 ◦C for 2 hours. The wear test was done by ball on disk method using of WC ball at 80 and 110 N load. For characterization of carbides, the etchant solution of CuCl2 (5 gr+HCl (100 mL + ethanol (100 mL was used. The hardness of samples before and after of tempering was measured by vicers method at 300 N load.. The amount of retained austenite was measured by X Ray Diffraction method. For 1DCT and 24DCT samples it was about 8% and 4%; in the other samples, the retained austenite peal was so decreased that it was not visible. The result showed that the hardness increases by deep cryogenic treatment in all speciments. While wear resistance increases in 1DCT and 24DCT samples, it decreases for 30DCT and 48DCT samples in compare with Conventional heat treatment (CHT sample in both applied loads, such that , 48DCT sample has the least wear resistance. The cause of increament of hardness is due to reduction in amount of retained austenite as a result of deep cryogenic treatment and decreasing in wear resistance after 24 hour, is due to carbide growth and nonhemogenuse distribution in microstructure and then weakening of matrix. So the 24 hour deep cryogenic treatment was the best optimal for AISI 5120 steel.

  6. Development of Ultra-Fine-Grained Structure in AISI 321 Austenitic Stainless Steel

    Science.gov (United States)

    Tiamiyu, A. A.; Szpunar, J. A.; Odeshi, A. G.; Oguocha, I.; Eskandari, M.

    2017-12-01

    Ultra-fine-grained (UFG) structure was developed in AISI 321 austenitic stainless steel (ASS) using cryogenic rolling followed by annealing treatments at 923 K, 973 K, 1023 K, and 1073 K (650 °C, 700 °C, 750 °C, and 800 °C) for different lengths of time. The α'-martensite to γ-austenite reversion behavior and the associated texture development were analyzed in the cryo-rolled specimens after annealing. The activation energy, Q, required for the reversion of α'-martensite to γ-austenite in the steel was estimated to be 80 kJ mol-1. TiC precipitates and unreversed triple junction α'-martensite played major roles in the development of UFG structure through the Zener pinning of grain boundaries. The optimum annealing temperature and time for the development of UFG structure in the cryo-rolled AISI 321 steel are (a) 923 K (650 °C) for approximately 28800 seconds and (b) 1023 K (750 °C) for 600 seconds, with average grain sizes of 0.22 and 0.31 µm, respectively. Annealing at 1023 K (750 °C) is considered a better alternative since the volume fraction of precipitated carbides in specimens annealed at 1023 K (750 °C) are less than those annealed at 923 K (650 °C). More so, the energy consumption during prolonged annealing time to achieve an UFG structure at 923 K (650 °C) is higher due to low phase reversion rate. The hardness of the UFG specimens is 195 pct greater than that of the as-received steel. The higher volume fraction of TiC precipitates in the UFG structure may be an additional source of hardening. Micro and macrotexture analysis indicated {110}〈uvw〉 as the major texture component of the austenite grains in the UFG structure. Its intensity is stronger in the specimen annealed at low temperatures.

  7. Erosion and corrosion resistance of laser cladded AISI 420 stainless steel reinforced with VC

    Science.gov (United States)

    Zhang, Zhe; Yu, Ting; Kovacevic, Radovan

    2017-07-01

    Metal Matrix Composites (MMC) fabricated by the laser cladding process have been widely applied as protective coatings in industries to improve the wear, erosion, and corrosion resistance of components and prolong their service life. In this study, the AISI 420/VC metal matrix composites with different weight percentage (0 wt.%-40 wt.%) of Vanadium Carbide (VC) were fabricated on a mild steel A36 by a high power direct diode laser. An induction heater was used to preheat the substrate in order to avoid cracks during the cladding process. The effect of carbide content on the microstructure, elements distribution, phases, and microhardness was investigated in detail. The erosion resistance of the coatings was tested by using the abrasive waterjet (AWJ) cutting machine. The corrosion resistance of the coatings was studied utilizing potentiodynamic polarization. The results showed that the surface roughness and crack susceptibility of the laser cladded layer were increased with the increase in VC fraction. The volume fraction of the precipitated carbides was increased with the increase in the VC content. The phases of the coating without VC consisted of martensite and austenite. New phases such as precipitated VC, V8C7, M7C3, and M23C6 were formed when the primary VC was added. The microhardness of the clads was increased with the increase in VC. The erosion resistance of the cladded layer was improved after the introduction of VC. The erosion resistance was increased with the increase in the VC content. No obvious improvement of erosion resistance was observed when the VC fraction was above 30 wt.%. The corrosion resistance of the clads was decreased with the increase in the VC content, demonstrating the negative effect of VC on the corrosion resistance of AISI 420 stainless steel

  8. SÍNDROME DE MORQUIO (MUCOPOLISACARIDOSIS TIPO IV) Y EMBARAZO

    OpenAIRE

    Salinas P.,Hugo; Preisler R.,Jessica; Astudillo D.,Julio; Cerda S.M.,Sergio; Castillo T.,Silvia; Fernández S.,Flor; Ide V.,Rodolfo

    2005-01-01

    Se presenta el caso de una paciente embarazada, portadora de Síndrome de Morquio (Mucopolisacaridosis tipo IV), que evoluciona con polihidroamnios y disnea. Se comenta el manejo y resolución del caso

  9. OTROS TIPOS ESPECÍFICOS DE DIABETES MELLITUS

    Directory of Open Access Journals (Sweden)

    DRA. M. Gabriela Sanzana G.

    2016-03-01

    En las “Diabetes Atípicas” (no incluidas en la clasificación ADA, se mencionan la DM tipo 2 en niños y adolescentes, favorecida por el aumento de la obesidad y del sedentarismo; la diabetes propensa a la cetosis, que debutan en cetoacidosis, con etiopatogenia y evolución de DM2; los Latent Autoinmune Diabetes of Adults (LADA, DM tipo 1 de lenta aparición y la diabetes postrasplante.

  10. Protótipos físicos e virtuais (CAD 3D: uma pesquisa descritiva sobre o processo de construção de uma saia godê

    Directory of Open Access Journals (Sweden)

    Gisely Andressa Pires

    2016-08-01

    Full Text Available Este artigo discute sobre a prática da construção de protótipos na indústria do vestuário. O protótipo refere-se à construção de um modelo que está em processo de planejamento e teste para ser comercializado. Atualmente a forma mais difundida é realizando a construção efetiva das peças, porém existe disponível no mercado softwares que realizam essa atividade virtualmente. Assim, esse estudo tem como objetivo investigar o processo construção de protótipos por meio de software CAD 3D de prototipagem de vestuário e das técnicas tradicionais manuais utilizadas atualmente na indústria a fim de verificar as caraterísticas de cada etapa e os resultados alcançados. Para tanto, foi desenvolvida uma pesquisa descritiva, como forma de abordagem do problema foram realizados dois experimentos que compreendem a construção de protótipos de uma saia godê orientados pela técnica virtual e a manual. Os resultados permitiram compreender que as duas possibilidades para a elaboração de protótipos produzem resultados similares, são eficientes e uma valiosa ferramenta para avaliar uma peça de vestuário antes de ser produzida a venda.

  11. Study of corrosion resistance of AISI 444 ferritic stainless steel for application as a biomaterial; Estudo da resistencia a corrosao do aco inoxidavel ferritico AISI 444 para aplicacao como biomaterial

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Rogerio Albuquerque

    2014-09-01

    Ferritic stainless steels are ferromagnetic materials. This property does not allow their use in orthopedic prosthesis. Nevertheless, in some specific applications, this characteristic is very useful, such as, for fixing dental and facial prostheses by using magnetic attachments. In this study, the corrosion resistance and cytotoxicity of the AISI 444 ferritic stainless steel, with low nickel content, extra-low interstitial levels (C and N) and Ti and Nb stabilizers, were investigated for magnetic dental attachments application. The ISO 5832-1 (ASTM F-139) austenitic stainless steel and a commercial universal keeper for dental attachment (Neo-magnet System) were evaluated for comparison reasons. The first stainless steel is the most used metallic material for prostheses, and the second one, is a ferromagnetic keeper for dental prostheses (NeoM). In vitro cytotoxicity analysis was performed by the red neutral incorporation method. The results showed that the AISI 444 stainless steel is non cytotoxic. The corrosion resistance was studied by anodic polarization methods and electrochemical impedance spectroscopy (EIS), in a saline phosphate buffered solution (PBS) at 37 °C. The electronic properties of the passive film formed on AISI 444 SS were evaluated by the Mott-Schottky approach. All tested materials showed passivity in the PBS medium and the passive oxide film presented a duplex nature. The highest susceptibility to pitting corrosion was associated to the NeoM SS. This steel was also associated to the highest dopant concentration. The comparatively low levels of chromium (nearly 12.5%) and molybdenum (0.3%) of NeoM relatively to the other studied stainless steels are the probable cause of its lower corrosion resistance. The NeoM chemical composition does not match that of the SUS444 standards. The AISI 444 SS pitting resistance was equivalent to the ISO 5832-1 pointing out that it is a potential candidate for replacement of commercial ferromagnetic alloys used

  12. Comportamiento del desgaste del flanco en el torneado en seco de alta velocidad del acero AISI 316L//Flank wear behavior in the dry high‐speed turning of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Yoandrys Morales-Tamayo

    2013-09-01

    Full Text Available El presente estudio experimental se centra en investigar los efectos de los parámetros corte en el desgaste de flanco con dos insertos recubiertos durante el torneado de acabado en seco a altas velocidades del acero inoxidable AISI 316L. Los efectos de los parámetros de corte fueron determinados utilizando un análisis de varianza y de regresión simple. Como principal resultado se obtuvo el efectosignificativo del avance y del tiempo de maquinado en el desgaste del flanco. El inserto de tres capas no sobrepasó el criterio de fin de vida del desgaste, mientras que el inserto de una capa sufrió un desgaste catastrófico para la mayor velocidad de corte. El desgaste del flanco tuvo mejor comportamiento para el avance de 0,08 mm/rev en todas las velocidades empleadas en este estudio.Palabras claves: torneado de alta velocidad, desgaste de flanco, acero inoxidable AISI 316L, estudio experimental, análisis de varianza y regresión.______________________________________________________________________________AbstractThe current experimental study is focused on investigating the effects of cutting parameters on flank wear in two coated carbide inserts during dry high speed finish turning of AISI 316L stainless steel. The effects of cutting parameters were determinate using analysis of variance and simple regression. As a main resulta significant effect of cutting feed and the machining time on flank wear was found. The three coating layers insert did not exceed the criterion of end of life of wear while the insert with one layer suffered a catastrophic wear at the highest cutting speed. The flank wear showed the best performance for the cuttingfeed of 0,08 mm/rev at all the speeds used in the study.Key words: high speed turning; flank wear; AISI 316L stainless steel, experimental study; analysis of variance and regression.

  13. Determinación de tensiones por rayos x del acero AISI 1045 deformado por rodillo // Determination of stress for x‐ray of the steel AISI 1045 deformed for roller

    Directory of Open Access Journals (Sweden)

    Tomás Fernández‐Columbié

    2012-01-01

    Full Text Available El objetivo del trabajo es realizar el análisis de las tensiones a muestras de acero AISI 1045 endurecidasen frío por rodillo. Con empleo del método de Willianson–Hall se determinó las macro ymicrodeformaciones; la deformación reticular del parámetro de red; el tamaño de las cristalitas; losesfuerzos en la red cristalina y la reducción del tamaño promedio de los granos, lo que permitió establecerlos mecanismos de endurecimiento del acero AISI 1045, deformado por rodadura. Fueron medidos yanalizados diferentes puntos teniendo en cuenta los índices de Miller para la fase ferrítica del acero. Losmodelos lineales obtenidos, son estadísticamente significativos, que muestran una tendencia creciente delas propiedades mecánicas y metalúrgicas, según se incrementan las variables independientes delproceso de experimentación.Palabras claves: rodillo, rodadura, deformación plástica.__________________________________________________________________AbstractThe objective of the paper is to carry out the analysis from the tensions to steel samples AISI 1045hardened cold for roller. With employment of the method of Willianson-Hall was determined the macro andmicro deformations; the reticular deformation of the net parameter; the size of the crystallites; the efforts inthe crystalline net and the reduction of the size average of the grains, what allowed to establish themechanisms of hardening of the steel AISI 1045, deformed by rolling. They were measured and analyzeddifferent points keeping in mind the indexes of Miller for the phase ferrite of the steel. The obtained linealmodels, they are statistically significant that they show a growing tendency of the mechanical estates andmetallurgical, as the independent variables of the experimentation process are increased.Key words: roller, rolling, plastic deformation.

  14. SMART INTERFACE: FERRAMENTA DE AUXÍLIO AO DESENVOLVIMENTO DE APLICAÇÕES JAVA CARD

    OpenAIRE

    Minora, Leonardo Ataíde; Aleixo, Fellipe Araújo; Diolino, Gleison Tavares

    2008-01-01

    Com a evolução da tecnologia de microprocessadores, hoje é possível colocar um minúsculo chip em um cartão de plástico, nas dimensões de um cartão de crédito convencional. Chip este com capacidade de armazenamento de informação e processamento. Esse tipo de cartão é chamado de Smart Card. É possível desenvolver aplicações para esses cartões utilizando um subconjunto da plataforma Java – Java Card. O subconjunto da plataforma Java para o desenvolvimento de aplicações próprias para executar em...

  15. Characterization of AISI 444 stainless steel corrosion products by neutron activation analysis; Caracterizacao de produtos de corrosao do aco inoxidavel AISI 444 pelo metodo de analise por ativacao com neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Rogero, Sizue Ota; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: sorogero@ipen

    2005-07-01

    Stainless steels present distinct mechanical properties and resistance to corrosion depending on the composition of their alloys. Consequently the characterization of the chemical composition of stainless steel becomes of great interest, due to the narrow relation between the element contents and its mechanical properties. The element determination in corrosion product solutions is also of great interest as an investigation method of the corrosive process, allowing evaluating if selective dissolution of the material occurred. The objective of this study was to apply the method of neutron activation analysis (NAA) to identify the products of corrosion of AISI 444 steels which are ferritic ones used in of exhaustion systems and catalytic converters. The corrosion products in the extracts (cell culture medium where the steel samples were immersed during 10 days at 37 deg C) were analyzed. The same extracts were used in the assay of cytotoxicity by the neutral red uptake method. The obtained results indicated the release of the elements Co, Fe, Mo and Zn in concentrations that presented no toxicity. Despite the AISI 444 steel showed no cytotoxicity, this metal cannot be used as biomaterial since it is ferromagnetic and presents susceptibility to the localized corrosion. The results indicated the viability of using NAA technique in studies of corrosion of AISI 444 stainless steel due to its high sensitivity and the possibility of a multielemental analysis. (author)

  16. Classificação e caracterização de tipos de minérios de cobre da Mina do Sossego - região de Carajás

    OpenAIRE

    Viviane Kotani Shimizu

    2012-01-01

    Neste trabalho é apresentada a classificação de cerca de 110 amostras de minério da Mina do Sossego com base nas ferramentas de difração de raios X e análise estatística por agrupamento (cluster analysis). A comparação, baseada na posição e intensidade dos picos difratados, permitiu a distinção dos tipos de minérios, sendo que as diferenças entre os grupos referem-se às proporções dos principais minerais constituintes: quartzo, feldspato, actinolita, óxidos de ferro, mica e clorita. Observou-...

  17. Receptor desencadeador expresso nas células mielóides Tipo 1 (TREM-1) no diagnóstico e prognóstico na meningite bacteriana em crianças

    OpenAIRE

    Vitor Félix Torres

    2015-01-01

    Base teórica: A meningite bacteriana é uma causa importante de morbidade e mortalidade na infância. Análise do líquido cefalorraquidiano (LCR) continua a ser a ferramenta de diagnóstico padrão ouro, porém novos biomarcadores para o diagnóstico e prognóstico ainda são necessários. Receptor Desencadeador Expresso nas Células Mielóides Tipo 1 (TREM-1) é um receptor transmembrana expresso em neutrófilos e monócitos, que desempenha um papel importante na modulação da resposta inflamatória. A sua f...

  18. Modelo para Construção de Base de Conhecimentos sobre Projetos Suportado por Ferramentas Colaborativas

    Directory of Open Access Journals (Sweden)

    Douglas Paulesky Juliani

    2013-01-01

    Full Text Available A utilização de ferramentas de colaboração para o gerenciamento de bases de conhecimento permite que as organizações possam armazenar e disseminar o conhecimento produzido nos projetos de maneira efetiva Aliar modernas soluções de tecnologia de informação a conceitos de gestão do conhecimento e gerenciamento de projetos, beneficiando com a manutenção e utilização da memória organizacional através da utilização de modelos especificados possibilitaa obtenção de vantagens competitivas.Este artigo tem por objetivo apresentar um modelo para a construção de uma base de conhecimentos, com basenas lições aprendidas no gerenciamento de projetos baseado no guia PMBOK (Um Guia do Conhecimento em Gerenciamento de Projetos, suportado por ferramentas colaborativas e fundamentos de gestão do conhecimento.DOI:10.5585/gep.v3i3.128

  19. Electrochemical study of the AISI 409 ferritic stainless steel: passive film stability and pitting nucleation and growth

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Juliana Sarango de [Universidade Federal de São Paulo (UNIFESP), Diadema, SP (Brazil). Departamento de Ciências Exatas e da Terra; Oliveira, Leandro Antônio de; Antunes, Renato Altobelli, E-mail: renato.antunes@ufabc.edu.br [Universidade Federal do ABC (CECS/UFABC), Santo André, SP (Brazil). Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas; Sayeg, Isaac Jamil [Universidade de São Paulo (USP), SP (Brazil). Instituto de Geociências

    2017-11-15

    The aim of the present work was to study the passive film stability and pitting corrosion behavior of the AISI 409 stainless steel. The electrochemical tests were carried out in 0.1 M NaCl solution at room temperature. The general electrochemical behavior was assessed using electrochemical impedance spectroscopy (EIS) measurements whereas the semiconducting properties of the passive film were evaluated by the Mott-Schottky approach. Pitting corrosion was investigated using potentiodynamic and potentiostatic polarization tests. Surface morphology was examined using confocal laser scanning microscopy and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the composition of precipitates that could act as preferential sites for the onset of pitting corrosion. The results showed that the passive film presents n-type semiconductive behavior. Grain boundaries played an important role as pitting initiation sites for the AISI 409 stainless steel. (author)

  20. An empirical-statistical model for laser cladding of WC-12Co powder on AISI 321 stainless steel

    Science.gov (United States)

    Erfanmanesh, Mohammad; Abdollah-Pour, Hassan; Mohammadian-Semnani, Hamidreza; Shoja-Razavi, Reza

    2017-12-01

    In this study, laser cladding of WC-12Co powder on AISI 321 steel substrate was optimized using an empirical-statistical viewpoint. The correlations that exist between key parameters of the process (i.e., laser power, scanning speed, powder feeding rate) and geometrical characteristics for single clads (i.e. height, width, dilution, and wetting angle) were predicted and analyzed by regression method (RA). The preliminary geometrical considerations allowed to choose the processing parameters which led to high quality clads with minimum porosity. All considerations finally resulted in the development of a processing map that shows the optimum parameters for laser cladding process of WC-12Co powder on AISI 321 stainless steel.

  1. Corrosion behaviour of AISI 304 stainless steel subjected to massive laser shock peening impacts with different pulse energies

    International Nuclear Information System (INIS)

    Lu, J.Z.; Qi, H.; Luo, K.Y.; Luo, M.; Cheng, X.N.

    2014-01-01

    Highlights: •Laser shock peening caused an obvious increase of corrosion resistance of 304 steel. •Corrosion resistance of stainless steel increased with increasing pulse energy. •Mechanism of laser shock peening on corrosion behaviour was also entirely determined. -- Abstract: Effects of massive laser shock peening (LSP) impacts with different pulse energies on ultimate tensile strength (UTS), stress corrosion cracking (SCC) susceptibility, fracture appearance and electrochemical corrosion resistance of AISI 304 stainless steel were investigated by slow strain rate test, potentiodynamic polarisation test and scanning electron microscope observation. The influence mechanism of massive LSP impacts with different pulse energies on corrosion behaviour was also determined. Results showed that massive LSP impacts effectively caused a significant improvement on UTS, SCC resistance, and electrochemical corrosion resistance of AISI 304 stainless steel. Increased pulse energy can also gradually improve its corrosion resistance

  2. OPTIMIZATION OF SURFACE ROUGHNESS OF AISI 304 AUSTENITIC STAINLESS STEEL IN DRY TURNING OPERATION USING TAGUCHI DESIGN METHOD

    Directory of Open Access Journals (Sweden)

    D. PHILIP SELVARAJ

    2010-09-01

    Full Text Available The present work is concentrated with the dry turning of AISI 304 Austenitic Stainless Steel (ASS. This paper presents the influence of cutting parameters like cutting speed, feed rate and depth of cut on the surface roughness of austenitic stainless steel during dry turning. A plan of experiments based on Taguchi’s technique has been used to acquire the data. An orthogonal array, the signal to noise (S/N ratio and the analysis of variance (ANOVA are employed to investigate the cutting characteristics of AISI 304 austenitic stainless steel bars using TiC and TiCN coated tungsten carbide cutting tool. Finally the confirmation tests that have been carried out to compare the predicted values with the experimental values confirm its effectiveness in the analysis of surface roughness.

  3. OPTIMIZATION OF SURFACE ROUGHNESS AND TOOL FLANK WEAR IN TURNING OF AISI 304 AUSTENITIC STAINLESS STEEL WITH CVD COATED TOOL

    Directory of Open Access Journals (Sweden)

    M. KALADHAR

    2013-04-01

    Full Text Available AISI 304 austenitic stainless steel is a popularly used grade in the various fields of manufacturing because of its high ductility, high durability and excellent corrosion resistance. High work hardening, low heat conductivity and high built up edge (BUE formation made this as difficult-to- machine material. Poor surface quality and rapid tool wear are the common problems encountered while machining it. In the present work, an attempt has been made to explore the influence of machining parameters on the performance measures, surface roughness and flank wear in turning of AISI 304 austenitic stainless steel with a two layer Chemical vapour deposition(CVD coated tool. In order to achieve this, Taguchi approach has been employed. The results revealed that the cutting speed most significantly, influences both surface roughness and flank wear. In addition to this the optimal setting of process parameters and optimal ranges of performance measures are predicted.

  4. Corrosion behavior of plasma sprayed hydroxyapatite and hydroxyapatite-silicon oxide coatings on AISI 304 for biomedical application

    Science.gov (United States)

    Singh, Gurpreet; Singh, Hazoor; Sidhu, Buta Singh

    2013-11-01

    The objective of this study is to evaluate corrosion resistance of plasma sprayed hydroxyapatite (HA) and HAsbnd silicon oxide (SiO2) coated AISI 304 substrates. In HAsbnd SiO2 coatings, 10 wt% SiO2 and 20 wt% SiO2 was mixed with HA. The feedstock and coatings were characterized by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy. The corrosion resistance was determined for the uncoated and coated samples. The corrosion resistance of the AISI 304 was found more after the deposition of the HAsbnd SiO2 coatings rather than HA coating and uncoated. All the coatings were crack free after 24 h dipping in Ringer's solution for electrochemical corrosion testing.

  5. Wear-corrosion of AISI 316L stainless steel in different concentrations of NaCl solution

    International Nuclear Information System (INIS)

    Quezada, E; Aguilar, W; Angelats, L; De la Cruz, P

    2006-01-01

    AISI 316L austenitic stainless steels have an excellent combination of mechanical and corrosion resistant properties, which means they are used in different fields such as agricultural industry, petrochemistry and marine structures. In this latter area the requirements are more demanding when the offshore structures are exposed to wear-corrosion in the saline environment. This work studied the effect of the concentration of NaCl on the resistance to wear-corrosion of AISI 316L stainless steel submitted to annealing thermal treatment. This resistance was determined by the method for measuring mass loss and the steel's electrochemical parameters from the polarization curves in the different corrosive mediums. The results show that the loss of mass in the stainless steel test pieces and the friction coefficients decrease with the increase in NaCl concentration while the current densities of corrosion increase (CW)

  6. Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

    Directory of Open Access Journals (Sweden)

    Richárd Székely

    2010-10-01

    Full Text Available This is a comparative study of the corrosion behaviour of welds in AISI 304 and AISI 904L stainless steels carried out in seawater model solution in the temperature range 5-35°C and the standard of corrosion testing of welds was followed. The corrosion rate and corrosion attack characteristics were determined for welds of the examined steels with several type of treatment. The aim of this work was to compare the steels based on their resistance against the corrosion in terms of pitting potential (Epit and repassivation potential (Erepass. Seawater is an electrochemically aggressive medium, which can initiate localised corrosion in welded stainless steels. Different electrochemical and testing methods were used, including cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy (EIS, pH measuring and penetration tests.

  7. Microstructural evolution and precipitation behavior in heat affected zone of Inconel 625 and AISI 904L dissimilar welds

    Science.gov (United States)

    Senthur Prabu, S.; Devendranath Ramkumar, K.; Arivazhagan, N.

    2017-11-01

    In the present investigation an attempt has been made to join the dissimilar combination of Inconel 625 super alloy and super austenitic stainless steel (AISI 904L) using manual multi-pass continuous current gas tungsten arc (CCGTA) welding processes. Two different filler wires such as ERNiCrMo-4 and ERNiCrCoMo-1 have been used to compare the metallurgical properties of these welded joints. Both optical microscopy and scanning electron microscopy techniques were adopted to disseminate the microstructure traits of these weldments. Formation of secondary phases at the HAZ and weld interface of AISI 904L was witnessed while using the ERNiCrCoMo-1 filler, along with Solidification Grain Boundary (SGB) and Migrated Grain Boundary (MGB) were also observed at the weld zone.

  8. Mapeamento dinâmico de cadeia de valor e simulação como ferramenta para otimização de sistemas de manufatura

    OpenAIRE

    Castilhos de Araújo Galindo Félix, Fernando

    2005-01-01

    O presente trabalho tem por objetivo explorar a possibilidade de uso de uma ferramenta de análise de sistemas de manufatura em conjunto com uma ferramenta computacional para simulação de linhas de manufatura. Para o embasamento teórico deste trabalho foi feita uma revisão literária referente aos Sistemas de Manufatura, Cadeia de Valor, Mapeamento de Fluxo de Valor e Simulação Computacional. Onde são investigados os conceitos teóricos ligados a estas áreas. No capítulo 3 dest...

  9. Determination of the sensitized zone extension in welded AISI 304 stainless steel using non-destructive electrochemical techniques

    OpenAIRE

    De Lima-Neto, Pedro; Farias, Jesualdo P.; Herculano, Luis Flávio G.; Miranda, Hélio C. de; Araújo, Walney S.; Jorcin, Jean-Baptiste; Pébère, Nadine

    2008-01-01

    Extension of sensitized zone (SZ) in welded AISI 304 stainless steel was determined by two non-destructive electrochemical tests: double loop electrochemical potentiokinetic reactivation technique (DLEPR) and local electrochemical impedance spectroscopy (LEIS). Welding was carried out using the shielded metal arc with two selected welding energies: the first one (0.7 kJ mm¡1) does not promote the sensitization of the 304 steel and it constitutes the reference sample and the second...

  10. Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

    Energy Technology Data Exchange (ETDEWEB)

    Shen, H.H.; Liu, L.; Liu, X.Z.; Guo, Q.; Meng, T.X.; Wang, Z.X.; Yang, H.J.; Liu, X.P., E-mail: liuxiaoping@tyut.edu.cn

    2016-12-01

    Highlights: • A Zr/ZrC modified layer was formed on AISI 440B stainless steel using plasma surface Zr-alloying. • The thickness of the modified layer increases with alloying temperature and time. • Formation mechanism of the modified layer is dependent on the mutual diffusion of Zr and substrate elements. • The modified surface shows an improved wear resistance. - Abstract: The surface Zr/ZrC gradient alloying layer was prepared by double glow plasma surface alloying technique to increase the surface hardness and wear resistance of AISI 440B stainless steel. The microstructure of the Zr/ZrC alloying layer formed at different alloying temperatures and times as well as its formation mechanism were discussed by using scanning electron microscopy, glow discharge optical emission spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The adhesive strength, hardness and tribological property of the Zr/ZrC alloying layer were also evaluated in the paper. The alloying surface consists of the Zr-top layer and ZrC-subsurface layer which adheres strongly to the AISI 440B steel substrate. The thickness of the Zr/ZrC alloying layer increases gradually from 16 μm to 23 μm with alloying temperature elevated from 900 °C to 1000 °C. With alloying time from 0.5 h to 4 h, the alloyed depth increases from 3 μm to 30 μm, and the ZrC-rich alloyed thickness vs time is basically parabola at temperature of 1000 °C. Both the hardness and wear resistance of the Zr/ZrC alloying layer obviously increase compared with untreated AISI 440B steel.

  11. Effects of strain-induced martensite and its reversion on the magnetic properties of AISI 201 austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Souza Filho, I.R. [Escola de Engenharia de Lorena, University of Sao Paulo, 12602-810 Lorena (Brazil); Sandim, M.J.R., E-mail: msandim@demar.eel.usp.br [Escola de Engenharia de Lorena, University of Sao Paulo, 12602-810 Lorena (Brazil); Cohen, R.; Nagamine, L.C.C.M. [Instituto de Física, University of Sao Paulo, 05314-970 Sao Paulo (Brazil); Hoffmann, J. [Karlsruher Institut für Technologie, D-72061 Karlsruhe (Germany); Bolmaro, R.E. [Instituto de Física Rosario, CONICET-UNR, 2000 Rosario (Argentina); Sandim, H.R.Z. [Escola de Engenharia de Lorena, University of Sao Paulo, 12602-810 Lorena (Brazil)

    2016-12-01

    Strain-induced martensite (SIM) and its reversion in a cold-rolled AISI 201 austenitic stainless steel was studied by means of magnetic properties, light optical (LOM) and scanning electron (SEM) microscopy, electron backscatter diffraction (EBSD), texture measurements, and Vickers microhardness testing. According to Thermo-calc© predictions, the BCC phase (residual δ-ferrite and SIM) is expected to be stable until 600 °C. The current material was cold rolled up to 60% thickness reduction and submitted to both isothermal and stepwise annealing up to 800 °C. Magnetic measurements were taken during annealing (in situ) of the samples and also for their post mortem conditions. The Curie temperatures (T{sub c}) of residual δ-ferrite and SIM have similar values between 550 and 600 °C. Besides T{sub c}, the focused magnetic parameters were saturation magnetization (M{sub s}), remanent magnetization (M{sub R}), and coercive field (H{sub c}). SIM reversion was found to occur in the range of 600–700 °C in good agreement with Thermo-calc© predictions. The microstructures of the material, annealed at 600 and 700 °C for 1 h, were investigated via EBSD. Microtexture measurements for these samples revealed that the texture components were mainly those found for the 60% cold rolled material. This is an evidence that the SIM reversion occurred by an athermal mechanism. - Highlights: • H{sub c} and M{sub R}/M{sub S} ratio give information about distribution of strain-induced martensite. • According to Thermo-calc©, the BCC phase in AISI 201 steel is stable until 600 °C. • Thermo-calc predictions agrees with magnetic properties of AISI 201 steel. • Possible magnetic anisotropy induced by rolling in AISI 201 steel is investigated.

  12. Ferramentas participativas no trabalho com cultivos, variedades e sementes. Um guia para profissionais que trabalham com abordagens participativas no manejo da agrobiodiversidade, no melhoramento de cultivos e no desenvolvimento do setor de sementes

    NARCIS (Netherlands)

    Boef, de W.S.; Thijssen, M.H.

    2007-01-01

    Sumário Nos nossos programas de treinamento sobre manejo local da agrobiodiversidade, melhoramento participativo de cultivos e apoio às fontes locais de semente, as ferramentas participativas ganham uma ampla atenção. Ferramentas são trabalhadas na teoria, são praticadas em situações em sala de

  13. Cold deformation effect on the microstructures and mechanical properties of AISI 301LN and 316L stainless steels

    International Nuclear Information System (INIS)

    Silva, Paulo Maria de O.; Abreu, Hamilton Ferreira G. de; Albuquerque, Victor Hugo C. de; Neto, Pedro de Lima; Tavares, Joao Manuel R.S.

    2011-01-01

    As austenitic stainless steels have an adequate combination of mechanical resistance, conformability and resistance to corrosion they are used in a wide variety of industries, such as the food, transport, nuclear and petrochemical industries. Among these austenitic steels, the AISI 301LN and 316L steels have attracted prominent attention due to their excellent mechanical resistance. In this paper a microstructural characterization of AISI 301LN and 316L steels was made using various techniques such as metallography, optical microscopy, scanning electronic microscopy and atomic force microscopy, in order to analyze the cold deformation effect. Also, the microstructural changes were correlated with the alterations of mechanical properties of the materials under study. One of the numerous uses of AISI 301LN and 316L steels is in the structure of wagons for metropolitan surface trains. For this type of application it is imperative to know their microstructural behavior when subjected to cold deformation and correlate it with their mechanical properties and resistance to corrosion. Microstructural analysis showed that cold deformation causes significant microstructural modifications in these steels, mainly hardening. This modification increases the mechanical resistance of the materials appropriately for their foreseen application. Nonetheless, the materials become susceptible to pitting corrosion.

  14. Optimization of process parameters in the RF-DC plasma N2-H2 for AISI420 molds and dies

    Science.gov (United States)

    Herdianto, Hengky; Djoko, D. J.; Santjojo, H.; Masruroh

    2017-11-01

    The RF-DC plasma N2-H2 was used to make precise AISI420 molds and dies have complex textured geometry. The quality of the molds and dies directly affect the quality of the produced parts. The excellent examples of molds were used for injection molding lenses and dies used for the precision forging of automotive drive train components. In this study, a temperature, DC bias, and duration as process parameters of the RF-DC plasma N2-H2 have been optimized for molds and dies fabrication. The mask-less micro-patterned method was utilized to draw the initial 2D micro patterns directly onto the AISI420 substrate surface. The unprinted substrate surfaces were selectively nitrided by the RF-DC plasma N2-H2 at 673 K for 5400 s by 70 Pa with hollow cathode device. Energy Dispersive X-ray was utilized to describe the nitrogen content distribution at the vicinity of the border between the unprinted surfaces. This exclusive nitrogen mapping proves that only the unprinted parts of the substrate have high content nitrogen solutes. XRD analysis was performed to investigate whether the iron nitrides were precipitated by RF-DC plasma N2-H2 in the AISI420.

  15. PARADIGMAS DE REPRESENTAÇÃO DE MODULAÇÃO DE ALVENARIAS EM FERRAMENTAS BIM

    Directory of Open Access Journals (Sweden)

    Ari Monteiro

    2009-12-01

    Full Text Available As novas ferramentas CAD que suportam o conceito de Building Information Modeling (BIM baseiam-se na modelagem 3D da geometria do edifício instanciando objetos contidos em famílias de componentes. Alguns destes objetos possuem geometria bastante detalhada, enquanto outros se restringem às suas fronteiras mais externas. No caso do objeto “parede”, esta representação normalmente limita-se às suas faces externas e uma lista de camadas utilizadas para representar sua composição interna (núcleo e revestimentos. Esta representação torna o arquivo leve, favorecendo o desempenho da aplicação. No entanto, para projetos que necessitam de um nível de detalhe superior àquele oferecido por esta solução, como o projeto para produção de vedações verticais em alvenaria (PPVVA, uma representação 3D completa dos elementos da parede é importante. Neste cenário, surge uma questão: como representar os elementos da parede de maneira a atender aos requisitos do PPVVA e, ao mesmo tempo, não degradar o desempenho de manipulação do modelo BIM? Este trabalho apresenta algumas abordagens para a representação da modulação: uma explícita (famílias de objetos e outras implícitas (array / modelagem generativa. Uma análise comparativa destas abordagens é apresentada, destacando-se as suas vantagens e desvantagens, tais como dificuldade de implementação, facilidade de utilização e impacto no desempenho da aplicação. A viabilidade de cada método foi estudada, restringindo-se ao software Autodesk Revit® Architecture 2009/2010, considerando-se os processamentos para geração de vistas 2D e quantificação de componentes, bem como consumo de memória e processamento ligados a cada abordagem, permitindo a tomada de decisão no nível de implementação. * Artigo disponível em versão completa em inglês REPRESENTATION PARADIGMS FOR MASONRY MODULATION IN BIM TOOLS ABSTRACT New CAD tools which support the BIM (Building Information

  16. Método predictivo de volatilidad tipo cambio

    Directory of Open Access Journals (Sweden)

    Jeffrey Viales Abellán

    2011-01-01

    Full Text Available Las series temporales descritas por precios de ciertos activos financieros tales como el de las acciones y divisas presentan dos principales características, excesos de kurtosis y clustering de volatilidad. Para recoger estas características se han utilizado modelos no lineales tales como los modelos Garch o Volatilidad Condicionada y los modelos de Volatilidad Estocástica, ambos tipos de modelo son empleados para la gestión del riesgo cambiario a corto plazo; el primer tipo de modelos definen la volatilidad en función de la misma volatilidad rezagada y de los shocks (innovaciones de volatilidad; el segundo tipo de modelos son similares a los modelos Garch con la variante de que la volatilidad incluye por si misma un término aleatorio de tipo proceso Wienner2; estos modelos son empleados para simular caminatas aleatorias del tipo de cambio con volatilidades simuladas por las ecuación estocásticas de volatilidad.En el presente trabajo se analizará el desempeño del modelo Garch en comparación a las medidas de volatilidad utilizadas actualmente para la gestión del riesgo cambiario; sus implicaciones para la gestión de riesgos.

  17. Fatigue crack growth behavior and overload effect of AISI 304 stainless steel in different atmospheres

    Science.gov (United States)

    Kelestemur, Mehmet Halidun

    1998-12-01

    AISI 304 stainless steel shows strain induced martensitic transformation at the crack tip. Such transformation may have effects on crack closure during fatigue crack propagation. Due to importance of AISI 304 in structural applications, the fatigue crack propagation and martensitic transformation in this material have to be investigated thoroughly. Fatigue crack growth behavior, overload retardation and characterization of martensitic transformation at the crack tip upon fatigue loading were investigated in 304 stainless steel at three different atmospheres, namely dry argon, moist air (75% relative humidity) and hydrogen. Comparison in various atmospheres showed that moist air did not influence that fatigue crack growth rate. However, in hydrogen atmosphere the material did not show threshold behavior and the crack growth rate was considerably higher. It was found that roughness-induced crack closure was the primary mechanism in the threshold region. Fractographic pictures taken by SEM and direct observation of crack profile showed that crack deflection and branching occurred during the fatigue crack propagation and plasticity-induced crack closure was not the primary closure mechanism. The influence of fatigue crack propagation on the rate and size of martensitic transformation at the crack tip was investigated. The overload retardation of the material was lower at hydrogen atmosphere. This low degree of retardation was explained by hydrogen embrittlement mechanism. Fractographic observations show striations at the overload zone in argon atmosphere indicating ductile fracture. In hydrogen atmosphere, overload area shows secondary cracks which represent brittle fracture. Crack closure measurements and modified Paris law did not show evidence for different retardation mechanisms at different atmospheres. It is found that primary retardation mechanisms were crack deflection, crack blunting and roughness-induced crack closure after application of overload(s). An

  18. Erosion and corrosion resistance of laser cladded AISI 420 stainless steel reinforced with VC

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhe [Center for Laser-aided Manufacturing, Lyle School of Engineering, Southern Methodist University, 3101 Dyer Street, Dallas, TX 75206 (United States); Yu, Ting [Center for Laser-aided Manufacturing, Lyle School of Engineering, Southern Methodist University, 3101 Dyer Street, Dallas, TX 75206 (United States); School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Kovacevic, Radovan, E-mail: kovacevi@smu.edu [Center for Laser-aided Manufacturing, Lyle School of Engineering, Southern Methodist University, 3101 Dyer Street, Dallas, TX 75206 (United States)

    2017-07-15

    Highlights: • The coatings of 420 stainless steel reinforced with VC were fabricated by high power direct diode laser. • The erosion resistance of the cladded layer was increased with the increase in the VC fraction. • No obvious improvement of erosion resistance was observed when the VC fraction was above 30 wt.%. • The corrosion resistance of the cladded layer was decreased with the increase in the VC fraction. - Abstract: Metal Matrix Composites (MMC) fabricated by the laser cladding process have been widely applied as protective coatings in industries to improve the wear, erosion, and corrosion resistance of components and prolong their service life. In this study, the AISI 420/VC metal matrix composites with different weight percentage (0 wt.%–40 wt.%) of Vanadium Carbide (VC) were fabricated on a mild steel A36 by a high power direct diode laser. An induction heater was used to preheat the substrate in order to avoid cracks during the cladding process. The effect of carbide content on the microstructure, elements distribution, phases, and microhardness was investigated in detail. The erosion resistance of the coatings was tested by using the abrasive waterjet (AWJ) cutting machine. The corrosion resistance of the coatings was studied utilizing potentiodynamic polarization. The results showed that the surface roughness and crack susceptibility of the laser cladded layer were increased with the increase in VC fraction. The volume fraction of the precipitated carbides was increased with the increase in the VC content. The phases of the coating without VC consisted of martensite and austenite. New phases such as precipitated VC, V{sub 8}C{sub 7}, M{sub 7}C{sub 3}, and M{sub 23}C{sub 6} were formed when the primary VC was added. The microhardness of the clads was increased with the increase in VC. The erosion resistance of the cladded layer was improved after the introduction of VC. The erosion resistance was increased with the increase in the VC content

  19. Evaluación del coeficiente de endurecimiento del acero AISI 1045 deformado por rodillo

    Directory of Open Access Journals (Sweden)

    D. Alcántara

    2011-12-01

    Full Text Available El objetivo del trabajo es determinar el comportamiento del coeficiente de endurecimiento n por la ecuación de Hollomon en muestras cilíndricas de acero AISI 1045, las cuales, después de ser deformadas, se sometieron a ensayos de tracción. Se utiliza un diseño de experimento donde se tienen en cuenta las variables número de revolución (n con 27, 54 y 110 rev/min, fuerza de compresión (P de 500, 1 500 y   2 500 N y avance (S de 0,075; 0,125 y 0,25 mm/rev. Finalmente, aplicando el método de regresión se obtuvo un coeficiente de endurecimiento, el cual se aproxima a la linealidad cuando restringimos el cálculo a rangos de deformación elevados. Este coeficiente de endurecimiento se aplica en la ecuación de Hollomon para determinar el nuevo valor de tensión de fluencia y aplicarlo para el cálculo del trabajo mínimo a realizar en un proceso de deformación en frío empleando rodillo simple.   Palabras clave: Deformación Plástica; tensión; deformación; endurecimiento.The objective of the work is to determine the behavior of the hardening coefficient n by the equation of Hollomon, in cylindrical samples of steel AISI 1045, those which, after the deformed, were subjected to traction rehearsals. He used an experiment design where are kept in mind the revolution number (n with 27, 54 and 110 rev/min, it compression forces (P of 500, 1 500 and 2 500 N and feed (S of 0.075; 0.125 and 0.25 mm/rev. Finally, applying the regression method a hardening coefficient was obtained, which approaches to the linearity when restrict the calculation to high ranges of deformation. This hardening coefficient is applied in the equation of Hollomon for determine the new value of flow tension and to apply in the calculation of the minimum work to carry out in a cold process of deformation using simple roller.   Keywords: Plastic deformation; stress; deformation; hardening.

  20. Erosion and corrosion resistance of laser cladded AISI 420 stainless steel reinforced with VC

    International Nuclear Information System (INIS)

    Zhang, Zhe; Yu, Ting; Kovacevic, Radovan

    2017-01-01

    Highlights: • The coatings of 420 stainless steel reinforced with VC were fabricated by high power direct diode laser. • The erosion resistance of the cladded layer was increased with the increase in the VC fraction. • No obvious improvement of erosion resistance was observed when the VC fraction was above 30 wt.%. • The corrosion resistance of the cladded layer was decreased with the increase in the VC fraction. - Abstract: Metal Matrix Composites (MMC) fabricated by the laser cladding process have been widely applied as protective coatings in industries to improve the wear, erosion, and corrosion resistance of components and prolong their service life. In this study, the AISI 420/VC metal matrix composites with different weight percentage (0 wt.%–40 wt.%) of Vanadium Carbide (VC) were fabricated on a mild steel A36 by a high power direct diode laser. An induction heater was used to preheat the substrate in order to avoid cracks during the cladding process. The effect of carbide content on the microstructure, elements distribution, phases, and microhardness was investigated in detail. The erosion resistance of the coatings was tested by using the abrasive waterjet (AWJ) cutting machine. The corrosion resistance of the coatings was studied utilizing potentiodynamic polarization. The results showed that the surface roughness and crack susceptibility of the laser cladded layer were increased with the increase in VC fraction. The volume fraction of the precipitated carbides was increased with the increase in the VC content. The phases of the coating without VC consisted of martensite and austenite. New phases such as precipitated VC, V 8 C 7 , M 7 C 3 , and M 23 C 6 were formed when the primary VC was added. The microhardness of the clads was increased with the increase in VC. The erosion resistance of the cladded layer was improved after the introduction of VC. The erosion resistance was increased with the increase in the VC content. No obvious improvement

  1. BLOG: FERRAMENTA ESTRATÉGICA DE COMUNICAÇÃO ORGANIZACIONAL/BLOG: STRATEGIC TOOL FOR ORGANIZATIONAL COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Mônica Mota Tassigny

    2012-08-01

    Full Text Available Este trabalho tem como objetivo geral debater a importância do blog como ferramenta da comunicação organizacional interna e externa, destacando-o como uma nova modalidade de comunicação que pode colaborar no gerenciamento de informações e na construção de uma imagem empresarial competitiva, motivando o público interno e fidelizando clientes. É um estudo de caso, de natureza qualitativa, a partir de pesquisa bibliográfica, documental e de campo. A investigação documental foi feita em um site relacionado à ferramenta GoogleDocs. Na pesquisa de campo, optou-se pela análise de conteúdo. Como resultado, observa-se que as empresas estão implantando processos de comunicação organizacionais mais participativos e estratégicos. Nessa perspectiva, concluiu-se que os blogs organizacionais constituem instrumentos com poder de comunicação bidirecional instantâneo, aptos a assegurarem uma interação de informações entre a organização e seus públicos, constituindo-se uma estratégia no fortalecimento da imagem frente ao público alvo, funcionando como ferramenta colaborativa de gestão da informação./This study aimed to discuss the general importance of the blogs as a tool for internal and externalorganizational communication, highlighting as a new mode of communication that can help the information management and build a competitive corporate image, motivating the workforce customerloyalty. It is a case study, qualitative in nature, a literature review, a documentary and a field research. The documentary research was done in a site related to GoogleDocs tool. In the field research was used content analysis. As a result, it is observed that companies are implementing organizational communication processes more participative and strategic. From this perspective, it was concluded that blogs are tools with organizational power of instant two-way communication, able to ensure an interaction of information between the organization and

  2. A simulação realística como ferramenta educacional para estudantes de medicina = Realistic simulation as an educacional tool for medical students

    Directory of Open Access Journals (Sweden)

    Brandão, Carolina Felipe Soares

    2014-01-01

    Conclusões: Embora a simulação realística esteja em franco crescimento e valorizada como importante recurso na formação, novos estudos precisam ser realizados e divulgados para fornecer evidências e mensurações concretas e efetivas dessa ferramenta educacional

  3. Principais indicadores e ferramentas utilizados pelos gestores: uma análise estatística da percepção dos alunos de MBA da Fundação Getúlio Vargas Management indicators and tools: perceptions of MBA students

    Directory of Open Access Journals (Sweden)

    Marcelo Cauduro de Castro

    2007-09-01

    Full Text Available O objetivo deste estudo foi identificar a relevância de indicadores e ferramentas de gestão na percepção dos alunos de MBA da Fundação Getúlio Vargas (FGV. Para isso, utilizou-se um questionário com 26 quesitos definidos a partir de pesquisas anteriores e uma escala de variação de importância do tipo Likert. A amostra foi composta de um total de 425 alunos. Desses, 97 entrevistados não selecionaram nenhum indicador ou ferramenta de gestão. Assim, 328 respostas foram analisadas e interpretadas. Os resultados demonstraram que o Fluxo de Caixa Projetado é o indicador de gestão mais relevante, seguido da Margem Líquida de Vendas. Os dados também apontaram, entre as cinco primeiras posições, indicadores considerados mais sofisticados, como, por exemplo, o Balanced Scorcard (BSC, o Earnings before Interest Taxes Depreciation and Amortization (EBITDA e o Economic Value Added (EVA®. Verificou-se também que as exigências relativas à informação contábil variavam de acordo com o perfil dos respondentes. Os resultados demonstram também que não existe um indicador ou ferramenta de gestão que seja considerado ótimo. Finalmente, há indícios apontados pela pesquisa de que, apesar de a contabilidade gerencial ser considerada uma disciplina global, suas especificidades e características podem ser locais ou regionais.The relevance of management indicators and tools, according to perception of 425 MBA students of the Fundação Getulio Vargas, was identified using a questionnaire with 26 queries based on previous surveys. Results from only 328 respondents were analyzed because 97 did not select any management indicator or tool. Project Cash Flow was the most relevant indicator followed by Net Revenues. In addition the three more sophisticated indicators of Balanced Scorecard (BSC, Earnings before Interest Taxes Depreciation and Amortization (EBITDA and Economic Value Added (EVA® were among the first five ranked. Since it was noted

  4. Hipnose e glicemia em pacientes com diabetes Mellitus tipo 1

    OpenAIRE

    Rodrigues, Fabiana Raquel Oliveira

    2016-01-01

    A Diabetes Mellitus tipo 1 é uma doença crónica, de elevado risco de mortalidade e elevada morbilidade que acarreta consequências precoces na saúde e na vida dos diabéticos. A presente investigação pretende averiguar a eficiência da hipnoterapia analítica, numa abordagem centrada na Pessoa e focada nas soluções que designamos por HSH - Hipnoterapia Sem (ou com) Hipnose, e da Visualização Guiada e Criativa, na monitorização da Diabetes Mellitus tipo 1 (glicemia e hemoglobina glicosilada). Para...

  5. La Planta única como tipo resistente a la escala

    OpenAIRE

    Colmenares Vilata, Silvia

    2014-01-01

    El sistema capitalista ha generado dos de los modelos espaciales de indiferencia funcional más extremos: por un lado, el espacio tecnificado y repetido del edificio de oficinas en altura, encarnado por la ?planta tipo? y, por otro, el espacio diáfano y extenso del gran contendor, que responde a la lógica de lo que llamaremos ?planta única?. En los edificios construidos para la industria automovilística y bélica americana se encuentra el germen de un tipo que servirá de modelo para los nuevos ...

  6. Susceptibility to stress corrosion in stainless steels type AISI 321 and 12X18H10T used in PWR type reactors (WWER)

    International Nuclear Information System (INIS)

    Matadamas C, N.

    1995-01-01

    Titanium stabilized stainless steels have been utilized in sovietic pressurized water reactors (VVER) for avoid the susceptibility to Intergranular Corrosion (IGC) present in other austenitic stainless steels. However the Intergranular Corrosion resistance of this kind of materials has been questioned because of Intergranular Stress Corrosion Cracking failures (IGSCC) have been reported. This paper study the electrochemical behavior of the AISI 321 stainless steel in a H 3 BO 3 Solution contaminated with chlorides and its susceptibility to Intergranular Corrosion.Electrochemical prediction diagrams of the stainless steels AISI 321 and 12X18H10T (sovietic) sensitized (600 Centigrade, 3 h.) were compared. Cylindrical and conical samples were used in Slow Strain Rate Tests (SSRT), to determine the susceptibility to Stress Corrosion Cracking (SCC) in AISI 321 and 12X18H10T stainless steels. The results obtained showed that the temperature of the solution is a very important factor to detect this susceptibility. Fractography studies on the fracture surfaces of the samples obtained in the SSRT at high temperature were realized. Corrosion velocities of both AISI 321 and 12X18H10T stainless steels were determined using conical samples in the CERT system at high temperature. E.D.A.X. analysis was employed in both AISI 321 and 12X18H10T stainless steels in order to explain the degree of sensitization. (Author)

  7. Desenvolvimento de uma ferramenta computacional para recuperação e correção de textos digitalizados

    Directory of Open Access Journals (Sweden)

    Marlon Marcon

    2013-05-01

    Full Text Available Atualmente, há diversas ferramentas computacionais voltadas para identificação e reconhecimento de palavras em arquivos digitais, onde um grande problema tem sido o tratamento de ruídos (falhas de aquisição e erros ortográficos. Estas inconveniências fazem com que os algoritmos de reconhecimento apresentem resultados abaixo do esperado. Este trabalho implementa uma solução para o reconhecimento de palavras com maior qualidade, aplicando algoritmos de remoção de ruído e melhora de contraste, bem como a adoção de um léxico aliado ao módulo de reconhecimento dos caracteres. Os resultados obtidos a partir dos testes de validação e correção das palavras com problemas com taxas de aproveitamento dentro dos limites esperados.

  8. O uso do computador como ferramenta para a implantação do processo de enfermagem

    Directory of Open Access Journals (Sweden)

    Yolanda Dora Martinez Évora

    2002-12-01

    Full Text Available Este texto tem por objetivo analisar o uso do computador como ferramenta auxiliar no processo de trabalho do enfermeiro. São várias as evidências de que a informática vem revolucionando os processos de cuidado, de gerência e de ensino dentro das estruturas dos serviços. Assim sendo, a informatização está conduzindo a enfermagem para o desenvolvimento de uma prática sistemática, organizada, possibilitando desenvolver um cuidado individualizado ao paciente. As autoras discorrem sobre um software para o apoio ao planejamento da assistência de enfermagem e tecem algumas considerações visando o crescimento e a modernização da prática de enfermagem brasileira.

  9. Ferramenta para extração de dados semi-estruturados para carga de um big data

    Directory of Open Access Journals (Sweden)

    João Carlos Furtado

    2015-11-01

    Full Text Available Big Data é um termo utilizado para descrever grandes volumes de dados, e vem ganhando destaque à medida que a sociedade se depara com um aumento sem precedentes na quantidade de informações geradas diariamente. As dificuldades em armazenar, analisar e utilizar esse volume de dados tem sido um considerável gargalo para as empresas. O objetivo do Big Data é permitir que as empresas consigam analisar dados de diversas fontes, apresentando os resultados em um menor tempo de requisição possível, auxiliando assim no processo de tomada de decisões. Esse trabalho tem como objetivo o desenvolvimento de uma ferramenta para a extração de dados semiestruturados na Web, para posterior carga em um Big Data.

  10. Projeto de software para simulação de vôo empregando a ferramenta ANALYTICE II

    Directory of Open Access Journals (Sweden)

    Gustavo Augusto Domeneghine Tiveroli

    2011-12-01

    Full Text Available Este artigo apresenta a utilização da ferramenta de simulação ANALYTICE II no desenvolvimento de um ambiente computacional de simulação de vôo tridimensional. O processo de desenvolvimento envolve três fases de modelagem: geométrica, cinemática e comportamental, que incluem respectivamente, a criação de um modelo 3D de uma aeronave; a definição de seus ângulos e limites de movimento; e, por fim, a programação por meio da linguagem C++, que no modelo determina as funções e o comportamento da aeronave no espaço tridimensional do animador gráfico interno do simulador. Testes com esse ambiente de simulação têm sido realizados com o modelo de um avião monomotor.

  11. Big Data e mídias sociais: monitoramento das redes como ferramenta de gestão

    Directory of Open Access Journals (Sweden)

    Gisiela Hasse Klein

    Full Text Available Resumo A pesquisa avalia se o monitoramento de mídias sociais pode ser uma ferramenta de previsão de padrões epidemiológicos. Para tanto, foram monitoradas as mídias sociais Facebook, Twitter, Instagram, Flickr, Youtube e blogs no Estado de Santa Catarina entre 24 de janeiro de 2016 e 27 de fevereiro de 2016. Os rumores sobre dengue, chikungunya, zika, Aedes aegypti e microcefalia foram relacionados ao número de casos suspeitos, confirmados ou descartados pela Vigilância Epidemiológica de Santa Catarina no mesmo período. Os resultados obtidos mostram que há forte correlação entre as variáveis e que o monitoramento pode ser usado como um modelo preditivo por profissionais da saúde e gestores públicos.

  12. FATORES HUMANOS E CONDIÇÕES DE TRABALHO DAS ATIVIDADES EM UMA FÁBRICA DE FERRAMENTAS

    Directory of Open Access Journals (Sweden)

    Pompeu Paes Guimarães

    2013-11-01

    Full Text Available Este trabalho tem por objetivo avaliar os fatores humanos e as condições de trabalho nas atividades de produção de ferramentas. Este envolve: área de corte 1  e 2, região de orvado, área de viragem, área de forjamento, área da marcadora, têmpera, inserção de cabos, esmeril, envernizamento e soldagem. Os fatores humanos dos trabalhadores foram caracterizados com o uso de um questionário estruturado abrangendo as condições gerais de trabalho, os fatores humanos do trabalhador, as condições de saúde, o treinamento, bem como a segurança no trabalho e conhecer a opinião dos trabalhadores sobre suas funções. A atividade de envernizamento foi a atividade de maior facilidade, menos perigosa e menos cansativa e o esmeril, de menor preferência, mais perigosa e cansativa. Foi detectado alto índice de acidentes no processo de produção de ferramentas afetando, principalmente, a região dos dedos (72%.  Foi detectada, na opinião dos trabalhadores, que o esmeril é a máquina que causa maiores problemas nas atividades de produção de ferramentas, alcançando altos índices de acidentes. Com isso, a satisfação do trabalhador fica comprometida, realçada no cansaço físico relatado após a  jornada de trabalho, descontentamento ao uso de EPI’s, como avental e respirador, sendo que estes deixaram de causar 51% de acidentes.Palavra-chave: Ergonomia, qualidade de vida, produção de ferramentas.HUMAN FACTORS AND WORKING CONDITIONS OF THE ACTIVITIESIN A TOOLS FACTORY ABSTRACTThis paper aimed to evaluate the human factors and working conditions in the production activities of tools. This involves: cutting area 1 and 2, orvado region, turning area, forging area, area marker, tempera, cables  insertion and, grinder, varnishing and welding. The human factors were characterized by using a structured questionnaire covering general working conditions, worker's human factors, health conditions, training and safety at work and know the

  13. Sistema especialista como ferramenta de apoio às boas práticas de manejo da tilapicultura

    Directory of Open Access Journals (Sweden)

    Ana Flavia Rodrigues Seixas

    2009-12-01

    Full Text Available A piscicultura brasileira, tem impulsionado a economia devido ao seu crescimento em torno de 30% ao ano, como também por tratar-se de fonte de proteína de alta qualidade e pela alta lucratividade. De origem africana, a tilapicultura está presente hoje em grande parte do território nacional, mas ainda sofrendo as pressões por maior qualidade do produto e adoção de práticas menos impactantes ao ambiente. Entre alguns desses impactos citam-se as poluição e interferências em níveis de biodiversidade e de qualidade da água. Assim, o produtor carece de informação e ferramentas que favoreçam a rápida transferência de práticas já identificadas pela pesquisa, que aumentem seu conhecimento e agilidade na incorporação destas às atividades da propriedade. O projeto “ Manejo e Gestão Ambiental da Aqüicultura” da Embrapa Meio Ambiente, componente do projeto em rede Aquabrasil, vem identificando Boas Práticas de Manejo (BPM de tilápia passíveis de uso imediato pelo produtor a partir de sua rápida observação da propriedade. Nele, o sistema informatizado Aquisys está em desenvolvimento para viabilizar o acesso dinâmico, via web, às avaliações e indicadores de produção, manejo e qualidade de água em atenção às BPM de tilápia. Este trabalho apresenta uma das ferramentas computacionais desenvolvidas: um sistema especialista de rápida avaliação de BPM na propriedade, desenvolvido em linguagem CLIPS.

  14. Influence of the density of the microwave plasma in the nitridation of the AISI 4140 steel

    International Nuclear Information System (INIS)

    Chirino O, S.; Camps C, E.; Escobar A, L.; Mejia H, J.A.

    2004-01-01

    A source of microwaves plasma type ECR was used to modify those mechanical properties of the surface of steel pieces AISI 4140. The experiments were carried out in a range of pressure among 4 X 10 -4 and 7 X 10 -4 Torr using one mixture of gases 60/40 hydrogen / nitrogen and an incident power of the microwaves of 400 W. Previous to the treatment of the samples, the plasma was studied using one Langmuir probe to determine the temperature of the electrons and the density of the plasma, the species excited in the plasma were determined by means of Optical emission spectroscopy. All the samples were treated during 50 min in a regime of low temperature (- 250 C), and the surface hardness it was increased up of 100% of their initial value, with a depth of penetration of the nitrogen of 4.5 μ m. The biggest hardness and depth of penetration of the nitrogen were obtained when the biggest density in the plasma was used to carry out the experiments. (Author)

  15. Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

    Directory of Open Access Journals (Sweden)

    Chen Ying An

    2010-09-01

    Full Text Available The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW, which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The results were analyzed by means of tensile tests, Vickers microhardness, metallographic tests and SEM-EDX. The strength of the joints varied with increasing friction time and the use of different pressure values. Joints were obtained with superior mechanical properties of the AA1050 aluminum, with fracture occurring in the aluminum away from the bonding interface. The analysis by EDX at the interface of the junction showed that interdiffusion occurs between the main chemical components of the materials involved. The RFW proves to be a great method for obtaining joints between dissimilar materials, which is not possible by fusion welding processes.

  16. Refining the microstructure of an AISI M2 tool steel by high-energy milling

    International Nuclear Information System (INIS)

    Postiglioni, R.V.; Alamino, A.E; Vurobi Junior, S.

    2009-01-01

    Samples of AISI M2 steel were produced by high-energy milling from chips of machining in Spex high energy mill, compaction and sintering of the powder obtained. The powder was analyzed by X-ray diffraction, and then compressed in discs of 8mm in diameter. The specimens have sintering at 1200 deg C for 1 hour under vacuum atmosphere, followed by annealing, quenching and tempering for 1 hour at 315 deg C and 540°C. Along with each disc, a sample of as-received steel was subjected to the same heat treatments to compare the final microstructure. After standard metallographic preparation, samples were etched with Beraha's reagent, characterized by optical microscopy, quantitative metallography, scanning electron microscopy with micro analysis and mapping by EDS, besides Vickers hardness. The steel produced by high-energy milling presented more refined carbide and better distribution in the microstructure. There was also reduction in the size of prior austenitic grains. (author)

  17. Revisiting Formability and Failure of AISI304 Sheets in SPIF: Experimental Approach and Numerical Validation

    Directory of Open Access Journals (Sweden)

    Gabriel Centeno

    2017-11-01

    Full Text Available Single Point Incremental Forming (SPIF is a flexible and economic manufacturing process with a strong potential for manufacturing small and medium batches of highly customized parts. Formability and failure in SPIF have been intensively discussed in recent years, especially because this process allows stable plastic deformation well above the conventional forming limits, as this enhanced formability is only achievable within a certain range of process parameters depending on the material type. This paper analyzes formability and failure of AISI304-H111 sheets deformed by SPIF compared to conventional testing conditions (including Nakazima and stretch-bending tests. With this purpose, experimental tests in SPIF and stretch-bending were carried out and a numerical model of SPIF is performed. The results allow the authors to establish the following contributions regarding SPIF: (i the setting of the limits of the formability enhancement when small tool diameters are used, (ii the evolution of the crack when failure is attained and (iii the determination of the conditions upon which necking is suppressed, leading directly to ductile fracture in SPIF.

  18. Cutting Temperature Investigation of AISI H13 in High Speed End Milling

    Directory of Open Access Journals (Sweden)

    Muhammad Riza

    2016-10-01

    Full Text Available Heat produced at the tool-chip interface during high speed milling operations have been known as a significant factor that affect to tool life and workpiece geometry or properties. This paper aims to investigate cutting temperature behaviours of AISI H13 (48 HRC under high speed machining circumstances during pocketing. The experiments were conducted on CNC vertical machining centre by using PVD coated carbide insert. Milling processes were done at cutting speeds 150, 200 and 250 m/min and feed rate were 0.05, 0.1 and 0.15 mm/tooth. Depths of cut applied were 0.1, 0.15 and 0.2 mm. Tool path method applied in this experiment was contour in. Results presented in this paper indicate that by increasing cutting speed the cutting temperature is lower than low cutting speed. However, by decreasing feed rate leads to cutting temperature low. Cutting temperature phenomena at the corner of pocket milling were also investigated. The phenomena showed that cutting temperature tends to decrease a moment when cutter comes to the corner of pocket and turning point of tool path and increase extremely a moment before leaving the corner and turning point.

  19. Heat treated twin wire arc spray AISI 420 coatings under dry and wet abrasive wear

    Science.gov (United States)

    Rodriguez, E.; González, M. A.; Monjardín, H. R.; Jimenez, O.; Flores, M.; Ibarra, J.

    2017-11-01

    The influence of applying two different heat treatments such as: deep cryogenic and tempering on dry/wet abrasive wear resistance of twin wire arc spray martensitic AISI 420 coatings was evaluated by using a modified rubber wheel type test apparatus. A load dependency was observed on the abrasive wear rate behavior of both; dry and wet tests. Three body (rolling) and two body (sliding) wear mechanisms were identified in dry conditions, prevailing rolling at lower and higher loads. However, at higher loads, more presence of grooving and pits formation was observed. Coatings tempered at 205 °C/1 h displayed better wear resistance than cryogenic treated ones. A change in wear mechanism between dry and wet conditions was observed; two body wear mechanism predominated respect to three body. In both; dry and wet conditions the microstructure (several inter-splat oxides) as well as strain and residual stress promotes brittle material removal which was more evident in cryogenic and as-sprayed samples during dry test and at higher loads in wet conditions.

  20. Experimental investigation on hard turning of AISI 4340 steel using cemented coated carbide insert

    Science.gov (United States)

    Pradeep Kumar, J.; Kishore, K. P.; Ranjith Kumar, M.; Saran Karthick, K. R.; Vishnu Gowtham, S.

    2018-02-01

    Hard turning is a developing technology that offers many potential advantages compared to grinding, which remains the standard finishing process for critical hardened surfaces. In this work, an attempt has been made to experimentally investigate hard turning of AISI 4340 steel under wet and dry condition using cemented coated carbide insert. Hardness of the workpiece material is tested using Brinell and Rockwell hardness testers. CNC LATHE and cemented coated carbide inserts of designation CNMG 120408 are used for conducting experimental trials. Significant cutting parameters like cutting speed, feed rate and depth of cut are considered as controllable input parameters and surface roughness (Ra), tool wear are considered as output response parameters. Design of experiments is carried out with the help of Taguchi’s L9 orthogonal array. Results of response parameters like surface roughness and tool wear under wet and dry condition are analysed. It is found that surface roughness and tool wear are higher under dry machining condition when compared to wet machining condition. Feed rate significantly influences the surface roughness followed by cutting speed. Depth of cut significantly influences the tool wear followed by cutting speed.

  1. Propagation of crevices in stainless steel AISI304L in conditions of hydrogen chemistry (HWC)

    International Nuclear Information System (INIS)

    Diaz S, A.; Fuentes C, P.; Merino C, F.; Castano M, V.

    2006-01-01

    Crevice growth velocities in samples of AISI 304L stainless steel thermally welded and sensitized were obtained by the Rising displacement method or of growing displacement. It was used a recirculation circuit in where the operation conditions of a BWR type reactor were simulated (temperature of 288 C and a pressure of 8 MPa) with the chemistry modified by the addition of hydrogen with and without the addition of impurities of a powerful oxidizer like the Cu ++ ion. CT pre cracked specimens were used and each rehearsal stayed to one constant displacement velocity of 1 x 10 -9 m/s (3.6 μm/hr), making a continuous pursuit of the advance of the crack by the electric potential drop technique. To the end of the rehearsal it was carried out the fractographic analysis of the propagation surfaces. The values of the growth velocities obtained by this methodology went similar to the opposing ones under normal conditions of operation; while the fractographic analysis show the cracks propagation in trans and intergranular ways, evidencing the complexity of the regulator mechanisms of the one IGSCC even under controlled ambient conditions or with mitigation methodologies like the alternative hydrogen chemistry. (Author)

  2. Effects of Austenitizing Conditions on the Microstructure of AISI M42 High-Speed Steel

    Directory of Open Access Journals (Sweden)

    Yiwa Luo

    2017-01-01

    Full Text Available The influences of austenitizing conditions on the microstructure of AISI M42 high-speed steel were investigated through thermodynamic calculation, microstructural analysis, and in-situ observation by a confocal scanning laser microscope (CSLM. Results show that the network morphology of carbides could not dissolve completely and distribute equably in the case of the austenitizing temperature is 1373 K. When the austenitizing temperature reaches 1473 K, the excessive increase in temperature leads to increase in carbide dissolution, higher dissolved alloying element contents, and unwanted grain growth. Thus, 1453 K is confirmed as the best austenitizing condition on temperature for the steel. In addition, variations on the microstructure and hardness of the steel are not obvious when holding time ranges from 15 to 30 min with the austenitizing temperature of 1453 K. However, when the holding time reaches 45 min, the average size of carbides tends to increase because of Ostwald ripening. Furthermore, the value of Ms and Mf decrease with the increase of cooling rate. Hence, high cooling rate can depress the martensitic transformation and increase the content of retained austenite. As a result, the hardness of the steel is the best (65.6 HRc when the austenitizing temperature reaches 1453 K and is held for 30 min.

  3. Changes of surface layer of nitrogen-implanted AISI316L stainless steel

    International Nuclear Information System (INIS)

    Budzynski, P.; Polanski, K.; Kobzev, A.P.

    2007-01-01

    The effects of nitrogen ion implantation into AISI316L stainless steel on friction, wear, and microhardness have been investigated at an energy level of 125 keV at a fluence of 1·10 17 - 1·10 18 N/cm 2 . The composition of the surface layer was investigated by RBS, XRD (GXRD), SEM and EDX. The friction coefficient and abrasive wear rate of the stainless steel were measured in the atmospheres of air, oxygen, argon, and in vacuum. As follows from the investigations, there is an increase in resistance to frictional wear in the studied samples after implantation; however, these changes are of different characters in various atmospheres. The largest decrease in wear was observed during tests in the air, and the largest reduction in the value of the friction coefficient for all implanted samples was obtained during tests in the argon atmosphere. Tribological tests revealed larger contents of nitrogen, carbon, and oxygen in the products of surface layer wear than in the surface layer itself of the sample directly after implantation

  4. Some Temperature Effects on AISI-304 Nitriding in an Inductively Coupled RF Plasma

    International Nuclear Information System (INIS)

    Valencia-Alvarado, R.; Barocio, S. R.; Mercado-Cabrera, A.; Pena-Eguiluz, R.; Munoz-Castro, A. E.; Piedad-Beneitez, A. de la; Rosa-Vazquez, J. de la; Lopez-Callejas, R.; Godoy-Cabrera, O. G.

    2006-01-01

    Some recent results obtained from nitriding AISI 304 stainless steel samples, 1.2 cm in diameter and 0.5 cm thick are reported here in the case of an 85% hydrogen and 15% nitrogen mixture work gas. The process was carried out from 300 to 400 W for (13.56 MHz) inductively coupled plasma within a 60 cm long pyrex glass tube 3.5 cm in diameter where the samples were biased up to -300 V with respect to earth. The resulting hardness appears to be a function of the substrate temperature which varied from 200 deg. C at a 0 V bias to 550 deg. C at -300 V. The plasma density at 400 W reached 3x1010 cm-3 with a 4 eV electron temperature. Prior to nitriding, all the samples were polished with 0.05 μm diamond paste, leading to a 30 nm average roughness (Ra). After nitriding at -300 V, the Ra rose until ∼400 nm while hardness values of 1500 HV under 300 g loads were measured. X ray diffraction indicates that the extended phase amplitude (γN), Fe and Cr nitride depends on the substrate temperature

  5. Effect of acetic acid on corrosion behavior of AISI 201, 304 and 430 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Vashishtha, Himanshu; Taiwade, Ravindra V.; Sharma, Sumitra [Visvesvaraya National Institute of Technology (VNIT), Nagpur (India). Dept. of Metallurgical and Materials Engineering

    2017-05-15

    Austenitic stainless steels are often used to handle organic acids such as acetic acid (CH{sub 3}COOH), which are extensively used in food contact applications and chemical industries for manufacturing medicines, nutrition and various chemical amalgams. In the present investigation an attempt has been made to compare the corrosion behavior of Cr-Ni (AISI type 304), Cr-Mn-Ni (type 201) and Cr (type 430) stainless steel for economical replacement of higher cost Cr-Ni grade. Immersion testing was performed at room temperature and boiling temperature in acetic acid. Atomic absorption spectroscopy was carried out to evaluate metal ion concentration in the immersion solution. The surface morphology of pit formation was characterized using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The effect of elemental leaching on electrical conductivity of the immersion solution was evaluated and correlated with pH measurements. A new mechanism has been proposed for the pit formation due to manganese sulfide inclusions. The replacement compatibility was further confirmed with anodic polarization testing and a successful replacement was established for room temperature applications.

  6. Effect of lubricant extreme-pressure additives on surface fatigue life of AISI 9310 spur gears

    Science.gov (United States)

    Scibbe, H. W.; Townsend, D. P.; Aron, P. R.

    1984-01-01

    Surface fatigue tests were conducted with AISI 9310 spur gears using a formulated synthetic tetraester oil (conforming to MIL-L-23699 specifications) as the lubricant containing either sulfur or phosphorus as the EP additive. Four groups of gears were tested. One group of gears tested without an additive in the lubricant acted as the reference oil. In the other three groups either a 0.1 wt % sulfur or phosphorus additive was added to the tetraester oil to enhance gear surface fatigue life. Test conditions included a gear temperature of 334 K (160 F), a maximum Hertz stress of 1.71 GPa (248 000 psi), and a speed of 10,000 rpm. The gears tested with a 0.1 wt % phosphorus additive showed pitting fatigue life 2.6 times the life of gears tested with the reference tetraester based oil. Although fatigue lives of two groups of gears tested with the sulfur additive in the oil showed improvement over the control group gear life, the results, unlike those obtained with the phosphorus oil, were not considered to be statistically significant.

  7. Effect of shot peening on surface fatigue life of carburized and hardened AISI 9310 spur gears

    Science.gov (United States)

    Townsend, D. P.; Zaretsky, E. V.

    1982-01-01

    Surface fatigue tests were conducted on two groups of AISI 9310 spur gears. Both groups were manufactured with standard ground tooth surfaces, with the second group subjected to an additional shot peening process on the gear tooth flanks. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a gear temperature of 350 K (170 F), a maximum Hertz stress of 1.71 billion N/sq m (248,000 psi), and a speed of 10,000 rpm. The shot peened gears exhibited pitting fatigue lives 1.6 times the life of standard gears without shot peening. Residual stress measurements and analysis indicate that the longer fatigue life is the result of the higher compressive stress produced by the shot peening. The life for the shot peened gear was calculated to be 1.5 times that for the plain gear by using the measured residual stress difference for the standard and shot peened gears. The measured residual stress for the shot peened gears was much higher than that for the standard gears.

  8. Effect of two synthetic lubricants on life of AISI 9310 spur gears

    Science.gov (United States)

    Townsend, Dennis P.; Shimski, John

    1991-01-01

    Spur-gear fatigue tests were conducted with two lubricants using a single lot of consumable-electrode vacuum-melted (CVM) AISI 9310 spur gears. The gears were case carburized and hardened to Rockwell C60. The gear pitch diameter was 8.89 cm. The lot of gears was divided into two groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-ester-based lubricants. One lubricant was 30 percent more viscous that the other. Both lubricants have similar pressure viscosity coefficients. Test conditions included a bulk gear temperature of 350 K, a maximum Hertz stress of 1.71 GPa at the pitch line, and a speed of 10,000 rpm. The surface fatigue life of gears tested with one lubricant was approximately 2.4 times that for gears tested with the other lubricant. The lubricant with the 30 percent higher viscosity gave a calculated elastohydrodynamic (EHD) film thickness that was 20 percent higher than the other lubricant. This increased EHD film thickness is the most probable reason for the improvement in surface fatigue life of gears tested with this lubricant over gears tested with the less viscous lubricant.

  9. Formation of microstructural features in hot-dip aluminized AISI 321 stainless steel

    Science.gov (United States)

    Huilgol, Prashant; Rajendra Udupa, K.; Udaya Bhat, K.

    2018-02-01

    Hot-dip aluminizing (HDA) is a proven surface coating technique for improving the oxidation and corrosion resistance of ferrous substrates. Although extensive studies on the HDA of plain carbon steels have been reported, studies on the HDA of stainless steels are limited. Because of the technological importance of stainless steels in high-temperature applications, studies of their microstructural development during HDA are needed. In the present investigation, the HDA of AISI 321 stainless steel was carried out in a pure Al bath. The microstructural features of the coating were studied using scanning electron microscopy and transmission electron microscopy. These studies revealed that the coating consists of two regions: an Al top coat and an aluminide layer at the interface between the steel and Al. The Al top coat was found to consist of intermetallic phases such as Al7Cr and Al3Fe dispersed in an Al matrix. Twinning was observed in both the Al7Cr and the Al3Fe phases. Furthermore, the aluminide layer comprised a mixture of nanocrystalline Fe2Al5, Al7Cr, and Al. Details of the microstructural features are presented, and their formation mechanisms are discussed.

  10. Structural analysis and intergranular corrosion tests of AISI 316L steel.

    Science.gov (United States)

    Stonawská, Z; Svoboda, M; Sozańska, M; Krístková, M; Sojka, J; Dagbert, C; Hyspecká, L

    2006-10-01

    Pure AISI 316L steel is investigated after solution heat treatment (1050 degrees C/H(2)O) and structural sensitization (650 degrees C). Two quite different intergranular corrosion tests are used to determine the degree of structural sensitization due to the precipitation of secondary phases along the grain boundaries (mainly the M(23)C(6) and sigma-phase): the oxalic acid etch test and the electrochemical potentio-kinetic reactivation test. Generally, the dissolution of chromium-rich carbides (M(23)C(6)) is provoked by oxalic acid etch tests, whereas the chromium-depleted zones, in the vicinity of chromium-rich carbides (M(23)C(6)), are attacked by electrochemical potentio-kinetic reactivation tests. Both intergranular corrosion tests are used to determine the maximum degree of structural sensitization. Thus structural analysis by carbon replicas reveals the Laves phase, and both the M(23)C(6) and (Cr,Mo)(x)(Fe,Ni)(y) phases. The results of intergranular corrosion tests are related to the findings of the structural analysis.

  11. Kinetic investigation of AISI 304 Stainless Steel boronized in indirect heated fluidized bed furnace

    Directory of Open Access Journals (Sweden)

    Topuz P.

    2016-01-01

    Full Text Available In this study, kinetic examinations on boronized AISI 304 Stainless Steel samples were described. Samples were boronized in indirect heated fluidized bed furnace consists of Ekabor 1™ boronizing agent at 1123, 1223 and 1323 K for 1,2 and 4 hours. Morphologically and typically examinations of borides formed on the surface of steel samples were studied by optical microscope, scanning electron microscope (SEM and X-Ray diffraction (XRD. Boride layer thickness formed on the steel X5CrNi 18-10 ranges from 12 to 176 μm. The hardness of the boride layer formed on the steel X5CrNi 18-10 varied between 1709 and 2119 Hv0,1. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of boronizing time and temperature. The kinetics of the reaction has been determined with K=Ko exp (-Q/RT equation. Activation energy (Q of boronized steel X5CrNi 18-10 was determined as 244 kj/mol.

  12. Laser micropolishing of AISI 304 stainless steel surfaces for cleanability and bacteria removal capability

    Science.gov (United States)

    De Giorgi, Chiara; Furlan, Valentina; Demir, Ali Gökhan; Tallarita, Elena; Candiani, Gabriele; Previtali, Barbara

    2017-06-01

    In this work, laser micropolishing (LμP) was employed to reduce the surface roughness and waviness of cold-rolled AISI 304 stainless steel sheets. A pulsed fibre laser operating in the ns regime was used and the influence of laser parameters in a N2-controlled atmospheres was evaluated. In the optimal conditions, the surface remelting induced by the process allowed to reduce the surface roughness by closing cracks and defects formed during the rolling process. Other conditions that did not improve the surface quality were analysed for defect typology. Moreover, laser treatments allowed the production of more hydrophobic surfaces, and no surface chemistry modification was identified. Surface cleanability was investigated with Escherichia coli (E. coli), evaluating the number of residual bacteria adhering to the substrate after a washing procedure. These results showed that LμP is a suitable way to lower the average surface roughness by about 58% and average surface waviness by approximately 38%. The LμP process proved to be effective on the bacteria cleanability as approximately five times fewer bacteria remained on the surfaces treated with the optimized LμP parameters compared to the untreated surfaces.

  13. Influence of post irradiation annealing on the mechanical properties and defect structure of AISI 304 steel

    Science.gov (United States)

    Van Renterghem, W.; Al Mazouzi, A.; Van Dyck, S.

    2011-06-01

    The effect of post irradiation annealing on the mechanical properties and the radiation induced defect structure was investigated on stainless steel, of type AISI 304, that was irradiated up to 24 dpa in the decommissioned Chooz A reactor. The material was investigated both in the as-irradiated state as well as after post irradiation annealing. In the as-irradiated specimen the typical radiation induced defects were found as well as γ'-precipitates (Ni 3Si). Annealing at 400 °C had almost no effect on the radiation induced defects, but annealing at 500 °C resulted in the immediate unfaulting of the Frank loops. As to the mechanical properties, annealing at 400 °C did not strongly affect the yield strength and the ductility of the material, although the fraction of intergranular fracture during slow strain rate tensile tests under pressurised water reactor conditions, was significantly reduced. Annealing at 500 °C did reduce the yield strength and restored substantially the ductility and the strain hardening capability of the material. The microstructure investigated by transmission electron microscopy correlates to the mechanical test results. It was found that the observed defect changes after post irradiation annealing provide a reasonable explanation for the observed changes of the mechanical properties.

  14. Niobized AISI 304 stainless steel bipolar plate for proton exchange membrane fuel cell

    Science.gov (United States)

    Wang, Lixia; Sun, Juncai; Li, Pengbin; Jing, Bo; Li, Song; Wen, Zhongsheng; Ji, Shijun

    2012-06-01

    AISI 304 stainless steel (SS) has been niobized by a plasma surface diffusion alloying method. A 3 μm niobized layer with dominant niobium elements has been formed on the 304 SS surface and the performances of the niobized 304 SS has been examined and evaluated as bipolar plate for proton exchange membrane fuel cell (PEMFC). Results show that the average contact angle with water for the niobized 304 SS is about 90.4°, demonstrating better hydrophobicity as compared with the untreated 304 SS (68.1°). The corrosion resistance of the 304 SS is considerably improved by the niobized layer with the corrosion current densities decreased at 0.2 and 0.4 μA cm-2 in simulated PEMFC anode purged with hydrogen and the cathode purged with air condition (0.05 M H2SO4 + 2 ppm F- solution at 70 °C), respectively. The interfacial contact resistance (ICR) for the as-prepared niobized 304 SS is 10.53 mΩ cm2 at the compaction of 140 N cm-2. Furthermore, after 4 h potentiostatic tests, the niobizied specimens exhibit much lower ICR than that for the untreated ones. Thus, the niobized layer can act as a conductively protective layer of the 304 SS bipolar plate for PEMFC.

  15. Deposition of titanium nitride on AISI-304 in a plasma focus environment

    Science.gov (United States)

    Zeb, S.; Qayyum, A.; Shafiq, M.; Zakaullah, M.

    2008-05-01

    Polycrystalline, smooth, and hard thin films of TiN are successfully deposited on AISI-304 substrates using a 1.5kJ Mather-type dense plasma focus device charged at 18kV. The purpose of this study is to investigate the structural and mechanical properties of the TiN thin films in terms of ion dose and substrate position to establish the optimum deposition conditions. The films are analyzed using XRD, SEM, electron microprobe and micro-hardness testing. XRD confirms the deposition of a polycrystalline TiN thin film together with the emergence of an iron chromium nickel phase. The surface hardness-in comparison to the unexposed substrate-is found to increase up to 250% when a film is deposited using 30 focus shots at an axial distance of 6cm. SEM micrographs show that the quality of the film is improved with an increasing number of focus shots. The constituent elements of the film are also confirmed by electron microprobe.

  16. Regression Modeling of EDM Process for AISI D2 Tool Steel with RSM

    Directory of Open Access Journals (Sweden)

    Shakir M. Mousa

    2018-01-01

    Full Text Available In this paper, Response Surface Method (RSM is utilized to carry out an investigation of the impact of input parameters: electrode type (E.T. [Gr, Cu and CuW], pulse duration of current (Ip, pulse duration on time (Ton, and pulse duration off time (Toff on the surface finish in EDM operation. To approximate and concentrate the suggested second- order regression model is generally accepted for Surface Roughness Ra, a Central Composite Design (CCD is utilized for evaluating the model constant coefficients of the input parameters on Surface Roughness (Ra. Examinations were performed on AISI D2 tool steel. The important coefficients are gotten by achieving successfully an Analysis of Variance (ANOVA at the 5 % confidence interval. The outcomes discover that Surface Roughness (Ra is much more impacted by E.T., Ton, Toff, Ip and little of their interactions action or influence. To predict the average Surface Roughness (Ra, a mathematical regression model was developed. Furthermore, for saving in time, the created model could be utilized for the choice of the high levels in the EDM procedure. The model adequacy was extremely agreeable as the constant Coefficient of Determination (R2 is observed to be 99.72% and adjusted R2-measurement (R2adj 99.60%.

  17. Nitriding the influence of plasma in resistance to wear micro abrasive tool steel AISI D2

    International Nuclear Information System (INIS)

    Gobbi, Vagner Joao; Gobb, Silvio Jose; Silva, Cosme Roberto Moreira da

    2010-01-01

    This work studies the influence of time of treatment in the formation of nitride layer of AISI D2 tool steel and the resistance to micro-abrasive wear from the technique of nitriding in plasma. The samples were nitrides at 400 ° C with a pressure of 4.5 mbar (450 Pa) and using a gas mixture of 80% vol.H2 and 20% vol.N2. The times of treatment were: 30, 60, 120, 180 and 360 minutes. The properties of the layers in the samples obtained nitrides were assessed by surface microhardness, profiles of microhardness, metallography analysis, X-ray diffraction and test for resistance to micro-abrasive wear. The best results for nitriding to 400 deg C, was obtained with the time of treatment of 360 minutes. In this case the increase in surface hardness was 94.6% and resistance to micro-abrasive wear of 15%. This increase in hardness may be associated with high concentration of nitrogen in the crystalline network of iron-α and additional training of nitrides. Low temperature of nitriding reduces between grain fragility to reduce the likelihood of precipitation of nitrides in a continuous manner in the austenite grain boundaries and the absence of previous ε'+ γ phases. (author)

  18. Effects of Cr2N Precipitation on the Antibacterial Properties of AISI 430 Stainless Steel

    Directory of Open Access Journals (Sweden)

    Je-Kang Du

    2016-03-01

    Full Text Available Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu2+ and Ag2+ ions have been added onto biomaterials for increasing the antibacterial properties, but they are known to damage biofilm. The occurrence of nanoparticles can also improve the antibacterial properties of biomaterials through various methods. In this study, we used Escherichia coli and analyzed the microstructures of American Iron and Steel Institute (AISI 430 stainless steel with a 0.18 mass % N alloy element. During a lower temperature aging, the microstructure of the as-quenched specimen is essentially a ferrite and martensite duplex matrix with some Cr2N precipitates formed. Additionally, the antibacterial properties of the alloy for E. coli ranged from 3% to 60%, consistent with the presence of Cr2N precipitates. When aged at a lower temperature, which resulted in nano-Cr2N precipitation, the specimen possessed the highest antibacterial activity.

  19. Machinability baja AISI 1040 pada proses bubut dengan variasi cutting speed dan feed rate

    Directory of Open Access Journals (Sweden)

    AAIA Sri Komaladewi

    2012-11-01

    Full Text Available In order to obtain desired results of machining process (turning, parameter of process and material characteristic to be machined should be well known. This is due to different machining conditions and material yield different material machinability as well. It is needed to investigate of material machinability (AISI 1040 such as force, power and shear angle under different cutting speed (80, 160 and 240 m/min and feed rate (0.1, 0.2, and 0.3 mm/rev. The results of investigation show that; at the same cutting speed the higher feed rate the higher cutting force needed; the higher cutting speed and feed rate, the higher power needed; at feed rate 0.1 mm./rev and 0.3 mm/rev, the higher cutting speed the shear angles has a trend to incline; at feed rate 0.2 mm/rev, cutting speed from 80 to 160 m/min yield increasing of shear angle, however, from 160 to 240 m/min shear angle declines.

  20. Effects of cold working on the pitting corrosion behavior s of AISI 304 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Kee Min; Kim, Jong Soo; Kim, Young Jun; Kwon, Houk Sang [KAIST, Daejon (Korea, Republic of)

    2015-12-15

    These microstructural changes by cold working can lead improvement of mechanical properties, however from a corrosion resistant point of view, the effects of cold working on the corrosion resistance of stainless steel have been argued. Several studies has been focused on the influence of cold working on the localized corrosion resistance of stainless steels. However, the opinions about the role of cold working on the localized corrosion resistance are highly in consistence. Some studies report that the pitting potential of austenitic stainless steels decreased with cold working level, on the other hands, other studies claimed that the pitting resistance was increased by cold working. Therefore it is necessary to verify how cold working affects pitting corrosion behavior of austenitic stainless steels. In the present work, the influence of cold working on the localized corrosion of AISI 304stainless steel in the neutral chloride solution was studied based on point defect model (PDM). The fraction of deformation-induced martensite was linearly increased with cold rolling level. Through cold rolling, the pitting potential was decreased, the metastable pitting event density was significantly increased and the repassivation potential was decreased. The overall localized corrosion resistance was decreased with cold working, however cold working level increased from 30 % to 50 %, localized corrosion resistance was recovered. The accumulated cation vacancy generates a void at metal/film interface, therefore film breakdown accelerates for cold worked alloys.

  1. Multi-response optimization of Micro-EDM process parameters on AISI304 steel using TOPSIS

    Energy Technology Data Exchange (ETDEWEB)

    Manivannan, R.; Kumar, M. Pradeep [CEG, Anna University, Chennai (India)

    2016-01-15

    The Technique for order preference by similarity to ideal solution (TOPSIS) method of optimization is used to analyze the process parameters of the micro-Electrical discharge machining (micro-EDM) of an AISI 304 steel with multi-performance characteristics. The Taguchi method of experimental design L27 is performed to obtain the optimal parameters for inputs, including feed rate, current, pulse on time, and gap voltage. Several output responses, such as the material removal rate, electrode wear rate, overcut, taper angle, and circularity at entry and exit points, are analyzed for the optimal conditions. Among all the investigated parameters, feed rate exerts a greater influence on the hole quality. ANOVA is employed to identify the contribution of each experiment. The optimal level of parameter setting is maintained at a feed rate of 4 μm/s, a current of 10 A, a pulse on time of 10 μs, and a gap voltage of 10 V. Scanning electron microscope analysis is conducted to examine the hole quality. The experimental results indicate that the optimal level of the process parameter setting over the overall performance of the micro-EDM is improved through TOPSIS.

  2. Surface severe plastic deformation of AISI 304 via conventional shot peening, severe shot peening and repeening

    Energy Technology Data Exchange (ETDEWEB)

    Unal, Okan, E-mail: unalokan78@gmail.com [Mechanical Engineering Department, Bartın University, Bartın 74100 (Turkey); Varol, Remzi [Mechanical Engineering Department, Suleyman Demirel University, Isparta 32200 (Turkey)

    2015-10-01

    Highlights: • CSP and SSP treatments transform austenite to metastable martensite structure. • Nanograin layer thickness after CSP and SSP is 8 μm and 22 μm, respectively. • Shot peening leads to carbon segregation from coarse to nano grain layer. • Repeening is an effective way to reduce surface roughness. - Abstract: Air blast conventional shot peening (CSP), severe shot peening (SSP) and repeening (RP) as a severe plastic deformation applications on AISI 304 austenitic stainless steel is addressed. Shot peened specimens are investigated based on optical, FESEM and digital microscope. The investigations present the austenite transformation to metastable martensite via mechanical twinning due to plastic deformation with high strain rates. It is found that SSP induces thicker nanograin layer with compared to CSP. In XRD studies, the austenite peaks broaden by means of severe shot peening and FWHM increase reveals the grain size reduction below 25 nm regimes on the surface. In EDAX line analysis of CSP specimen, carbon content increase has been detected from deformed layer through the nanocrystalline layer then the content reduces. The carbon segregation takes place due to the energy level distinction between dislocations and Fe−C bonds. 3d contour digital microscope studies and roughness investigations reveal that SSP has deleterious side effect on the surface roughness and surface flatness. However, RP is an effective way to reduce the surface roughness to reasonable values.

  3. The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

    Science.gov (United States)

    Cios, G.; Tokarski, T.; Żywczak, A.; Dziurka, R.; Stępień, M.; Gondek, Ł.; Marciszko, M.; Pawłowski, B.; Wieczerzak, K.; Bała, P.

    2017-10-01

    This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (-60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to 70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α' → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov-Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

  4. Dynamic Recrystallization Behavior of AISI 422 Stainless Steel During Hot Deformation Processes

    Science.gov (United States)

    Ahmadabadi, R. Mohammadi; Naderi, M.; Mohandesi, J. Aghazadeh; Cabrera, Jose Maria

    2018-02-01

    In this work, hot compression tests were performed to investigate the dynamic recrystallization (DRX) process of a martensitic stainless steel (AISI 422) at temperatures of 950, 1000, 1050, 1100 and 1150 °C and strain rates of 0.01, 0.1 and 1 s-1. The dependency of strain-hardening rate on flow stress was used to estimate the critical stress for the onset of DRX. Accordingly, the critical stress to peak stress ratio was calculated as 0.84. Moreover, the effect of true strain was examined by fitting stress values to an Arrhenius type constitutive equation, and then considering material constants as a function of strain by using a third-order polynomial equation. Finally, two constitutive models were used to investigate the competency of the strain-dependent constitutive equations to predict the flow stress curves of the studied steel. It was concluded that one model offers better precision on the flow stress values after the peak stress, while the other model gives more accurate results before the peak stress.

  5. Effect of laser shock peening on bending fatigue performance of AISI 9310 steel spur gear

    Science.gov (United States)

    Peng, Chong; Xiao, Yuzhe; Wang, Yanzhong; Guo, Wei

    2017-09-01

    The effect of laser shock peening (LSP) on bending fatigue performance of AISI 9310 steel spur gear has been investigated in this study. To help to explain bending fatigue test results, residual stress distribution induced by LSP is studied by means of finite element modelling, results of which are verified by X-ray diffraction analysis. It is found that a compressive layer of desirable depth can be induced on the gear root fillet after LSP, and both magnitude and depth of compressive stress increase with laser energy. The bending fatigue test is conducted using the single-tooth bending method to compare fatigue performance of laser peened teeth and non-peened teeth, which is followed by relevant statistical analysis. S-N curves acquired from the fatigue test reveal that bending fatigue lives of gear teeth has been significantly improved after LSP in comparison with those non-peened teeth, and the bending fatigue limit is enhanced correspondingly. It is noticeable that higher laser energy does not necessarily lead to much better fatigue performance of test gears.

  6. Effect of Beam Oscillation on Microstructure and Mechanical Properties of AISI 316L Electron Beam Welds

    Science.gov (United States)

    Kar, Jyotirmaya; Roy, Sanat Kumar; Roy, Gour Gopal

    2017-04-01

    The properties of electron beam-welded AISI 316L stainless steel butt joints prepared with and without beam oscillation were evaluated by microstructural analysis, mechanical testing like microhardness measurements, tensile tests at room and elevated temperature 973 K (700 °C), three-point bend, and Charpy impact tests. All joints, irrespective of being prepared with or without beam oscillation, were found to be defect free. Welds produced by beam oscillation exhibited narrower fusion zone (FZ) with lathy ferrite morphology, while the weld without beam oscillation was characterized by wider FZ and skeletal ferrite morphology. During tensile tests at room and elevated temperature 973 K (700 °C), all samples fractured in the base metal (BM) and showed almost the same tensile properties as that of the BM. However, the notch tensile tests at room temperature demonstrated higher strength for joints prepared with the oscillating beam. Besides, face and root bend tests, as well as Charpy impact tests, showed higher bending strength and notch toughness, respectively, for joints prepared with beam oscillation.

  7. Surface modifications of AISI 420 stainless steel by low energy Yttrium ions

    Directory of Open Access Journals (Sweden)

    Nassisi Vincenzo

    2018-01-01

    Full Text Available In this work, we study surface modifications of AISI 420 stainless steel specimens in order to improve their surface properties. Oxidation resistance and surface micro-hardness were analyzed. Using an ion beam delivered by a Laser Ion Source (LIS coupled to an electrostatic accelerator, we performed implantation of low energy yttrium ions on the samples. The ions experienced an acceleration passing through a gap whose ends had a potential difference of 60 kV. The gap was placed immediately before the samples surface. The LIS produced high ions fluxes per laser pulse, up to 3x1011 ions/cm2, resulting in a total implanted flux of 7x1015 ions/cm2. The samples were characterized before and after ion implantation using two analytical techniques. They were also thermally treated to investigate the oxide scale. The crystal phases were identified by an X-ray diffractometer, while the micro-hardness was assayed using the scratch test and a profilometer. The first analysis was applied to blank, implanted and thermally treated sample surface, while the latter was applied only to blank and implanted sample surfaces. We found a slight increase in the hardness values and an increase to oxygen resistance. The implantation technique we used has the advantages, with respect to conventional methods, to modify the samples at low temperature avoiding stray diffusion of ions inside the substrate bulk.

  8. Surface modifications of AISI 420 stainless steel by low energy Yttrium ions

    Science.gov (United States)

    Nassisi, Vincenzo; Delle Side, Domenico; Turco, Vito; Martina, Luigi

    2018-01-01

    In this work, we study surface modifications of AISI 420 stainless steel specimens in order to improve their surface properties. Oxidation resistance and surface micro-hardness were analyzed. Using an ion beam delivered by a Laser Ion Source (LIS) coupled to an electrostatic accelerator, we performed implantation of low energy yttrium ions on the samples. The ions experienced an acceleration passing through a gap whose ends had a potential difference of 60 kV. The gap was placed immediately before the samples surface. The LIS produced high ions fluxes per laser pulse, up to 3x1011 ions/cm2, resulting in a total implanted flux of 7x1015 ions/cm2. The samples were characterized before and after ion implantation using two analytical techniques. They were also thermally treated to investigate the oxide scale. The crystal phases were identified by an X-ray diffractometer, while the micro-hardness was assayed using the scratch test and a profilometer. The first analysis was applied to blank, implanted and thermally treated sample surface, while the latter was applied only to blank and implanted sample surfaces. We found a slight increase in the hardness values and an increase to oxygen resistance. The implantation technique we used has the advantages, with respect to conventional methods, to modify the samples at low temperature avoiding stray diffusion of ions inside the substrate bulk.

  9. Thermodynamic modeling and kinetics simulation of precipitate phases in AISI 316 stainless steels

    International Nuclear Information System (INIS)

    Yang, Y.; Busby, J.T.

    2014-01-01

    This work aims at utilizing modern computational microstructural modeling tools to accelerate the understanding of phase stability in austenitic steels under extended thermal aging. Using the CALPHAD approach, a thermodynamic database OCTANT (ORNL Computational Thermodynamics for Applied Nuclear Technology), including elements of Fe, C, Cr, Ni, Mn, Mo, Si, and Ti, has been developed with a focus on reliable thermodynamic modeling of precipitate phases in AISI 316 austenitic stainless steels. The thermodynamic database was validated by comparing the calculated results with experimental data from commercial 316 austenitic steels. The developed computational thermodynamics was then coupled with precipitation kinetics simulation to understand the temporal evolution of precipitates in austenitic steels under long-term thermal aging (up to 600,000 h) at a temperature regime from 300 to 900 °C. This study discusses the effect of dislocation density and difusion coefficients on the precipitation kinetics at low temperatures, which shed a light on investigating the phase stability and transformation in austenitic steels used in light water reactors

  10. Inductive plasma source for the ion treatment of AISI-304 SS

    International Nuclear Information System (INIS)

    Piedad-Beneitez, A de la; Lopez-Callejas, R; Granda-Gutierrez, E E; Rodriguez-Mendez, B G; Perez-Martinez, J A; Flores-Fuentes, A A; Valencia-Alvarado, R; Barocio, S R; Mercado-Cabrera, A; Pena-Eguiluz, R; Munoz-Castro, A E

    2008-01-01

    The design and construction of a simple inductive plasma source is described as constituted by an evacuated Pyrex glass cylinder reactor with 190 mm inner diameter and 500 mm length. This discharge vessel is coaxially surrounded by a cylindrically wound antenna, 240 mm in diameter, made of 3.2 mm wide copper wire. The antenna is supplied by a 13.56 MHz RF generator whose resulting electric field is able to create the plasma. When nitrogen is admitted to the vessel, the plasma generation takes place within the 0.1-50 Pa work pressure and 300-600 W RF power. The plasma density has been established by double Langmuir probes between 3.2 x 10 15 and 2.4 x 10 18 m -3 . This inductive plasma set up is meant to modify the surface of AISI-304 stainless steel by means of ion deposition, thanks to the sample bias provided by an external - 400 V dc supply, in order to improve the steel hardness without compromising its corrosion resistance. Once accelerated by the negative bias, the plasma ions impinge on the sample nitriding it by diffusion. The treated samples were characterized by x-ray diffraction (XRD) indicating the formation of the expanded gamma phase, by scanning electron microscopy (SEM) providing the atomic percentages of nitrogen, and by microhardness (HV) measurement.

  11. Process Evaluation of AISI 4340 Steel Manufactured by Laser Powder Bed Fusion

    Science.gov (United States)

    Jelis, Elias; Hespos, Michael R.; Ravindra, Nuggehalli M.

    2018-01-01

    Laser powder bed fusion (L-PBF) involves the consolidation of metal powder, layer by layer, through laser melting and solidification. In this study, process parameters are optimized for AISI 4340 steel to produce dense and homogeneous structures. The optimized process parameters produce mechanical properties at the center of the build plate that are comparable to wrought in the vertical and horizontal orientations after heat treatment and machining. Four subsequent builds are filled with specimens to evaluate the mechanical behavior as a function of location and orientation. Variations in the mechanical properties are likely due to recoater blade interactions with the powder and uneven gas flow. The results obtained in this study are analyzed to assess the reliability and reproducibility of the process. A different build evaluates the performance of near-net-shaped tensile specimens angled 35°-90° from the build plate surface (horizontal). Ductility measurements and surface roughness vary significantly as a function of the build angle. In the stress-relieved and as-built conditions, the mechanical behavior of vertically oriented specimens exhibits somewhat lower and more variable ductility than horizontally oriented specimens. Therefore, several process variables affect the mechanical properties of parts produced by the L-PBF process.

  12. History dependence and consequences of the microchemical evolution of AISI 316

    International Nuclear Information System (INIS)

    Garner, F.A.; Porter, D.L.

    1982-04-01

    The onset of void swelling in AISI 316 can be correlated with the removal of the elements nickel and silicon into precipitate phases. This conclusion was reached earlier based on measurement of microscopic volumes and has now been confirmed by the use of bulk extraction and elemental analysis of precipitates formed during irradiation. It appears that the average level of nickel remaining in the alloy matrix can be used as an index to assess the degree of completion of the microchemical evolution. The dependence of nickel removal on neutron flux and fluence, irradiation temperature, applied stress and preirradiation thermal-mechanical treatment is consistent with the behavior of swelling in response to these variables. It appears that at 400 0 C the microchemical evolution is very sluggish and still in progress at 14 x 10 22 n/cm 2 (E > 0.1 MeV). This suggests that the swelling rate at low temperatures will continue to increase with fluence and will approach that measured at higher temperatures. This higher swelling rate can be realized for some temperature histories which accelerate the kinetics of phase evolution

  13. Dry Sliding Wear Behavior of Super Duplex Stainless Steel AISI 2507: a Statistical Approach

    Directory of Open Access Journals (Sweden)

    Davanageri M.

    2016-12-01

    Full Text Available The dry sliding wear behavior of heat-treated super duplex stainless steel AISI 2507 was examined by taking pin-on-disc type of wear-test rig. Independent parameters, namely applied load, sliding distance, and sliding speed, influence mainly the wear rate of super duplex stainless steel. The said material was heat treated to a temperature of 850°C for 1 hour followed by water quenching. The heat treatment was carried out to precipitate the secondary sigma phase formation. Experiments were conducted to study the influence of independent parameters set at three factor levels using the L27 orthogonal array of the Taguchi experimental design on the wear rate. Statistical significance of both individual and combined factor effects was determined for specific wear rate. Surface plots were drawn to explain the behavior of independent variables on the measured wear rate. Statistically, the models were validated using the analysis of variance test. Multiple non-linear regression equations were derived for wear rate expressed as non-linear functions of independent variables. Further, the prediction accuracy of the developed regression equation was tested with the actual experiments. The independent parameters responsible for the desired minimum wear rate were determined by using the desirability function approach. The worn-out surface characteristics obtained for the minimum wear rate was examined using the scanning electron microscope. The desired smooth surface was obtained for the determined optimal condition by desirability function approach.

  14. Parametric optimization during machining of AISI 304 Austenitic Stainless Steel using CVD coated DURATOMIC cutting insert

    Directory of Open Access Journals (Sweden)

    M. Kaladhar

    2012-08-01

    Full Text Available In this work, Taguchi method is applied to determine the optimum process parameters for turning of AISI 304 austenitic stainless steel on CNC lathe. A Chemical vapour deposition (CVD coated cemented carbide cutting insert is used which is produced by DuratomicTM technology of 0.4 and 0.8 mm nose radii. The tests are conducted at four levels of Cutting speed, feed and depth of cut. The influence of these parameters are investigated on the surface roughness and material removal rate (MRR. The Analysis Of Variance (ANOVA is also used to analyze the influence of cutting parameters during machining. The results revealed that cutting speed significantly (46.05% affected the machined surface roughness values followed by nose radius (23.7%. The influence of the depth of cut (61.31% in affecting material removal rate (MRR is significantly large. The cutting speed (20.40% is the next significant factor. Optimal range and optimal level of parameters are also predicted for responses.

  15. Reactive sintering and microstructure development of tungsten carbide-AISI 304 stainless steel cemented carbides

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, C.M. [Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); CEMUC-Mechanical Engineering Department, University of Coimbra, Rua Luís Reis Santos, Pinhal de Marrocos, 3030-788 Coimbra (Portugal); Oliveira, F.J. [Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Senos, A.M.R., E-mail: anamor@ua.pt [Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

    2017-06-01

    Sintering of WC-stainless steel (SS) composites within a typical binder range from 6 up to 15 wt% SS was investigated through constant heating rate dilatometry, in vacuum conditions, complemented by differential thermal analysis and by the study of the high temperature wetting behavior of SS on WC. The densification starts ∼900 °C with a typical densification curve for all compositions, where three distinct regions are discernible: the first one with a slow densification rate, followed by a second region where a sharp increase in the densification rate up to a maximum value dependent on the binder amount is observed and, finally, a third one with a slowdown of the densification rate until the end of the thermal cycle. The attained final density at 1450 °C is dependent on the binder amount, increasing proportionally to its initial content. The final microstructure presents a normal grain size distribution and appreciable amounts of eta-phase, besides the major WC phase and residual iron rich phase. The reactive densification behavior and the role of the liquid phase are interpreted accordingly with structural and kinetic data. - Highlights: • Sintering of WC-AISI304 composites starts ∼900 °C and involves three stages. • Densification is largely dominated by a reactive liquid phase sintering process. • Eta-phase constitutes a transient liquid phase during sintering. • Sintering cycles are dependent on the initial binder content.

  16. Crack propagation in stainless steel AISI 304L in Hydrogen Chemistry conditions (HWC)

    International Nuclear Information System (INIS)

    Diaz S, A.; Fuentes C, P.; Merino C, F.; Castano M, V.

    2006-01-01

    Velocities of crack growth in samples type CT pre cracking of stainless steel AISI 304l solder and sensitized thermally its were obtained by the Rising Displacement method or of growing displacement. It was used a recirculation circuit that simulates the operation conditions of a BWR type reactor (temperature of 280 C and a pressure of 8 MPa) with the chemistry modified by the addition of hydrogen with and without the addition of impurities of a powerful oxidizer like the Cu + ion. In each essay stayed a displacement velocity was constant of 1x10 -9 m/s, making a continuous pursuit of the advance of the crack by the electric potential drop technique. Contrary to the idea of mitigation of the crack propagation velocity by effect of the addition of the hydrogen in the system, the values of the growth velocities obtained by this methodology went similar to the opposing ones under normal operation conditions. To the finish of the rehearsal one carries out the fractographic analysis of the propagation surfaces, which showed cracks growth in trans and intergranular way, evidencing the complexity of the regulator mechanisms of the IGSCC like in mitigation conditions as the alternative Hydrogen Chemistry. (Author)

  17. Investigations on Surface Milling of Hardened AISI 4140 Steel with Pulse Jet MQL Applicator

    Science.gov (United States)

    Bashir, Mahmood Al; Mia, Mozammel; Dhar, Nikhil Ranjan

    2016-06-01

    In this article, an experimental investigation was performed in milling hardened AISI 4140 steel of hardness 40 HRC. The machining was performed in both dry and minimal quantity lubricant (MQL) conditions, as part of neat machining, to make a strong comparison of the undertaken machining environments. The MQL was impinged int the form of pulse jet, by using the specially developed pulse-jet-attachment, to ensure that the cutting fluid can be applied in different timed pulses and quantities at critical zones. The tool wear, cutting force and surface roughness were taken as the quality responses while cutting speed, table feed rate and flow rate of the pulse were considered as influential factors. The depth of cut was kept constant at 1.50 mm because of its less significant effects and the straight oil was adopted as cutting fluid in pulse-jet-MQL. The effects of different factors, on the quality responses, are analyzed using ANOVA. It is observed that MQL applicator system exhibits overall better performance when compared to dry milling by reducing surface roughness, cutting force and prolonging tool life but a flow rate of 150 ml/h has tremendous effects on the responses. This investigation and afterward results are expected to aid the industrial practitioner and researcher to adopt the pulse-MQL in high speed milling to prolong tool life, reduce tool wear, diminish cutting force generation and promote better surface finish.

  18. Surface modification of AISI H13 tool steel by laser cladding with NiTi powder

    Science.gov (United States)

    Norhafzan, B.; Aqida, S. N.; Chikarakara, E.; Brabazon, D.

    2016-04-01

    This paper presents laser cladding of NiTi powder on AISI H13 tool steel surface for surface properties enhancement. The cladding process was conducted using Rofin DC-015 diffusion-cooled CO2 laser system with wavelength of 10.6 µm. NiTi powder was pre-placed on H13 tool steel surface. The laser beam was focused with a spot size of 90 µm on the sample surface. Laser parameters were set to 1515 and 1138 W peak power, 18 and 24 % duty cycle and 2300-3500 Hz laser pulse repetition frequency. Hardness properties of the modified layer were characterized by Wilson Hardness tester. Metallographic study and chemical composition were conducted using field emission scanning electron microscope and energy-dispersive X-ray spectrometer (EDXS) analysis. Results showed that hardness of NiTi clad layer increased three times that of the substrate material. The EDXS analysis detected NiTi phase presence in the modified layer up to 9.8 wt%. The metallographic study shows high metallurgical bonding between substrate and modified layer. These findings are significant to both increased hardness and erosion resistance of high-wear-resistant components and elongating their lifetime.

  19. Machining tools in AISI M2 high-speed steel obtained by spray forming process

    International Nuclear Information System (INIS)

    Jesus, Edilson Rosa Barbosa de.

    2004-01-01

    The aim of the present work was the obtention of AISI M2 high-speed steel by spray forming technique and the material evaluation when used as machining tool. The obtained material was hot rolled at 50% and 72% reduction ratios, and from which it was manufactured inserts for machining tests. The performance of inserts made of the spray formed material was compared to inserts obtained from conventional and powder metallurgy (MP) processed materials. The spray formed material was chemical, physical, mechanical and microstructural characterised. For further characterisation, the materials were submitted to machining tests for performance evaluation under real work condition. The results of material characterisation highlight the potential of the spray forming technique, in the obtention of materials with good characteristics and properties. Under the current processing, hot rolling and heat treatments condition, the analysis of the results of the machining tests revealed a very similar behaviour among the tested materials. Proceeding a criterious analysis of the machining results tests, it was verified that the performance presented by the powder metallurgy material (MP) was slight superior, followed by conventional obtained material (MConv), which presented a insignificant advantage over the spray formed and hot rolled (72% reduction ratio) material. The worst result was encountered for the spray forming and hot rolled (50% reduction ratio) material that presented the highest wear values. (author)

  20. Softening mechanisms of the AISI 410 martensitic stainless steel under hot torsion simulation

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Thiago Santana de; Silva, Eden Santos; Rodrigues, Samuel Filgueiras; Nascimento, Carmem Celia Francisco; Leal, Valdemar Silva; Reis, Gedeon Silva, E-mail: samuel.filgueiras@ifma.edu.br [Instituto Federal do Maranhao (PPGEM/IFMA), Sao Luis, MA (Brazil)

    2017-03-15

    This study investigated the softening mechanisms of the AISI 410 martensitic stainless steel during torsion simulation under isothermal continuous in the temperature range of 900 to 1150 °C and strain rates of 0.1 to 5.0s{sup -1}. In the first part of the curves, before the peak, the results show that the critical (ε-c) and peak (ε-p) strains are elevated for higher strain rate and lower temperatures contributing for higher strain hardening rate (h). Moreover, this indicated that dynamic recrystallization (DRX) and dynamic recovery (DRV) are not effective in this region. After the peak, the reductions in stresses are associated to the different DRX/DRV competitions. For lower temperatures and higher strain rates there is a delay in the DRX while the DRV is acting predominantly (with low Avrami exponent (n) and high t{sub 0.5}). The steady state was reached after large strains showing DRX grains, formation of retained austenite and the presence of chromium carbide (Cr{sub 23}C{sub 6}) and ferrite δ at the martensitic grain boundaries. These contribute for impairing the toughness and ductility on the material. The constitutive equations at the peak strain indicated changes in the deformation mechanism, with variable strain rate sensitivity (m), which affected the final microstructure. (author)