Protótipo do primeiro interferômetro brasileiro - BDA

Science.gov (United States)

Cecatto, J. R.; Fernandes, F. C. R.; Neri, J. A. C. F.; Bethi, N.; Felipini, N. S.; Madsen, F. R. H.; Andrade, M. C.; Soares, A. C.; Alonso, E. M. B., Sawant, H. S.

2004-04-01

A interferometria é uma poderosa ferramenta usada para investigar estruturas espaciais de fontes astrofísicas fornecendo uma riqueza de detalhes inatingível pelas técnicas convencionais de imageamento. Em particular, a interferometria com ondas de rádio abre o horizonte de conhecimento do Universo nesta ampla banda do espectro eletromagnético, que vai de cerca de 20 kHz até centenas de GHz já próximo ao infravermelho, e que está acessível a partir de instrumentos instalados em solo. Neste trabalho, apresentamos o interferômetro designado por Arranjo Decimétrico Brasileiro (BDA). Trata-se do primeiro interferômetro a ser desenvolvido no Brasil e América Latina que já está em operação na fase de protótipo. Apresentamos o desenvolvimento realizado até o momento, o sítio de instalação do instrumento, o protótipo e os principais resultados dos testes de sua operação, as perspectivas futuras e a ciência a ser desenvolvida com o instrumento nas fases II e III. Neste trabalho é dada ênfase ao desenvolvimento, testes de operação e principais resultados do protótipo. É discutida brevemente a ciência que pode ser feita com o instrumento. Tanto os detalhes técnicos quanto os principais parâmetros estimados para o instrumento nas próximas fases de desenvolvimento e o desempenho do protótipo serão publicados em breve.

APRESENTANDO OUTROS SISTEMAS SOLARES NAS AULAS DE CIÊNCIAS ATRAVÉS DE FERRAMENTAS ONLINE E APLICATIVOS DIGITAIS

Directory of Open Access Journals (Sweden)

Michele Rascalha

2017-11-01

Full Text Available A descoberta dos exoplanetas – planetas que orbitam outras estrelas - tem fortes implicações não apenas sobre nosso conhecimento a respeito dos sistemas solares, mas também sobre o estudo da vida no universo, uma vez que expande as possibilidades de habitabilidade em nossa galáxia. Embora as pesquisas nessa área estejam evoluindo aceleradamente desde o final da década de 1990, os livros didáticos e os programas curriculares de Ciências da Natureza adotados na Educação Básica ainda apresentam uma visão ultrapassada da Astronomia, ignorando a diversidade de planetas e sistemas solares já identificados pela Ciência. Tal fato acaba por obliterar o acesso dos estudantes a esse tipo de conhecimento, consequentemente limitando o trabalho dos professores. O objetivo do presente artigo é apresentar como algumas ferramentas de divulgação científica e pesquisa podem servir ao propósito de desenvolver o tema vida e universo nas escolas. Tais ferramentas incluem aplicativos para tablets, sites oficiais, simuladores e projetos de citizen science – por meio dos quais os internautas podem contribuir diretamente com as pesquisas científicas.

Investigation on AISI 304 austenitic stainless steel to AISI 4140 low alloy steel dissimilar joints by gas tungsten arc, electron beam and friction welding

International Nuclear Information System (INIS)

Arivazhagan, N.; Singh, Surendra; Prakash, Satya; Reddy, G.M.

2011-01-01

Research highlights: → Beneficial effects of FRW, GTAW and EBW joints of dissimilar AISI 304 and AISI 4140 materials. → Comparative study of FRW, GTAW and EBW joints on mechanical properties. → SEM/EDAX, XRD analysis on dissimilar AISI 304 and AISI 4140 materials. -- Abstract: This paper presents the investigations carried out to study the microstructure and mechanical properties of AISI 304 stainless steel and AISI 4140 low alloy steel joints by Gas Tungsten Arc Welding (GTAW), Electron Beam Welding (EBW) and Friction Welding (FRW). For each of the weldments, detailed analysis was conducted on the phase composition, microstructure characteristics and mechanical properties. The results of the analysis shows that the joint made by EBW has the highest tensile strength (681 MPa) than the joint made by GTAW (635 Mpa) and FRW (494 Mpa). From the fractographs, it could be observed that the ductility of the EBW and GTA weldment were higher with an elongation of 32% and 25% respectively when compared with friction weldment (19%). Moreover, the impact strength of weldment made by GTAW is higher compared to EBW and FRW.

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

OpenAIRE

Botella, J.; Merino, C.; Heredia, M. A.; Almagro, J.

1999-01-01

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...

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.

Resistência à corrosão de junta dissimilar soldada pelo processo TIG composta pelos aços inoxidáveis AISI 316L e AISI 444

Directory of Open Access Journals (Sweden)

Luis Henrique Guilherme

2014-03-01

Full Text Available O aço inoxidável AISI 444 tornou-se uma opção para substituir a liga AISI 316L devido ao seu menor custo e satisfatória resistência à corrosão. Entretanto, o uso da liga AISI 444 no feixe tubular de trocadores de calor acarreta na soldagem de uma junta dissimilar. O presente estudo teve por objetivo avaliar a resistência à corrosão da junta tubo-espelho soldada pelo processo TIG composta pelas ligas AISI 316L e AISI 444. A manufatura das amostras consistiu em replicar o projeto da junta tubo-espelho de trocadores de calor. Realizou-se em juntas soldadas ensaios de sensitização, perda de massa por imersão desde a temperatura ambiente até 90 ºC, e ensaios eletroquímicos de polarização potenciodinâmica nos eletrólitos 0,5 mol/L de HCl e 0,5 mol/L de H2SO4. Os resultados mostraram que a junta dissimilar sofreu corrosão galvânica com maior degradação na zona afetada pelo calor (ZAC do tubo AISI 444. Porém, os mecanismos de corrosão localizada (pite e intergranular demonstraram ser mais ativos para a liga AISI 316L. Conclui-se que a junta dissimilar apresentou melhor resistência à corrosão do que a junta soldada composta unicamente pela liga AISI 316L em temperaturas de até 70 ºC, conforme as condições observadas neste trabalho.

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.

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

The surface fatigue life of contour induction hardened AISI 1552 gears

Science.gov (United States)

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

1995-07-01

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.

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

Corrosion behaviour of AISI 204Cu and AISI 304 stainless steels in simulated pore solution

Energy Technology Data Exchange (ETDEWEB)

Kocijan, Aleksandra [Institute of Metals and Technology, Ljubljana (Slovenia)

2013-10-15

The evolution of the passive films on AISI 204Cu and AISI 304 stainless steels in simulated pore solution for steel reinforcements in concrete, and with and without the addition of chloride, was studied using cyclic voltammetry and potentiodynamic measurements. The passive layers were studied at open-circuit potential by means of X-ray photoelectron spectroscopy. The passive films on both materials predominantly contained Cr-oxides, whereas the Fe-species were markedly depleted. Mn-enrichment was also observed. The addition of chloride ions did not have a significant influence on the composition of the passive layers. The surface morphology of the products formed on the surface of both investigated materials at open-circuit potential and at high over-potentials in the presence of chloride was studied using scanning electron microscopy. (orig.)

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)

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.

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.

Characterization of AISI 4140 borided steels

International Nuclear Information System (INIS)

Campos-Silva, I.; Ortiz-Dominguez, M.; Lopez-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martinez-Trinidad, J.

2010-01-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2 B 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 2 B 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 K C (π/2) > K C > K C (0) for the different applied loads and experimental parameters of the boriding process.

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.

Characterization of AISI 4140 borided steels

Energy Technology Data Exchange (ETDEWEB)

Campos-Silva, I., E-mail: icampos@ipn.mx [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Ortiz-Dominguez, M.; Lopez-Perrusquia, N.; Meneses-Amador, A. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), E-28049 Cantoblanco, Madrid (Spain); Martinez-Trinidad, J. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico)

2010-02-01

The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe{sub 2}B 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{sub 2}B 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 {mu}m 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 K{sub C}({pi}/2) > K{sub C} > K{sub C}(0) for the different applied loads and experimental parameters of the boriding process.

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

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

Novel water-air circulation quenching process for AISI 4140 steel

Science.gov (United States)

Zheng, Liyun; Zheng, Dawei; Zhao, Lixin; Wang, Lihui; Zhang, Kai

2013-11-01

AISI 4140 steel is usually used after quenching and tempering. During the heat treatment process in industry production, there are some problems, such as quenching cracks, related to water-cooling and low hardness due to oil quenching. A water-air circulation quenching process can solve the problems of quenching cracks with water and the high cost quenching with oil, which is flammable, unsafe and not enough to obtain the required hardness. The control of the water-cooling and air-cooling time is a key factor in the process. This paper focuses on the quenching temperature, water-air cycle time and cycle index to prevent cracking for AISI 4140 steel. The optimum heat treatment parameters to achieve a good match of the strength and toughness of AISI 4140 steel were obtained by repeated adjustment of the water-air circulation quenching process parameters. The tensile strength, Charpy impact energy at -10 °C and hardness of the heat treated AISI 4140 steel after quenching and tempering were approximately 1098 MPa, 67.5 J and 316 HB, respectively.

A utilização da avaliação tipo "teste" on-line como apoio ao ensino presencial: uma abordagem quantitativa sobre a sua contribuição no ensino de ferramentas estatística multivariadas Use of on-line evaluation type "test" as support for presential teaching: a quantitative approach on its contribution to the teaching of multivariate statistics tools

Directory of Open Access Journals (Sweden)

Erica Ferreira Marques

2011-07-01

Full Text Available Este artigo busca mostrar o quanto a aplicação de uma ferramenta de avaliação tipo "teste" em um ambiente virtual pode contribuir como apoio ao ensino presencial do estudo de ferramentas estatísticas multivariadas para os alunos de graduação em Administração da FEARP/USP, segundo a opinião destes matriculados na disciplina Estatística Aplicada à Administração II. Este trabalho fez parte de um projeto de pesquisa temático desenvolvido na própria instituição, denominado LaViE, que é um ambiente virtual de ensino-aprendizagem de estatística aplicado e desenvolvido para o apoio ao ensino presencial desta área. Baseando-se na importância de um mecanismo de avaliação de conteúdo, o LaViE visou contribuir para o ensino presencial disponibilizando ferramentas de conteúdo, interação e "teste seu conhecimento". Para tanto, esta ferramenta de avaliação foi desenvolvida baseada em questões testes on-line com níveis diferentes de "adaptação" pelo aluno para cada módulo apresentado na disciplina em questão. Neste caso, foram criados três níveis de adaptação: básico (I, intermediário (II e avançado (III. A metodologia utilizada para verificação da eficiência desta ferramenta tipo "teste" no ambiente virtual foi baseada, então, em uma avaliação quantitativa de acordo com a opinião dos alunos (usuários. Nessa pesquisa foram investigados quatro pressupostos. Esses dados foram coletados quando essa disciplina foi ministrada, porém em dois períodos diferentes; no segundo semestre de 2005, como projeto-piloto, e no segundo semestre de 2006. Dessa forma, pôde ser feita uma análise comparativa da opinião dos alunos sobre o sistema em dois momentos diferentes. Para esse levantamento foram utilizados dois questionários aplicados diretamente aos alunos em sala de aula momentos antes da avaliação presencial da disciplina e um outro logo após essa avaliação presencial. Observou-se, por este estudo, a import

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

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.

Analysis of AISI 304 Tensile Strength as an Anchor Chain of Mooring System

Science.gov (United States)

Hamidah, I.; Wati, R.; Hamdani, R. A.

2018-05-01

The background of this research is the use of mild steel (i.e., St37) as anchor chain that works on the corrosive environment of seawater which is possible to decrease its tensile strength. The longer soaked in seawater, the more significant the lowering of its tensile strength. Anchor chain needs to be designed by considering its tensile strength and corrosion resistance, so it’s able to support mooring system well. The primary purpose of this research is obtaining the decreasing of stainless steel 304 (AISI 304) tensile strength which is corroded by seawater as anchor chain of the mooring system. It is also essential to obtain the lifetime of AISI304 and St37 as anchor chain with the same load, the corrosion rate of AISI 304, and St 37 in seawater. The method which was employed in this research is an experiment with four pieces of stainless steel AISI 304, and of St 37 corrosion testing samples, six pieces of stainless steel 304, and six pieces of St 37 for tensile testing samples. The result of this research shows that seawater caused stainless steel AISI 304 as anchor chain has decreased of tensile strength about 1.68 % during four weeks. Also, it indicates that AISI 304 as anchor chain has a lifetime about 130 times longer than St 37. Further, we found that the corrosion rate of stainless steel 304 in seawater is 0.2042 mpy in outstanding category, while the St 37 samples reached up to 27.0247 mpy ranked as fair category. This result recommends that AISI 304 more excellence than St 37 as anchor chain of the mooring system.

Projeto de layout de biblioteca assistido por ferramenta de software para criação de arranjo físico em 3D: estudo aplicado à biblioteca da faculdade iDEZ

Directory of Open Access Journals (Sweden)

Sanderli José da Silva Segundo

2013-06-01

Full Text Available Introdução: Projetar uma biblioteca consiste em concentrar esforços para criar ou aprimorar atividades que estejam de acordo com a função e objetivos da mesma e da instituição a qual está subordinada. Regularmente os responsáveis por diferentes tipos de bibliotecas se deparam com o problema de gestão do seu espaço físico. O estudo do layout proporciona experimentar novas formas e permite modificações de ambientação com o intuito de buscar os requisitos citados. Contudo fazer isso em um ambiente real, nem sempre é possível, nestes casos uma ferramenta que permita ao bibliotecário projetar, promover alterações e visualizar os resultados em formatos 3D é de grande auxilio.Objetivo: Estudar o arranjo físico de bibliotecas sob a ótica de OS&M usando ferramentas 3D.Metodologia: Apresenta um estudo de caso na biblioteca da Faculdade iDEZ, localizada em João Pessoa – PB, onde foi aplicado os princípios da disciplina de Organização, Sistemas e Métodos (OS&M para arranjo físico (layout utilizando uma ferramenta de software livre para auxiliar projetos em terceira dimensão.Resultados: São indicadas e discutidas as motivações que levam um profissional de informação a ter que gerenciar seu espaço físico e as barreiras encontradas. O resultado obtido na avaliação indicou o Sweet Home 3D como ferramenta com melhor pontuação.Conclusão: A proposta de projeto resultante do estudo de caso, facilitou a visualização das mudanças, sendo aceita e implementada pelos gestores da biblioteca.

Reassessment of the swelling behavior of AISI 304 stainless steel

International Nuclear Information System (INIS)

Garner, F.A.; Porter, D.L.

1982-03-01

Published swelling data derived from EBR-II irradiations of AISI 304 and 304L have been reanalyzed in light of insights gained from irradiation of AISI 316 and Fe-15Cr-25Ni. The primary influence of temperature, displacement rate and compositional variations in the 300 series stainless steels lies in the duration of the transient regime of swelling and not in the steady-state or constant swelling rate regime

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.

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)

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.

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.

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.

The effect of plasma arc process parameters on the properties of dissimilar AISI 1040/AISI 304 steel plate welds

Energy Technology Data Exchange (ETDEWEB)

Kilic, Musa; Kirik, Ihsan; Orhan, Nuri [Firat Univ., Elazig (Turkey); Celik, Ferkan [Science Industry and Technology Ministry of Turkey (Turkey)

2012-11-01

In this study, 10 mm thick AISI 1040 and AISI 304 steel plates were welded in the butt position without pretreatment by plasma transferred arc (PTA) welding technique. Therefore, mechanical behaviour, microstructure, penetration depth and length were investigated. After welding, microstructural changes in the interface regions of the welded specimens were examined by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Micro-hardness as well as V-notch Charpy tests were performed to determine the mechanical properties of the welds. The influence of the welding parameters on the dimension and shape of the joints has been found out. From the results, it was derived that with the parameters used, a partly keyhole weld bead formed with a penetration depth of 10 mm and a width of 11 mm in butt position. (orig.)

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)

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.

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.

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

2016-10-01

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.

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.

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)

Experimental study on joining of AA6063 and AISI 1040 steel

Science.gov (United States)

Hynes, N. Rajesh Jesudoss; Raja, S.

2018-05-01

Feasibility of joining of dissimilar metals with different physical, chemical and thermal properties such as AA6063 alloy and AISI 1040 steel is worthwhile study, since it has tremendous applications in all most of all engineering domains. The mechanism of bonding is studied using scanning electron microscopy. Impact strength of AA2024/AISI joints, axial shortening distance, micro hardness distribution and joint strength are determined. Micro hardness profile shows increased hardness value at the joint interface, due to grain refinement.

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.

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.

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)

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

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.

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.

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.

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)

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)

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.

ESTUDO COMPARATIVO DA COMPETITIVIDADE DAS EMPRESAS DE MÁQUINAS FERRAMENTAS BRASILEIRAS: ANÁLISE MULTICRITÉRIOS

OpenAIRE

Sanches, João Carlos Santiago

2007-01-01

O principal objetivo desta dissertação foi analisar por meio de estudo comparativo, o posicionamento competitivo de três máquinas ferramentas multitarefas. As hipóteses iniciais partiram das seguintes suposições: a) a indústria nacional de máquinas ferramentas esta sendo penalizada pela política industrial praticada pelo governo federal; e b) a importância relativa atribuída aos elementos multicriteriais das especificações das máquinas nacionais quando demonstram tendências elevadas, nem semp...

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

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.

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.

Modelo de identificação e análise de impactos da implantação de ferramentas case.

OpenAIRE

Eduardo Yassuji Kido

2009-01-01

Este trabalho propõe um modelo de identificação e análise de impactos provenientes da adoção de ferramentas CASE (Computer Aided Software Engineering) interativas baseado no padrão IEEE 1175.2 Práticas Recomendadas para Interconexão de Ferramentas CASE com foco na produtividade e na qualidade do processo de desenvolvimento de software nas organizações. Os impactos são analisados considerando as funções e características da ferramenta CASE e as ações gerenciais necessárias para a adoção da fe...

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)

Microestrutura de uma Solda Dissimilar entre o Aço Inoxidável Ferrítico AISI 410S e o Aço Inoxidável Austenítico AISI 304L Soldado pelo Processo FSW

Directory of Open Access Journals (Sweden)

Tathiane Caminha Andrade

2015-12-01

Full Text Available Resumo O presente trabalho visa investigar a microestrutura formada na soldagem dissimilar entre chapas de aços inoxidáveis ferríticos AISI 410S e aços inoxidáveis austeníticos AISI 304L pelo processo friction stir welding. A soldagem foi realizada com o ajuste dos seguintes parâmetros: rotação 450 rpm; velocidade de soldagem de 1,0 mm/s; e força axial 40 kN. O aço AISI 410S foi posicionado no lado de avanço enquanto que o aço AISI 304L foi posicionado no lado de retrocesso. A análise consistiu de preparação metalográfica e caracterização microestrutural por microscopia ótica e microscopia eletrônica de varredura. Para o aço AISI 410S foi observada a formação de martensita associada com ferrita na zona de mistura (ZM, zona termomecanicamente afetada (ZTMA e na zona afetada pelo calor (ZAC. As características do processo de soldagem FSW resultaram num refino de grão para o aço inoxidável ferrítico, posicionado no lado de avanço, tanto na ZM quanto nas ZTMA e ZAC. O mesmo comportamento não foi observado para o lado austenítico.

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.

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

Análisis experimental del torneado de alta velocidad del acero AISI 1045 // Experimental analysis of high speed turning of AISI 1045 steel gears

Directory of Open Access Journals (Sweden)

Luís Wilfredo Hernández‐González

2012-01-01

Full Text Available El objetivo de este trabajo es el estudio experimental de la evolución del desgaste del flanco de dosinsertos de carburo recubiertos y un cermet, durante el torneado en seco del acero AISI 1045 con 500 y600 m/min de velocidad de corte. Los resultados fueron comparados utilizando el análisis de varianza y deregresión. La investigación mostró un efecto significativo de la velocidad de corte y del tiempo demaquinado en el desgaste del flanco. El mejor desempeño fue para el carburo recubierto con tres capas,mientras que a elevada velocidad de corte el carburo con dos capas sufrió el mayor desgaste, lo cual sedebe a que cuando pierde sus recubrimientos el substrato del inserto queda desprotegido y el desgastecrece rápidamente por la extremas condiciones del mecanizado por alta velocidad. Además, se planteanrecomendaciones del tiempo de maquinado de los insertos dadas las condiciones de elaboración por altavelocidad.Palabras claves: torneado de alta velocidad, desgaste del flanco, acero AISI 1045, estudio experimental.__________________________________________________________________________AbstractThis work deals with the experimental study of the flank wear evolution of two coating carbide inserts and acermet insert during the dry turning of AISI 1045 steel with 500 and 600 m/min cutting speed. The resultswere compared using the variance and regression analysis. The investigation showed a significant effectof cutting speed and machining time on the flank wear in high speed machining. The three coating layersinsert showed the best performance while the two layers insert had the worst behaviour of the cutting toolwear at high cutting speed, this is because once the coating film is peeled off, the substrate of the insertbecomes uncovered and the wear grows rapidly due to the extreme machining conditions for high speed.Besides, the machining time recommendations of inserts for the cutting conditions at high speed areexposed.Key words: high

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.

The effect of surface nanocrystallization on plasma nitriding behaviour of AISI 4140 steel

International Nuclear Information System (INIS)

Li Yang; Wang Liang; Zhang Dandan; Shen Lie

2010-01-01

A plastic deformation surface layer with nanocrystalline grains was produced on AISI 4140 steel by means of surface mechanical attrition treatment (SMAT). Plasma nitriding of SMAT and un-SMAT AISI 4140 steel was carried out by a low-frequency pulse excited plasma unit. A series of nitriding experiments has been conducted at temperatures ranging from 380 to 500 deg. C for 8 h in an NH 3 gas. The samples were characterized using X-ray diffraction, scanning electron microscopy, optical microscopy and Vickers microhardness tester. The results showed that a much thicker compound layer with higher hardness was obtained for the SMAT samples when compared with un-SMAT samples after nitriding at the low temperature. In particular, plasma nitriding SMAT AISI 4140 steel at 380 deg. C for 8 h can produced a compound layer of 2.5 μm thickness with very high hardness on the surface, which is similar to un-SMAT samples were plasma nitrided at approximately 430 deg. C within the same time.

The effect of surface nanocrystallization on plasma nitriding behaviour of AISI 4140 steel

Science.gov (United States)

Li, Yang; Wang, Liang; Zhang, Dandan; Shen, Lie

2010-11-01

A plastic deformation surface layer with nanocrystalline grains was produced on AISI 4140 steel by means of surface mechanical attrition treatment (SMAT). Plasma nitriding of SMAT and un-SMAT AISI 4140 steel was carried out by a low-frequency pulse excited plasma unit. A series of nitriding experiments has been conducted at temperatures ranging from 380 to 500 °C for 8 h in an NH 3 gas. The samples were characterized using X-ray diffraction, scanning electron microscopy, optical microscopy and Vickers microhardness tester. The results showed that a much thicker compound layer with higher hardness was obtained for the SMAT samples when compared with un-SMAT samples after nitriding at the low temperature. In particular, plasma nitriding SMAT AISI 4140 steel at 380 °C for 8 h can produced a compound layer of 2.5 μm thickness with very high hardness on the surface, which is similar to un-SMAT samples were plasma nitrided at approximately 430 °C within the same time.

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.

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.

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.

Wear and friction behaviour of duplex-treated AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Podgornik, B.; Vizintin, J. [Ljubljana Univ. (Slovenia). Centre of Tribology and Technical Diagnostics; Waenstrand, O.; Larsson, M.; Hogmark, S. [The Aangstroem Laboratory, Uppsala University, Box 534, SE-75121, Uppsala (Sweden)

1999-11-01

In this study samples of AISI 4140 steel were pretreated by plasma nitriding and coated with two different physical vapour deposited coatings (TiN and TiAlN). A hardened AISI 4140 sample and a coated sample were also included in the investigation. To examine the influence of the nitrided zone on the performance of the coating-substrate composite, two different nitriding conditions - a conventional 25% N{sub 2} and an N{sub 2}-poor gas mixture - were used. The specimens were investigated with respect to their microhardness, surface roughness, scratch adhesion and dry sliding wear resistance. Wear tests in which the duplex-treated pins were mated to hardened ball bearing steel discs were performed in a pin-on-disc machine under dry sliding conditions. Metallography, scanning electron microscopy and profilometry were used to analyse the worn surfaces in order to determine the dominant friction and wear characteristics of the samples investigated. The results show improved wear properties of the plasma-nitrided hard-coated specimens compared with uncoated and pre-hardened ones. Although previous investigations showed a negative effect of the compound layer, it was found that a precisely controlled plasma nitriding process can lead to a dense, uniform and highly adherent compound layer with a positive effect on the wear properties of pre-nitrided and hard-coated AISI 4140 steel. (orig.)

Modeling and Investigation of the Wear Resistance of Salt Bath Nitrided Aisi 4140 via ANN

Science.gov (United States)

Ekinci, Şerafettin; Akdemir, Ahmet; Kahramanli, Humar

2013-05-01

Nitriding is usually used to improve the surface properties of steel materials. In this way, the wear resistance of steels is improved. We conducted a series of studies in order to investigate the microstructural, mechanical and tribological properties of salt bath nitrided AISI 4140 steel. The present study has two parts. For the first phase, the tribological behavior of the AISI 4140 steel which was nitrided in sulfinuz salt bath (SBN) was compared to the behavior of the same steel which was untreated. After surface characterization using metallography, microhardness and sliding wear tests were performed on a block-on-cylinder machine in which carbonized AISI 52100 steel discs were used as the counter face. For the examined AISI 4140 steel samples with and without surface treatment, the evolution of both the friction coefficient and of the wear behavior were determined under various loads, at different sliding velocities and a total sliding distance of 1000 m. The test results showed that wear resistance increased with the nitriding process, friction coefficient decreased due to the sulfur in salt bath and friction coefficient depended systematically on surface hardness. For the second part of this study, four artificial neural network (ANN) models were designed to predict the weight loss and friction coefficient of the nitrided and unnitrided AISI 4140 steel. Load, velocity and sliding distance were used as input. Back-propagation algorithm was chosen for training the ANN. Statistical measurements of R2, MAE and RMSE were employed to evaluate the success of the systems. The results showed that all the systems produced successful results.

Magnetic Barkhausen emission in lightly deformed AISI 1070 steel

Energy Technology Data Exchange (ETDEWEB)

Capo Sanchez, J., E-mail: jcapo@cnt.uo.edu.cu [Departamento de Fisica, Facultad de Ciencias Naturales, Universidad de Oriente, Av. Patricio Lumumba s/n, 90500 Santiago de Cuba (Cuba); Campos, M.F. de [EEIMVR-Universidade Federal Fluminense, Av. dos Trabalhadores 420, Vila Santa Cecilia, 27255-125 Volta Redonda, RJ (Brazil); Padovese, L.R. [Departamento de Engenharia Mecanica, Escola Politecnica, Universidade de Sao Paulo, Av. Prof. Mello Moraes, 2231, 05508-900 Sao Paulo (Brazil)

2012-01-15

The Magnetic Barkhausen Noise (MBN) technique can evaluate both micro- and macro-residual stresses, and provides indication about the relevance of contribution of these different stress components. MBN measurements were performed in AISI 1070 steel sheet samples, where different strains were applied. The Barkhausen emission is also analyzed when two different sheets, deformed and non-deformed, are evaluated together. This study is useful to understand the effect of a deformed region near the surface on MBN. The low permeability of the deformed region affects MBN, and if the deformed region is below the surface the magnetic Barkhausen signal increases. - Highlights: > Evaluated residual stresses by the magnetic Barkhausen technique. > Indication about the relevance of micro-and macro-stress components. > Magnetic Barkhausen measurements were carried out in AISI 1070 steel sheet samples. > Two different sheets, deformed and non-deformed, are evaluated together. > Magnetic Barkhausen signal increases when deformed region is below the surface.

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.)

Resistance spot welding of AISI 430 ferritic stainless steel: Phase transformations and mechanical properties

International Nuclear Information System (INIS)

Alizadeh-Sh, M.; Marashi, S.P.H.; Pouranvari, M.

2014-01-01

Highlights: • Phase transformations during RSW of AISI430 are detailed. • Grain growth, martensite formation and carbide precipitation are dominant phase transformations. • Failure mode of AISI430 resistance spot welded joints are analyzed. • Larger FZ size provided improved load bearing capacity and energy absorption capability. - Abstract: The paper aims at investigating the process–microstructure–performance relationship in resistance spot welding of AISI 430 ferritic stainless steel. The phase transformations which occur during weld thermal cycle were analyzed in details, based on the physical metallurgy of welding of the ferritic stainless steels. It was found that the microstructure of the fusion zone and the heat affected zone is influenced by different phenomena including grain growth, martensite formation and carbide precipitation. The effects of welding cycle on the mechanical properties of the spot welds in terms of peak load, energy absorption and failure mode are discussed

Microstructural Evolutions During Reversion Annealing of Cold-Rolled AISI 316 Austenitic Stainless Steel

Science.gov (United States)

Naghizadeh, Meysam; Mirzadeh, Hamed

2018-06-01

Microstructural evolutions during reversion annealing of a plastically deformed AISI 316 stainless steel were investigated and three distinct stages were identified: the reversion of strain-induced martensite to austenite, the primary recrystallization of the retained austenite, and the grain growth process. It was found that the slow kinetics of recrystallization at lower annealing temperatures inhibit the formation of an equiaxed microstructure and might effectively impair the usefulness of this thermomechanical treatment for the objective of grain refinement. By comparing the behavior of AISI 316 and 304 alloys, it was found that the mentioned slow kinetics is related to the retardation effect of solute Mo in the former alloy. At high reversion annealing temperature, however, an equiaxed austenitic microstructure was achieved quickly in AISI 316 stainless steel due to the temperature dependency of retardation effect of molybdenum, which allowed the process of recrystallization to happen easily. Conclusively, this work can shed some light on the issues of this efficient grain refining approach for microstructural control of austenitic stainless steels.

The effect of surface nanocrystallization on plasma nitriding behaviour of AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Li Yang [Department of Materials Science and Engineering, Dalian Maritime University, Institute of Metals and Technology, 1 Linghai Street, Dalian 116026 (China); Wang Liang, E-mail: wlimt@yahoo.com [Department of Materials Science and Engineering, Dalian Maritime University, Institute of Metals and Technology, 1 Linghai Street, Dalian 116026 (China); Zhang Dandan; Shen Lie [Department of Materials Science and Engineering, Dalian Maritime University, Institute of Metals and Technology, 1 Linghai Street, Dalian 116026 (China)

2010-11-15

A plastic deformation surface layer with nanocrystalline grains was produced on AISI 4140 steel by means of surface mechanical attrition treatment (SMAT). Plasma nitriding of SMAT and un-SMAT AISI 4140 steel was carried out by a low-frequency pulse excited plasma unit. A series of nitriding experiments has been conducted at temperatures ranging from 380 to 500 deg. C for 8 h in an NH{sub 3} gas. The samples were characterized using X-ray diffraction, scanning electron microscopy, optical microscopy and Vickers microhardness tester. The results showed that a much thicker compound layer with higher hardness was obtained for the SMAT samples when compared with un-SMAT samples after nitriding at the low temperature. In particular, plasma nitriding SMAT AISI 4140 steel at 380 deg. C for 8 h can produced a compound layer of 2.5 {mu}m thickness with very high hardness on the surface, which is similar to un-SMAT samples were plasma nitrided at approximately 430 deg. C within the same time.

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.

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.

The Effects of Shallow Cryogenic Process On The Mechanical Properties of AISI 4140 Steel

Directory of Open Access Journals (Sweden)

Eşref KIZILKAYA

2018-03-01

Full Text Available In this study, shallow cryogenic treatments were carried out for various holding time to AISI 4140 steel and the effects of heat treatment parameters on wear behavior, impact strength and tensile strength were investigated. Three different holding times were used for cryogenic heat treatments. After the cryogenic process, single tempering was applied. In addition, the abrasion tests were carried out at three different forces (5N, 10N and 15N at a constant slip speed (3.16 m / s and at three different slip distances (95 m, 190 m, 285 m. It has been determined that the shallow cryogenic process parameters significantly influence the mechanical properties of the AISI 4140 steel as a result of experimental studies., Low heat treatment times in cryogenic heat treatment have been found to have a positive effect on many mechanical properties, especially wear. The mechanical properties of the AISI 4140 steel can be optimized by controlling the shallow cryogenic heat treatment parameters.

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

Science.gov (United States)

2013-05-01

H.K.D.H. Bhadeshia, A Model for the Microstruc- ture of Some Advanced Bainitic Steels , Mater. Trans., 1991, 32, p 689–696 19. G.J. Davies and J.G. Garland...REPORT Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding 14. ABSTRACT 16. SECURITY...Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding Report Title ABSTRACT A fully coupled (two-way

Effects of a laser surface processing induced heat-affected zone on the fatigue behavior of AISI 4340 steel

International Nuclear Information System (INIS)

McDaniels, R.L.; White, S.A.; Liaw, K.; Chen, L.; McCay, M.H.; Liaw, P.K.

2008-01-01

The effects of the heat-affected zone (HAZ) in AISI 4340 steel created by laser-surface alloying (LSA) on high-cycle fatigue behavior have been investigated. This research was performed by producing several lots of laser-processed AISI 4340 steel using different laser processing parameters, and then subjecting the samples to high-cycle fatigue and Knoop microindentation hardness studies. Samples of tested material from each lot were examined using scanning-electron microscopy (SEM) in order to establish the effects of laser processing on the microstructure of the fatigue-tested AISI 4340 steel. When these three techniques, microindentation hardness testing, high-cycle fatigue testing, and SEM, are combined, a mechanistic understanding of the effect of the HAZ on the fatigue behavior of this alloy might be gained. It was found that the HAZ did not appear to have an adverse effect on the high-cycle fatigue behavior of LSA-processed AISI 4340 steel

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. 

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.

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.

Study of Surface Wear and Damage Induced by Dry Sliding of Tempered AISI 4140 Steel against Hardened AISI 1055 Steel

Directory of Open Access Journals (Sweden)

A. Elhadi

2016-12-01

Full Text Available In industry, the sliding mechanical systems are subject to friction and wear phenomena. These phenomena can be the origin of a reduction of the efficiency of the mechanical system even to be responsible for its incapacity. Generally, the materials of the parts which are moving relative (tribological couple of these systems are low alloy steels and carbon steels, thanks to their good mechanical and tribological properties. The present work aimed to study, the surface wear and damage induced by dry sliding of hard carbon steel AISI 1055 (disc against tempered low alloy steel AISI 4140 (pin with different hardness and applied loads was investigated. The results revealed that the interaction between the applied load and pin hardness result in complex thermo-mechanical behaviour of the worn surfaces. When a lower hardness pin is used, the main wear mechanisms observed on the discs were abrasion, adhesion, and oxidation. When a higher hardness pin is used, the wear of the discs is governed by delamination, oxidation, and plastic deformation. In particular, third-body wear occurs at high applied load resulting in higher wear rate of high hardness pins compared to low hardness pins.

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.

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.

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...... damage factor is highest. Subsequently the stress history is imposed as boundary conditions in a periodic unit cell model, where an alumina inclusion is embedded in a AISI 52100 matrix. Cracks are assumed to grow radially from the inclusion under cyclic loading. The growth is predicted by means...

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

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.

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.

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.

Ultrasonic evaluation of friction stud welded AA 6063/AISI 1030 steel joints

International Nuclear Information System (INIS)

Hynes, N. Rajesh Jesudoss; Nagaraj, P.; Sujana, J. Angela Jennifa

2014-01-01

Highlights: • Friction stud welding of AA 6063 and AISI 1030 was done successfully. • Ultrasonic evaluation of interfacial properties. • EDX analysis confirms intermetallic compound (FeAl) in the interfacial region. - Abstract: Friction stud welding is a promising technique in many applications related to oil and gas industries. It is used to attach grating to offshore oil platforms in areas where arc welding is not permitted because of the risk of causing a fire or explosion. Attachment of anodes inside seawater discharge pipelines in a gas processing plant is performed by this process. This solid state joining process permits metal combinations such as welding of aluminum studs to steel which would be problematic with arc welding because of the formation of thick and brittle inter-metallic compounds. In the present work, AA 6063 is joined to AISI 1030 steel using friction stud welding machine. Properties that are of interest to manufacturing applications such as Young’s modulus, longitudinal velocity, bulk modulus and shear modulus are evaluated by means of an ultrasonic flaw detector. At the interface of the joint, there is an increase of 4.4%, 1.8%, 1.15% and 4.42% is observed for the properties Young’s modulus, longitudinal velocity, bulk modulus and shear modulus respectively. This is due to the formation of intermetallic compound and increase in hardness at the interfacial region. Energy Dispersive X-ray analysis confirms the presence of FeAl as the intermetallic compound. Scanning Electron Microscope evaluation shows the presence of an unbound zone at the center of the inner region which is due to the minimum rotational speed and low axial load experienced at that point. In the unbound zone, there is an incomplete bond between dissimilar metals and it is detrimental to joint strength. Optimum value of friction time and usage of pure aluminum interlayer during the friction stud welding process hinders the formation of unbound zone and enhances the

The effects of induction hardening on wear properties of AISI 4140 steel in dry sliding conditions

International Nuclear Information System (INIS)

Totik, Y.; Sadeler, R.; Altun, H.; Gavgali, M.

2002-01-01

Wear behaviour of induction hardened AISI 4140 steel was evaluated under dry sliding conditions. Specimens were induction hardened at 1000 Hz for 6, 10, 14, 18, 27 s, respectively, in the inductor which was a three-turn coil with a coupling distance of 2.8 mm. Normalised and induction hardened specimens were fully characterised before and after the wear testing using hardness, profilometer, scanning electron microscopy and X-ray diffraction. The wear tests using a pin-on-disc machine showed that the induction hardening treatments improved the wear behaviour of AISI 4140 steel specimens compared to normalised AISI 4140 steel as a result of residual stresses and hardened surfaces. The wear coefficients in normalised specimens are greater than that in the induction hardened samples. The lowest coefficient of the friction was obtained in specimens induction-hardened at 875 deg. C for 27 s

The effects of induction hardening on wear properties of AISI 4140 steel in dry sliding conditions

Energy Technology Data Exchange (ETDEWEB)

Totik, Y.; Sadeler, R.; Altun, H.; Gavgali, M

2002-02-15

Wear behaviour of induction hardened AISI 4140 steel was evaluated under dry sliding conditions. Specimens were induction hardened at 1000 Hz for 6, 10, 14, 18, 27 s, respectively, in the inductor which was a three-turn coil with a coupling distance of 2.8 mm. Normalised and induction hardened specimens were fully characterised before and after the wear testing using hardness, profilometer, scanning electron microscopy and X-ray diffraction. The wear tests using a pin-on-disc machine showed that the induction hardening treatments improved the wear behaviour of AISI 4140 steel specimens compared to normalised AISI 4140 steel as a result of residual stresses and hardened surfaces. The wear coefficients in normalised specimens are greater than that in the induction hardened samples. The lowest coefficient of the friction was obtained in specimens induction-hardened at 875 deg. C for 27 s.

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.

ETNOBOTÂNICA COMO FERRAMENTA PARA IDENTIFICAÇÃO DE INDICAÇÕES GEOGRÁFICAS E MARCAS COLETIVASEM COMUNIDADE DA REGIÃO SERRANA DO RIO DE JANEIRO

Directory of Open Access Journals (Sweden)

Odara Horta Boscolo

2015-03-01

Full Text Available A Etnobotânica estuda as sociedades humanas e suas interações culturais e simbólicas com as plantas. Indicação Geográfica (IG é um tipo de proteção que reflete o esforço coletivo de defesa e gestão dos direitos de propriedade intelectual. Marca Coletiva (MC é utilizada para identificar produtos ou serviços provindos de membros de uma determinada entidade. As IG e as MC podem ser usadas ​​como ferramentas estratégicas para diferenciar e proteger os ativos intangíveis por meio de produtos de propriedade intelectual gerados por comunidades locais no mercado, agregando valor a sua cultura e meio ambiente, oferecendo ao consumidor um sinal distintivo da sua tipicidade. A pesquisa etnobotânica foi realizada em uma comunidade rural no estado do Rio de Janeiro. Foi sugerida a possibilidade de proteção da Indicação Geográfica "Rio Bonito de Cima de Friburgo" para o inhame, seus métodos de produção e uma MC para a Oficina das Ervas. Estas proposições auxiliam na manutenção e criação de postos de trabalho como uma possibilidade de compartilhar os benefícios econômicos para toda a cadeia produtiva e indiretamente estimular outras atividades rentáveis, como o ecoturismo. Assim, etnobotânica destaca-se como uma ferramenta de pesquisa para indicar potenciais produtos e serviços que podem ser protegidos com IG ou MC e representa mais uma oportunidade de um retorno à comunidade pelo estudo realizado.

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

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.

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_2N) 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_2N) and iron (Fe_2N, Fe3_N, and Fe_4N) 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

Magnetic Barkhausen emission for characterizing AISI 1045 steel plastically deformed

Directory of Open Access Journals (Sweden)

Gelaysi Moreno-Vega

2018-04-01

Full Text Available The aim of this work was to correlate parameters of the metallurgical structure such as size and reorganizing the grains, as well as the hardening capacity and the samples distortion of AISI 1045 steel plastically deformed by roll and then fractioned, with average values root means square RMS of a Barkhausen Emission. The analyzed samples were deformed by using forces of 500, 1500 and 2500 N, angular speed of 27, 54, and 110 r.p.m and tool advance of 0,075; 0,125 and 0,25 mm / rev. Then, they underwent a traction process using a CRITM DNS 200 machine, with a load of 200 kN. It was observed that the EMB signal presented an increasing performance in correspondence with the deformation decline and the increasing in tension and the hardness degree. The study of commercial steel AISI 1045 plastically deformed with roller and then pulled with EMB technique, allowed corroborating the potential of this technique as a non-destructive testing.

Sintering, microstructure and properties of WC-AISI304 powder composites

International Nuclear Information System (INIS)

Marques, B.J.; Fernandes, C.M.; Senos, A.M.R.

2013-01-01

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) 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

Surface modifications induced by hydrogen in AISI 304 stainless steel

International Nuclear Information System (INIS)

Evangelista, G.E.; Miranda, P.E.V. de

1983-01-01

Hydrogen induced surface modifications of type AISI 304 SS were studied by charging the samples in a 1N a 1N H 2 SO 4 electrolyte at room temperature. Current densities were varied from 500 to 4000 A/m 2 and charging times from 2 to 50 hours. Charged specimens were analysed using optical and electron scanning microscopy. Vickers microhardness tests with small load was also performed. Metallographic etching metodologies were developed (in black and white and colored photographies) which permited identification of all phases present. It was shown that delayed cracks appear somewhat curved on austenite and perfectly strainght on martensite, following the intersections of a phase platlets. These are the regions where α' martensite is located. The habit plane of these cracks might belong to (100) sub(γ) or (221) sub(γ) plane families. A new phenomenon termed hydrogen induced softening was observed on type AISI 304 SS at elevated current densities and/or charging times. (Author) [pt

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

Aspects of plasma cutting in AISI 321 stainless steel

International Nuclear Information System (INIS)

Souza Barros, I. de; Cardoso, P.E.

1985-10-01

The utilization of plasma cutting process in AISI 321 stainless steel heavy plates for fabricating nozzles for nuclear reactors was evaluated. The effect of current, electric potential and cutting speed are studied. The superficial irregularity and the microstructure of the zone affected by the cut were analyzed by measurements of roughness, optical metallography and microhardness. (E.G.) [pt

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.

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

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.

Características fenotípicas dos pacientes com anemia falciforme de acordo com os haplótipos do gene da βS-globina em Fortaleza, Ceará

Directory of Open Access Journals (Sweden)

Lilianne B. Silva

2010-02-01

anemia falciforme, portanto a utilização de técnicas moleculares para a detecção do haplótipo envolvido deve ser considerada como uma importante ferramenta diagnóstica para prever o quadro clínico destes pacientes. Rev. Bras. Hematol. Hemoter.

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.

Estimation of embrittlement during aging of AISI 316 stainless steel ...

Indian Academy of Sciences (India)

Unknown

rical relation connecting the aging temperature, aging time and nitrogen ... strength, high tensile strength, are easy to fabricate and ... However, the ferrite is a metastable phase which ... 2. Experimental. 2.1 Materials. Nuclear grade AISI 316 stainless steel plates ( .... fore, it is desirable to develop empirical relations con-.

Swelling of AISI 304L in response to simultaneous variations in stress and displacement rate

International Nuclear Information System (INIS)

Porter, D.L.; Garner, F.A.

1984-01-01

The duration of the transient regime of neutron-induced swelling in annealed AISI 304L at 400 0 C is sensitive to both stress and displacement rate variations. The simultaneous application of both variables exerts a synergistic effect on the transient regime. The duration of this regime cannot be reduced below a required intrinsic exposure of approx. 10 dpa, however, which has been found to be characteristic of all Fe-Ni-Cr austenitic alloys. This is four times larger than that currently assumed in the stress-affected swelling equation for 20% cold-worked AISI 316

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)

Estudo da influência do tratamento criogênico no aço AISI H13

OpenAIRE

Sandra dos Santos Vales

2011-01-01

Há alguns anos, diversos estudos da influência dos parâmetros do tratamento térmico vêm sendo desenvolvidos, para a obtenção de propriedades que permitam atingir os requisitos de trabalho e que gerem ferramentas de vida útil estendida. Nesse contexto, tem sido demonstrado que o tratamento criogênico não só provoca a transformação da austenita residual, trazendo melhorias no dimensional da ferramenta, mas também pode promover a precipitação de carbonetos finos, com ganho em tenacidade e propri...

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.

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.

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.

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

Some mechanical properties of borided AISI H13 and 304 steels

International Nuclear Information System (INIS)

Taktak, Sukru

2007-01-01

In the present study, mechanical properties of borides formed on AISI H13 hot work tool and AISI 304 stainless steels have been investigated. Both steels have high chromium content and have a widespread use in the engineering application. Boriding treatment was carried out in slurry salt bath consisting of borax, boric acid, and ferrosilicon at temperature range of 800-950 deg. C for 3, 5, and 7 h. X-ray diffraction analysis of boride layers on the surface of steels revealed various peaks of FeB, Fe 2 B, CrB, and Ni 3 B. Metallographic studies showed that the boride layer has a flat and smooth morphology in the 304 steel while H13 steel was a ragged morphology. The characterization of the boride layer is also carried out by means of the micro-hardness, surface roughness, adhesion, and fracture toughness studies

Partial substitution of vanadium by niobium in AISI H13 steel

International Nuclear Information System (INIS)

Itman Filho, A.; Balancin, O.

1987-01-01

The aim of this work was to study the tempering resistence in conditions of use of the AISI H13 steel, after partial substitution of vanadium by niobium. Four alloys of this steel were elaborated and in three of them the niobim was added in the contents of 0,2; 0,5 and 1,0%. Metallographic techniques were performed to compare qualitatively the niobium effect in several processing and thermal analisys of the steels. Grain size measurements were made after austenitization of the steels, hardness measurements in prepared samples were made after quenching and tempering, tensile testing at elevated temperature was investigated and yield strength, reduction of area after steel breaking and elongation were calculated. After these studies it was possible to certify that the partial substitution of vanadium by niobium did not alter significantly the basic mechanical properties of the AISI H13. (Author) [pt

Evaluación del comportamiento a fatiga de una unión soldada a tope de acero AISI 1015//Evaluation of the fatigue behaviour of a butt welded joint of AISI 1015 steel

Directory of Open Access Journals (Sweden)

Pavel Michel Almaguer‐Zaldivar

2015-01-01

Full Text Available Las uniones soldadas son un componente importante de una estructura, por lo que siempre es necesario conocer la respuesta de las mismas sometidas a cargas cíclicas. El objetivo de este trabajo es obtener la curva S-N de una unión soldada a tope de acero AISI 1015 y electrodo E6013 como material de aporte. Los ensayos a fatiga se realizaron de acuerdo a la norma ASTM en una máquina universal MTS810. Se utilizaron probetas de sección rectangular. El ciclo de carga fueasimétrico a tracción, con un coeficiente de asimetría de 0,1. Se obtuvo que la unión estudiada tiene un límite de resistencia a la fatiga de 178 MPa, a un punto de corte de 2 039 093 ciclos.Palabras claves: unión soldada, fatiga, curva S-N, AISI 1015, electrodo E6013._______________________________________________________________________________AbstractWelded joints are an important component in structures, by this reason is necessary to know the behaviour of these elements under cyclic loads. The objective of this work is to obtain the S-N curve of the butt welded joint of AISI 1015 steel and electrode E6013 as the contribution material. Fatiguetest was realized within the ASTM standard in the MTS810 testing machine. Rectangular cross section specimens was used. Cyclic loads was asymmetric tensile and the asymmetry ratio used was 0,1. In this study was obtained the fatigue limit equal to 178 MPa, at the cut point of 2 039 093 cycles.Key words: welded joint, fatigue, S-N curve, AISI 1015 steel, electrode E6013.

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

Indian Academy of Sciences (India)

application of cutting fluid results in longer tool life and better surface finish. ... parameters for turning of AISI 304 stainless steel by considering the process ... In the design of experiments (DOE) the full factorial method was used in .... Esme U 2009 Application of Taguchi method for the optimization of resistance spot welding.

Deformation induced martensite in AISI 316 stainless steel

Directory of Open Access Journals (Sweden)

Solomon, N.

2010-04-01

Full Text Available The forming process leads to a considerable differentiation of the strain field within the billet, and finally causes the non-uniform distribution of the total strain, microstrusture and properties of the material over the product cross-section. This paper focus on the influence of stress states on the deformation-induced a’ martensitic transformation in AISI Type 316 austenitic stainless steel. The formation of deformation-induced martensite is related to the austenite (g instability at temperatures close or below room temperature. The structural transformation susceptibility is correlated to the stacking fault energy (SFE, which is a function not only of the chemical composition, but also of the testing temperature. Austenitic stainless steels possess high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Nevertheless, the deformation-induced martensite transformation may enhance the rate of work-hardening and it may or may not be in favour of further material processing. Due to their high corrosion resistance and versatile mechanical properties the austenitic stainless steels are used in pressing of heat exchanger plates. However, this corrosion resistance is influenced by the amount of martensite formed during processing. In order to establish the links between total plastic strain, and martensitic transformation, the experimental tests were followed by numerical simulation.

El proceso de conformación da a lugar a una considerable diferenciación del campo de tensiones dentro de una barra de extrusión y, finalmente, causa una distribución no uniforme de la tensión total, la microestructura y propiedades del material sobre el corte transversal. En este trabajo se estudia la influencia de los estados de tensión sobre la transformación martensítica inducida por deformación en un acero inoxidable austenítico tipo AISI 316. La formación de martensita inducida por

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)

The influence of plasma nitriding on the fatigue behavior of austenitic stainless steel types AISI 316 and AISI 304

International Nuclear Information System (INIS)

Varavallo, Rogerio; Manfrinato, Marcos Dorigao; Rossino, Luciana Sgarbi; Spinelli, Dirceu; Riofano, Rosamel Melita Munoz

2010-01-01

The plasma nitriding process has been used as an efficient method to optimize the surface properties of steel and alloy in order to increase their wear, fatigue and corrosion resistance. This paper reports on a study of the composition and influence of the nitrided layer on the high-cycle fatigue properties of the AISI 316 and 304 type austenitic stainless steels. Test specimens of AISI 316 and 304 steel were nitrided at 400 deg C for 6 hours under a pressure of 4.5 mbar, using a gas mixture of 80% volume of H 2 and 20% volume of N 2 . The rotary fatigue limit of both nitrided and non-nitrided steels was determined, and the effect of the treatment on the fatigue limit of the two steels was evaluated. The mechanical properties of the materials were evaluated based on tensile tests, and the nitrided layer was characterized by microhardness tests, scanning electron microscopy and X-ray diffraction. The resulting nitride layer showed high hardness and mechanical strength, increasing the fatigue limit of the nitrided material in comparison with the non-nitrided one. The fatigue limit of the 316 steel increased from 400 MPa to 510 MPa in response to nitriding, while that of the 304 steel increased from 380 MPa to 560 MPa. One of the contributing factors of this increase was the introduction of residual compressive stresses during the surface hardening process, which reduce the onset of crack formation underneath the nitride layer. (author)

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.

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

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)

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

Directory of Open Access Journals (Sweden)

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.

O patrocínio esportivo como ferramenta de marketing empresarial

OpenAIRE

Mayorkis, Stephanie

2010-01-01

Apresenta uma visão geral do marketing esportivo, adaptando-se conceitos clássicos de marketing ao esporte, identificando seu potencial e oportunidades. A grande parte das informações foi levantada com base em dados do mercado norte-americano, já que no Brasil o assunto começou a se desenvolver mais recentemente. Foi dada ênfase ao patrocínio esportivo no sentido de mostrar o seu potencial como ferramenta de marketing, que faz parte do composto promocional, para ajudar as empresas a ati...

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 ...

Effects of gaseous nitriding AISI4140 alloy steel on corrosion and hardness properties

Science.gov (United States)

Tamil Moli, L.; Wahab, N.; Gopinathan, M.; Karmegam, K.; Maniyarasi, M.

2016-10-01

Corrosion is one of the major problems in the industry especially on machinery since it weakens the structure of the machinery part and causes the mechanical failure. This will stop the production and increase the maintenance cost. In this study, the corrosion behaviour of gas nitriding on a screw press machine shaft made from AISI 4140 steel was investigated. Pitting corrosion was identified as a major cause of the shaft failure and this study was conducted to improve the corrosion resistance on the AISI 4140 alloy steel shaft by gas nitriding as a surface hardening treatment. Gas nitriding was performed with composition of 15% ammonia and 85% nitrogen at temperatures of 525 °C, 550 °C and 575 °C and with the soaking time of 30, 45 and 60 minutes, respectively. The samples were prepared as rectangular sized of 30mm x 12mm x 3mm for immersion testing. The results showed that corrosion rate of untreated samples was 77% higher compared to the nitrided samples. It was also found that hardness of the nitrided samples was higher than untreated sample. All in all, it can be concluded that gaseous nitriding can significantly improve the surface hardness and the corrosion resistance of the shaft made of AISI 4140 alloy steel, hence reduces the pitting that is the root cause of failure.

AFM surface imaging of AISI D2 tool steel machined by the EDM process

International Nuclear Information System (INIS)

Guu, Y.H.

2005-01-01

The surface morphology, surface roughness and micro-crack of AISI D2 tool steel machined by the electrical discharge machining (EDM) process were analyzed by means of the atomic force microscopy (AFM) technique. Experimental results indicate that the surface texture after EDM is determined by the discharge energy during processing. An excellent machined finish can be obtained by setting the machine parameters at a low pulse energy. The surface roughness and the depth of the micro-cracks were proportional to the power input. Furthermore, the AFM application yielded information about the depth of the micro-cracks is particularly important in the post treatment of AISI D2 tool steel machined by EDM

AFM surface imaging of AISI D2 tool steel machined by the EDM process

Science.gov (United States)

Guu, Y. H.

2005-04-01

The surface morphology, surface roughness and micro-crack of AISI D2 tool steel machined by the electrical discharge machining (EDM) process were analyzed by means of the atomic force microscopy (AFM) technique. Experimental results indicate that the surface texture after EDM is determined by the discharge energy during processing. An excellent machined finish can be obtained by setting the machine parameters at a low pulse energy. The surface roughness and the depth of the micro-cracks were proportional to the power input. Furthermore, the AFM application yielded information about the depth of the micro-cracks is particularly important in the post treatment of AISI D2 tool steel machined by EDM.

Wear Evaluation of AISI 4140 Alloy Steel with WC/C Lamellar Coatings Sliding Against EN 8 Using Taguchi Method

Science.gov (United States)

Kadam, Nikhil Rajendra; Karthikeyan, Ganesarethinam

2016-10-01

The purpose of the experiments in this paper is to use the Taguchi methods to investigate the wear of WC/C coated nitrided AISI 4140 alloy steel. A study of lamellar WC/C coating which were deposited by a physical vapor deposition on nitrided AISI 4140 alloy steel. The investigation includes wear evaluation using Pin-on-disk configuration. When WC/C coated AISI 4140 alloy steel slides against EN 8 steel, it was found that carbon-rich coatings show much lower wear of the countersurface than nitrogen-rich coatings. The results were correlated with the properties determined from tribological and mechanical characterization, therefore by probably selecting the proper processing parameters the deposition of WC/C coating results in decreasing the wear rate of the substrate which shows a potential for tribological application.

Cavitation erosion resistance of AISI 316L stainless steel laser surface-modified with NiTi

International Nuclear Information System (INIS)

Chiu, K.Y.; Cheng, F.T.; Man, H.C.

2005-01-01

The present study is part of a project on the surface modification of AISI 316 stainless steel using various forms of NiTi for enhancing cavitation erosion resistance. In this study, NiTi powder was preplaced on the AISI 316L substrate and melted with a high-power CW Nd:YAG laser. With appropriate laser processing parameters, an alloyed layer of a few hundred micrometers thick was formed and fusion bonded to the substrate without the formation of a brittle interface. EDS analysis showed that the layer contained Fe as the major constituent element while the XRD patterns of the surface showed an austenitic structure, similar to that of 316 stainless steel. The cavitation erosion resistance of the modified layer (316-NiTi-Laser) could reach about 29 times that of AISI 316L stainless steel. The improvement could be attributed to a much higher surface hardness and elasticity as revealed by instrumented nanoindentation tests. Among various types of samples, the cavitation erosion resistance was ranked in descending order as: NiTi plate > 316-NiTi-Laser > 316-NiTi-TIG > AISI 316L, where 316-NiTi-TIG stands for samples surfaced with the tungsten inert gas (TIG) process using NiTi wire. Though the laser-surfaced samples and the TIG-surfaced samples had similar indentation properties, the former exhibited a higher erosion resistance mainly because of a more homogeneous alloyed layer with much less defects. In both the laser-surfaced and TIG-surfaced samples, the superelastic behavior typical of austenitic NiTi was only partially retained and the superior cavitation erosion resistance was thus still not fully attained

Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior

Directory of Open Access Journals (Sweden)

Oh M.C.

2015-06-01

Full Text Available The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

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

Directory of Open Access Journals (Sweden)

Hamad Al-Khalid

2011-12-01

Full Text Available 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.

Experimental estimation and optimization of process parameters under minimum quantity lubrication and dry turning of AISI-4340 with different carbide inserts

Energy Technology Data Exchange (ETDEWEB)

Saini, Akash; Setia, Sunil [Lovely Professional University, Phagwara (India); Dhiman, Suresh; Sharma, Rajesh [National Institute of Technology, Hamirpur (India)

2014-06-15

An experimental study has been performed on AISI 4340 steel in this paper. The influence of approach angle, feed rate, cutting speed and depth of cut has been on cutting forces and tool tip temperature has been experimentally investigated. Before conducting experiments on the AISI 4340 steel work-piece, the chemical composition test, microstructure test were performed and hardness of the work-piece was improved by heat treatment. A total of 64 experiments each by two different coated carbide inserts (PVD and CVD-coated) were conducted on AISI-4340 steel under different environmental conditions (dry and MQL machining). During the experiments, approach angle, cutting speed, feed rate are varied to four levels and the depth of cut is kept constant to investigate the effect of the same on the three cutting forces component and the temperature variations on the tool-tip. It is observed that the main cutting force was largest among the three cutting force components in case of AISI 4340 steel turning and MQL machining show beneficial effects compared to dry machining.

Experimental estimation and optimization of process parameters under minimum quantity lubrication and dry turning of AISI-4340 with different carbide inserts

International Nuclear Information System (INIS)

Saini, Akash; Setia, Sunil; Dhiman, Suresh; Sharma, Rajesh

2014-01-01

An experimental study has been performed on AISI 4340 steel in this paper. The influence of approach angle, feed rate, cutting speed and depth of cut has been on cutting forces and tool tip temperature has been experimentally investigated. Before conducting experiments on the AISI 4340 steel work-piece, the chemical composition test, microstructure test were performed and hardness of the work-piece was improved by heat treatment. A total of 64 experiments each by two different coated carbide inserts (PVD and CVD-coated) were conducted on AISI-4340 steel under different environmental conditions (dry and MQL machining). During the experiments, approach angle, cutting speed, feed rate are varied to four levels and the depth of cut is kept constant to investigate the effect of the same on the three cutting forces component and the temperature variations on the tool-tip. It is observed that the main cutting force was largest among the three cutting force components in case of AISI 4340 steel turning and MQL machining show beneficial effects compared to dry machining.

Susceptibility to stress corrosion in stainless steels type AISI 321 and 12X18H10T used in PWR type reactors (WWER); Susceptibilidad a la corrosion bajo esfuerzo de barras de acero inoxidable AISI 321 y 12X18H10T en ambientes utilizados en reactores VVER

Energy Technology Data Exchange (ETDEWEB)

Matadamas C, N

1996-12-31

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{sub 3}BO{sub 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).

Erosion of heat-treated AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Goretta, K.C. (Materials and Components Tech. Div., Argonne National Lab., IL (United States)); Thompson, A.C. (Materials and Components Tech. Div., Argonne National Lab., IL (United States)); Routbort, J.L. (Materials Science Div., Argonne National Lab., IL (United States))

1993-03-15

Solid-particle erosion was studied on AISI 4140 steel heat treated to have a Vickers hardness (Hv) of 288-650 kg mm[sup -2]. The experiments were conducted in vacuum with 143 [mu]m Al[sub 2]O[sub 3] abrasive impacting at 50-100 m s[sup -1] at an angle of 30 or 90 . Erosion rates were nearly independent of hardness for Hv[<=]365 kg mm[sup -2], but increased with hardness for Hv>365 kg mm[sup -2]. The improved erosion resistances of the softer alloys were attributed to increased ductilities. (orig.). Letter-to-the-editor

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

Atomic diffusion in laser surface modified AISI H13 steel

Science.gov (United States)

Aqida, S. N.; Brabazon, D.; Naher, S.

2013-07-01

This paper presents a laser surface modification process of AISI H13 steel using 0.09 and 0.4 mm of laser spot sizes with an aim to increase surface hardness and investigate elements diffusion in laser modified surface. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, pulse repetition frequency (PRF), and overlap percentage. The hardness properties were tested at 981 mN force. Metallographic study and energy dispersive X-ray spectroscopy (EDXS) were performed to observe presence of elements and their distribution in the sample surface. Maximum hardness achieved in the modified surface was 1017 HV0.1. Change of elements composition in the modified layer region was detected in the laser modified samples. Diffusion possibly occurred for C, Cr, Cu, Ni, and S elements. The potential found for increase in surface hardness represents an important method to sustain tooling life. The EDXS findings signify understanding of processing parameters effect on the modified surface composition.

Comunicação de moda: um breve olhar sobre o desfile como ferramenta na contemporaneidade

Directory of Open Access Journals (Sweden)

Cynthia Hansen

2013-05-01

Full Text Available O objetivo desta pesquisa é refletir sobre a utilidade dos desfiles como ferramenta de comunicação para marcas e criadores de moda na contemporaneidade. A partir da investigação exploratória bibliográfica sobre o conceito, função e evolução histórica dos desfiles, bem como sobre argumentos de autores que refutam e que corroboram a utilidade desses eventos em vista da forma como são realizados hoje, foi possível verificar que os desfiles servem como ferramenta de comunicação mercadológica geradora de publicidade, uma vez que são colocados em circulação na mídia na tentativa de impressionar e buscar reconhecimento das marcas perante o público, tanto especializado quanto leigo.

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.

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

Treatment of nitridation by microwave post discharge plasma in an AISI 4140 steel; Tratamiento de nitruracion por plasma post-descarga micro-ondas en un acero AISI 4140

Energy Technology Data Exchange (ETDEWEB)

Medina F, A. [Instituto Tecnologico de Morelia, Morelia e Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Rodriguez L, V.; Zamora R, L. [ININ, Mexico D.F. (Mexico); Oseguera P, J

1998-07-01

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)

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.

Eletroerosão por fio em metal duro para ferramentas de estampagem de lâminas de motores elétricos

OpenAIRE

Hespanhol, Heber de Carvalho

2009-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Mecânica. O processo de eletroerosão por fio é utilizado atualmente na fabricação da maioria das matrizes e punções de metal duro (carbeto de tungstênio), usados em ferramentas de estampagem de aços para motores elétricos. As indústrias de eletrodomésticos, motores elétricos industriais, transformadores e compressores herméticos, utilizam ferramentas progressivas de...

A three-dimensional thermal finite element analysis of AISI 304 stainless steel and copper dissimilar weldment

Science.gov (United States)

Singh, Gurdeep; Saxena, Ravindra K.; Pandey, Sunil

2018-04-01

The aim of this study to developed a 3-D thermal finite element model for dissimilar material welding of AISI-304 stainless steel and copper. Welding of similar material is widely studied using experimental and numerical methods but the problem becomes trivial for the welding of dissimilar materials especially in ferrous and nonferrous materials. Finite element analysis of dissimilar material welding is a cost-effective method for the understanding and analysis of the process. The finite element analysis has been performed to predict the heat affected zone and temperature distribution in AISI-304 stainless steel and copper dissimilar weldment using MSC Marc 2017®. Due to the difference in physical properties of these materials the behavior of heat affected zone and temperature distribution are perceived to be different. To verify the accuracy of the thermal finite element model, the welding process was simulated with butt-welded joints having same dimensions and parameters from Attarha and Far [1]. It is found from the study that the heat affected zone is larger in copper weld pads than in AISI 304 stainless steel due to large difference in thermal conductivity of these two weld pads.

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.

Residual stress stability and alternating bending strength of AISI 4140 after shot peening and successive annealing

Energy Technology Data Exchange (ETDEWEB)

Menig, R.; Schulze, V.; Voehringer, O. [Inst. fuer Werkstoffkunde I, Univ. of Karlsruhe (TH), Karlsruhe (Germany)

2002-07-01

Increases of residual stress stability and alternating bending strength of shot peened AISI 4140 are obtained by successive annealing treatments. This is caused by static strain aging effects, which lead to pinning of dislocations by carbon atoms and finest carbides. It will be shown that by short-time annealing of a quenched and tempered AISI 4140 it is possible to maximize the positive effect of static strain aging, while minimizing the detrimental effect of thermal residual stress relaxation, which was measured by X-ray diffraction method. Static strain aging effects were also found to be responsible for an increase of the quasi static and cyclic surface yield strengths. (orig.)

On electrical resistivity of AISI D2 steel during various stages of cryogenic treatment

Science.gov (United States)

Lomte, Sachin Vijay; Gogte, Chandrashekhar Laxman; Peshwe, Dilip

2012-06-01

The effect of dislocation densities and residual stresses is well known in tool steels. Measurement of electrical resistivity in order to monitor dislocation densities or residual stresses has seldom been used in investigating the effect of cryogenic treatment on tool steels. Monitoring residual stresses during cryogenic treatment becomes important as it is directly related to changes due to cryogenic treatment of tool steels. For high carbon high chromium (HCHC- AISI D2) steels, not only wear resistance but dimensional stability is an important issue as the steels are extensively used in dies, precision measuring instruments. This work comprises of study of measurement of electrical resistivity of AISI D2 steel at various stages of cryogenic treatment. Use of these measurements in order to assess the dimensional stability of these steels is discussed in this paper.

Finite Element Simulation and Experimental Verification of Internal Stress of Quenched AISI 4140 Cylinders

Science.gov (United States)

Liu, Yu; Qin, Shengwei; Hao, Qingguo; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

2017-03-01

The study of internal stress in quenched AISI 4140 medium carbon steel is of importance in engineering. In this work, the finite element simulation (FES) was employed to predict the distribution of internal stress in quenched AISI 4140 cylinders with two sizes of diameter based on exponent-modified (Ex-Modified) normalized function. The results indicate that the FES based on Ex-Modified normalized function proposed is better consistent with X-ray diffraction measurements of the stress distribution than FES based on normalized function proposed by Abrassart, Desalos and Leblond, respectively, which is attributed that Ex-Modified normalized function better describes transformation plasticity. Effect of temperature distribution on the phase formation, the origin of residual stress distribution and effect of transformation plasticity function on the residual stress distribution were further discussed.

Analisa pertumbuhan keausan pahat karbida coated dan uncoated pada alloy steel AISI 4340

Directory of Open Access Journals (Sweden)

Sobron Lubis

2017-03-01

Full Text Available Abstrak: Keausan pahat merupakan data yang sangat penting dalam perencanaan pemesinan. Penelitian ini menjelaskan tentangpercobaan pertumbuhan keausan pahat pada karbida coated dan uncoated dalam pembubutan bahan alloy steel AISI 4340.Penelitian dilakukan dengan memperhatikan pertumbuhan keausan pada menit 12, 24, 36, 48, 60 sampai didapat VB sebesar0.3 mm untuk kedua mata pahat, sedangkan kondisi pemotongan lain seperti gerak makan, kedalaman potong, kecepatanpotong konstan. Tujuan penelitian ini adalah untuk mengkaji secara ilmiah pertumbuhan keausan yang terjadi pada mata pahatkarbida coated dan uncoated pada proses pemotongan alloy steel AISI 4340. Metode grafik digunakan untuk analisispercobaan, untuk melihat perbandingan pertumbuhan keausan mata pahat karbida coated dan uncoated serta mekanismekeausan yang terjadi, serta korelasi pertumbuhan keausan dengan kekasaran permukaan benda kerja. Hasil penelitianmendapatkan keausan pahat karbida coated pada menit 60 dengan VB sebesar 0.366 mm, sedangkan pada karbida uncoatedpada menit 36 sebesar 0.45 mm. Mekanisme keausan yang terjadi adalah keausan adhesi.Kata Kunci: Pahat potong karbida, baja paduan, keausan pahat, keausan tepi. Abstract: A tool life is an important data in planning a machining process. In this research, an experiment describe about growth of toolwear on carbide coated and uncoated cutting tools used in turning process of an alloy steel of AISI 4340. The experiment wasconducted by observing the growth of tool wear on minutes 12, 24, 36, 48, 60 until get VB 0.3 mm for both of cutting tools, whilethe other cutting conditions such a feed rate, depth of cut, cutting speed constant. The purpose of this experiment is to examinescientifically the growth of tool wear on carbide coated and uncoated in turning process of and alloy steel of AISI 4340. Graphicalmethod used for analisis of the experiment, to compare the growth of tool wear on cutting tool carbide coated and uncoated, andthe

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)

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.

Ferramenta para aprendizagem de automação e controle discreto

OpenAIRE

Maia, José da Silva

2002-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Produção. Ferramenta para Aprendizagem de Automação e Controle Discreto: Controlador Lógico Programável (PLC) na modalidade e-learning, estabelece uma proposta de transferência de ambiente de aprendizagem do modelo presencial tradicional para o modelo EAD híbrida, na modalidade e-learning assíncrona. Descreve as etapas de projetos, bem como trata dos princípios do...

Wear resistance of DLC coating deposited on pretreated AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Podgornik, B.; Vizintin, J. [Ljubljana Univ. (Slovenia). Centre of Tribology and Technical Diagnostics; Ronkainen, H.; Holmberg, K. [VTT Manufacturing Technology (Finland). Operational Reliability

2000-07-01

In the last few years, the application of nitrided steels as substrates for hard coatings has been increasingly reported. Diamond-like carbon (DLC) coatings, in particular, have attracted significant attention owing to their desirable tribological properties. The aim of the present study was to investigate the possibilities of using hard DLC coatings on softer substrates, such as AISI 4140 steel. (orig.)

Avaliação de ferramentas de Business Process Management (BPMS pela ótica da gestão do conhecimento

Directory of Open Access Journals (Sweden)

Alessandro Marcus Afonso de Oliveira

Full Text Available O artigo analisa como as ferramentas de BPMS podem auxiliar na prática da Gestão do Conhecimento. O modelo de pesquisa foi construído a partir das interfaces da Gestão por Processos com Gestão do Conhecimento bem como nos modelos do BPMI e WfMC. Para o caso estudado, concluiu-se que uma ferramenta BPMS, apesar de apoiar a socialização de maneira limitada, apresenta funcionalidades que suportam plenamente a externalização, combinação e internalização do conhecimento sobre processos de negócio.

Microstructure and Mechanical Properties of Laser Clad and Post-cladding Tempered AISI H13 Tool Steel

Science.gov (United States)

Telasang, Gururaj; Dutta Majumdar, Jyotsna; Wasekar, Nitin; Padmanabham, G.; Manna, Indranil

2015-05-01

This study reports a detailed investigation of the microstructure and mechanical properties (wear resistance and tensile strength) of hardened and tempered AISI H13 tool steel substrate following laser cladding with AISI H13 tool steel powder in as-clad and after post-cladding conventional bulk isothermal tempering [at 823 K (550 °C) for 2 hours] heat treatment. Laser cladding was carried out on AISI H13 tool steel substrate using a 6 kW continuous wave diode laser coupled with fiber delivering an energy density of 133 J/mm2 and equipped with a co-axial powder feeding nozzle capable of feeding powder at the rate of 13.3 × 10-3 g/mm2. Laser clad zone comprises martensite, retained austenite, and carbides, and measures an average hardness of 600 to 650 VHN. Subsequent isothermal tempering converted the microstructure into one with tempered martensite and uniform dispersion of carbides with a hardness of 550 to 650 VHN. Interestingly, laser cladding introduced residual compressive stress of 670 ± 15 MPa, which reduces to 580 ± 20 MPa following isothermal tempering. Micro-tensile testing with specimens machined from the clad zone across or transverse to cladding direction showed high strength but failure in brittle mode. On the other hand, similar testing with samples sectioned from the clad zone parallel or longitudinal to the direction of laser cladding prior to and after post-cladding tempering recorded lower strength but ductile failure with 4.7 and 8 pct elongation, respectively. Wear resistance of the laser surface clad and post-cladding tempered samples (evaluated by fretting wear testing) registered superior performance as compared to that of conventional hardened and tempered AISI H13 tool steel.

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

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)

In pile AISI 316L. Low cycle fatigue. Final report

International Nuclear Information System (INIS)

Van Nieuwenhove, R.; Moons, F.

1994-12-01

In pile testing of the effect of neutron irradiation on the fatigue life of the reference material AISI 316L was performed in the framework of the European fusion technology program. The overall programme, carried out at SCK CEN (Mol,Belgium), exists of two instrumented rigs for low cycle fatigue testing, which were consecutively loaded in the BR-2 reactor during periods Jan (94) June (94) and Aug (94)-Dec(94). In each experiment, two identical samples were loaded by means of a pneumatically driven system. The samples were instrumented with thermocouples, strain gages, linear variable displacement transducers, and activation monitors. The experimental conditions are given. Type of fatigue test: load controlled, symmetric, uniaxial, triangular wave shape; stress range: about 580 MPa; sample shape: hourglass, diameter 3.2 mm, radius 12.5 mm; environment: NaK (peritectic); temperature: 250 C; maximum dpa value up to fracture: 1.7. Two of four samples were broken (one in each experiment) after having experienced 17 419 respectively 11 870 stress cycles. These new data points confirm earlier results from pile fatigue tests: irradiation causes no degradation of fatigue life of AISI 316L steel, at least for the parameters corresponding to these experiments

The Effects of The Industrial Cryogenic Process on The Wear Behaviours of AISI D2 Cold Work Tool Steels

OpenAIRE

Ersöz, Enes; Ovalı, İsmail

2018-01-01

In this study, industrial cryogenic process afterconventional heat treatment process for various holding time was applied toAISI D2 (DIN 1.2379) cold work tool steel. The effects of the industrialcryogenic process on the wear behavior was investigated. In the wear test 5,10and 15 N forces were carried out to all group specimens at a constant shearrate (3,16 m/s) and three different wear distances. Experimental results showthat cryogenic processing of AISI D2 cold work tool steels have a signi...

Effects of Nitrogen on the DOS and the Passive Film Breakdown Potential of AISI 304 Stainless Steel

International Nuclear Information System (INIS)

Choe, Han Cheol; Kim, Kwan Hyu; Kim, Myung Soo; Lee, Ho Jong

1992-01-01

Effects of nitrogen on the degree of sensitization (DOS) and the passive film breakdown potential (Eb) of AISI 304 stainless steel were studied by potentiostat. AISI 304 stainless steel samples containing 0.02 ∼ 0.10wt% nitrogen were sensitized by heat treatment at 650 .deg. C. The DOS was measured using the double-loop reactivation method of the electrochemical potentiodynamic reactivation (EPR) test with the potential scan rate of 150 mV/min in the electrolyte of 0.5 M H 2 SO 4 + 0.01 M KSCN solution at 25 .deg. C. The passive film breakdown potential (Eb) and repassivation potential (Er) were detected by using the cyclic potentiodynamic polarization test (CPPT) in 0.5M HCI solution at 25 .deg. C. In addition, corrosion morphologies were observed by SEM and optical microscope. It was found that nitrogen additions up to 0.1wt% decreased DOS and increased Eb and Er of AISI 304 stainless steel, whereas the increasing sensitization time increased the DOS and decreased Eb and Er. The corrosion morphologies showed severe pits and intergranular attacks in the samples of low nitrogen content and high DOS

Design e construção de nova interface para a BVS Psicologia (BVS-PSI Brasil e a experiência de criação do protótipo da BVS ULAPSI: facilitando a vida de usuários

Directory of Open Access Journals (Sweden)

Antonio Marcos Amorim

2006-01-01

Full Text Available Relata-se a experiência de atualização da BVS Psicologia Brasil (http://www.bvs-psi.org.br/ e criação do protótipo da BVS ULAPSI (Biblioteca Virtual da União de Entidades Latino-Americanas de Psicologia, ocorrida em 2005, pela Biblioteca do Instituto de Psicologia da USP (SBD/IPUSP como unidade gerenciadora, em parceria com a BIREME e o Fórum das Entidades Brasileiras de Psicologia. Discutiu-se o processo de adoção de ferramentas tecnológicas e outros aspectos relacionados sempre que uma Unidade de Informação intente tal empreitada. As novas tecnologias sejam da metodologia BIREME ou softwares proprietários permitiram maior flexibilidade na inclusão de novas fontes de informação. Os profissionais técnicos e os administradores devem realizar um trabalho cooperativo na tomada de decisões, considerando a rápida introdução de novas interfaces. Assim são evitados problemas no uso de ferramentas em uma assimilação e manutenção pela equipe responsável. Em curto prazo, os profissionais devem prever as dificuldades, pois é quando ocorre o lançamento de uma biblioteca virtual.

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_3N, Fe_4N and CrN phases for all temperatures, but with different concentrations. Nitriding increased significantly the AISI H13 wear resistance. (author)

Zr/ZrC modified layer formed on AISI 440B stainless steel by plasma Zr-alloying

Science.gov (United States)

Shen, H. H.; Liu, L.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

2016-12-01

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.

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.

Determination of Proper Austenitization Temperatures for Hot Stamping of AISI 4140 Steel

Science.gov (United States)

Samadian, Pedram; Parsa, Mohammad Habibi; Shakeri, Amid

2014-04-01

High strength steels are desirable materials for use in automobile bodies in order to reduce vehicle weight and increase the safety of car passengers, but steel grades with high strength commonly show poor formability. Recently, steels with controlled microstructures and compositions are used to gain adequate strength after hot stamping while maintaining good formability during processing. In this study, microstructure evolutions and changes in mechanical properties of AISI 4140 steel sheets resulting from the hot stamping process at different austenitization temperatures were investigated. To determine the proper austenitization temperatures, the results were compared with those of the cold-worked and cold-worked plus quench-tempered specimens. Comparisons showed that the austenitization temperatures of 1000 and 1100 °C are proper for hot stamping of 3-mm-thick AISI 4140 steel sheets due to the resultant martensitic microstructure which led to the yield and ultimate tensile strength of 1.3 and 2.1 GPa, respectively. Such conditions resulted in more favorable simultaneous strength and elongation than those of hot-stamped conventional boron steels.

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

Mechanical behaviour of AISI 304/307 weldments creep tested at 7000C

International Nuclear Information System (INIS)

Pope, A.M.; Monteiro, S.N.; Silveira, T.L.

Preliminary observations on the mechanical behavior of AISI 304/347 weldments creep tested at 700 0 C are presented. The results are compared with those of similar welded joints isothermally treated at the same temperature for different times. The peculiar aspects in the mechanical behavior are discussed based on precipitation reactions which occur in the joint materials [pt

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.

Corrosion of stainless steel grades in molten NaOH/KOH eutectic at 250 C: AISI304 austenitic and 2205 duplex

Energy Technology Data Exchange (ETDEWEB)

Bozzini, B.; Bogani, F.; Scarselli, G. [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Via per Monteroni, 73100 Lecce (Italy); Barella, S.; Boniardi, M. [Dipartimento di Meccanica, Politecnico di Milano, via La Masa 34, 20156 Milano (Italy); Giovannelli, G.; Natali, S. [Dipartimento DICMA, Universita di Roma ' ' La Sapienza' ' , via Eudossiana 18, 00184 Roma (Italy)

2012-11-15

The present paper focuses on the corrosion of an austenitic (AISI304) and a duplex (2205) stainless steel grade in molten KOH/NaOH 50 w/o eutectic at 250 C. Experimental activities have been performed consisting in electrochemical measurements (linear sweep voltammetry and electrochemical impedance spectrometry) complemented by metallographic (in-plane and cross-sectional SEM micrography), structural (X-ray diffractometry) and compositional (EDX line-profiles) characterisation of the materials attacked under electrochemically controlled conditions. Electrochemical measurements have shown that AISI304 exhibits a passivating behaviour, characterised by two passivation peaks and a transpassive threshold, while duplex, does not yield a clear indication of passivation. AISI304 was found to fail by intergranular corrosion and to be covered in both passive and transpassive conditions, by an incoherent scale, containing electrolyte species. Duplex samples, instead tends to fail by homogeneous attack and exhibit a range of scale structures, depending on the applied potential. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

Microhardness measurement in AISI 321 stainless steel with niobium additions before and after fast neutron irradiation

International Nuclear Information System (INIS)

Galli, V.L.; Lucki, G.

1980-01-01

Data about influence of neutron irradiation on the microhardness of stainless steel of type AISI 321 with 0.05 and 0.1wt.% Nb additions are presented. The microhardness measurements were made in the range of 300 to 650 0 C, before and after fast neutron irradiation with fluences about 10 17 n/cm 2 . Our results indicate that radiation damage peaks occur around 480 0 C for the stainless steel of type AISI 321 without Nb addition, around 500 0 C for the composition with 0.05 wt.% Nb addition and around 570 0 C for the composition with 0.1 wt.% Nb addition. Microhardness data are in agreement with those obtained by means of electrical resistivity measurements, performed at the same conditions. (Author) [pt

Experimental Investigation of the Effect of Burnishing Force on Service Properties of AISI 1010 Steel Plates

Science.gov (United States)

Gharbi, F.; Sghaier, S.; Morel, F.; Benameur, T.

2015-02-01

This paper presents the results obtained with a new ball burnishing tool developed for the mechanical treatment of large flat surfaces. Several parameters can affect the mechanical behavior and fatigue of workpiece. Our study focused on the effect of the burnishing force on the surface quality and on the service properties (mechanical behavior, fatigue) of AISI 1010 steel hot-rolled plates. Experimental results assert that burnishing force not exceeding 300 N causes an increase in the ductility. In addition, results indicated that the effect of the burnishing force on the residual surface stress was greater in the direction of advance than in the cross-feed direction. Furthermore, the flat burnishing surfaces did not improve the fatigue strength of AISI 1010 steel flat specimens.

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.

Evaluación del comportamiento estructural y de resistencia a la corrosión de armaduras de acero inoxidable austenítico AISI 304 y dúplex AISI 2304 embebidas en morteros de cemento Pórtland

Directory of Open Access Journals (Sweden)

Medina, E.

2012-12-01

Full Text Available 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.

Se ha evaluado el comportamiento mecánico y estructural de dos aceros inoxidables corrugados, el austenítico EN 1.4301 (AISI 304 y el dúplex EN 1.4362 (AISI 2304, y se han comparado con el tradicional acero al carbono B500SD. El estudio se ha realizado en tres niveles: a nivel de barra, de sección y de pieza. Las diferentes características mecánicas de los aceros inoxidables condicionan el comportamiento a nivel de sección y de pieza estructural. El estudio del comportamiento frente a la corrosión de los dos aceros inoxidables se ha realizado mediante mediciones electroquímicas monitorizando el potencial de corrosión y la resistencia de polarización de armaduras embebidas en probetas de mortero contaminado con diferentes concentraciones de cloruros durante un tiempo de exposición de un año. Ambos aceros inoxidables permanecen en estado pasivo en las probetas para todos los contenidos de cloruros.

Efeito dos parâmetros de processo na obtenção e na microestrutura de juntas alumínio-aço realizadas mediante soldagem por atrito com pino não consumível (SAPNC

Directory of Open Access Journals (Sweden)

Edwar Andrés Torres López

2013-09-01

Full Text Available Os resultados bem-sucedidos apresentados na literatura acerca da soldagem por atrito com pino não consumível das juntas alumínio-aço, desconsideram o aspecto e formação de defeitos na junta como pontos de referência para sua avaliação. Igualmente aumenta a controvérsia acerca da presença de compostos intermetálicos do tipo Fe xAl y, somado à falta de informação sobre sua origem. O objetivo deste trabalho é determinar parâmetros adequados para a obtenção de juntas alumínio-aço livres de defeitos e sua relação com a formação de fases deletérias durante a soldagem por atrito com pino. Foram obtidas juntas soldadas consolidadas e foi determinada a microestrutura resultante destas juntas soldadas da liga de alumínio 6063-T5 e aço AISI SAE 1020. Utilizou-se uma ferramenta de carbeto de tungstênio (WC-14Co a velocidades de rotação e de avanço de 300 rpm e 150 mm.min-1, respectivamente. Foram empregados deslocamentos da ferramenta de +0,5; +1,0 e +1,5 mm. Os resultados realçam a importância do aporte energético na obtenção de juntas alumínio-aço com aspecto superficial e penetração adequados. A análise microestrutural revela a formação de sete regiões na junta soldada, destacando a zona termo-mecanicamente afetada no lado do aço, uma banda de grãos ultra finos de ferrita e a ausência de compostos intermetálicos na interface alumínio-aço.

Effect of caffeine inhibitor in corrosion rate and microstructure of KS01 carbon steel and AISI 1045 at media sea water

International Nuclear Information System (INIS)

Sulistioso Giat S; Setyo Purwanto; Deswita; Ari Handayani; Berta Vidyananda

2013-01-01

Many synthetic materials are good inhibitors for the prevention of corrosion . Many inhibitors are toxic, because of the influence of these toxic properties, recently use organic materials as corrosion inhibitors, that are not hazardous and environmentally friendly. In this study caffeine compounds used as corrosion inhibitors. This compound could be used as corrosion inhibitor because of the existence of their chemical groups that containing free electron pair, that is nitrogen. Corrosion rate testing conducted in sea water medium taken from the Northern region of Indramayu with variations of the concentration of caffeine 0, 50, 100, 150, and 200 ppm to determine the optimum concentration of caffeine in corrosion rate of carbon steel AISI 1045 and KS01 that a widely used on the cooling system in the industry. Corrosion rate of KS-01 steel before used in inhibitor media is 25,07 mpy that less than corrosion rate of carbon steel AISI 1045, is 45,82 mpy . The results of this study indicate that caffeine is able to inhibit the corrosion rate of both of samples with optimum efficiency KS01 for 64.38%, and AISI 1045 of 66.63%. The optimum concentration of caffeine to inhibited AISI 1045 is 150 ppm and for KS01 is 100 ppm,. Beside that analysis of microstructure for both samples have done, for media before and after inhibitor addition. (author)

The influence of Reynolds number on the galvanic corrosion of the copper/AISI 304 pair in aqueous LiBr solutions

International Nuclear Information System (INIS)

Montanes, M.T.; Sanchez-Tovar, R.; Garcia-Anton, J.; Perez-Herranz, V.

2009-01-01

The influence of Reynolds number on the galvanic corrosion of the copper/AISI 304 stainless steel pair in a concentrated lithium bromide solution was investigated according to the mixed potential theory. A hydraulic circuit was designed to study dynamic corrosion processes in situ. A potential relation between corrosion current density (i corr ) and Reynolds number (Re) was found for copper, showing a mixed control of a chemical step and mass transport through the corrosion products film with the predominance of the former. No dependence of i corr on Re could be established for AISI 304, showing a chemical step control. Moreover, under stagnant conditions, partial passivation may occur in AISI 304; however, under flowing conditions passivation is not possible. Copper is the anodic element of the pair under all flowing conditions analysed. The galvanic phenomenon is more important as Re increases, but the results show compatibility of both materials at all Re values analysed. Similarly, a potential relation between galvanic current density (i G ) and Re was found, showing a mixed control of a chemical step and mass transport with the predominance of the latter. Copper corrosion resistance decreases more rapidly as Re increases due to the AISI 304 galvanic effect: there is a synergy between the galvanic effect and the hydrodynamic conditions. Under stagnant conditions, the galvanic behaviour of the materials is close to the compatibility limit and an inversion of the anodic element of the galvanic pair takes place.

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.

Effect of noble metals on the corrosion of AISI 316L stainless steel in nitric acid

International Nuclear Information System (INIS)

Robin, R.; Andreoletti, G.; Fauvet, P.; Terlain, A.

2004-01-01

In the spent fuel treatment, the solutions of fission products contain dissolution fines, in particular platinoids. These solutions are stored into AISI 316L stainless steel tanks, and the contact of noble metallic particles such as platinoids with austenitic stainless steels may induce a shift of the steel corrosion potential towards the trans-passive domain by galvanic coupling. In that case, the steel may be polarized up to a potential value above the range of passive domain, that induces an increase of the corrosion current. The galvanic corrosion of AISI 316L stainless steel in contact with different platinoids has been investigated by electrochemical and gravimetric techniques. Two types of tests were conducted in 1 mol/L nitric acid media at 80 deg C: (1) polarization curves and (2) immersion tests with either platinoid powders (Ru, Rh, Pd) or true insoluble dissolution fines (radioactive laboratory test). The results of the study have shown that even if galvanic coupling enhances the corrosion rate by about a factor 10 in these conditions, the corrosion behavior of AISI 316L remains low (a corrosion rate below 6 μm/year, few small intergranular indentations). No specific effect of irradiation and of elements contained in radioactive fines (other than Ru, Rh and Pd) was observed on corrosion behavior. A platinoids-ranking has also been established according to their coupling potential: Ru > Pd > Rh. (authors)

Estereótipos e mulheres na cultura marroquina

OpenAIRE

Sadiqi,Fatima

2008-01-01

Estereótipos sobre as mulheres no Marrocos podem ser caracterizados como crenças culturais incompletas e inexatas mantidas por algumas pessoas e que se encontram inscritos em expressões lingüísticas ou em discursos subliminares. A cultura popular marroquina emprega representações poderosas para transmitir e sustentar tais estereótipos. Embora existam alguns estereótipos positivos, a maioria dos estereótipos sobre as mulheres no Marrocos é negativa e reflete ditames patriarcais subliminares qu...

Carbides crystalline structure of AISI M2 high-speed steel

International Nuclear Information System (INIS)

Serna, M.M.; Galego, E.; Rossi, J.L.

2005-01-01

The aim of this study was to identify the crystallographic structure of the extracted carbides of AISI M2 steel spray formed The structure determination of these carbides. The structure determination of these carbides is a very hard work. Since these structures were formed by atom migration it is not possible to reproduce them by a controlled process with a determined chemical composition. The solution of this problem is to obtain the carbide by chemical extraction from the steel. (Author)

CARACTERIZAÇÃO PÓS-COLHEITA E SENSORIAL DE GENÓTIPOS DE BANANEIRAS TIPO PRATA

Directory of Open Access Journals (Sweden)

ARIANE CASTRICINI

2015-03-01

Full Text Available RESUMO O norte de Minas Gerais é grande produtor de banana ‘Prata-Anã’ irrigada, cultura altamente suscetível ao Mal-do-Panamá. O uso de genótipos resistentes é uma alternativa, mas os frutos devem apresentar características pós-colheita o mais próximo possível da ‘Prata-Anã’, para melhor aceitação pelos consumidores. O objetivo do trabalho foi caracterizar frutos em pós-colheita, identificar a preferência e a intenção de compra de diferentes genótipos de bananeira tipo Prata. Os genótipos Prata-Anã, BRS Platina e Fhia-18. foram caracterizados no ponto de colheita (verdes e maduros (estádio seis de maturação, por avaliações químicas, físicas e sensoriais. Quando verde, ‘BRS Platina’ apresentou maior massa fresca e tamanho que ‘Fhia-18’ e ‘Prata-Anã’. ‘Fhia-18.’ teve a tonalidade verde da casca mais intensa que a dos demais genótipos. Madura, ‘BRS Platina’ foi mais firme, mas com a mesma resistência ao despencamento que ‘Fhia-18’ e superior à ‘Prata-Anã’. ‘Fhia-18’ apresentou cor da casca com amarelo mais clara e tão brilhante quanto da ‘Prata-Anã’, mas ‘BRS Platina’ teve a tonalidade de amarelo mais intensa. Bananas ‘Fhia-18’ foram mais ácidas, ‘BRS Platina’, com menor acidez titulável, e ‘Prata-Anã’, o maior teor de sólidos solúveis. Os genótipos Prata-Anã e BRS Platina tiveram maior preferência e intenção de compra pelos consumidores, sendo as bananas ‘Prata-Anã’ em dedos e ‘BRS Platina’ e ‘Fhia-18’ em dedos, buquê e penca, as mais preferidas. Entretanto, a maioria compraria bananas ‘Prata-Anã’ em buquê e ‘BRS Platina’ e ‘Fhia-18’ em penca. Enquanto verdes, os genótipos foram semelhantes à ‘Prata-Anã’, e maiores diferenças químicas e físicas ocorreram quando maduros.

Dynamic strain ageing of deformed nitrogen-alloyed AISI 316 stainless steels

International Nuclear Information System (INIS)

Ehrnsten, U.; Toivonen, A.; Ivanchenko, M.; Nevdacha, V.; Yagozinskyy, Y.; Haenninen, H.

2004-01-01

Intergranular stress corrosion cracking has occurred in BWR environment in non-sensitized, deformed austenitic stainless steel materials. The affecting parameters are so far not fully known, but deformation mechanisms may be decisive. The effect of deformation and nitrogen content on the behaviour of austenitic stainless steels was investigated. The materials were austenitic stainless steels of AISI 316L type with different amounts of nitrogen (0.03 - 0.18%) and they were mechanically deformed 0, 5 and 20%. The investigations are focused on the dynamic strain ageing (DSA) behaviour. A few crack growth rate measurements are performed on nuclear grade AISI 316NG material with different degrees of deformation (0, 5 and 20%). The effects of DSA on mechanical properties of these materials are evaluated based on peaks in ultimate tensile strength and strain hardening coefficient and minimum in ductility in the DSA temperature range. Additionally, internal friction measurements have been performed in the temperature range of -100 to 600 deg. C for determining nitrogen interactions with other alloying elements and dislocations (cold-worked samples). The results show an effect of nitrogen on the stainless steel behaviour, e.g. clear indications of dynamic strain ageing and changes in the internal friction peaks as a function of nitrogen content and amount of deformation. (authors)

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.

Effects of heat treatment conditions on microstructure and mechanical properties of AISI 420 steel

Energy Technology Data Exchange (ETDEWEB)

Scheuer, C.J.; Fraga, R.A.; Cardoso, R.P.; Brunatto, S.F. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Departamento de Engenharia Mecanica. Grupo de Tecnologia de Fabricacao Assistida por Plasma e Metalurgia do Po

2014-07-01

The cycle control of heat treatments, on the quenching and tempering operation of AISI 420 stainless steel, is essential for improved material performance. The adequate choice of heat treatment parameters, can lead an optimization on its mechanical properties and corrosion resistance. Thus, this paper aims to investigate the effects of quenchants medium, and austenitizing and tempering temperatures, on the microstructure and mechanical properties of AISI 420 steel. Different heat treatments cycles were studied: 1) samples were austenitized at 1050°C and water, oil and air quenched; 2) samples were austenitized at range temperatures of 950-1050°C and oil quenched; and 3) as-quenched samples were tempering at range temperatures of 400-500°C. Treated samples were characterized by optical microscopy, X-ray diffractometry and hardness measurements. The samples hardness increases with increasing cooling rate (water > oil > air quenched). Water quenched samples presented crack after cooling to room temperature. Samples hardness also increases with austenitizing temperature increasing, and decreases with increasing tempering temperature. (author)

Surface nanocrystallization by surface mechanical attrition treatment and its effect on structure and properties of plasma nitrided AISI 321 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Lin Yimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Middle Tianshui Road, Lanzhou 730000 (China) and Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China)]. E-mail: linyimin_2001@yahoo.com.cn; Lu Jian [LASMIS, University of Technology of Troyes, 10000 Troyes (France); Wang Liping [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Middle Tianshui Road, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Xu Tao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Middle Tianshui Road, Lanzhou 730000 (China); Xue Qunji [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Middle Tianshui Road, Lanzhou 730000 (China)]. E-mail: qjxue@ns.lzb.ac.cn

2006-12-15

A plastic deformation surface layer with nanocrystalline grains was produced on AISI 321 austenitic stainless steel by means of surface mechanical attrition treatment (SMAT). Low-temperature nitriding of SMAT and un-SMAT AISI 321 stainless steel was carried out in pulsed-DC glow discharge. The effect of SMAT pretreatment on the microstructure and properties of the stainless steel were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Vickers hardness tester and UMT-2MT tribometer. The results show that the plasma nitriding of AISI 321 steel can be enhanced considerably by means of SMAT process before nitriding, and a much thicker nitrogen diffusion layer with higher hardness was obtained for the SMAT samples when compared with un-SMAT samples. In addition, the wear resistance and load capacity of the nitrided layers on the SMAT samples was much higher than that of the un-SMAT samples due to the thicker S phase case and the gradient nitrogen diffusion layer.

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)

O e-mail como ferramenta de marketing: uma revisão da literatura

OpenAIRE

Fortes, Nuno; Rita, Paulo

2004-01-01

Este artigo, assente exclusivamente em revisão bibliográfica, pretende apresentar as potencialidades do e-mail como uma ferramenta de comunicação de marketing. Em virtude do universo do e-mail marketing estar ensombrado por um crescente fenómeno de spam, são apresentadas duas abordagens alternativas, mas complementares - o marketing de permissão e o marketing viral-, capazes de manterem em níveis elevados os indicadores de eficácia das campanhas.

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.

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...

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)

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

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...

TIPOS DE DISCURSO

OpenAIRE

Garcia, Afrânio; UERJ

2012-01-01

O professor Adilson Citelli, em seu excelente livro Linguageme persuasão, apresenta cinco tipos de discurso:§ discurso dominante§ discurso autorizado§ discurso polêmico,§ discurso lúdico§ discurso autoritário.

Plasma nitriding process by direct current glow discharge at low temperature increasing the thermal diffusivity of AISI 304 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Prandel, L. V.; Somer, A.; Assmann, A.; Camelotti, F.; Costa, G.; Bonardi, C.; Jurelo, A. R.; Rodrigues, J. B.; Cruz, G. K. [Universidade Estadual de Ponta Grossa, Grupo de Espectroscopia Optica e Fotoacustica de Materiais, Departamento de Fisica, Av. Carlos Cavalcanti, 4748, CEP 84030-900, Ponta Grossa, PR (Brazil)

2013-02-14

This work reports for the first time on the use of the open photoacoustic cell technique operating at very low frequencies and at room temperature to experimentally determine the thermal diffusivity parameter of commercial AISI304 stainless steel and AISI304 stainless steel nitrided samples. Complementary measurements of X-ray diffraction and scanning electron microscopy were also performed. The results show that in standard AISI 304 stainless steel samples the thermal diffusivity is (4.0 {+-} 0.3) Multiplication-Sign 10{sup -6} m{sup 2}/s. After the nitriding process, the thermal diffusivity increases to the value (7.1 {+-} 0.5) Multiplication-Sign 10{sup -6} m{sup 2}/s. The results are being associated to the diffusion process of nitrogen into the surface of the sample. Carrying out subsequent thermal treatment at 500 Degree-Sign C, the thermal diffusivity increases up to (12.0 {+-} 2) Multiplication-Sign 10{sup -6} m{sup 2}/s. Now the observed growing in the thermal diffusivity must be related to the change in the phases contained in the nitrided layer.

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

Directory of Open Access Journals (Sweden)

Sylvia Dundeková

2014-11-01

Full Text Available Mechanical and fatigue properties of material are dependent on its microstructure. The microstructure of AISI 316L stainless steel commonly used for the production of medical tools, equipment and implants can be easily influenced by its heat treatment. Microstructural changes and fatigue properties of AISI 316L stainless steel due to the heat treatment consisted of annealing at the temperature of 815°C with the dwell time of 500 hours were analyzed in the present paper. Precipitation of intermetallic phases and carbides was observed as a response of the material to the applied heat treatment. Small negative influence was observed in the case of fatigue region bellow 105 cycles; however the fatigue limit remains unchanged due to the structural sensitization.

Corrosion behavior of plasma sprayed hydroxyapatite and hydroxyapatite-silicon oxide coatings on AISI 304 for biomedical application

International Nuclear Information System (INIS)

Singh, Gurpreet; Singh, Hazoor; Sidhu, Buta Singh

2013-01-01

The objective of this study is to evaluate corrosion resistance of plasma sprayed hydroxyapatite (HA) and HA-silicon oxide (SiO 2 ) coated AISI 304 substrates. In HA-SiO 2 coatings, 10 wt% SiO 2 and 20 wt% SiO 2 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 HA-SiO 2 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.

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

UTILIZAÇÃO DE WEBQUESTS NA FORMA DE BLOG COMO FERRAMENTA DE APRENDIZAGEM NA DISCIPLINA CIÊNCIA DOS MATERIAIS

Directory of Open Access Journals (Sweden)

Fábio Edenei Mainginski

Full Text Available Esta pesquisa visa apresentar uma ferramenta metodológica utilizada, no ensino de engenharia, como uma proposta do Programa de Mestrado em Ensino de Ciência e Tecnologia do campus Ponta Grossa, da Universidade Tecnológica Federal do Paraná. A ferramenta utilizada foi a webquest, considerada uma metodologia para organizar o processo de ensi no utilizando recursos da internet, o que auxilia os estudantes na construção do conhecimento em um ambiente de aprendizagem. Tal metodologia foi aplicada aos estudantes da disciplina Ciência dos Materiais dos cursos de Engenharia em Controle e Automação e Engenharia Mecânica. O referen cial teórico que embasou o trabalho foi construído pelos estudos de David Ausubel sobre aprendizagem significativa, bem como pelas Tecnologias da Informação e Comunicação na Educação (TICs. A conclusão que pode ser obtida com a utilização dessa junção de ferramentas (webquest e blog é que quando os meios interativos aliam-se ao processo de ensino, há o enriqueci mento da aprendizagem do aluno. O fato de a informação ficar disponibi lizada o tempo todo aumenta a possibilidade de intervenções. Os aspectos de interação social, reintegração do aluno às aulas e ativador da curiosidade foram os pontos positivos apontados pelos alunos.

Percebendo uma ferramenta de ensino a distância na formação em saúde em uma faculdade de odontologia do sul Brasil

OpenAIRE

Grando, Alessandra Maria; Bulgarelli, Patricia Távora; Mestriner, Soraya Fernandes; Bulgarelli, Alexandre Fávero

2016-01-01

Esta pesquisa objetivou observar a efetividade e a aplicabilidade da ferramenta digital Moodle no ensino da Odontogeriatria. Alunos da Faculdade de Odontologia, da Universidade Federal do Rio Grande do Sul, foram os pioneiros, nesta disciplina, na utilização desta plataforma on-line de ensino à distância. A partir da perspectiva construcionista social e a utilização de dois grupos focais para coleta de dados, conseguimos analisar as percepções dos alunos que utilizaram a referida ferramenta n...

Effects of static strain aging on residual stress stability and alternating bending strength of shot peened AISI 4140

Energy Technology Data Exchange (ETDEWEB)

Menig, R.; Schulze, V.; Voehringer, O. [Inst. fuer Werkstoffkunde 1, Univ. Karlsruhe (TH), Karlsruhe (Germany)

2002-07-01

Increases of residual stress stability and alternating bending strength of shot peened AISI 4140 are obtained by successive annealing treatments. This is caused by static strain aging effects, which lead to pinning of dislocations by carbon atoms and very small carbides. It will be shown that by well directed annealing of a quenched and tempered AISI 4140 it is possible to maximize the positive effects of static strain aging, without causing extended thermal residual stress relaxation. The amount of yield stress increases caused by static strain aging is quantified using tensile tests. Static strain aging is also found to be responsible for an increase of the quasi static and cyclic surface yield strength present after shot peening. (orig.)

BMMobile: uma linha de produtos para dimensionamento de bombeio mecânico em dispositivos móveis

OpenAIRE

Sousa, Matheus Alves de

2010-01-01

Com o aumento da capacidade de processamento, armazenamento e a variedade de tipos de comunicação existentes, como Bluetooth, infravermelho, redes sem fio, etc., os dispositivos móveis deixaram de ser apenas dispositivos com função especifica e passaram a ser ferramentas com diversos tipos de funcionalidade. No campo empresarial os benefícios que estes tipos de dispositivos oferecem são consideráveis, uma vez que a portabilidade permite que tarefas que antes só poderiam ser ...

Comparative tribological studies of duplex surface treated AISI 1045 steels fabricated by combinations of plasma nitriding and aluminizing

International Nuclear Information System (INIS)

Haftlang, Farahnaz; Habibolahzadeh, Ali; Sohi, Mahmoud Heydarzadeh

2014-01-01

Highlights: • AlN coating was applied on AISI 1045 steel via plasma nitriding and aluminizing. • Aluminizing of pre-nitrided specimen provides the highest surface hardness. • The lowest wear rate was obtained via aluminizing of pre-nitrided specimen. • Wear mechanism of the modified layer consists of oxidative and spallung wear. - Abstract: Duplex surface treatments via aluminizing and plasma nitriding were carried out on AISI 1045 steel. A number of work pieces were aluminized and subsequently plasma nitrided (Al–PN) and other work pieces were plasma nitrided and then aluminized (PN–Al). Aluminizing was carried out via pack process at 1123 K for 5 h and plasma nitriding was performed at 823 K for 5 h. The fabricated steels were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and microhardness testing. Tribological behaviors of the duplex treated AISI 1045 steels were examined against tungsten carbide pin using a pin-on-disc apparatus at room temperature. The PN–Al specimen showed higher surface hardness, lower wear rate and coefficient of friction than the Al–PN one. It was noticed from the worn surfaces that tribo-oxidation plays an important role in wear behavior of both specimens

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.

Estudio mediante difracción de rayos X de las tensiones residuales producidas durante el depósito de películas delgadas de TiN sobre sustratos metálicos

Directory of Open Access Journals (Sweden)

Mónica Monsalve

2010-01-01

Full Text Available En este trabajo se analizó la influencia que tiene el espesor de la película y el tipo de sustrato en el nivel y tipo de esfuerzos residuales generados en recubrimientos de TiN obtenidos por dos técnicas de deposición física en fase vapor: pulverización catódica con magnetrón e implantación iónica. Los sustratos utilizados fueron un acero inoxidable AISI 304 y un acero de herramientas AISI M2. Las tensiones residuales, las fases presentes y la orientación cristalográfica de las películas depositadas fueron obtenidas mediante análisis de difracción de rayos X por incidencia rasante. Se encontró que los esfuerzos residuales fueron mayores en las películas depositadas por la técnica de pulverización catódica con magnetrón que en las depositadas por la técnica de implantación iónica. En ambos casos estos esfuerzos son de compresión y disminuyen en la medida que aumenta el espesor de la película. Esto se debe a la forma como se entrega la energía, la capa en crecimiento y el momentum de las partículas ionizadas, lo que influye directamente en la microestructura y aumento o disminución de los esfuerzos residuales. En cuanto al tipo de sustrato se obtuvieron esfuerzos mayores en las películas depositadas sobre el acero AISI 304 que en las depositadas sobre el acero AISI M2, lo cual se debe posiblemente a que este último acero tiene un menor coeficiente de expansión térmica.

A preliminary study of laser cladding of AISI 316 stainless steel using preplaced NiTi wire

International Nuclear Information System (INIS)

Cheng, F.T.; Lo, K.H.; Man, H.C.

2004-01-01

NiTi wire of diameter 1 mm was preplaced on AISI 316 stainless steel samples by using a binder. Melting of the NiTi wire to form a clad track on the steel substrate was achieved by means of a high-power CW Nd:YAG laser using different processing parameters. The geometry and microstructure of the clad deposit were studied by optical microscopy and scanning electron microscopy (SEM), respectively. The hardness and compositional profiles along the depth of the deposit were acquired by microhardness testing and energy-dispersive spectroscopy (EDS), respectively. The elastic behavior of the deposit was analyzed using nanoindentation, and compared with that of the NiTi wire. The dilution of the NiTi clad by the substrate material beneath was substantial in single clad tracks, but could be successively reduced in multiple clad layers. A strong fusion bonding with tough interface could be obtained as evidenced by the integrity of Vickers indentations in the interfacial region. In comparison with the NiTi cladding on AISI 316 using the tungsten inert gas (TIG) process, the laser process was capable of producing a much less defective cladding with a more homogeneous microstructure, which is an essential cladding quality with respect to cavitation erosion and corrosion resistance. Thus, the present preliminary study shows that laser cladding using preplaced wire is a feasible method to obtain a thick and homogeneous NiTi-based alloy layer on AISI 316 stainless steel substrate

Aplicação da ferramenta de cep num processo siderúrgico

Directory of Open Access Journals (Sweden)

Rafael Zimmermann Stefani

2014-08-01

Full Text Available O presente trabalho tem como objetivo apresentar uma aplicação prática da utilização de cartas de controle dentro de um projeto Seis Sigma propiciando um melhor entendimento da variabilidade relacionado a dureza da água no molde, um parâmetro crítico do processo que repercute na formação de defeitos em barras laminadas a partir de tarugos lingotados numa aciaria elétrica. No case apresentado, a utilização da ferramenta possibilita a identificação de uma anomalia para remoção imediata.

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

Tool life and surface roughness of ceramic cutting tool when turning AISI D2 tool steel

International Nuclear Information System (INIS)

Wan Emri Wan Abdul Rahaman

2007-01-01

The tool life of physical vapor deposition (PVD) titanium nitride (TiN) coated ceramic when turning AISI D2 tool steel of hardness 54-55 HRC was investigated. The experiments were conducted at various cutting speed and feed rate combinations with constant depth of cut and under dry cutting condition. The tool life of the cutting tool for all cutting conditions was obtained. The tool failure mode and wear mechanism were also investigated. The wear mechanism that is responsible for the wear form is abrasion and diffusion. Flank wear and crater wear are the main wear form found when turning AISI D2 grade hardened steel with 54-55 HRC using KY 4400 ceramic cutting tool. Additionally catastrophic failure is observed at cutting speed of 183 m/min and feed rate of 0.16 mm/ rev. (author)

LaCrO3 composite coatings for AISI 444 stainless steel solid oxide fuel cell interconnects

Directory of Open Access Journals (Sweden)

Wilson Acchar

2012-12-01

Full Text Available Doped lanthanum chromite-based ceramics are the most widely used interconnector material in solid fuel cells (SOFC since they exhibit significant electrical and thermal conductivity, substantial corrosion resistance and adequate mechanical strength at ambient and high temperatures. The disadvantage of this material is its high cost and poor ductility. The aim of this study is to determine the mechanical and oxidation behavior of a stainless steel (AISI 444 with a LaCrO3 deposition on its surface obtained through spray pyrolisis. Coated and pure AISI 444 materials were characterized by mechanical properties, oxidation behavior, X-ray diffraction and scanning electronic microscopy. Results indicated that the coated material displays better oxidation behavior in comparison to pure stainless steel, but no improvement in mechanical strength. Both materials indicate that deformation behavior depends on testing temperatures.

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

Um levantamento sobre do uso de ferramentas da Web 2.0 entre os estudantes da Ciência da Informação da Universidade Federal de Santa Catarina

Directory of Open Access Journals (Sweden)

Eduarda Bodaneze de Oliveira

2014-04-01

Full Text Available http://dx.doi.org/10.5007/1518-2924.2014v19n39p153   Nas últimas décadas, puderam-se verificar enormes mudanças nas relações sociais e grandes transformações nos sistemas de comunicação que tornaram mais rápidos os fluxos de informação por meio dos recursos da Internet. A ideia de uma Web 2.0 (a Web colaborativa agrega ideais de colaboração, interação e participação que proporcionam, através de uma organização em rede, uma intensa produção de informação. Este trabalho analisa o uso de ferramentas da Web 2.0 pelos alunos do Departamento de Ciência da Informação da Universidade Federal de Santa Catarina através da caracterização do perfil dos estudantes como usuários destas ferramentas, da identificação das áreas de interesse, das ferramentas mais utilizadas e das principais finalidades de uso das redes sociais Facebook, Twitter e LinkedIn. O estudo concluiu que há um grande potencial, dentro do segmento avaliado, para a troca de informações e difusão de conhecimentos através das ferramentas da Web 2.0. Além disso, estas ferramentas são vistas pelo público-alvo da pesquisa como sendo de grande utilidade, tanto para funções pessoais e de relacionamento quanto para interesses acadêmicos e profissionais.

Funcionamiento psicofisiológico y susceptibilidad a la sintomatología premenstrual en mujeres Tipo A y Tipo B

Directory of Open Access Journals (Sweden)

Francesc Palmero

2002-01-01

Full Text Available El presente trabajo se centra en explorar el papel que juega el componente emocional del Patrón de Conducta Tipo A (PCTA en diversas áreas relacionadas con la salud. En este contexto nuestra investigación desarrolla dos objetivos diferenciados. El primero trata de constatar la relación entre determinadas características del PCTA y el mecanismo psicofisiológico en una tarea experimental de estrés real (situación de examen, considerando si existen diferencias entre los dos grupos de personas, Tipo A y Tipo B, tanto en la dimensión tónica como en la dimensión fásica de la tasa cardiaca. El segundo de nuestros objetivos trata de establecer la relación existente entre determinadas características del PCTA y la experiencia de sintomatología relacionada con el ciclo menstrual, considerando tanto la sintomatología premenstrual global, como la sintomatología premenstrual específica, diferenciando tres grandes grupos de síntomas: fisiológicos, psicológicos y conductuales. La muestra final estuvo conformada por 28 mujeres Tipo A y 29 mujeres Tipo B. Los instrumentos utilizados fueron el inventario de Actividad de Jenkins (JAS, el calendario menstrual de síntomas de registro diario (CMSRD y un polígrafo que permitió registrar la tasa cardiaca. En cuanto a nuestro primer objetivo, los datos hacen pensar en la existencia de distintos perfiles psicofisiológicos en ambos grupos de mujeres; en el segundo objetivo, parece que las mujeres Tipo A experimentan de forma clara más síntomas psicológicos que las mujeres Tipo B.

Physical and Tribological Properties of Nitrided AISI 316 Stainless Steel Balls

Directory of Open Access Journals (Sweden)

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.

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...

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.

Effect of the oxygen partial pressure on ferritic stainless steel AISI 441 at high temperatures

International Nuclear Information System (INIS)

Salgado, M.F.; Carvalho, I.S.; Santos, R.S.; Correa, O.V.; Ramanathan, L.V.

2014-01-01

Stainless steels can be exposed to aggressive gases at high temperatures. To understand the behavior of oxidation of the steel AISI 441 was made oxidation at temperatures between 850 ° C and 950 ° C, at two different atmospheres: synthetic air, using tubular furnace and Argon, containing 1ppm O_2, in thermobalance. The kinetics of oxidation of the films was established by measuring the mass gain per unit of area as a function of the oxidation time. The microstructure and chemical composition of the oxides were analyzed by SEM, EDS and XRD. Chemical analysis showed that films formed on steel AISI 441 had mostly chromium oxide and the following elements: Cr, Mn, Fe, Ti and Si. Regarding the kinetics of oxidation, it was observed that in synthetic air, the steel oxidation increased gradually with the temperature, but in argon, it showed the highest oxidation at 900 ° C and the lowest oxidation at 950 ° C. (author)

Relating high-temperature flow stress of AISI 316 stainless steel to strain and strain rate

International Nuclear Information System (INIS)

Matteazzi, S.; Paitti, G.; Boerman, D.

1982-01-01

The authors have performed an experimental determination of tensile stress-strain curves for different strain rates (4.67 x 10 - 5 , 4.67 x 10 - 2 s - 1 ) and for a variety of temperature conditions (773-1073 K) of AISI 316H stainless steel (annealed conditions) and also a computer analysis of the experimental curves using a fitting program which takes into consideration different constitutive relations describing the plastic flow behaviour of the metals. The results show that the materials tested are clearly affected by strain rate only at the highest temperature investigated (1073 K) and that the plastic strain is the more significant variable. Of the constitutive equations considered, Voce's relation gives the best fit for the true stress-time-strain curves. However, the Ludwik and Ludwigson equations also provide a description of the experimental data, whereas Hollomon's equation does not suitably characterize AISI 316H stainless steel and can be applied with some accuracy only at 1073 K. (author)

Reação de resistência tipo I e tipo II a Giberela em cultivares de trigo

Directory of Open Access Journals (Sweden)

Rafael Hansen Alves

2013-09-01

Full Text Available O objetivo deste trabalho foi avaliar as reações de resistência tipo I e tipo II à giberela em 28 cultivares de trigo em casa de vegetação. A inoculação de Fusarium graminearum foi realizada no estádio de florescimento. Para a resistência tipo I, a avaliação foi feita 21 dias após a inoculação. Foi determinada a severidade no estádio de espiga seca e a porcentagem de grãos giberelados. A avaliação da severidade foi feita pela porcentagem de espiguetas infectadas, no estádio de espiga verde atribuindo-se uma nota em uma escala linear de zero (nenhuma infecção a 100 (100% de espiguetas infectadas. Para a resistência tipo II, as avaliações foram realizadas aos 7, 14 e 21 dias após a inoculação, contando-se as espiguetas com sintomas da doença, excluindo as duas espiguetas que foram inoculadas. As cultivares Frontana, BRS 177, BRS 179, BRS Umbu, BRS Camboim, Abalone, Ônix, Pampeano e Fundacep 30 apresentaram menor severidade da doença e menor porcentagem de grãos giberelados, demonstrando serem fontes de resistência tipo I. As cultivares BRS Guamirim, CD 120, Onix, Rubi, Fundacep 50, BRS 179, Pampeano, Abalone, CD 114, IPR 85, Safira, BRS Louro, CD 117, CDF 2002116, CD 115, BRS 177, CD 0529 e BRS Camboim apresentaram a menor área abaixo da curva de progresso da doença, demonstrando a presença da resistência do tipo II.

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

International Nuclear Information System (INIS)

Aadhavan, R.; Suresh Babu, K.

2017-01-01

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"−"3 kg"2 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.

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.

Effect of mechanical activation on jell boronizing treatment of the AISI 4140

Science.gov (United States)

Yılmaz, S. O.; Karataş, S.

2013-06-01

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO2-Na2O) powders for 873-1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as function of treatment time and temperature in the range of 873-1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 μm was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000-2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe2B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

Improving by postoxidation of corrosion resistance of plasma nitrocarburized AISI 316 stainless steels

Science.gov (United States)

Yenilmez, A.; Karakan, M.; Çelik, İ.

2017-01-01

Austenitic stainless steels are widely used in several industries such as chemistry, food, health and space due to their perfect corrosion resistance. However, in addition to corrosion resistance, the mechanic and tribological features such as wear resistance and friction are required to be good in the production and engineering of this type of machines, equipment and mechanic parts. In this study, ferritic (FNC) and austenitic (ANC) nitrocarburizing were applied on AISI 316 stainless steel specimens with perfect corrosion resistance in the plasma environment at the definite time (4 h) and constant gas mixture atmosphere. In order to recover corrosion resistance which was deteriorated after nitrocarburizing again, plasma postoxidation process (45 min) was applied. After the duplex treatment, the specimens' structural analyses with XRD and SEM methods, corrosion analysis with polarization method and surface hardness with microhardness method were examined. At the end of the studies, AISI 316 surface hardness of stainless steel increased with nitrocarburizing process, but the corrosion resistance was deteriorated with FNC (570 °C) and ANC (670 °C) nitrocarburizing. With the following of the postoxidation treatment, it was detected that the corrosion resistance became better and it approached its value before the process.

The electrochemical behaviour of stainless steel AISI 304 in alkaline solutions with different pH in the presence of chlorides

International Nuclear Information System (INIS)

Freire, L.; Carmezim, M.J.; Ferreira, M.G.S.; Montemor, M.F.

2011-01-01

Highlights: → The passivation and passivation breakdown of AISI 304 in alkaline solutions with different pH was studied. → The electrochemical behaviour and the corrosion resistance in chloride environments were evaluated using d.c. potentiodynamic polarization and electrochemical impedance spectroscopy. → The results were modelled using a hierarchically distributed circuit and revealed a more susceptible surface at pH 9. → The passive film characterization was carried out by SEM and EDS analysis, revealing the existence of MnS inclusions and the increase of Cr/Fe ratio in the attacked areas, preferably the vicinity of those inclusions. - Abstract: Nowadays, stainless steel reinforcements appear as an effective solution to increase the durability of reinforced concrete structures exposed to very aggressive environments. AISI 304 is widely used for this purpose. Although the improved durability of reinforcing AISI 304, when compared to carbon steel, there is a high probability of pitting susceptibility in the presence of chlorides. Thus, the present work aims at studying the passivation and passivation breakdown of AISI 304 in alkaline solutions of different pH (pH from 13 to 9), simulating the interstitial concrete electrolyte. These solutions were contaminated with different concentrations of chloride ions (3% and 10%, as NaCl). The electrochemical behaviour was evaluated by d.c. potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The morphological features and the changes observed in the surface composition were evaluated by Scanning Electron Microscopy (SEM) together with EDS chemical analysis. The results evidence that pH plays an important role in the evolution of the film resistance and charge transfer processes. Moreover, the effect is highly dependent upon the chloride content and immersion time.

Transparência e Replicabilidade na Pesquisa Empírica em Direito: conceitos e ferramentas

OpenAIRE

Oliveira, Paulo

2018-01-01

Com o crescimento das pesquisas empíricas em Direito quais as práticas devem ser adotadas pelos pesquisadores para acompanhar o Padrão Ouro da pesquisa? Quais os conceitos necessários para que a Pesquisa Empírica possa crescer de forma sustentável e democrática? Esse artigo tenta delinear alguns conceitos importantes da Ciência 2.0 e mostra algumas das principais ferramentas para atingir plenamente o ideal de Ciência Aberta.

Application of the EPR technique in welded couplings in 08X18H10T (AISI 321) stainless steel

International Nuclear Information System (INIS)

Fuentes, D.A.; Menendez, C.M.; Dominguez, H.; Sendoya, F.

1993-01-01

Stainless steel samples, one AISI 304 and the other 08X18H10T of Soviet origin (equivalent to AISI 320) were welded for the TIG method, submitted to a thermal treatment in order to its sensitization against the intergranular corrosion, then the samples were submitted to the EPR technique in order to establish the sensitization degree which is an indicative of susceptibility to intergranular corrosion. The result were corroborated by two different methodologies, the ASTM A262 standard and the soviet standard GOST 6032-89. The state of the tested surface was analyzed using optical microscopy in order to quantify the number of pricking since its presence disturbs the normalized charge, Pa. (Author)

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.

Processing of plane strain compression test results for investigation of AISI-304 stainless steel constitutive behavior

International Nuclear Information System (INIS)

Aksenov, Sergey A.; Puzino, Yuriy A.; Bober, Stanislav A.; Kliber, Jiri

2015-01-01

The paper is oriented toward the determination of constitutive equation constants by the inverse analysis of plane strain compression test results. The interpretation of such results is complicated by the inhomogeneity of strain rate distribution in the specimen caused by rigid ends, the lateral spreading of a specimen friction and the variation of temperature during the test. The results of plane strain compression tests of AISI-304 stainless steel are presented and significant deviations of temperature are observed at higher strain rates. Finite element simulation was performed to estimate the inhomogeneity of strain rate within the specimen and evaluate the effect of friction on the test results. Constitutive equations of the material were obtained by inverse analysis minimizing the deviations between the measured load values and the ones predicted by numerical simulation. Keywords: PSCT, AISI-304, Gleeble, constitutive equations, hot forming, FEM, inverse analysis.

Microstructural interpretation of the fluence and temperature dependence of the mechanical properties of irradiated AISI 316

International Nuclear Information System (INIS)

Johnson, G.D.; Garner, F.A.; Brager, H.R.; Fish, R.L.

1980-01-01

The effects of neutron irradiation on the mechanical properties of annealed and 20% cold-worked AISI 316 irradiated in EBR-II were determined for the temperature regime of 370 to 760 0 C for fluences up to 8.4 x 10 22 n/cm 2 (E > 0.1 MeV). At irradiation temperatures below about 500 0 C, both annealed and cold-worked material exhibit a substantial increase in the flow stress with increasing fluence. Furthermore, both materials eventually exhibit the same flow stress, which is independent of fluence. At temperatures in the range of 538 to 650 0 C, the cold-worked material exhibits a softening with increasing fluence. Annealed AISI 316 in this temperature regime exhibits hardening and at a fluence of 2 to 3 x 10 22 n/cm 2 (E > 0.1 MeV) reaches the same value of flow stress as the cold-worked material

INTER-RELAÇÃO DA FERRAMENTA APQP E DO GUIA PMBOK PARA EFICIÊNCIA NAS ETAPAS DE IMPLEMENTAÇÃO DE NOVOS PROJETOS NA INDÚSTRIA AUTOMOTIVA

Directory of Open Access Journals (Sweden)

Jean Cristhiano Franco

2014-06-01

Full Text Available O desenvolvimento de novos projetos na industria automotiva apresenta-se como um projeto de grande porte, regido por metodologias, guias e ferramentas estruturadas que visam garantir a eficácia do projeto. Esta pesquisa foi desenvolvida com o intuito de contribuir para um maior entendimento entre a ferramenta APQP, de grande aplicação na industria automotiva, e o guia PMBOK, considerado referência no gerenciamento de projetos. Neste âmbito, este estudo realiza uma análise comparativa entre suas principais características, identificando suas semelhanças e divergências. Dentre os diversos resultados do estudo, é possível identificar que o guia PMBOK é mais completo que a ferramenta APQP utilizada no setor automobilístico, uma vez que traz de forma mais detalhada as etapas e as técnicas que são indicadas nas atividades, segundo as boas práticas dos PMPs (Project Management Professional.

Vacancy clustering behavior in hydrogen-charged martensitic steel AISI 410 under tensile deformation

International Nuclear Information System (INIS)

Sugita, K; Mutou, Y; Shirai, Y

2016-01-01

The formation and accumulation of defects under tensile deformation of hydrogen- charged AISI 410 martensitic steels were investigated by using positron lifetime spectroscopy. During the deformation process, dislocations and vacancy-clusters were introduced and increased with increasing strains. Between hydrogen-charged and uncharged samples with the same tensile strains there was no significant difference in the dislocation density and monovacancy equivalent vacancy density. (paper)

Cladding of Ni superalloy powders on AISI 4140 steel with concentrated solar energy

Energy Technology Data Exchange (ETDEWEB)

Fernandez, B.J.; Lopez, V.; Vazquez, A.J. [Centro Nacional de Investigaciones Metalurgicas, CENIM-CSIC, Madrid (Spain); Martinez, D. [Plataforma Solar de Almeria, Tabernas Almeria (Spain)

1998-05-12

The present work deals with Ni alloy cladding on AISI 4140 steel samples made with high power density concentrated solar beams. The quality of the cladding is high concerning the adherence, low dilution and high hardness of the coating. Some considerations are presented concerning the future of high power density beams related to SUrface Modification of Metallic mAterials with SOLar Energy (SUMMA cum SOLE)

Kajian Aus Pahat pada pembubutan Baja Aisi 4340 Menggunakan Pahat Karbida PVD Berlapis

OpenAIRE

Carnegie, Dale

2017-01-01

120401084 Pada industri pemotongan logam, cairan pendingin banyak digunakan untuk memperoleh umur pahat yang lebih lama, tetapi cairan pendingin yang digunakan pada proses pemotongan logam mempunyai beberapa dampak negatif bagi kesehatan dan lingkungan. Oleh karena itu dilakukan permesinan kering pada penelitian ini untuk membuat proses pemotongan logam yang bersih dan aman terhadap lingkungan. Proses pembubutan dilakukan juga dengan permesinan keras untuk membubut material baja AISI 4340 ...

Parâmetros de desempenho e carcaça de genótipos de frangos tipo caipira

Directory of Open Access Journals (Sweden)

R.C. Veloso

2014-08-01

Full Text Available Objetivou-se com este trabalho avaliar as características de desempenho e de carcaça de sete genótipos de frangos tipo caipira da linhagem Redbro. 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. Os frangos foram alojados em 28 boxes, sendo 30 frangos por boxe, em galpão de alvenaria com acesso a um piquete de 45m², em quatro repetições. As características de desempenho (conversão alimentar, ganho em peso médio diário, consumo de ração médio diário foram avaliadas nos períodos: um a 28, um a 56, um a 70 e um a 84 dias de idade. O peso corporal foi avaliado aos 28, 56, 70 e 84 dias de idade. As características de carcaça (peso e rendimento de carcaça, peito e pernas foram obtidas a partir do abate de dois frangos por boxe, aos 85 dias de idade. As análises estatísticas foram realizadas utilizando-se o "proc glm" do SAS. Verificou-se que, em todos os períodos, os frangos do genótipo Colorpak apresentaram maior peso corporal, consumo de ração médio diário, ganho em peso médio diário e melhor conversão alimentar. Entretanto, os genótipos Caboclo e Gigante Negro apresentaram menores consumo de ração médio diário, ganho de peso médio diário e pior conversão alimentar. Quanto ao rendimento de cortes, observou-se que os genótipos Caboclo e Gigante Negro apresentaram os menores valores, e o Carijó, Colorpak, Pesadão Vermelho, Pescoço Pelado e Tricolor obtiveram os melhores rendimentos de pernas. Para o rendimento de peito, o Carijó e o Pesadão Vermelho obtiveram os maiores valores. A escolha do genótipo deve ser feita de acordo com o interesse do mercado, pois há diferenças no desempenho e no rendimento de carcaça e dos cortes.

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

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

Effect of cerium and lanthanum on the microstructure and mechanical properties of AISI D2 tool steel

International Nuclear Information System (INIS)

Hamidzadeh, Mohammad Ali; Meratian, Mahmood; Saatchi, Ahmad

2013-01-01

AISI D2 tool steel has excellent wear resistance with high dimensional stability. This type of steel is suitable for making molds. This paper describes investigations into the effect of adding Ce/La on microstructure of AISI D2 type cold work tool steels obtained by means of optical microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometry (EDS) and image analyzer. The results showed that after modification with Ce/La, the morphology, size and distribution of M 7 C 3 carbides change greatly. The carbide network tends to break, and all carbides are refined and distributed homogeneously in the matrix, and also reduce the size of chromium carbides and increase the dissolution of carbides during heat treatment. The results of mechanical tests show that the toughness of the alloy increased about 75% without reducing the hardness of the alloy

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

A aplicação do sistema de custo padrão na indústria têxtil:O caso da FISIPE-Fibras Sintéticas de Portugal, S.A.

OpenAIRE

Esteves, Filipa Margarido

2013-01-01

No cenário empresarial actual, em que a concorrência é cada vez maior, trazendo grande competitividade a nível global, os agentes económicos têm de estar munidos de ferramentas de gestão que lhes permita mais facilmente sobreviver neste ambiente competitivo e volátil. Neste sentido, os vários tipos de sistemas de custeio de que as empresas se utilizam constituem ferramentas importantes para a produção de informação atempada e pertinente de suporte ao processo decisório. Entr...

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.

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.

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.

Ontem, hoje e amanhã: sobre a web e as ferramentas colaborativas emergentes para o professor de língua estrangeira

Directory of Open Access Journals (Sweden)

Alan Ricardo Costa

2016-12-01

Full Text Available Considerando que “[...] só é possível prever o futuro quando se olha para o passado” (LEFFA, 2012, p.404, se faz necessário investigar o passado e o presente da web, das Tecnologias de Informação e Comunicação (TIC e das tecnologias educacionais para o ensino e a aprendizagem de Línguas Estrangeira (LE, para especular sobre o futuro, por mais incerto que este seja. Assim, o objetivo deste trabalho é apresentar e discutir as mudanças nas TIC e ferramentas educacionais, do passado para o presente, para apontar perspectivas emergentes ao alcance do professor de LE. Os resultados - que partem de observações sobre alguns recursos e ferramentas digitais disponíveis no Repositório Acción E/LE (Espanhol como Língua Estrangeira - indicam que: (1 recursos online e TIC em geral não tendem a negar o antigo, mas sim incorporá-lo ao novo, fazendo com que tais recursos estejam em contínua evolução; (2 esta evolução, consequentemente, acontece de forma gradual e complexa: nem todas as TIC e tecnologias educacionais mudam ao mesmo tempo ou na mesma medida; (3 a tendência mais visível e emergente é, possivelmente, a colaboração em massa subjacente às ferramentas e seus usos, o que explica o surgimento dos Recursos Educacionais Abertos (REA, por exemplo.

O oraloma da diabetes melitos tipo 1 vs diabetes melitos tipo 2 - um estudo comparativo

OpenAIRE

Brás, Vítor Daniel Moreira

2013-01-01

A Diabetes Melitos é uma doença de grande prevalência a nível mundial e os seus mecanismos fisiopatológicos não são ainda totalmente conhecidos. Actualmente, a terapêutica seguida em casos de Diabetes Melitos é eminentemente sintomática consistindo na administração de insulina nos casos de Diabetes Melitos tipo 1 ou quando se verifica a falência das células beta do pâncreas de pacientes com Diabetes Melitos tipo 2, ou no controlo da glicemia nos casos de Diabetes Melitos ...

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

On the tempered martensite embrittlement in AISI 4140 low alloy steel

Energy Technology Data Exchange (ETDEWEB)

Darwish, F.A. (Dept. of Materials Science and Metallurgy, Catholic Univ., Rio de Janeiro, RJ (Brazil)); Pereira, L.C.; Gatts, C. (Dept. of Metallurgy and Materials Engineering, Federal Univ., Rio de Janeiro, RJ (Brazil)); Graca, M.L. (Materials Div., Technical Aerospace Center, Sao Jose dos Campos, SP (Brazil))

1991-02-01

In the present investigation the Auger electron spectroscopy (AES) technique was used to determine local carbon and phosphorus concentrations on the fracture surfaces of as-quenched and quenched-and-tempered (at 350deg C) AISI 4140 steel specimens austenitized at low and high temperatures. The AES results were rationalized to conclude that, although carbide growth as well as phosphorus segregation are expected to contribute to tempered martensite embrittlement, carbide precipitation on prior austenite grain boundaries during tempering is seen to be the microstructural change directly responsible for the occurrence of the referred embrittlement phenomenon. (orig.).

O uso racional e o reúso como ferramentas para o gerenciamento de águas e efluentes na indústria estudo de caso da Kodak Brasileira.

OpenAIRE

José Carlos Mierzwa

2002-01-01

Neste trabalho os conceitos de uso racional e reúso, como ferramentas para o gerenciamento de águas e efluentes na indústria são propostos e avaliados. São apresentadas e discutidas algumas considerações sobre a necessidade do desenvolvimento e implantação de programas que objetivam o gerenciamento da água e sobre a importância da aplicação desses programas na indústria. A avaliação e validação das ferramentas propostas foram efetuadas por meio de um Estudo de Caso desenvolvido na Empresa KOD...

Effect of mechanical activation on jell boronizing treatment of the AISI 4140

International Nuclear Information System (INIS)

Yılmaz, S.O.; Karataş, S.

2013-01-01

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO 2 –Na 2 O) powders for 873–1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe 2 B sublayers as function of treatment time and temperature in the range of 873–1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 μm was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000–2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe 2 B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

Effect of mechanical activation on jell boronizing treatment of the AISI 4140

Energy Technology Data Exchange (ETDEWEB)

Yılmaz, S.O., E-mail: osyilmaz@firat.edu.tr [F.U. Engineering Faculty, Metallurgical and Material Science, 23119 Elazığ (Turkey); Karataş, S. [F.U. Engineering Faculty, Metallurgical and Material Science, 23119 Elazığ (Turkey)

2013-06-15

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO{sub 2}–Na{sub 2}O) powders for 873–1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe{sub 2}B sublayers as function of treatment time and temperature in the range of 873–1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 μm was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000–2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe{sub 2}B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

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.

Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

Science.gov (United States)

Umbrello, Domenico; Rizzuti, Stefania; Outeiro, José C.; Shivpuri, Rajiv

2007-04-01

In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change.

Modeling of the flow stress for AISI H13 Tool Steel during Hard Machining Processes

International Nuclear Information System (INIS)

Umbrello, Domenico; Rizzuti, Stefania; Outeiro, Jose C.; Shivpuri, Rajiv

2007-01-01

In general, the flow stress models used in computer simulation of machining processes are a function of effective strain, effective strain rate and temperature developed during the cutting process. However, these models do not adequately describe the material behavior in hard machining, where a range of material hardness between 45 and 60 HRC are used. Thus, depending on the specific material hardness different material models must be used in modeling the cutting process. This paper describes the development of a hardness-based flow stress and fracture models for the AISI H13 tool steel, which can be applied for range of material hardness mentioned above. These models were implemented in a non-isothermal viscoplastic numerical model to simulate the machining process for AISI H13 with various hardness values and applying different cutting regime parameters. Predicted results are validated by comparing them with experimental results found in the literature. They are found to predict reasonably well the cutting forces as well as the change in chip morphology from continuous to segmented chip as the material hardness change

Tribological behavior of an austenitic stainless steel AISI 316L nitrurated by DC-pulsed plasma

International Nuclear Information System (INIS)

De Las Heras, E; Walther, F; Corengia, P.A; Quinteiro, M.O; Cabo, A; Bruhl, S; Sommadossi, S

2004-01-01

Austenitic stainless steels are widely used in different applications because they withstands corrosion. Ionic nitruration has proven to be an adequate technique for modifying this type of steel, in order to improve its resistance to wear without diminishing its resistance to corrosion. While many publications have reported improvements in the tribological properties of the nitrurated AISI 316, systematic studies that evaluate this behavior using industrial equipment for its thermochemical treatment are of interest. This work studied the tribological behavior of an AISI 316L steel nitrurated by DC pulsed plasma in an industrial machine in an atmosphere of 25% N 2 and 75% H 2 for 20 h at 400 o C by means of abrasion tests under different conditions in an A 135 Amsler-disk machine. In order to characterize the abraded samples microhardness, optic and scanning electron microscopy profiles to determine the abrasion mechanisms were performed. The results showed substantial improvement in the abrasion resistance of the nitrurated samples compared to the non nitrurated ones and the different abrasion mechanisms are discussed to explain the test results (CW)

Strain hardening behavior and microstructural evolution during plastic deformation of dual phase, non-grain oriented electrical and AISI 304 steels

Energy Technology Data Exchange (ETDEWEB)

Soares, Guilherme Corrêa; Gonzalez, Berenice Mendonça; Arruda Santos, Leandro de, E-mail: leandro.arruda@demet.ufmg.br

2017-01-27

Strain hardening behavior and microstructural evolution of non-grain oriented electrical, dual phase, and AISI 304 steels, subjected to uniaxial tensile tests, were investigated in this study. Tensile tests were performed at room temperature and the strain hardening behavior of the steels was characterized by three different parameters: modified Crussard–Jaoul stages, strain hardening rate and instantaneous strain hardening exponent. Optical microscopic analysis, X-ray diffraction measurements, phase quantification by Rietveld refinement and hardness tests were also carried out in order to correlate the microstructural and mechanical responses to plastic deformation. Distinct strain hardening stages were observed in the steels in terms of the instantaneous strain hardening exponent and the strain hardening rate. The dual phase and non-grain oriented steels exhibited a two-stage strain hardening behavior while the AISI 304 steel displayed multiple stages, resulting in a more complex strain hardening behavior. The dual phase steels showed a high work hardening capacity in stage 1, which was gradually reduced in stage 2. On the other hand, the AISI 304 steel showed high strain hardening capacity, which continued to increase up to the tensile strength. This is a consequence of its additional strain hardening mechanism, based on a strain-induced martensitic transformation, as shown by the X-ray diffraction and optical microscopic analyses.

Effect of cerium and lanthanum on the microstructure and mechanical properties of AISI D2 tool steel

Energy Technology Data Exchange (ETDEWEB)

Hamidzadeh, Mohammad Ali, E-mail: mahamidzadeh@yahoo.com [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Meratian, Mahmood; Saatchi, Ahmad [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2013-06-01

AISI D2 tool steel has excellent wear resistance with high dimensional stability. This type of steel is suitable for making molds. This paper describes investigations into the effect of adding Ce/La on microstructure of AISI D2 type cold work tool steels obtained by means of optical microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometry (EDS) and image analyzer. The results showed that after modification with Ce/La, the morphology, size and distribution of M{sub 7}C{sub 3} carbides change greatly. The carbide network tends to break, and all carbides are refined and distributed homogeneously in the matrix, and also reduce the size of chromium carbides and increase the dissolution of carbides during heat treatment. The results of mechanical tests show that the toughness of the alloy increased about 75% without reducing the hardness of the alloy.

Electrochemical study of the AISI 409 ferritic stainless steel: passive film stability and pitting nucleation and growth

International Nuclear Information System (INIS)

Souza, Juliana Sarango de; Oliveira, Leandro Antônio de; Antunes, Renato Altobelli; Sayeg, Isaac Jamil

2017-01-01

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)

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)

Interactions Between Fibroblast Cells and Laser Beam Welded AISI 2205 Duplex Stainless Steel

Directory of Open Access Journals (Sweden)

Ceyhun KÖSE

2018-05-01

Full Text Available Because of their high mechanical strength, excellent corrosion resistance and good weldability, duplex stainless steels are mostly used in industries such as oil, chemistry, petrochemistry, food and occasionally used in medical industry. These properties have enabled us to use duplex stainless steels in biomedical applications recently. Accordingly, duplex stainless steel material can be highly important to examine the toxic effect on the cells. In this study, the effect of the AISI 2205 duplex stainless steels which are joined by CO2 laser beam welding on viability of L929 fibroblast cells has been studied in vitro for the first time. For this aim, the cells were kept in DMEM/F-12 (Thermofisher Scientific 31331-028 medium for 7 days. The viability study was experimentally studied using the MTT (Thiazolyl Blue Tetrazolium Bromide method for 7 days. The cell viability of the laser beam welded sample has been detected to be higher than that of the base metal and the control based on 7th day data. According to the obtained results, it was revealed that laser beam welded and base metal AISI 2205 duplex stainless steel has been found suitable to study for biomedical applications. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.18006

The influence of delta ferrite in the AISI 416 stainless steel hot workability

International Nuclear Information System (INIS)

Cardoso, P.H.S.; Kwietniewski, C.; Porto, J.P.; Reguly, A.; Strohaecker, T.R.

2003-01-01

Delta ferrite in martensitic stainless steels may have an adverse effect on the mechanical properties of these materials at high temperature. The occurrence of such phase is determined by the material chemical composition (mainly Cr and C), as-received microstructure condition and hot working temperature. The aim of this investigation is to assess the influence of delta ferrite on the hot workability of the martensitic AISI 416 stainless steel. Hence, different heats of this material (differing in chemical composition and as-received microstructure) were submitted to heating tests in order to observe the microstructural transformations that take place at high temperature and then examine the influence of these transformations on the mechanical behaviour. Phase characterisation and quantification were carried out using scanning electron microscopy/energy-dispersive X-ray microanalysis and image analysis. The heating tests were performed in the temperature range of 1100-1350 deg. C and hot workability in two heats with different delta ferrite content was assessed by hot torsion tests in the temperature range of 1000-1250 deg. C. The results have indicated that chemical composition and as-received microstructure strongly affect delta ferrite formation, which in turn deteriorates hot workability of the martensitic AISI 416 stainless steel

Transport and calorimetric properties of AISI 321 by pulse thermal diffusivity and calorimetric techniques

International Nuclear Information System (INIS)

Perovic, N.L.; Maglic, K.D.; Stanimirovic, A.M.; Vukovic, G.S.

1995-01-01

The study of the thermophysical properties of AISI 321 stainless steel was the last part of work within the IAEA-coordinated Research Programme for the Establishment of a Database of Thermophysical Properties of LW and HW Reactor Materials (IAEA CRP) effected at the Institute of Nuclear Sciences Vinca (NIV). The AISI 321 stainless steel belongs to the group of construction materials whose thermophysical and calorimetric properties have significance for the IAEA CRP. Because there have been few investigations of the thermal properties of this material, the CRP foresaw the need for new measurements, which are reported in this paper. Experimental research performed at NIV consisted of the investigation of thermal diffusivity, electric resistivity, and specific heat capacity of this austenitic stainless steel. The thermal diffusivity was measured by the laser pulse technique, and the elastic resistivity and specific heat capacity were determined by use of millisecond-resolution pulse calorimetry. All measurements were performed from ambient temperature to above 1000 o C, within which temperature range the material maintains its structure and stable thermophysical properties. Values for the thermal conductivity were computed from data on the thermal diffusivity, specific heat capacity, and the room-temperature density. (author)

Wear and Adhesive Failure of Al2O3 Powder Coating Sprayed onto AISI H13 Tool Steel Substrate

Science.gov (United States)

Amanov, Auezhan; Pyun, Young-Sik

2016-07-01

In this study, an alumina (Al2O3) ceramic powder was sprayed onto an AISI H13 hot-work tool steel substrate that was subjected to sanding and ultrasonic nanocrystalline surface modification (UNSM) treatment processes. The significance of the UNSM technique on the adhesive failure of the Al2O3 coating and on the hardness of the substrate was investigated. The adhesive failure of the coating sprayed onto sanded and UNSM-treated substrates was investigated by a micro-scratch tester at an incremental load. It was found, based on the obtained results, that the coating sprayed onto the UNSM-treated substrate exhibited a better resistance to adhesive failure in comparison with that of the coating sprayed onto the sanded substrate. Dry friction and wear property of the coatings sprayed onto the sanded and UNSM-treated substrates were assessed by means of a ball-on-disk tribometer against an AISI 52100 steel ball. It was demonstrated that the UNSM technique controllably improved the adhesive failure of the Al2O3 coating, where the critical load was improved by about 31%. Thus, it is expected that the application of the UNSM technique to an AISI H13 tool steel substrate prior to coating may delay the adhesive failure and improve the sticking between the coating and the substrate thanks to the modified and hardened surface.

Genótipos de haptoglobina e hipertensão refratária em pacientes com diabete melito tipo 2

Directory of Open Access Journals (Sweden)

Vânia Pereira Albuquerque Wobeto

2011-10-01

Full Text Available FUNDAMENTO: Tem sido sugerido que o polimorfismo da haptoglobina pode influenciar na patogênese das complicações microvasculares e macrovasculares em pacientes diabéticos. OBJETIVO: O objetivo principal deste estudo transversal foi de realizar uma investigação da existência ou não de uma associação entre os genótipos de haptoglobina e a prevalência de eventos isquêmicos cardiovasculares (angina estável, angina instável e infarto agudo do miocárdio, hipertensão arterial sistêmica, hipertensão refratária, obesidade e dislipidemia em 120 pacientes com diabete melito tipo 2, seguidos no Hospital Universitário da Unicamp, em Campinas, Estado de São Paulo. MÉTODOS: A genotipagem da haptoglobina foi realizada por reações em cadeia da polimerase alelo-específicas. As frequências dos genótipos de haptoglobina foram comparadas com a presença/ausência de doença cardiovascular, hipertensão arterial sistêmica, hipertensão refratária, obesidade e dislipidemia; medições de pressão arterial sistólica e diastólica; glicemia, colesterol (total, lipoproteínas de alta densidade - HDL e lipoproteínas de baixa densidade - LDL e triglicerídeos; assim como níveis de creatinina sérica. RESULTADOS: Embora nenhuma associação entre o genótipo de haptoglobina e a presença de doença cardiovascular tenha sido identificada, encontramos um excesso significativo de pacientes com o genótipo Hp2-1 entre as pessoas com hipertensão refratária, que também apresentavam uma maior pressão arterial sistólica e diastólica e níveis de colesterol total e LDL. CONCLUSÃO: Nossos resultados sugerem que os pacientes com diabete melito tipo 2 com o genótipo Hp2-1 podem apresentar uma maior chance de desenvolver hipertensão refratária. Estudos adicionais em populações diabéticas são necessários para confirmar esses achados.

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

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

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

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

Tensile Fracture Behavior and Failure Mechanism of Additively-Manufactured AISI 4140 Low Alloy Steel by Laser Engineered Net Shaping

Directory of Open Access Journals (Sweden)

Hoyeol Kim

2017-11-01

Full Text Available AISI 4140 powder was directly deposited on AISI 4140 wrought substrate using laser engineered net shaping (LENS to investigate the compatibility of a LENS-deposited part with the substrate. Tensile testing at room temperature was performed to evaluate the interface bond performance and fracture behavior of the test specimens. All the samples failed within the as-deposited zone, indicating that the interfacial bond is stronger than the interlayer bond inside the deposit. The fracture surfaces were analyzed using scanning electron microscopy (SEM and energy disperse X-ray spectrometry (EDS. Results show that the tensile fracture failure of the as-deposited part is primarily affected by lack-of-fusion defects, carbide precipitation, and oxide particles inclusions, which causes premature failure of the deposit by deteriorating the mechanical properties and structural integrity.

Internal state variable plasticity-damage modeling of AISI 4140 steel including microstructure-property relations: temperature and strain rate effects

Science.gov (United States)

Nacif el Alaoui, Reda

Mechanical structure-property relations have been quantified for AISI 4140 steel. under different strain rates and temperatures. The structure-property relations were used. to calibrate a microstructure-based internal state variable plasticity-damage model for. monotonic tension, compression and torsion plasticity, as well as damage evolution. Strong stress state and temperature dependences were observed for the AISI 4140 steel. Tension tests on three different notched Bridgman specimens were undertaken to study. the damage-triaxiality dependence for model validation purposes. Fracture surface. analysis was performed using Scanning Electron Microscopy (SEM) to quantify the void. nucleation and void sizes in the different specimens. The stress-strain behavior exhibited. a fairly large applied stress state (tension, compression dependence, and torsion), a. moderate temperature dependence, and a relatively small strain rate dependence.

EFFECTS OF CARBURIZING AND NITRIDING PROCESSES ON THE COST AND QUALITY OF GEARS PRODUCED WITH AISI 4140 AND 8620 STEELS

Directory of Open Access Journals (Sweden)

Claudio José Leitão

2012-09-01

Full Text Available This study compares the effects of nitriding and carburizing processes applied to gears subjected to contact stresses below 1300 MPa. The manufacturing cost, as well the depth of hardened layer and the distortion produced by two processes are analyzed. AISI 4140 gears quenched, tempered, liquid and gas nitriding and AISI 8620 gears after liquid carburizing, quenching and tempering are analyzed. The dimensional control of the gears was carried out before and after heat and thermochemical treatments. It is concluded that liquid or gas nitriding processes are about 30% more economical than liquid carburizing an also they reduce the dimensional changes. By the other hand liquid carburizing achieves greater case depth. Liquid nitriding process presents the lowest cost, dimensional changes and case depth.

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

Tribological properties of plasma and pulse plasma nitrided AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Podgornik, B.; Vizintin, J. [Ljubljana Univ. (Slovenia). Center of Tribology and Tech. Diagnostics; Leskovsek, V. [Inst. of Metals and Technologies, Ljubljana (Slovenia)

1998-10-10

Plasma nitriding is usually used for ferrous materials to improve their surface properties. Knowledge of the properties of thin surface layers is essential for designing engineering components with optimal wear performance. In our study, we investigated the microstructural, mechanical and tribological properties of plasma- and pulse plasma-nitrided AISI 4140 steel in comparison to hardened steel. The influence of nitriding case depth as well as the presence of a compound layer on its tribological behaviour was also examined. Plasma and pulse plasma nitriding were carried out using commercial nitriding processes. Nitrided samples were fully characterised, using metallographic, SEM microscopic, microhardness and profilometric techniques, before and after wear testing. Wear tests were performed on a pin-on-disc wear testing machine in which nitrided pins were mated to hardened ball bearing steel discs. The wear tests were carried out under dry conditions where hardened samples were used as a reference. The resulting wear loss as well as the coefficient of friction was monitored as a function of load and test time. Several microscopic techniques were used to analyse the worn surfaces and wear debris in order to determine the dominant friction and wear characteristics. Results showed improved tribological properties of AISI 4140 steel after plasma and pulse plasma nitriding compared to hardening. However, the compound layer should be removed from the surface by mechanical means or by decreasing the amount of nitrogen in the nitriding atmosphere, to avoid impairment of the tribological properties by fracture of the hard and brittle compound layer followed by the formation of hard abrasive particles. (orig.) 10 refs.

Static strain aging type AISI-304 austenitic stainless steel

International Nuclear Information System (INIS)

Trindade, M.B.

1981-03-01

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, continuously relaxing and unloaded. The aging times varied between 10s and 100h, using a plastic pre deformation of 9% in most of the cases. 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 Snoek type mechanisms are responsible for the aging in such conditions. (Author) [pt

CRIAÇÃO DE UMA FERRAMENTA COMPUTACIONAL PARA CONTROLE DE ATIVIDADES DE CURTO PRAZO

Directory of Open Access Journals (Sweden)

Michele Tereza Marques Carvalho

2016-12-01

Full Text Available Tem-se observado que o crescimento da competitividade no setor da construção civil tem levado as empresas a procurarem por melhorias de desempenho relacionados aos resultados obtidos nas frentes de trabalho. Isso acontece por meio de programas de melhoria da qualidade e produtividade, onde pode-se citar a capacitação da mão de obra, melhoria das técnicas de produção e aperfeiçoamento da linguagem utilizada entre todas as partes envolvidas na realização das tarefas. Desta forma, o foco deste trabalho é o desenvolvimento de uma ferramenta computacional que integre todos os indicadores de planejamento e controle, gráficos, diários de obras e programações  necessárias para permitir uma observação completa da obra e uma análise do planejamento realizado que aponte os seus pontos fortes e fracos, facilitando o processo de tomada de decisão. Este instrumento mostrará aonde o planejamento e controle estão falhando e assim será possível melhorar as diretrizes mais rapidamente, dado que estas falhas demoram a ser identificadas tanto pelos planejadores quanto pelos responsáveis pelas frentes de trabalho. Com os dados obtidos em mãos será realizada uma análise sobre os resultados alcançados com o desenvolvimento da ferramenta, a veracidade dos dados utilizados e a necessidade de seu desenvolvimento e emprego em outras obras.

Designing of CK45 carbon steel and AISI 304 stainless steel dissimilar welds

OpenAIRE

Pouraliakbar,Hesam; Hamedi,Mohsen; Kokabi,Amir Hossein; Nazari,Ali

2014-01-01

Gas tungsten arc welding of CK45 and AISI304 stainless steel was performed through preparation of different types of samples using ER308L and ERNi-1 wires. Welded samples were studied by different techniques including optical metallography, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction, hardness measurements and impact test. It was observed that in the buttered specimen, the structure of the weld metal was completely austenitic wh...

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)

Fatigue of welded joint in a stainless steel AISI 304 L

International Nuclear Information System (INIS)

Kuromoto, N.K.; Guimaraes, A.S.; Miranda, P.E.V. de

1986-01-01

The flexion fatigue behavior for the base metal and welded joint of an AISI 304 L stainless steel type, used in the Angra-1 reactor, was determined. An automatic welding process was used with improved procedures in order to assure better welding metallurgy. Fatigue tests samples reinforcements were done to allow the evaluation of metallurgical variables, specially the role played by delta ferrite. The resulting welded joint showed better fatigue life than the base metal. Delta ferrite was found to play an important role on the initiation and propagation processes of the fatigue cracks. (Author) [pt

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...

Characterization of metallurgical and mechanical properties on the multi-pass welding of Inconel 625 and AISI 316L

Energy Technology Data Exchange (ETDEWEB)

Kumar, K. Gokul; Ramkumar, K. Devendranath; Arivazhagan, N. [VIT University, Vellore (India)

2015-03-15

This article investigated the weldability, metallurgical and mechanical properties of Inconel 625 and AISI 316L stainless steel weldments obtained by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) processes employing ERNiCr-3 and ER2209 fillers. Microstructure studies showed the migrated grain boundaries at the weld zone of ERNiCr-3 weldments and multidirectional grain growth for ER2209 weldments. It was inferred from the tension tests that the fracture occurred at the parent metal of AISI 316L in all the cases. Charpy V-notch impact tests accentuated that the CCGTA weldments employing ERNiCr-3 filler offered better impact toughness of 77 J at room temperature. Further a detailed study has been carried out to analyze the structure - property relationships of these weldments using the combined techniques of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis.

A logística integrada como ferramenta para a competitividade em uma agroindústria

OpenAIRE

Gelásio Carlini

2002-01-01

Nos últimos anos a economia mundial e a economia brasileira têm sofrido mudanças importantes. Fusões e aquisições estratégicas têm se multiplicado na busca de estratégias para a competitividade envolvendo a integração de todas as atividades na agregação de valor que seja percebido pelo cliente. No presente trabalho, a adoção do planejamento e do gerenciamento do processo logístico pode tornar-se uma ferramenta competitiva para a efetiva sustentação de estratégias na busca de novos mercados e ...

Evaluation of corrosion products formed by sulfidation as inhibitors of the naphthenic corrosion of AISI-316 steel

Science.gov (United States)

Sanabria-Cala, J. A.; Montañez, N. D.; Laverde Cataño, D.; Y Peña Ballesteros, D.; Mejía, C. A.

2017-12-01

Naphthenic acids present in oil from most regions worldwide currently stand as the main responsible for the naphthenic corrosion problems, affecting the oil-refining industry. The phenomenon of sulfidation, accompanying corrosion processes brought about by naphthenic acids in high-temperature refining plant applications, takes place when the combination of sulfidic acid (H2S) with Fe forms layers of iron sulphide (FeS) on the material surface, layers with the potential to protect the material from attack by other corrosive species like naphthenic acids. This work assessed corrosion products formed by sulfidation as inhibitors of naphthenic corrosion rate in AISI-316 steel exposed to processing conditions of simulated crude oil in a dynamic autoclave. Calculation of the sulfidation and naphthenic corrosion rates were determined by gravimetry. The surfaces of the AISI-316 gravimetric coupons exposed to acid systems; were characterized morphologically by X-Ray Diffraction (XRD) and X-ray Fluorescence by Energy Dispersive Spectroscopy (EDS) combined with Scanning Electron Microscopy (SEM). One of the results obtained was the determination of an inhibiting effect of corrosion products at 250 and 300°C, where lower corrosion rate levels were detected. For the temperature of 350°C, naphthenic corrosion rates increased due to deposition of naphthenic acids on the areas where corrosion products formed by sulfidation have lower homogeneity and stability on the surface, thus accelerating the destruction of AISI-316 steel. The above provides an initial contribution to oil industry in search of new alternatives to corrosion control by the attack of naphthenic acids, from the formation of FeS layers on exposed materials in the processing of heavy crude oils with high sulphur content.

Comparative study on structure, corrosion and hardness of Zn-Ni alloy deposition on AISI 347 steel aircraft material

Energy Technology Data Exchange (ETDEWEB)

Gnanamuthu, RM. [Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1732 Deogyeong-daero, Gihung, Yongin, Gyeonggi 446-701 (Korea, Republic of); Mohan, S., E-mail: sanjnamohan@yahoo.com [Central Electrochemical Research Institute, (CSIR), Karaikudi 630 006, Tamilnadu (India); Saravanan, G. [Central Electrochemical Research Institute, (CSIR), Karaikudi 630 006, Tamilnadu (India); Lee, Chang Woo, E-mail: cwlee@khu.ac.kr [Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1732 Deogyeong-daero, Gihung, Yongin, Gyeonggi 446-701 (Korea, Republic of)

2012-02-05

Highlights: Black-Right-Pointing-Pointer Electrodeposition of Zn-Ni alloy on AISI 347 steel as an aircraft material has been carried out from various baths. Black-Right-Pointing-Pointer The effect of pulse duty cycle on thickness, current efficiency and hardness reached maximum values at 40% duty cycle and for 50 Hz frequencies average current density of 4 A dm{sup -2}. Black-Right-Pointing-Pointer The XRF characterizations of 88:12% Zn-Ni alloy provided excellent corrosion resistance. Black-Right-Pointing-Pointer It is found that Zn-Ni alloy on AISI 347 aircraft material has better structure and corrosion resistance by pulse electrodeposits from electrolyte-4. - Abstract: Zn-Ni alloys were electrodeposited on AISI 347 steel aircraft materials from various electrolytes under direct current (DCD) and pulsed electrodepositing (PED) techniques. The effects of pulse duty cycle on thickness, current efficiency and hardness of electrodeposits were studied. Alloy phases of the Zn-Ni were indexed by X-ray diffraction (XRD) techniques. Microstructural morphology, topography and elemental compositions were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray fluorescence spectroscopy (XRF). The corrosion resistance properties of electrodeposited Zn-Ni alloy in 3.5% NaCl aqueous solution obtained by DCD and PED were compared using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) technique. Elemental analysis showed that 88% of Zn and 12% of Ni obtained from electrolyte-4 by PED technique at 40% duty cycle for 50 Hz frequencies having better corrosion resistance than that of deposits obtained from other electrolytes.

Improvement in cavitation erosion resistance of AISI 316L stainless steel by friction stir processing

Energy Technology Data Exchange (ETDEWEB)

Hajian, M. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Abdollah-zadeh, A., E-mail: zadeh@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Rezaei-Nejad, S.S.; Assadi, H. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Hadavi, S.M.M. [Department of Materials Science and Engineering, MA University of Technology, Tehran (Iran, Islamic Republic of); Chung, K. [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Engineering Research Institute, Seoul National University, Seoul (Korea, Republic of); Shokouhimehr, M. [Department of Chemical Engineering, College of Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2014-07-01

Commercial AISI 316L plates with the initial grain size of 14.8 μm were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 μm. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3–6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

Ferramentas de Digital Analytics e seu Poder de Previsão sobre o Desempenho: Uma Análise do Mercado Automobilístico Brasileiro

Directory of Open Access Journals (Sweden)

Roger Kenji Kimura

2016-06-01

Full Text Available O objetivo deste artigo foi entender como as ferramentas de Digital Analytics e seu poder de previsão sobre o desempenho atuam na análise do mercado automobilístico brasileiro. Foram selecionadas as 10 empresas automobilísticas presentes no Brasil com as maiores vendas e coletou-se dados destas páginas durante o período de dois meses, por meio de ferramentas de Digital Analytics. Optou-se pela técnica multivariada de regressão linear múltipla, analisando-se a relação das variáveis independentes (atributos coletados com a dependente (vendas. Como resultado, verificou-se que algumas ferramentas possuem um conjunto melhor de parâmetros que explicam as vendas das montadoras. Dos sete softwares de Digital Analytics observados, seis apresentaram significância no poder de explicação. Esta pesquisa teve característica exclusivamente quantitativa, na qual as variáveis independentes que foram significativas para este estudo puderam ser agrupadas em: “Mídias Sociais” e “Não Mídias Sociais”, prevalecendo uma maior concentração de variáveis “Não Mídias Sociais”. 96 Normal 0 21 false false false PT-BR X-NONE X-NONE

Marketing e saúde - 11 P\\'s: avaliação de um protocolo de ferramentas e técnicas de marketing aplicado a consultórios odontológicos

OpenAIRE

Heloisa Ribeiro Borges

2011-01-01

Foi realizado um estudo entre 10 dentistas da cidade de Itu, interior do estado de São Paulo, para avaliar o impacto do conhecimento e aplicação das ferramentas de marketing nos consultórios odontológicos. Para isso foi feito um levantamento inicial e selecionado profissionais que não haviam tido nenhum contato especifico com cursos ou consultorias de marketing anteriormente. O protocolo final sugerido com 11Ps foi uma fusão adaptada baseada nas tradicionais ferramentas de marketing divulgada...

Uma ferramenta para automação da geração do leiaute de circuitos analógicos sobre uma matriz de transistores MOS pré-difundidos

OpenAIRE

Alessandro Gonçalves Girardi

2003-01-01

Este trabalho apresenta o LIT, uma ferramenta de auxílio ao projeto de circuitos integrados analógicos que utiliza a técnica da associação trapezoidal de transistores (TAT) sobre uma matriz digital pré-difundida. A principal característica é a conversão de cada transistor simples de um circuito analógico em uma associação TAT equivalente, seguido da síntese automática do leiaute da associação séria-paralela de transistores. A ferramenta é baseada na matriz SOT (sea-of-transistors), cuja arqui...

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.

Experimental investigation of various surface integrity aspects in hard turning of AISI 4340 alloy steel with coated and uncoated cermet

Science.gov (United States)

Das, Anshuman; Patel, S. K.; Sateesh Kumar, Ch.; Biswal, B. B.

2018-03-01

The newer technological developments are exerting immense pressure on domain of production. These fabrication industries are busy finding solutions to reduce the costs of cutting materials, enhance the machined parts quality and testing different materials, which can be made versatile for cutting materials, which are difficult for machining. High-speed machining has been the domain of paramount importance for mechanical engineering. In this study, the variation of surface integrity parameters of hardened AISI 4340 alloy steel was analyzed. The surface integrity parameters like surface roughness, micro hardness, machined surface morphology and white layer of hardened AISI 4340 alloy steel were compared using coated and uncoated cermet inserts under dry cutting condition. From the results, it was deduced that coated insert outperformed uncoated one in terms of different surface integrity characteristics.

Study on tempering behaviour of AISI 410 stainless steel

International Nuclear Information System (INIS)

Chakraborty, Gopa; Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V.; Panneerselvam, G.; Dasgupta, Arup

2015-01-01

Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M 23 C 6 ) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe 2 C and M 23 C 6 types of carbides coexisting in the material. The nucleation of Fe 2 C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M 23 C 6 carbides, instead of Fe 2 C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of carbide precipitation varies with

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...

PESQUISA EM EDUCAÇÃO: O WORDSMITH COMO FERRAMENTA DE EXPLORAÇÃO DE CORPORA

Directory of Open Access Journals (Sweden)

Maria Zuleide da Costa Pereira; Samara Wanderley Xavier Barbosa

2014-09-01

Full Text Available Este texto constitui-se a partir da implementação das ações de um projeto do Programa Institucional de Bolsas de Iniciação Científica (PIBIC da UFPB, intitulado “Os Sentidos do Currículo nas Escolas da Rede Municipal de Ensino de João Pessoa/PB”, e desenvolvido no período de 2013 a 2014. O objetivo do plano/projeto é destacar o papel do software Worsmith Tools 6, como ferramenta de análise de corpora, na exploração dos sentidos de educação, currículo e ensino nos documentos curriculares analisados, que são os documentos de políticas curriculares nacionais (Lei de Diretrizes e Bases de nº 9394/96, Parâmetros Curriculares Nacionais de 1ª a 4ª série, Diretrizes Curriculares Gerais para Educação Básica e Diretrizes Curriculares para o Ensino Fundamental de Nove Anos e os locais (Projetos Político-Pedagógicos de nove escolas da Rede Municipal de Ensino. Dessa forma, mostramos os recursos do conjunto de ferramentas utilizadas, exemplificando de que modo elas contribuíram para uma análise documental mais exata e confiável do que outras perspectivas de análise linguística permitiriam. De fato, ao mesmo tempo em que facilitaram às possíveis articulações entre educação, currículo e ensino, o conjunto de ferramentas em questão, como argumenta Sardinha (2004, nos deu a possibilidade de analisar vários aspectos da linguagem, tais como: a composição lexical, o tema dos textos selecionados e a organização da retórica e composicional dos gêneros discursivos. Metodologicamente, organizamos os documentos em análise num conjunto de textos informatizados, de tal forma que se tornaram adequados para o pesquisador analisar, sempre tendo em vista a autenticidade, a legibilidade e a extensão dos textos, e a seleção criteriosa dos enunciados que comporiam o corpus. Para empreender a análise propriamente dita, decidimos utilizar o Worsmith Tools 6 e suas três ferramentas o Wordlist, o Concord e o Keywords, cada

Validação de um Sistema Robotizado Recém Desenvolvido para a Soldagem pelo Processo Friction Stir Welding por meio da União e Caracterização de Juntas da Liga de Alumínio 5052 H34

Directory of Open Access Journals (Sweden)

Bruno Silva Cota

2017-12-01

Full Text Available Resumo Este projeto trata da validação de um sistema recém desenvolvido para a soldagem pelo processo friction stir welding, que foi adaptado a um robô antropomórfico com capacidade de 500 kg e seis graus de liberdade. Para garantir que o sistema projetado é capaz de soldar materiais pelo processo FSW, ou seja, garantir que possui rigidez, resistência e torque suficientes para realizar a operação de soldagem, faz-se necessário realizar a validação do mesmo. Para tanto, foi necessário soldar um material conhecido, com parâmetros já estabelecidos, e utilizar uma ferramenta apropriadamente dimensionada. Dessa forma, escolheu-se a liga 5052 H43 de 3 mm de espessura, usada na produção de navios, embarcações e estruturas automotivas. Para a soldagem das juntas finais foi usada uma ferramenta fabricada em AISI H13, com pino cônico liso e diâmetro do ombro de 18 mm. A velocidade rotacional da ferramenta foi mantida constante em 378 rpm, e a velocidade de avanço em 7,5 mm/min, sendo a inclinação da ferramenta de 2°. Verificou-se após os ensaios que o sistema de soldagem projetado se mostrou eficaz em aplicações de soldagem FSW, apresentando torque e resistência mecânica suficientes para a união de materiais com baixo ponto de fusão. Por meio dos parâmetros utilizados, bem como da geometria da ferramenta, foi possível obter juntas da liga de alumínio 5052 H34 soldadas com: bom aspecto superficial, baixos valores de rebarba, ausência de sulcos ou vazios ao longo da linha de soldagem e com penetração total.

Micro friction stir lap welding of AISI 430 ferritic stainless steel: a study on the mechanical properties, microstructure, texture and magnetic properties

Science.gov (United States)

Mostaan, Hossein; Safari, Mehdi; Bakhtiari, Arash

2018-04-01

In this study, the effect of friction stir welding of AISI 430 (X6Cr17, material number 1.4016) ferritic stainless steel is examined. Two thin sheets with dimensions of 0.4 × 50 × 200 mm3 are joined in lap configuration. Optical microscopy and field emission electron microscopy were used in order to microstructural evaluations and fracture analysis, respectively. Tensile test and microhardness measurements are employed in order to study the mechanical behaviors of welds. Also, vibrational sample magnetometry (VSM) is employed for characterizing magnetic properties of welded samples. Texture analysis is carried out in order to clarify the change mechanism of magnetic properties in the welded area. The results show that AISI 430 sheets are successfully joined considering both, the appearance of the welding bead and the strength of the welded joint. It is found that by friction stir welding of AISI 430 sheets, texture components with easy axes magnetization have been replaced by texture components with harder magnetization axes. VSM analysis showed that friction stir welding leads to increase in residual induction (Br) and coercivity (Hc). This increase is attributed to the grain refining due the friction stir welding and formation of texture components with harder axes of magnetizations.

Thermogalvanic corrosion and galvanic effects of copper and AISI 316L stainless steel pairs in heavy LiBr brines under hydrodynamic conditions

International Nuclear Information System (INIS)

Sánchez-Tovar, R.; Montañés, M.T.; García-Antón, J.

2012-01-01

Highlights: ► Thermogalvanic corrosion results in an increase of the current densities. ► Thermogalvanic effect increases as temperature difference between tubes is higher. ► Potentials fit linearly with increase in temperature. ► ZRA shows hot cathodes for AISI 316L while cold ones for copper and galvanic pairs. ► Weight loss tests show a combined effect between thermogalvanic and galvanic effects. - Abstract: Thermogalvanic corrosion of the copper/copper and AISI 316L/AISI 316L stainless steel pairs was studied in heavy lithium bromide brines under hydrodynamic conditions. The galvanic coupling effect between copper and stainless steel was also analysed. The cold electrode (25 °C) was the stainless steel for the galvanic pair, whereas copper temperature varied (25, 50 and 75 °C). A hydrodynamic circuit was designed to study thermogalvanic corrosion by means of the zero resistance ammeter technique. Hot cathodes take place in stainless steel pairs while cold cathodes are present in copper/copper and stainless steel/copper pairs; this agrees with the thermal temperature coefficient of the potential sign. Thermogalvanic corrosion increases corrosion rates, especially working with copper. Weight loss measurements show that there is a combined effect due to the thermogalvanic and the galvanic effects.

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.

Effect of friction time on the microstructure and mechanic properties of friction welded AISI 1040/Duplex stainless steel

Directory of Open Access Journals (Sweden)

İhsan Kırık

2000-06-01

Full Text Available In this study, the effect on the characteristic microstructure and mechanic properties of friction time on the couple steels AISI 1040/AISI 2205 stainless steel joining with friction welding method was experimentally investigated. Friction welding experiment were carried out in privately prepared PLC controlled continuous friction welding machine by us. Joints were carried out under 1700 rpm rotation speed, with 30MPa process friction pressure, 60MPa forging pressure, 4 second forging pressure and under 3, 5, 7, 9 and 11 second friction time, respectively. After friction welding, the bonding interface microstructures of the specimens were examined by SEM microscopy and EDS analysis. After weld microhardness and tensile strength of specimens were carried out. The result of applied tests and observations pointed out that the properties of microstructure were changed with friction time increased. The excellent tensile strength of joint observed on 1700 rpm rotation speed and 3 second friction time sample.

Corrosion Behavior of Heat Affected Zone of AISI 321 stainless steel

International Nuclear Information System (INIS)

Ahn, Yong Sik; Park, Hwa Soon; Kim, Yeong Hwan; Won, Tae Yeon; Lee, Sang Lae

1994-01-01

Intergranular corrosion behavior of heat affected zone(HAZ) has been investigated for Ti-stabilized austenitic stainless steel AISI 321. It was observed that grain boundaries at HAZ of the steel with Ti/C ratio of 6.2 were corroded significantly after sensitization heat treatment. The increase of the Ti/C ratio up to 9.6 results in the evident decrease of intergranular corrosion. Weld simulation and intergranular corrosion test in 65% HNO 3 was performed. Influence of various thermal cycles on the intergranular corrosion was investigated. These results are discussed in terms of the behavior of TiC and Cr 23 C 6 precipitates

Tipos de pasteurização e agentes coagulantes na fabricação do queijo tipo prato

OpenAIRE

Ramos, Thaís de Melo

2013-01-01

O presente trabalho foi realizado com os objetivos de avaliar a influência do tipo de pasteurização pelos sistemas de aquecimento indireto high temperature short time, ou HTST, e injeção direta de vapor (IDV), e avaliar a influência de duas diferentes enzimas coagulantes na fabricação do queijo tipo prato. O delineamento experimental utilizado neste experimento foi um fatorial 2 x 2 x 5 inteiramente casualizado, sendo dois sistemas de pasteurização (HTST e IDV), duas enzimas coagulantes e cin...

The pitting resistance of AISI 316 stainless steel passivated in diluted nitric acid

International Nuclear Information System (INIS)

Barbosa, M.A.

1983-01-01

The pitting resistance of AISI 316 stainless steel after passivation in diluted nitric acid was studied in comparison with that of non-passivated specimens. The passivation treatment increased the pitting potential but decreased the resistance to crevice corrosion under open circuit conditions in aerated sea water. Immersion in the nitric acid solution was found to remove the sulphide inclusions from the metal surface, thus eliminating the most susceptible sites for attack. In the absence of sulphide particles pitting nucleated at aluminium-rich oxides. (author)

Diabetes tipo 2 en niños: Serie de casos

Directory of Open Access Journals (Sweden)

Helard Manrique-Hurtado

2015-01-01

Full Text Available Objetivos: Describir las características clínicas y bioquímicas de un grupo de niños y adolescentes con diagnóstico reciente de diabetes tipo 2. Material y métodos: Estudio descriptivo, retrospectivo, tipo de serie de casos. Se definió caso al niño o adolescente con glucosa plasmática en ayunas mayor a 126 mg/dl, ausencia de antiGAD y péptido C mayor a 1,5 ng/dl. Se excluyeron a los pacientes con diagnóstico previo de diabetes mellitus tipo 1, diabetes tipo MODY o diabetes secundaria a uso de fármacos. Resultados: La edad media fue 14,3 años, 59% fueron mujeres y 43% tenía por lo menos un padre con diabetes tipo 2. Al momento del diagnóstico, el índice de masa corporal fue 32,8 kg/m2, 85% tenía acantosis nigricans y 68% estaba en estadio Tanner IV y V. El tratamiento inicial incluyó el uso de hipoglicemiantes orales en 75% de los casos, siendo más frecuente el uso de metformina (64,3%. Solamente el 41% de los pacientes recibía algún tipo de insulina. Conclusiones: Los niños y adolescentes con diabetes tipo 2, tienen una frecuencia aumentada de obesidad/sobrepeso, acantosis nigricans y antecedente familiar de DM2. En general, tienen mal control metabólico y reciben metformina como tratamiento inicial.

INFLUENCIA DE LOS RECUBRIMIENTOS DÚPLEX SOBRE LAS PROPIEDADES MECÁNICAS Y RESISTENCIA AL DESGASTE DEL ACERO AISI 4140 BONIFICADO

Directory of Open Access Journals (Sweden)

Francisco Javier Bolívar Osorio

Full Text Available El acero AISI 4140 es un acero de baja aleación al cromo/molibdeno de elevada resistencia mecánica y buena tenacidad, el cual se utiliza para la fabricación de piezas de maquinaria como piñones, cigüeñales, ejes de levas, etc. Sin embargo, su resistencia al desgaste es bastante limitada y suele ser mejorada mediante el tratamiento superficial de la nitruración. El propósito de este trabajo consistió en mejorar las propiedades mecánicas e incrementar la resistencia al desgaste del acero 4140 mediante la aplicación de un tratamiento superficial DUPLEX consistente en la nitruración líquida (conocida como Teniffer seguido del depósito de un recubrimiento duro de nitruro de titanio (TiN. La microestructura cristalina fue evaluada mediante difracción de rayos X, la morfología y la composición química fue determinada por microscopía SEM y espectroscopía de energía dispersiva de rayos X (EDS, las propiedades tribológicas fueron analizadas mediante mediciones en un tribómetro de tipo esfera sobre disco y la microdureza se determinó por el método Vickers. Las muestras tratadas con el recubrimiento dúplex mostraron una resistencia al desgaste 4 veces mayor que la muestra en estado bonificado, lo cual demuestra la aplicación potencial que tiene el acero 4140 sometido a este tratamiento dúplex.

Casting AISI 316 steel by gel cast

International Nuclear Information System (INIS)

Ozols, A; Thern, G; Rozenberg, S; Barreiro, M; Marajofsky, A

2004-01-01

The feasibility of producing AISI 316 steel components from their powders and avoiding their compaction is analyzed. A casting technique is tested that is similar to gel casting, used for ceramic materials. In the initial stage, the process consists of the formulation of a concentrated barbotine of powdered metal in a solution of water soluble organic monomers, which is cast in a mold and polymerized in situ to form a raw piece in the shape of the cavity. The process can be performed under controlled conditions using barbotines with a high monomer content from the acrylimide family. Then, the molded piece is slowly heated until the polymer is eliminated, and it is sintered at temperatures of 1160 o C to 1300 o C under a dry hydrogen atmosphere, until the desired densities are attained. The density and micro structure of the materials obtained are compared with those for the materials compacted and synthesized by the conventional processes. The preliminary results show the feasibility of the process for the production of certain kinds of structural components (CW)

Utilização de uma ferramenta multimídia para identificação de Artrópodes: avaliação de estudantes do Ensino Fundamental

Directory of Open Access Journals (Sweden)

Tiago José Benedito Eugênio

2012-01-01

Full Text Available No presente artigo apresentamos um modelo de montagem e produção de um CD-ROM com recursos para identificação de 22 animais, que disponibiliza, para o aluno, uma chave multimídia para identificação de artrópodes. Tratamos de avaliar esta chave multimídia como ferramenta didática em quatro turmas (sétimo, oitavo e nono ano do Ensino Fundamental de uma escola privada do município de Parnamirim, RN. A avaliação foi dividida em duas etapas: avaliação através de questionário imediatamente após o contato com a chave multimídia, e comparação entre as notas obtidas em exames por escrito de alunos que tiveram e não tiveram contato com a ferramenta didática. Ao todo, 89 alunos participaram das duas etapas da avaliação. Constatamos, de forma geral, uma avaliação positiva e um desempenho significativamente maior dos alunos que interagiram com a ferramenta didática no exame por escrito.

Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

Directory of Open Access Journals (Sweden)

Rômulo Ribeiro Magalhães de Sousa

2012-04-01

Full Text Available AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN, with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a very hard layer containing mainly ε-Fe3N and expanded ferrite phases.

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.

Uma nova heurística para o problema de minimização de trocas de ferramentas A new heuristic for the minimization of tool switches problem

Directory of Open Access Journals (Sweden)

Antônio Augusto Chaves

2012-01-01

Full Text Available O problema de minimização de troca de ferramentas (MTSP busca uma sequência de processamento de um conjunto de tarefas, de modo a minimizar o número de trocas de ferramentas requeridas. Este trabalho apresenta uma nova heurística para o MTSP, capaz de produzir bons limitantes superiores para um algoritmo enumerativo. Esta heurística possui duas fases: uma fase construtiva que é baseada em um grafo em que os vértices correspondem a ferramentas e existe um arco k = (i, j que liga os vértices i e j se e somente se as ferramentas i e j são necessárias para a execução de alguma tarefa k; e uma fase de refinamento baseada na meta-heurística Busca Local Iterativa. Resultados computacionais mostram que a heurística proposta tem um bom desempenho para os problemas testados, contribuindo para uma redução significativa no número de nós gerados de um algoritmo enumerativo.The minimization of tool switches problem (MTSP seeks a sequence to process a set of jobs so that the number of tool switches required is minimized. This study presents a new heuristic for the MTSP. This heuristic has two phases: a constructive phase, based on a graph where the vertices correspond to tools and there is an arc k = (i, j linking vertices i and j if and only if the tools i and j are required to execute some job; and an improvement phase, based on an Iterated Local Search. Computational results show that the proposed heuristic has a good performance on the instances tested contributing to a significant reduction in the number of nodes generated by an enumerative algorithm.

Análise da Inteligibilidade de textos via ferramentas de Processamento de Língua Natural: adaptando as métricas do Coh-Metrix para o Português

Directory of Open Access Journals (Sweden)

Carolina Evaristo Scarton

2010-04-01

Full Text Available Este artigo apresenta o projeto de adaptação de métricas da ferramenta Coh-Metrix para o português do Brasil (Coh-Metrix-Port. Descreve as ferramentas de processamento de língua natural para o português que foram utilizadas, juntamente com as decisões tomadas para a criação da Coh-Metrix-Port. O artigo traz duas aplicações da ferramenta Coh-Metrix-Port: (i a avaliação de textos jornalísticos e sua versão para crianças, mostrando as diferenças entre os textos supostamente complexos e textos simples, isto é, os textos reescritos; (ii a criação de classificadores binários (com córpus de textos dedicados a adultos e crianças, analisando a influência do gênero no desempenho destes classificadores (gêneros jornalístico e de divulgação científica e de textos de outras fontes. A precisão do melhor classificador treinado foi conseguida com a implementação de Support Vector Machines (SMO do WEKA e foi de 97%. Como as métricas desta ferramenta ajudam a discriminar com boa precisão textos dedicados a adultos e a crianças, acreditamos que elas possam também ajudar a avaliar se textos disponíveis na Web são simples o suficiente para serem inteligíveis por analfabetos funcionais e pessoas com outras deficiências cognitivas, como afasia e dislexia, e também para crianças e adultos em fase de letramento e assim permitir o acesso dos textos da Web para uma gama maior de usuários.

Fabricación aditiva mediante sinterizado láser de polvos de acero inoxidable martensítico AISI 420

OpenAIRE

Vega Nava, Sergio

2014-01-01

Busqueda de los parámetros de fabricación adecuados y los tratamientos térmicos a realizar, con el fin de alcanzar durezas de 50 HRC y una adecuada porosidad, en el acero inoxidable AISI 420 obtenido mediante sinterizado láser.

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...

In-reactor creep rupture of 20% cold-worked AISI 316 stainless steel

International Nuclear Information System (INIS)

Lovell, A.J.; Chin, B.A.; Gilbert, E.R.

1981-01-01

Results of an experiment designed to measure in-reactor stress-to-rupture properties of 20% cold-worked AISI 316 stainless steel are reported. The in-reactor rupture data are compared with postirradiation and unirradiated test results. In-reactor rupture lives were found to exceed rupture predictions of postirradiation tests. This longer in-reactor rupture life is attributed to dynamic point defect generation which is absent during postirradiation testing. The in-reactor stress-to-rupture properties are shown to be equal to or greater than the unirradiated material stress-to-rupture properties for times up to 7000 h. (author)

Behaviour of AISI-SAE 8615 steel in ferritic nitrocarburizing using urea-metanol

International Nuclear Information System (INIS)

Barrena, M.I.; Castro, A.

1998-01-01

The present work shows the behaviour of low carbon alloyed steels as AISI-SAE 8615, after a ferritic nitrocarburizing process. Nitrocarburizing takes place at 570 degree centigree for 3 h in an atmosphere by combustion of methanol and urea under different flow rates. Metallographic studies were performed by optical microscopy. Harness profiles were measured and carbon percentages were also analyzed by emission spectrometry in order to determine the extension of the nitrocarburizing process. Optimal flow conditions have been found. The influence of the flow rate on the nitrocarburizing layer thickness has been also studied. (Author) 12 refs

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.

Filosofia da ciência como ferramenta microeconômica

Directory of Open Access Journals (Sweden)

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.

Effects of fresh gas flow, tidal volume, and charcoal filters on the washout of sevoflurane from the Datex Ohmeda (GE) Aisys, Aestiva/5, and Excel 210 SE Anesthesia Workstations.

Science.gov (United States)

Sabouri, A Sassan; Lerman, Jerrold; Heard, Christopher

2014-10-01

We investigated the effects of tidal volume (VT), fresh gas flow (FGF), and a charcoal filter in the inspiratory limb on the washout of sevoflurane from the following Datex Ohmeda (GE) Anesthesia Workstations (AWSs): Aisys, Aestiva/5, and Excel 210SE. After equilibrating the AWSs with 2% sevoflurane, the anesthetic was discontinued, and the absorbent anesthesia breathing circuit (ABC), reservoir bag, and test lung were changed. The lung was ventilated with 350 or 200 mL·breath(-1), 15 breaths·min(-1), and a FGF of 10 L·min(-1) while the washout of sevoflurane was performed in triplicate using a calibrated Datex Ohmeda Capnomac Ultima™ and a calibrated MIRAN SapphIRe XL ambient air analyzer until the concentration was ≤ 10 parts per million (ppm). The effects of decreasing the FGF to 5 and 2 L·min(-1) after the initial washout and of a charcoal filter in the ABC were recorded separately. The median washout times with the Aisys AWS (14 min, P Excel 210SE (32 min). The mean (95% confidence interval) washout time with the Aisys increased to 23.5 (21.5 to 25.5) min with VT 200 mL·breath(-1) (P < 0.01). Decreasing the FGF from 10 to 5 and 2 L·min(-1) with the Aisys caused a rebound in sevoflurane concentration to ≥ 50 ppm. Placement of a charcoal filter in the inspiratory limb reduced the sevoflurane concentration to < 2 ppm in the Aisys and Aestiva/5 AWSs within two minutes. The GE AWSs should be purged with large FGFs and VTs ~350 mL·breath(-1) for ~25 min to achieve 10 ppm sevoflurane. The FGF should be maintained to avoid a rebound in anesthetic concentration. Charcoal filters rapidly decrease the anesthetic concentration to < 2 ppm.

Microstructure and mechanical properties of Ti/TiN film coated on AISI 304 stainless steel

International Nuclear Information System (INIS)

Park, Ji Yoon; Kim, Kwan Hyu; Choe, Han Cheol

1999-01-01

The microstructure and mechanical properties of Ti/TiN film coated on AISI 304 stainless steels have been studied. AISI 304 stainless steels containing 0.1∼1.0 wt% Ti were fabricated by using vacuum furnace and followed by solutionization treatment at 1050 .deg. C for 1hr. The specimens were coated by Ti and TiN with 1 μm and 2 μm thickness by electron-beam PVD method. The microstructure and phase analysis were carried out by using XRD, WDS and SEM. Mechanical properties such as hardness (micro-Vickers) and wear resistance were examined. Coated films showed fine columnar structure and some defects. Surface roughness increased in all specimens after TiN coating. XRD patterns showed that the TiN(111) peak was major in TiN single-layer and the other peaks were very weak, but TiN(220) and TiN(200) peaks were developed in Ti/TiN double-layer. The hardness of the coating film was higher in Ti/TiN double-layer than in TiN single-layer and not affected by the Ti content of substrate. Ti/TiN double-layer showed better wear resistance than TiN single-layer. The observed wear traces were sheared type in all coated specimens

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.

Características dos folhetos publicitários como ferramenta promocional: hipermerca dos vs. pequenos supermercados

OpenAIRE

Gázquez-Abad, Juan Carlos; Martínez-López, Francisco J.; Mondéjar-Jiménez, Juan Antonio

2011-01-01

Os folhetos publicitários tornaram-se uma das modalidades promocionais a que as empresas varejistas de distribuição destinam maior orçamento. Sem embargo, esta importância econômica não tem sido relatada na literatura de marketing. Torna-se necessário, portanto, um maior número de trabalhos que analisem as características dos folhetos publicitários como ferramenta promocional. Neste trabalho apresenta-se um marco de investigação que procura analisar, tanto desde uma perspectiva qualitativa, c...

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

Science.gov (United States)

Collins, Sunniva R.; Michal, Gary M.

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 conforming 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 107 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 grade 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 incidence of exogenous oxides and by controlling the shape of the sulfides.

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

Determination of type, magnitude and direction of residual stresses generated in the welding of AISI H-13 steel with the hole drilling method

International Nuclear Information System (INIS)

Mejia; I; Maldonado, C; Bedolla, A; Velez, M; Medina, A; Bejar, L

2006-01-01

AISI H-13 steel is considered to be a highly ultra resistant steel because its resistance to stress surpasses 1380 MPa. This steel is widely used in tools that heavily used, especially under high temperatures, such as: awls, molds for pressing, extrusion dies, extrusion tools from heat impact, tools for producing screws, bolts, rivets and taps, molds for centrifugal smelting, tools for presses with shaped pieces, knives for hot cutting, among others. The weldability of AISI H-13 steel is generally poor, but it is possible if the proper precautions are taken. Cracking is perhaps the factor that most limits the weldability of AISI H-13 steel. The tendency to crack during welding for this type of steel occurs in the base metal and the zone close to the supporting material (cold cracking). The interlayer covering technique is used in the repair, welding and recovery of pieces of high alloy steels in order to avoid cracking and to lower the residual stresses generated by obstructed contraction and martensitic transformation. This work defined the type, magnitude and direction of residual stresses at different distances starting from the center of the welded union on the 25.4 mm thick AISI H-13 steel sheet. The welding was carried out in a test piece with Y-Groove geometry following JIS Z 3158 standard, using the SMAW process and an AISI 312 stainless steel interlayer between the base metal and the supporting metal. The hole-drilling method was used to measure the type, magnitude and direction of residual stresses using extensometric gauge rosette CEA-06-062UM-120 and CEA-06-062RE-120 following the guidelines established by ASTM E 837 standard. Based on the relaxed deformations that were measured, the type, magnitude and direction of residual stresses were determined with the H-DRILL residual stress program for biaxial condition. The results indicate that under these welding conditions the residual strains at different distances from the welded union are from stress and

Microstructure and Mechanical Properties of Thixowelded AISI D2 Tool Steel

Directory of Open Access Journals (Sweden)

M. N. Mohammed

2018-05-01

Full Text Available Rigid perpetual joining of materials is one of the main demands in most of the manufacturing and assembling industries. AISI D2 cold work tool steels is commonly known as non-weldable metal that a high quality joint of this kind of material can be hardly achieved and almost impossible by conventional welding. In this study, a novel thixowelding technology was proposed for joining of AISI D2 tool steel. The effect of joining temperature, holding time and post-weld heat treatment on microstructural features and mechanical properties were also investigated. Acceptable joints without defect were achieved through the welding temperature of 1300 °C, while the welding at lower temperature resulted in a series of cracks across the entire joint that led to spontaneous fracture after joining. Tensile test results showed that maximum joint tensile strength of 271 MPa was achieved at 1300 °C and 10 min holding time, which was 35% of that of D2 base metal. Meanwhile, tensile strength of the joined parts after heat treatment showed a significant improvement over the non-heat treated condition with 560 MPa, i.e., about 70% of that of the strength value of the D2 base metal. This improvement in the tensile strength attributed to the dissolution of some amounts of eutectic chromium carbides and changes in the microstructure of the matrix. The joints are fractured at the diffusion zone, and the fracture exhibits a typical brittle characteristic. The present study successfully confirmed that by avoiding dendritic microstructure, as often resulted from the fusion welding, high joining quality components obtained in the semi-solid state. These results can be obtained without complex or additional apparatuses that are used in traditional joining process.

Comparação de programas comerciais de cálculo automático para estruturas porticadas

OpenAIRE

Oliveira, António F. M.; Lourenço, Paulo B.

2001-01-01

O presente trabalho pretende sensibilizar técnicos e investigadores para a problemática associada ao cálculo estrutural baseado em programas de cálculo automático comerciais. É notória a evolução que este tipo de programas experimentou nas últimas décadas, desde a emergência do computador como ferramenta disponível ao cálculo estrutural. Não é de difícil constatação que, quanto maior é a capacidade de cálculo dos programas, menor é o domínio do utilizador sobre as ferramentas que utiliza. Pre...

Cyclic deformation behaviour of quenched and tempered AISI 4140 at two-step tensile-compressive-loading

Energy Technology Data Exchange (ETDEWEB)

Schulze, V.; Lang, K.-H.; Voehringer, O.; Macherauch, E. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Werkstoffkunde 1

1997-08-30

The cyclic deformation behaviour in stress-controlled two-step experiments with one or more changes between two blocks of certain lengths and amplitudes was investigated at the technically important steel AISI 4140 (German grade 42 CrMo 4). In all two-step experiments cyclic worksoftening behaviour is found. The degree of work softening is discussed in comparison to single-step experiments. In several cases effects of static strain-ageing can be found. (orig.) 10 refs.

Studies on the determination of surface deuterium in AISI 1062, 4037, and 4140 steels by secondary ion mass spectrometry

Science.gov (United States)

Sastri, V. S.; Donepudi, V. S.; McIntyre, N. S.; Johnston, D.; Revie, R. W.

1988-12-01

The concentration of deuterium at the surface of cathodically charged high strength steels AISI 1062, 4037, and 4140 has been determined by secondary ion mass spectrometry (SIMS). The beneficial effects of pickling in NAP (a mixture of nitric, acetic, and phosphoric acids) to remove surfacebound deuterium have been observed.

Eye tracking e métricas na Web como ferramentas para estratégias inovadoras de comunicação

Directory of Open Access Journals (Sweden)

Gisele Elios da Silva

2016-04-01

Full Text Available O estudo proposto visou explorar estratégias inovadoras de direcionamento de conteúdo comunicacional perante o uso das ferramentas Eye Tracking na Web e Métricas para monitoramento de interesse do consumidor online, aspectos que poderiam ser apontados como semelhantes entre o uso das referidas ferramentas e a aplicabilidade dos dados de interação social marca-consumidor. Para tanto, revisou-se a literatura em busca de subsídios para a estruturação de um quadro a contemplar as semelhanças identificadas e outro a exemplificar sua aplicabilidade. Quanto ao objetivo deste estudo, optou-se pela pesquisa exploratória e coleta de dados em fontes secundárias. Os resultados preliminares destacaram que uma comunicação inovadora consiste em fazer diferente do tradicional e corriqueiro, adequando-se às mudanças culturais, monitorando tendências de comportamento do consumidor e seus interesses, em busca de compreender o processo de decisão de compra e, sobretudo, desenvolver mensagens significantes. Destacou-se também que interações entre empresas e consumidores se convertem em conhecimento e diferenciais competitivos.

Aplicação da ferramenta SWOT para avaliação das técnicas de dano ao choque térmico em materiais refratários SWOT as a tool to evaluate the thermal shock damage technique of refractory materials

Directory of Open Access Journals (Sweden)

L. R. G. Gonçalves

2010-12-01

Full Text Available A literatura indica diversos tipos de ensaios e diferentes métodos de avaliação de dano por choque térmico. Adicionalmente sabe-se que, em determinadas aplicações, esse tipo de dano é um dos principais responsáveis pela degradação do revestimento refratário. Neste contexto e buscando a melhor forma de reproduzir as condições em serviço do revestimento refratário, o presente trabalho foi realizado visando analisar qual tipo de ensaio de choque térmico e método de avaliação do dano são os mais adequados para avaliar o desempenho destes materiais. Essa análise foi baseada em uma revisão bibliográfica e resultados obtidos em laboratório, em que se comparou e avaliou as vantagens e desvantagens dos métodos mais relevantes encontrados na literatura. Por fim, com o auxilio da ferramenta SWOT foi possível verificar se o método adotado pelos autores desse trabalho é adequado para auxiliar na seleção do refratário para aplicação em calcinadores de leito fluidizado.The literature shows different tests and techniques for evaluating the thermal shock damage. Additionally, it is known that, for certain applications, this type of wear mechanism is one of the main causes of fluid flash calciner refractory degradation. Within this context and in order to find the best way to reproduce the refractory lining service conditions, this work was carried out to point out which thermal shock test and damage assessment method are more suitable to evaluate these materials. This analysis was based on a literature review and laboratory experiments, comparing and evaluating the advantages and disadvantages of the most important methods available. Finally, with the support of the SWOT tool it was possible to evaluate whether the method adopted by the authors of this work is appropriated for helping the selection of the refractories for calciners application.

AVALIAÇÃO DO JOGO DIDÁTICO “DESAFIO DA REPRODUÇÃO” COMO FERRAMENTA PARA ABORDAGEM DE TEMAS RELACIONADOS À VIDA SEXUAL

Directory of Open Access Journals (Sweden)

Rosa Cristina COSTA

2016-12-01

Full Text Available O presente trabalho teve por objetivo avaliar, por meio de questionário de opinião discente, o jogo didático “Desafio da Reprodução”, desenvolvido como ferramenta complementar na abordagem de conteúdos relacionados à anatomia dos aparelhos reprodutores masculino e feminino, gravidez, uso de métodos contraceptivos e doenças sexualmente transmissíveis, no Ensino Fundamental Regular. Os dados obtidos indicam uma boa avaliação do jogo didático, de forma que podemos considera-lo adequado como ferramenta de apoio no processo de ensino-aprendizagem dos temas abordados, pois cumpriu seus objetivos de favorecer a consolidação do conhecimento científico e respeitar a diversidade de conhecimento tácito de cada aluno, proporcionando a construção e fixação do conhecimento de forma gradual, dinâmica e lúdica.

Joining of hybrid AA6063-6SiCp-3Grp composite and AISI 1030 steel by friction welding

Directory of Open Access Journals (Sweden)

N. Rajesh Jesudoss Hynes

2017-10-01

Full Text Available Joining of metals and aluminium hybrid metal matrix composites has significant applications in aviation, ship building and automotive industries. In the present work, investigation is carried out on Friction Welding of AISI 1030 steel and hybrid AA6063-6SiCp-3Grpcomposite, that are difficult to weld by fusion welding technique. Silicon carbide and graphite particle reinforced AA6063 matrix hybrid composite was developed successfully using stir casting method and the joining feasibility of AISI1030 steel with AA6063-6SiCp-3Grp hybrid composite was tried out by friction stud welding technique. During friction stage of welding process, the particulates (SiC & Graphite used for reinforcement, tend to increase the viscosity and lead to improper mixing of matrix and reinforcement. This eventually results in lower strength in dissimilar joints. To overcome this difficulty AA1100 interlayer is used while joining hybrid composite to AISI 1030 steel. Experimentation was carried out using Taguchi based design of experiments (DOE technique. Multiple regression methods were applied to understand the relationship between process parameters of the friction stud welding process. Micro structural examination reveals three separate zones namely fully plasticized zone, partially deformed zone and unaffected base material zone. Ultra fine dynamically recrystallized grains of about 341 nm were observed at the fully plasticized zone. EDX analysis confirms the presence of intermetallic compound Fe2Al5 at the joint interface. According to the experimental analysis using DOE, rotational speed and interlayer sheet thickness contribute about 39% and 36% respectively in determining the impact strength of the welded joints. It is found that joining with 0.5 mm interlayer sheet provides efficient joints. Developed regression model could be used to predict the axial shortening distance and impact strength of the welded joint with reasonable accuracy.

Bainitic transformation in steel under continuous cooling conditions

OpenAIRE

Higuera Cobos, Oscar Fabián; Tristancho Reyes, José Luís; Flórez García, Luís Carlos

2007-01-01

En esta investigación se evalúo el cambio microestructural que presenta el acero AISI –SAE 4140 al ser sometido a condiciones de enfriamiento continuo con el fin de analizar la transformación bainítica. Se determinó que la microestructura a distancias de 0.2 a 2mm es martensítico y a distancias mayores de 30mm se observó un comportamiento bainítico. El tipo de bainita encontrada fue del tipo nodular o globular. In this research were evaluates the change microestructural that presents the ...

Biometria e armazenamento de sementes de genótipos de cacaueiro

Directory of Open Access Journals (Sweden)

Lucimara Ribeiro Venial

2017-03-01

Full Text Available Genótipos de Theobroma cacao L. devem ser melhor estudados, para se identificar aqueles que produzem sementes mais desenvolvidas e viáveis após o armazenamento. Objetivou-se com este trabalho estudar a biometria e dois tempos de armazenamento de sementes de genótipos de cacaueiro. A biometria foi avaliada em oito genótipos de cacaueiro (tratamentos. Foram instalados testes de germinação em delineamento inteiramente ao acaso, no esquema fatorial 8 x 2 (genótipos: CCN51, PH16, CEPEC2002, Ipiranga, SJ02, PS1319, TSH1188 e Comum x dois períodos de armazenamento: 0 e dois dias. O genótipo TSH1188 apresentou maior comprimento, relação comprimento/largura, espessura e massa de 100 sementes. A absorção de água das sementes recém-colhidas dos genótipos é lenta, justificada pelos altos teores de água, o que não caracteriza padrão-trifásico. Os teores de água reduziram em média 2,3 vezes nas sementes armazenadas em relação às recém-colhidas. A germinação das sementes recém-colhidas dos genótipos foi de 100%. Após o armazenamento, as sementes do PS1319 apresentaram a menor redução da germinação (39%, enquanto as dos PH16, CEPEC2002 e SJ02 reduziram 96%. A velocidade de germinação foi maior e o tempo médio menor que dois dias nas sementes recém-colhidas do PS1319, indicando serem mais tolerante à dessecação. Sugere-se o uso dos genótipos TSH1188 e PS1319 em programas de melhoramento genético.

O uso do CMS Joomla e suas ferramentas hipertextuais na produção de sites educativos e de material didático online

Directory of Open Access Journals (Sweden)

Marcos Antônio Pereira Coelho

2011-10-01

Full Text Available Anecessidade de atualização dos conteúdos, os preços relativamente baixos dos provedores de acesso, dentre outros fatores, fazem com que, cada vez mais, empresas, escolas e outras instituições tenham os eu espaço na web. Uma escola que produza e disponibilize material com alguma regularidade terá necessidades que vão além de um blog. Seria necessário, então, criar redes de informações onde possam inserir, modificar e consultar os conteúdos com vistas a promover a interação direta com os alunos e a sociedade em geral. O presente artigo tem como objetivo apresentar as ferramentas hipertextuais do Sistema de Gestão de Conteúdos, Joomla,e suas ferramentas hipertextuais que podem ser utilizadas na produção de material didático online.

Study on tempering behaviour of AISI 410 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Gopa, E-mail: gopa_mjs@igcar.gov.in [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V. [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Panneerselvam, G. [Chemistry Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Dasgupta, Arup [Metallurgy & Materials Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India)

2015-02-15

Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M{sub 23}C{sub 6}) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe{sub 2}C and M{sub 23}C{sub 6} types of carbides coexisting in the material. The nucleation of Fe{sub 2}C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M{sub 23}C{sub 6} carbides, instead of Fe{sub 2}C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of

Detecção e classificação de curto-circuitos em sistemas de distribuição usando rede neural artificial ARTMAP nebulosa

OpenAIRE

Martins, João Roberto Deroco [UNESP

2010-01-01

Este trabalho apresenta uma metodologia para detecção e classificação de faltas do tipo curto-circuito. Esta operação de diagnóstico tem como principal operador um banco de redes neurais artificiais (RNAs) do tipo ARTMAP Nebulosa. Tal ferramenta segue a principal filosofia das RNAs: o reconhecimento de padrões, através de um trei- namento supervisionado inicial, responsável por atualizar os parâmetros das redes con- comitantemente com os resultados desejados. Finalizada a fase de adaptação, a...

Simulation of Thermo-viscoplastic Behaviors for AISI 4140 Steel

Science.gov (United States)

Li, Hong-Bin; Feng, Yun-Li

2016-04-01

The thermo-viscoplastic behaviors of AISI 4140 steel are investigated over wide ranges of strain rate and deformation temperature by isothermal compression tests. Based on the experimental results, a unified viscoplastic constitutive model is proposed to describe the hot compressive deformation behaviors of the studied steel. In order to reasonably evaluate the work hardening behaviors, a strain hardening material constant (h0) is expressed as a function of deformation temperature and strain rate in the proposed constitutive model. Also, the sensitivity of initial value of internal variable s to the deformation temperature is discussed. Furthermore, it is found that the initial value of internal variable s can be expressed as a linear function of deformation temperature. Comparisons between the measured and predicted results confirm that the proposed constitutive model can give an accurate and precise estimate of the inelastic stress-strain relationships for the studied high-strength steel.

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

OpenAIRE

Alves, Eder Paduan; Piorino Neto, Francisco; An, Chen Ying

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 ...

Corrosion Resistance Evaluation of Welded AISI 316 Stainless Steel by Electrochemical Method

International Nuclear Information System (INIS)

Baik, Shin Young; Kim, Kwan Hyu

1990-01-01

Electrochemical potentiokinetic polarization technique is known as quantitative, non-destructive and a rapid method for detecting sensitization and is essentially suitable for use in industrial fields and as laboratory research tools. In this study, electrochemical method was tested as a convenient means of the corrosion resistance evaluation for AISI 316L and 316 stainless steel(SS) and their welded sections. The sections were welded by TIG, MIG, CO 2 and ARC in 0.5N HCl as well as 1N H 2 SO 4 electrolyte with or without 0.01N KSCN. The results confirmed that electrochemical method could be used conveniently for corrosion resistance evaluation except reactivation aspect

Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

Science.gov (United States)

Kilinc, B.; Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

2015-03-01

Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe12Nb5B3 and Fe2NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe2B, NbB2, NbFeB and Fe0,2 Nb0,8 phases. The hardness of the presence phases are changing between 1689±85 HV0.01, and 181±7 HV0.1. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe12Nb5B3 and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

Irradiation creep and swelling of AISI 316 to exposures of 130 dpa at 385?400$deg;C

Science.gov (United States)

Garner, F. A.; Porter, D. L.

1988-07-01

The creep and swelling of AISI 316 stainless steel have been studied at 385 to 400°C in EBR-II to doses of 130 dpa. Most creep capsules were operated at constant stress and temperature but mid-life changes in these variables were also made. This paper concentrates on the behavior of the 20% cold-worked condition but five other conditions were also studied. Swelling at ⩽ 400° C was found to lose the sensitivity to stress exhibited at higher temperatures while the creep rate was found to retain linear dependencies on both stress and swelling rate. The creep coefficients extracted at 400°C agree with those found in other experiments conducted at higher temperatures. In the temperature range of ⩽ 400° C, swelling is in the recombinationdominated regime and the swelling rate falls strongly away from the ~1%/dpa rate observed at higher temperatures. These lower rates of creep and swelling, coupled with the attainment of high damage levels without failure, encourage the use of AISI 316 in the construction of water-cooled fusion first walls operating at temperatures below 400°C.

Influence of sintering atmosphere on the mechanical properties of steel P / M AISI 430L; Influencia de la atmosfera de sinterizacion en las propiedades mecanicas de los aceros P/M AISI 430L

Energy Technology Data Exchange (ETDEWEB)

Iglesias, F. J.; Martinez, C.; Costes, M. T.; Ruiz, J. M.; Garcia, L. E.; Corpas, F.

2014-04-01

It has studied the stainless steel powder metallurgy AISI 430L. It has compared the sintering in two different atmospheres; in vacuum, and in an atmosphere containing nitrogen. It has developed a heat treatment with the aim of improving the mechanical properties. This has been done through microstructural modification of complex nitrides of iron and chromium precipitates during the phase of sintering. Physical properties have been evaluated and are been performing a microstructural analysis for microstructure related to the increase in mechanical properties. (Author)

Tratamiento térmico del acero inoxidable ferrítico AISI 430L sinterizado en atmósfera de N2-H2

Directory of Open Access Journals (Sweden)

Ruiz-Prieto, J. M.

2005-12-01

Full Text Available In this Work the influence of sintering AISI 430L stainless steel in N2-H2 atmosphere on its properties and microstructure have been studied. The presence of nitrogen in the sintering atmosphere leads to complex nitrides formation the AISI 430L sintered steel microstructure. A subsequent heat treatment was applied to modify this microstructure in order to improve the mechanical properties and corrosion resistance of these ferritic stainless steels.Los aceros inoxidables ferríticos, son aceros que contienen esencialmente cromo (12-30 % junto con níquel y molibdeno en cantidades que, en general, no sobrepasan el 1 % y, en ocasiones, se les adicionan otros elementos como son el aluminio, silicio, titanio o niobio. En el presente trabajo de investigación se ha evaluado la influencia del nitrógeno presente en la atmósfera de sinterización sobre la microestructura y propiedades del acero inoxidable ferrítico AISI 430L. Además, se ha realizado un tratamiento térmico posterior de hipertemple y maduración con el objeto de incrementar las propiedades mecánicas y a corrosión de este acero inoxidable, mediante la modificación microestructural de los nitruros complejos de hierro y cromo precipitados durante la etapa de sinterización.

Modification and characterization of the AISI 410 martensitic stainless steels surface; Modificacao e caracterizacao da superficie do aco inoxidavel martensitico AISI 410

Energy Technology Data Exchange (ETDEWEB)

Bincoleto, A.V.L. [Universidade Federal de Sao Carlos (PPG-CEM/UFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Nascente, P.A.P. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

2010-07-01

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)

Diseño de antenas tipo DRA (Dielectric Resonator Antennas)

OpenAIRE

Soria Gallego, Juan

2013-01-01

En este trabajo se va a estudiar un tipo de antenas conocidas como antenas resonantes dieléctricas (DRA) desde el punto de vista de diseño y características radiantes, así como de sus posibles aplicaciones. Las DRAs son un tipo de antenas cada vez más usadas ya que presentan numerosas ventajas respecto a otro tipo de antenas, entre ellas que son fáciles de diseñar, baratas y muy eficientes. Por ello, cada vez aparecen nuevos diseños y nuevas aplicaciones. Entre ellas se ha extendido el uso...

MARKETING PROMOCIONAL COMO FERRAMENTA GERENCIAL PARA AUMENTAR A PRODUTIVIDADE E A QUALIDADE EM SERVIÇOS EDUCACIONAIS

OpenAIRE

Silva, Fabiana Ferreira; Silva, Aline Kelly Moura

2010-01-01

Este ensaio teórico-empírico apresenta como o conhecimento e a utilização das ferramentas do composto de marketing podem auxiliar no alcance dos objetivos organizacionais através do gerenciamento adequado do fluxo de informações na empresa. O lócus de investigação foi constituído por uma instituição de educação profissional reconhecida nacionalmente, que apesar de ter todos os seus processos padronizados e orientações específicas para cada ação, as unidades localizadas nas cidades do interior...

Tribological properties of CrN coatings deposited by nitro-chromizing treatment on AISI D2 steel

Energy Technology Data Exchange (ETDEWEB)

Durmaz, M., E-mail: mdurmaz@sakarya.edu.tr; Abakay, E.; Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey); Kilinc, B. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

2015-03-30

In this work, the wear test of uncoated and chromium nitride coated AISI D2 cold work tool steel against alumina ball realized at 0.1 m/s sliding speeds and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575°C for 8 h in the first step of the coating process, and then chromium nitride coating was performed thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000°C for 2 h. Nitro-chromized samples were characterized by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM), micro-hardness and ball on disk wear tests. The coating layer formed on the AISI D2 steel was compact and homogeneous. X-ray studies showed that the phase formed in the coated layer is Cr{sub 2}N. The depth of the layer was 8.15 µm. The average hardness of the layer was 2160±15 HV{sub 0.025}. For uncoated and chromium nitride materials, wear rate increased with increasing load. The results of friction coefficient and wear rate of the tested materials showed that the CrN coating presents the lowest results.

Tribological properties of CrN coatings deposited by nitro-chromizing treatment on AISI D2 steel

International Nuclear Information System (INIS)

Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.; Kilinc, B.

2015-01-01

In this work, the wear test of uncoated and chromium nitride coated AISI D2 cold work tool steel against alumina ball realized at 0.1 m/s sliding speeds and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575°C for 8 h in the first step of the coating process, and then chromium nitride coating was performed thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000°C for 2 h. Nitro-chromized samples were characterized by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM), micro-hardness and ball on disk wear tests. The coating layer formed on the AISI D2 steel was compact and homogeneous. X-ray studies showed that the phase formed in the coated layer is Cr 2 N. The depth of the layer was 8.15 µm. The average hardness of the layer was 2160±15 HV 0.025 . For uncoated and chromium nitride materials, wear rate increased with increasing load. The results of friction coefficient and wear rate of the tested materials showed that the CrN coating presents the lowest results

Tribological properties of CrN coatings deposited by nitro-chromizing treatment on AISI D2 steel

Science.gov (United States)

Durmaz, M.; Kilinc, B.; Abakay, E.; Sen, U.; Sen, S.

2015-03-01

In this work, the wear test of uncoated and chromium nitride coated AISI D2 cold work tool steel against alumina ball realized at 0.1 m/s sliding speeds and under the loads of 2.5N, 5N and 10N. Steel samples were nitrided at 575°C for 8 h in the first step of the coating process, and then chromium nitride coating was performed thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-chromium, ammonium chloride and alumina at 1000°C for 2 h. Nitro-chromized samples were characterized by X-Ray diffraction analysis (XRD), scanning electron microscopy (SEM), micro-hardness and ball on disk wear tests. The coating layer formed on the AISI D2 steel was compact and homogeneous. X-ray studies showed that the phase formed in the coated layer is Cr2N. The depth of the layer was 8.15 µm. The average hardness of the layer was 2160±15 HV0.025. For uncoated and chromium nitride materials, wear rate increased with increasing load. The results of friction coefficient and wear rate of the tested materials showed that the CrN coating presents the lowest results.

New Observations on High-Speed Machining of Hardened AISI 4340 Steel Using Alumina-Based Ceramic Tools

Directory of Open Access Journals (Sweden)

Mohamed Shalaby

2018-05-01

Full Text Available High-speed machining (HSM is used in industry to improve the productivity and quality of the cutting operations. In this investigation, pure alumina ceramics with the addition of ZrO2, and mixed alumina (Al2O3 + TiC tools were used in the dry hard turning of AISI 4340 (52 HRC at different high cutting speeds of 150, 250, 700 and 1000 m/min. It was observed that at cutting speeds of 150 and 250 m/min, pure alumina ceramic tools had better wear resistance than mixed alumina ones. However, upon increasing the cutting speed from 700 to 1000 m/min, mixed alumina ceramic tools outperformed pure ceramic ones. Scanning electron microscopy (SEM and X-ray photoelectron spectroscopy (XPS were used to investigate the worn cutting edges and analyze the obtained results. It was found that the tribo-films formed at the cutting zone during machining affected the wear resistances of the tools and influenced the coefficient of friction at the tool-chip interface. These observations were confirmed by the chip compression ratio results at different cutting conditions. Raising cutting speed to 1000 m/min corresponded to a remarkable decrease in cutting force components in the dry hard turning of AISI 4340 steel.

Characterizing AISI 1045 steel surface duplex-treated by alternating current field enhanced pack aluminizing and nitriding

Science.gov (United States)

Xie, Fei; Zhang, Ge; Pan, Jianwei

2018-02-01

Thin cases and long treating time are shortcomings of conventional duplex treatment of aluminizing followed by nitriding (DTAN). Alternating current field (ACF) enhanced DTAN was carried out on AISI 1045 steel by applying an ACF to treated samples and treating agents with a pair of electrodes for overcoming those shortcomings. By investigating cases' structures, phases, composition and hardness distributions of differently treated samples, preliminary studies were made on characterizations of the ACF enhanced duplex treatment to AISI 1045 steel. The results show that, with the help of the ACF, the surface Al-rich phase Al5Fe2 formed in conventional pack aluminizing can be easily avoided and the aluminizing process is dramatically promoted. The aluminizing case can be nitrided either with conventional pack nitriding or ACF enhanced pack nitriding. By applying ACF to pack nitriding, the diffusion of nitrogen into the aluminizing case is promoted. AlN, Fe2∼3N and solid solution of N in iron are efficiently formed as a result of reactions of N with the aluminizing case. A duplex treated case with an effective thickness of more than 170 μm can be obtained by the alternating current field enhanced 4 h pack aluminizing plus 4 h pack nitriding.

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.

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.

Pre- and postirradiation properties of brazed joints of AISI 316L stainless steel

International Nuclear Information System (INIS)

Brossa, M.; Franconi, E.; Guerreschi, U.; Pierazzi, L.; Poggi, P.; Rustia, V.

1994-01-01

An extensive test campaign has been performed to verify the reliability and the endurance of brazed joints between AISI 316L parts for structural applications in the nuclear field. The tests, conducted for comparison with three different high melting temperature alloys, included tensile tests (normal and shear), fatigue tests (fatigue crack propagation, low cycle fatigue, 4-point bending fatigue) and impact tests; besides, tensile tests have been performed with both unirradiated and irradiated specimens. Generally, the tests demonstrated satisfactory mechanical properties of the joints and revealed occasionally strong differences in the behaviour of the different brazing alloys, thus providing important design indications. ((orig.))

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.

pH effect on pit potential and protection potential of stainless steels AISI-304, 310 and 316 in NaCl solution

International Nuclear Information System (INIS)

Cabral, U.Q.; Sathler, L.; Mariano Neto, F.

1973-06-01

For three austenitic stainless steels, AISI 304, 310 and 316, the pH influence on the rupture, protection and corrosion potentials was studied in a 0,5N NACl solution. The pit potentials determined by the chronogalvonometric method, are pH independent within the acid range. They showed a rough linear variation within the basic range having a maximum corresponding to the pH value of 8.8. The electrochemical hysteresis method, employed for determining the protection potential, presented a total pH independence for the AISI 316. The other steels showed a small dependence within the basic range but with a tendency for the protection potential to become slightly more active with increasing pH, within the acid range. It was also noted for the three steels studied that the corrosion potental became more active with increasing pH, within the basic range [pt

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

Micromechanical of fracture initiation for an AISI 4140 loaded in the I mode at low temperature

International Nuclear Information System (INIS)

Darwish, F.A.I.

1984-01-01

The variation of fracture morphology with the notch sharpness for an AISI 4140 steel tested at liquid nitrogen temperature in different micro-structural states is presented. The appearance in some cases of a shear lip along the root of rounded notches is presented and discussed in terms of the sequence of local events leading to microcrack formation. The dependence of the steel toughness on the fracture morphology is also presented and discussed. (Author) [pt

Comparison of high temperature wear behaviour of plasma sprayed WC–Co coated and hard chromium plated AISI 304 austenitic stainless steel

International Nuclear Information System (INIS)

Balamurugan, G.M.; Duraiselvam, Muthukannan; Anandakrishnan, V.

2012-01-01

Highlights: ► WC–12wt.%Co powders were deposited to a thickness of 300 μm on to steel substrates. ► The micro hardness of the above coatings was lower than that of chromium plating. ► Wear resistance of chromium coating was increased up to five times of AISI 304 austenitic stainless steel. ► Wear resistance of chromium coat higher than plasma coat at different temperatures. -- Abstract: The wear behaviour of plasma sprayed coating and hard chrome plating on AISI 304 austenitic stainless steel substrate is experimentally investigated in unlubricated conditions. Experiments were conducted at different temperatures (room temp, 100 °C, 200 °C and 300 °C) with 50 N load and 1 m/s sliding velocity. Wear tests were carried out by dry sliding contact of EN-24 medium carbon steel pin as counterpart on a pin-on-disc wear testing machine. In both coatings, specimens were characterised by hardness, microstructure, coating density and sliding wear resistance. Wear studies showed that the hard chromium coating exhibited improved tribological performance than that of the plasma sprayed WC–Co coating. X-ray diffraction analysis (XRD) of the coatings showed that the better wear resistance at high temperature has been attributed to the formation of a protective oxide layer at the surface during sliding. The wear mechanisms were investigated through scanning electron microscopy (SEM) and XRD. It was observed that the chromium coating provided higher hardness, good adhesion with the substrate and nearly five times the wear resistance than that obtained by uncoated AISI 304 austenitic stainless steel.

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.

Análisis estadístico exploratorio de dos tipos de secado de quinua

OpenAIRE

Mena Reinoso, Angel Patricio

2015-01-01

El presente trabajo “Análisis Estadístico Exploratorio de dos Tipos de Secado de Quinua” permite realizar una validación estadística del tipo de secador que posea una alta eficiencia, rendimiento en el secado de este tipo de cereal (Chenopodium quinoa Willd). Para el efecto se empleó el secador de bandejas y un secador solar tipo invernadero, el experimento se llevó a cabo con tres tipos de muestras, una con cascara y las otras escarificadas. La quinua fue sometida a un secado ...

El grado cero de la inconmensurabilidad: la teoría del Actor-Red como caja de herraminetas = O grau zero da incomensurabilidade: a Teoria do Ator-Rede como caixa de ferramentas

Directory of Open Access Journals (Sweden)

Silva, Carlos

2010-01-01

Full Text Available Em 1972, Gilles Deleuze disse que uma teoria é exatamente como uma caixa de ferramentas. Trinta e seis anos depois, um professor da Universidade Autônoma de Barcelona, experto em Teoria do Ator-Rede [ANT], afirmou que esta não deveria tomar-se como um corpo sistemático de conhecimentos, isto é, como uma teoria, mas como uma caixa de ferramentas. Com o fim de constatar a atualidade dessa afirmação, decidi acercar-me a três artigos baseados na ANT. Escolhi os artigos usando de um motor de busca na Internet, o qual pudesse considerar-se o substituto pós-moderno da seleção ao acaso. Assim, em primeiro lugar, apresento uma visão geral de alguns dos princípios da ANT. Em segundo lugar, desdobro minha leitura dos artigos a partir da descrição densa de alguns conceitos da ANT. Finalmente, concluo que a metáfora da caixa de ferramentas é na verdade uma prática que permite se aproximar a diferentes esferas do saber, incluindo a psicologia social, além de qualquer postulado de incomensurabilidade

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.

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.)

High temperature oxidation behavior of austenitic stainless steel AISI 304 in steam of nanofluids contain nanoparticle ZrO2

International Nuclear Information System (INIS)

Prajitno, Djoko Hadi; Syarif, Dani Gustaman

2014-01-01

The objective of this study is to evaluate high temperature oxidation behavior of austenitic stainless steel SS 304 in steam of nanofluids contain nanoparticle ZrO 2 . The oxidation was performed at high temperatures ranging from 600 to 800°C. The oxidation time was 60 minutes. After oxidation the surface of the samples was analyzed by different methods including, optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). X-ray diffraction examination show that the oxide scale formed during oxidation of stainless steel AISI 304 alloys is dominated by iron oxide, Fe 2 O 3 . Minor element such as Cr 2 O 3 is also appeared in the diffraction pattern. Characterization by optical microscope showed that cross section microstructure of stainless steel changed after oxidized with the oxide scale on the surface stainless steels. SEM and x-ray diffraction examination show that the oxide of ZrO 2 appeared on the surface of stainless steel. Kinetic rate of oxidation of austenite stainless steel AISI 304 showed that increasing oxidation temperature and time will increase oxidation rate

The evolution of primary and secondary niobium carbonitrides in AISI 347 stainless steel during manufacturing and long-term ageing

Energy Technology Data Exchange (ETDEWEB)

Erneman, J. [Department of Applied Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Schwind, M. [Outokumpu Stainless AB, PB 74, SE-774 22 Avesta (Sweden); Andren, H.-O. [Department of Applied Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Nilsson, J.-O. [AB Sandvik Materials Technology, R and D Centre, SE-81181 Sandviken (Sweden)]. E-mail: jan-olof.nilsson@sandvik.com; Wilson, A. [AB Sandvik Materials Technology, R and D Centre, SE-81181 Sandviken (Sweden); Agren, J. [Department of Materials Science and Engineering, Royal Institute of Technology, SE-10044 Stockholm (Sweden)

2006-01-15

Nb(C,N) precipitates were studied in a niobium-stabilised stainless steel (AISI 347) statically aged at 700 {sup o}C. Scanning electron microscopy and energy filtered transmission electron microscopy were used to determine the volume fraction and precipitate size of primary and secondary Nb(C,N) after ageing times between 0 and 70,000 h. The experimental data were correlated with simulations of Nb(C,N) formation based on the assumption that the process is controlled by diffusion. These simulations provide a rationale for the existence of two sets of niobium carbonitrides in commercial tubes of AISI 347. Growth of primary Nb(C,N) occurred essentially during manufacturing, with no significant growth at 700 {sup o}C. Rapid dissolution and re-precipitation of secondary Nb(C,N) occurred during manufacturing. Coarsening at 700 {sup o}C of secondary particles was modelled using the Lifshitz-Slyozov-Wagner theory, which overestimated the coarsening rate. These problems were overcome with a model developed by the authors. This model takes both growth and coarsening into account.

The evolution of primary and secondary niobium carbonitrides in AISI 347 stainless steel during manufacturing and long-term ageing

International Nuclear Information System (INIS)

Erneman, J.; Schwind, M.; Andren, H.-O.; Nilsson, J.-O.; Wilson, A.; Agren, J.

2006-01-01

Nb(C,N) precipitates were studied in a niobium-stabilised stainless steel (AISI 347) statically aged at 700 o C. Scanning electron microscopy and energy filtered transmission electron microscopy were used to determine the volume fraction and precipitate size of primary and secondary Nb(C,N) after ageing times between 0 and 70,000 h. The experimental data were correlated with simulations of Nb(C,N) formation based on the assumption that the process is controlled by diffusion. These simulations provide a rationale for the existence of two sets of niobium carbonitrides in commercial tubes of AISI 347. Growth of primary Nb(C,N) occurred essentially during manufacturing, with no significant growth at 700 o C. Rapid dissolution and re-precipitation of secondary Nb(C,N) occurred during manufacturing. Coarsening at 700 o C of secondary particles was modelled using the Lifshitz-Slyozov-Wagner theory, which overestimated the coarsening rate. These problems were overcome with a model developed by the authors. This model takes both growth and coarsening into account

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

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.

COMPARATIVE USABILITY ASSESSMENT OF REBA (RAPID ENTIRE BODY ASSESSMENT ERGONOMIC EVALUATION TOOL ON PAPER AND APP VERSIONS

Directory of Open Access Journals (Sweden)

Isabella de Souza Sierra

2017-11-01

Full Text Available Ferramentas para auxílio de análise ergonômica são frequentemente utilizadas quando há a necessidade de avaliação de riscos musculoesqueléticos no trabalho. Dessas ferramentas, uma das mais conhecidas é a REBA (Rapid Entire Body Assessment. Seu amplo uso fez com que suas formas de distribuição e aplicação fossem alteradas por vários autores, de forma a tentar encontrar a melhor maneira de aplicação. Inclusive, com o advento de celulares e tablets, foram feitas diversas versões em aplicativo da ferramenta. Pouco pode ser encontrado sobre a usabilidade desse método, ainda mais em qual versão é mais apropriado, em termos de usabilidade. Objetivou-se neste artigo realizar uma avaliação de usabilidade da ferramenta REBA em duas diferentes versões para verificar a influência que a usabilidade da ferramenta tem nos seus resultados. Acredita-se que qualquer tipo de ferramenta para uma avaliação ergonômica deve, de forma intrínseca, ser usável, pois sua usabilidade tem influência direta em sua confiabilidade e replicabilidade. Sendo assim, fez-se uma análise comparativa de usabilidade com a ferramenta em versão papel e aplicativos para celular com oito sujeitos para a verificação de tal usabilidade. Encontrou-se melhor usabilidade para o aplicativo, mas confiabilidade equiparada para as duas versões. Assim, constata-se que as duas podem ser igualmente usadas para avaliação REBA.

Um estudo sobre a utilização de sistemas, programas e ferramentas da qualidade em empresas do interior de São Paulo A study on the use of quality systems, programs and tools in companies of interior of São Paulo State

Directory of Open Access Journals (Sweden)

José Augusto de Oliveira

2011-01-01

Full Text Available O desenvolvimento e implantação de sistemas de gestão da qualidade e o uso de programas e ferramentas da qualidade são algumas das opções mais utilizadas pelos gestores para aumentar a competitividade de suas empresas. Nesse contexto, o objetivo deste artigo é apresentar o resultado de uma pesquisa tipo survey em que se verificaram e analisaram as principais características do processo de certificação ISO 9001, seus benefícios, suas dificuldades e quais programas e ferramentas da qualidade são utilizados em 236 empresas do interior do Estado de São Paulo. A pesquisa revelou que a certificação ISO 9001 gera benefícios significativos às organizações, tais como: melhoria dos processos internos e nos seus produtos; aumento da satisfação dos clientes; diminuição do número de não conformidades e de devoluções; aumento da produtividade e do lucro; melhoria no gerenciamento dos recursos e valorização da imagem da empresa no mercado. Ela também ratificou a importância da utilização dos programas e ferramentas da qualidade como forma de as empresas se adequarem melhor aos requisitos da norma ISO 9001. As dificuldades de desenvolvimento e implantação desses sistemas não se confirmaram para a amostra pesquisada. Apenas a resistência à mudança, dentre todas apresentadas, mereceu destaque para os pesquisados.The development and implementation of quality management systems and the use of quality tools and programs are some of the most widely used options by managers to increase the competitiveness of their companies. Thus, the goal of this paper is to present the result of a research type survey which analyzed the main characteristics of the ISO 9001 certification process, its benefits and difficulties and which quality programs and tools are used in 236 company headquartered in the interior of São Paulo State. The survey showed that the ISO 9001 certification generates significant benefits to organizations, such as

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.

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.

Ferramentas para mediação de fontes de informação: avaliação sobre seus usos em bibliotecas universitárias nacionais e internacionais

Directory of Open Access Journals (Sweden)

Valéria Aparecida Moreira Novelli

Full Text Available A pesquisa relata o uso de ferramentas para mediação de fontes de informação por bibliotecas universitárias nacionais e internacionais. O estudo foi de caráter exploratório e utilizou análise de conteúdo, com abordagem quantitativa e qualitativa, de websites de 24 bibliotecas selecionadas dentre as melhores universidades internacionais e nacionais segundo indicadores da Webometrics Ranking of World's Universities, World University Rankings 2011-2012 e Índice Geral de Cursos. Objetivou-se investigar e identificar tendências de aplicações de ferramentas para as atividades de mediação dos processos de acesso, busca e aprendizagem do uso de fontes de informação em bibliotecas universitárias. Os resultados apontam um panorama geral de como as bibliotecas universitárias estão realizando o processo de mediação de fontes de informação, especialmente em relação às bases de dados bibliográficas. Observou-se variações na escala de implementação dessas ferramentas entre as bibliotecas internacionais e as bibliotecas nacionais, bem como o destaque de algumas delas. Conclui-se que diante da disponibilidade e acessibilidade cada vez mais crescente das fontes de informação, torna-se necessário que estas sejam utilizadas de forma eficaz e eficiente. Neste contexto cabe ao bibliotecário refletir, selecionar e implementar ações e ferramentas mais viáveis à realidade de cada biblioteca, considerando as características específicas das gerações e categorias de usuários, a diversidade de tecnologias ofertadas a estes usuários e também aos não usuários, autonomia, estímulo e facilidades para o acesso, busca e uso das fontes de informação.

Study on Surface Integrity of AISI 1045 Carbon Steel when machined by Carbide Cutting Tool under wet conditions

Directory of Open Access Journals (Sweden)

Tamin N. Fauzi

2017-01-01

Full Text Available This paper presents the evaluation of surface roughness and roughness profiles when machining carbon steel under wet conditions with low and high cutting speeds. The workpiece materials and cutting tools selected in this research were AISI 1045 carbon steel and canela carbide inserts graded PM25, respectively. The cutting tools undergo machining tests by CNC turning operations and their performances were evaluated by their surface roughness value and observation of the surface roughness profile. The machining tests were held at varied cutting speeds of 35 to 53 m/min, feed rate of 0.15 to 0.50 mm/rev and a constant depth of cut of 1 mm. From the analysis, it was found that surface roughness increased as the feed rate increased. Varian of surface roughness was suspected due to interaction between cutting speeds and feed rates as well as nose radius conditions; whether from tool wear or the formation of a built-up edge. This study helps us understand the effect of cutting speed and feed rate on surface integrity, when machining AISI 1045 carbon steel using carbide cutting tools, under wet cutting conditions.

The effects of strain induced martensite on stress corrosion cracking in AISI 304 stainless steel

International Nuclear Information System (INIS)

Lee, W. S.; Kwon, S. I.

1989-01-01

The effects of strain induced martensite on stress corrosion cracking behavior in AISI 304 stainless steel in boiling 42 wt% MgCl 2 solution were investigated using monotonic SSRT and cyclic SSRT with R=0.1 stress ratio. As the amount of pre-strain increased, the failure time of the specimens in monotonic SSRT test decreased independent of the existence of strain induced martensite. The strain induced martensite seems to promote the crack initiation but to retard the crack propagation during stress corrosion cracking

Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

Energy Technology Data Exchange (ETDEWEB)

Kilinc, B., E-mail: bkilinc@sakarya.edu.tr; Durmaz, M.; Abakay, E. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, SakaryaUniversity, Esentepe Campus, 54187Sakarya (Turkey); Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

2015-03-30

Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

Laser transformation hardening effect on hardening zone features and surface hardness of tool steel AISI D2

Directory of Open Access Journals (Sweden)

D. Lesyk

2017-06-01

Full Text Available The relationship of technological input regimes of the laser transformation hardening on change the hardening depth, hardening width, and hardening angle, as well as surface hardness of the tool steel AISI D2 using multifactor experiment with elements of the analysis of variance and regression equations was determined. The laser transformation hardening process implemented by controlling the heating temperature using Nd:YAG fiber laser with scanner, pyrometer and proportional-integral-differential controller. The linear and quadratic regression models are developed, as well as response surface to determine the effect of the heating temperature and feed rate of the treated surface on the energy density of the laser beam, hardening depths, hardening width, hardening angle, and surface hardness are designed. The main effect on the energy density of the laser beam has a velocity laser treatment, on the other hand, the main effect on the geometrical parameters of the laser hardened zone and surface hardness has temperature heating are shown. The optimum magnitudes of the heating temperature (1270 °C and feed rate of the treated surface (90 mm/min for laser transformation hardening of the tool steel AISI D2 using fiber laser with scanner were defined.

O uso de ferramentas da internet para auxiliar adultos na aprendizagem de inglês como língua estrangeira

OpenAIRE

Annie Lezan Bittencourt de Moura

2007-01-01

A utilização de tecnologias em sala de aula tem despertado, cada vez mais, o interesse de estudiosos no desenvolvimento de ferramentas que auxiliem no ensino aprendizagem, particularmente naquele de língua estrangeira. Este trabalho teve como objetivo principal analisar se a tecnologia, quando aliada às aulas presenciais, pode auxiliar alunos adultos, com mais de 40 anos, a obterem um melhor resultado na aprendizagem. Para isso, a questão central de pesquisa proposta foi descobrir que efeito ...

Inovação tecnológica no setor de máquinas ferramentas Brasileiro: Um estudo de caso

OpenAIRE

Marcos Eugênio da Silva

1982-01-01

O objetivo do presente trabalho é, a partir da análise da historia de urna firma brasileira produtora de máquinas ferramentas, buscar evidencias empíricas que permitam responder a duas questões: i) Houve inovação tecnológica na firma? ii) Se houve, como se processou a aprendizagem desta tecnologia e em que medida pode-se dizer que a firma gerou tecnologia, dado que ela se encontra localizada em um país subdesenvolvido?

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

Estimation of Fatigue Life of Laser Welded AISI304 Stainless Steel T-Joint Based on Experiments and Recommendations in Design Codes

DEFF Research Database (Denmark)

Lambertsen, Søren Heide; Damkilde, Lars; Kristensen, Anders Schmidt

2013-01-01

In this paper the fatigue behavior of laser welded T-joints of stainless steel AISI304 is investigated experimentally. In the fatigue experiments 36 specimens with a sheet thickness of 1 mm are exposed to one-dimensional cyclic loading. Three different types of specimens are adopted. Three groups...

Modelling of Tool Wear and Residual Stress during Machining of AISI H13 Tool Steel

Science.gov (United States)

Outeiro, José C.; Umbrello, Domenico; Pina, José C.; Rizzuti, Stefania

2007-05-01

Residual stresses can enhance or impair the ability of a component to withstand loading conditions in service (fatigue, creep, stress corrosion cracking, etc.), depending on their nature: compressive or tensile, respectively. This poses enormous problems in structural assembly as this affects the structural integrity of the whole part. In addition, tool wear issues are of critical importance in manufacturing since these affect component quality, tool life and machining cost. Therefore, prediction and control of both tool wear and the residual stresses in machining are absolutely necessary. In this work, a two-dimensional Finite Element model using an implicit Lagrangian formulation with an automatic remeshing was applied to simulate the orthogonal cutting process of AISI H13 tool steel. To validate such model the predicted and experimentally measured chip geometry, cutting forces, temperatures, tool wear and residual stresses on the machined affected layers were compared. The proposed FE model allowed us to investigate the influence of tool geometry, cutting regime parameters and tool wear on residual stress distribution in the machined surface and subsurface of AISI H13 tool steel. The obtained results permit to conclude that in order to reduce the magnitude of surface residual stresses, the cutting speed should be increased, the uncut chip thickness (or feed) should be reduced and machining with honed tools having large cutting edge radii produce better results than chamfered tools. Moreover, increasing tool wear increases the magnitude of surface residual stresses.

Perspectivas em Redes Sociais: a inteligência coletiva como ferramenta de análise de métricas e indicadores de desempenho

Directory of Open Access Journals (Sweden)

Paula Toledo Palomino

2013-12-01

Full Text Available O presente artigo visa fazer uma análise do funcionamento das redes sociais enquanto repositório da inteligência coletiva do universo virtual. Pretende-se analisar a história e o conceito teórico das redes sociais, bem como alguns processos para a utilização de métricas para criação de indicadores de desempenho, de forma a possibilitar uma mineração de dados e análise estruturada dos mesmos, gerando relatórios gerenciais e estratégicos que possam ser utilizados para uma grande variedade de objetivos, desde como medidores de audiência para produtos audiovisuais, como indicadores em gestão de marcas corporativas. O presente trabalho abordará um estudo de caso, onde o twitter passou a ser utilizado como ferramenta para medição de audiência em novelas e séries de TV, a fim de exemplificar os conceitos abordados nos capítulos anteriores, culminando na conclusão demonstrando a importância que estas ferramentas e ambientes virtuais possuem na atualidade.

Experimental Determination of Temperature During Rotary Friction Welding of AA1050 Aluminum with AISI 304 Stainless Steel

OpenAIRE

Alves, Eder Paduan; Piorino Neto, Francisco; An, Chen Ying; Silva, Euclides Castorino da

2012-01-01

Abstract: The purpose of this study was the temperature monitoring at bonding interface during the rotary friction welding process of dissimilar materiais: AA1050 aluminum with AISI 304 stainless steel. As it is directly related to the mechanical strenght of the junction, its experimental determination in real time is of fundamental importance for understanding and characterizing the main process steps, and the definition and optimization of parameters. The temperature gradients were obtained...

Study of Carbide Evolution During Thermo-Mechanical Processing of AISI D2 Tool Steel

Science.gov (United States)

Bombac, D.; Fazarinc, M.; Podder, A. Saha; Kugler, G.

2013-03-01

The microstructure of a cold-worked tool steel (AISI D2) with various thermo-mechanical treatments was examined in the current study to identify the effects of these treatments on phases. X-ray diffraction was used to identify phases. Microstructural changes such as spheroidization and coarsening of carbides were studied. Thermodynamic calculations were used to verify the results of the differential thermal analysis. It was found that soaking temperature and time have a large influence on dissolution, precipitation, spheroidization, and coalescence of carbides present in the steel. This consequently influences the hot workability and final properties.

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

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)

Applications of the essay at slow deformation velocity in pipes of stainless steel AISI-304; Aplicaciones del ensayo a velocidad de deformacion lenta en tuberias de acero inoxidable AISI-304

Energy Technology Data Exchange (ETDEWEB)

Zamora R, L.; Mora R, T. De la [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2004-07-01

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.

A IDENTIFICAÇÃO DE TIPOS DE LIDERANÇA A PARTIR DE ARQUÉTIPOS

Directory of Open Access Journals (Sweden)

Adriana Nunes Lacerda e Prestupa

2009-09-01

junguianos analisados por Moore e Gillette (1993 foram relacionados com características de líderes dentro do contexto organizacional. Desta forma foi possível apresentar uma tipologia rica e aplicável, onde o individuo pode se identificar e também entender o processo e a maturação das características dos arquétipos estudados para melhor desempenho dentro das organizações.

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.

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)

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.

High temperature oxidation behavior of austenitic stainless steel AISI 304 in steam of nanofluids contain nanoparticle ZrO2

Energy Technology Data Exchange (ETDEWEB)

Prajitno, Djoko Hadi, E-mail: djokohp@batan.go.id; Syarif, Dani Gustaman, E-mail: djokohp@batan.go.id [Research Center for Nuclear Materials and Radiometry, Jl. Tamansari 71, Bandung 40132 (Indonesia)

2014-03-24

The objective of this study is to evaluate high temperature oxidation behavior of austenitic stainless steel SS 304 in steam of nanofluids contain nanoparticle ZrO{sub 2}. The oxidation was performed at high temperatures ranging from 600 to 800°C. The oxidation time was 60 minutes. After oxidation the surface of the samples was analyzed by different methods including, optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). X-ray diffraction examination show that the oxide scale formed during oxidation of stainless steel AISI 304 alloys is dominated by iron oxide, Fe{sub 2}O{sub 3}. Minor element such as Cr{sub 2}O{sub 3} is also appeared in the diffraction pattern. Characterization by optical microscope showed that cross section microstructure of stainless steel changed after oxidized with the oxide scale on the surface stainless steels. SEM and x-ray diffraction examination show that the oxide of ZrO{sub 2} appeared on the surface of stainless steel. Kinetic rate of oxidation of austenite stainless steel AISI 304 showed that increasing oxidation temperature and time will increase oxidation rate.

Comparative study of the microbiological corrosion among an AISI 304L and an API X65; Estudio comparativo de la corrosion microbiologica entre un AISI 304L y un API X65

Energy Technology Data Exchange (ETDEWEB)

Diaz S, A.; Arganis J, C.; Luna C, P.; Carapia M, L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Gonzalez F, E. [ITT, Toluca, Estado de Mexico (Mexico)

2004-07-01

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)

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.

Helium and its effects on the creep-fatigue behaviour of electron beam welds in the steel AISI-316-L

International Nuclear Information System (INIS)

Paulus, M.

1992-12-01

Within the scope of R and D work for materials development for the NET fusion experiment (Next European Torus) and the International Thermonuclear Experimental Reactor (ITER), the task reported was to examine electron beam welds in the austenitic stainless steel AISI 316 L (NET reference material) for their fatigue behaviour under creep load, and the effects of helium implantation on there mechanical properties. (orig.) [de

Comparative study of AISI M3:2 high speed steel produced through different techniques of manufacturing; Estudo comparativo de acos rapidos AISI M3:2 produzidos por diferentes processos de fabricacao

Energy Technology Data Exchange (ETDEWEB)

Araujo Filho, Oscar Olimpio de

2006-07-01

In this work AISI M3:2 high speed steels obtained through different techniques of manufacturing, submitted to the same heat treatment procedure were evaluated by measuring their mechanical properties of transverse rupture strength and hardness. Sinter 23 obtained by hot isostatic pressing (HIP), VWM3C obtained by the conventional route and a M3:2 high speed steel obtained by cold compaction of water atomized powders and vacuum sintered with and without the addition of a small quantity of carbon were evaluated after the same heat treatment procedure. The vacuum sintered M3:2 high speed steel can be an alternative to the more expensive high speed steel produced by hot isostatic pressing and with similar properties presented by the conventional one. The characterization of the vacuum sintered M3:2 high speed steel was performed by measuring the densities of the green compacts and after the sintering cycle. The sintering produced an acceptable microstructure and densities near to the theoretical. The transverse rupture strength was evaluated by means of three point bending tests and the hardness by means of Rockwell C and Vickers tests. The technique of scanning electronic microscopy (SEM) was used to evaluate the microstructure and to establish a relation with the property of transverse rupture strength. The structure was determined by means of X-ray diffraction (XRD) patterns and the retained austenite was detected to all the conditions of heat treatment. The main contribution of this work is to establish a relation between the microstructure and the mechanical property of transverse rupture strength and to evaluate the AISI M3:2 vacuum sintered high speed steel as an alternative to the similar commercial high speed steels. (author)

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

termodinámico en placas de acero AISI 4140 y pistas de rodamiento utilizando adhesivos anaeróbicos

Directory of Open Access Journals (Sweden)

Germán García

2006-01-01

Full Text Available Se evaluó el trabajo de adhesión termodinámico de placas planas de acero (AISI 4140 y AISI 52100 en contacto con dos adhesivos anaeróbicos de uso comercial, mediante la medición de los ángulos de contacto termodinámico de avance y retroceso obtenidos por el método de inmersión y emersión. Se utilizó el método de van Oss para calcular las componentes polares y no polares de adhesión para cada par metal-adhesivo. Se analizó también el efecto de la aplicación de un activador de superficie sobre el trabajo de adhesión en húmedo y se relacionaron los resultados con las características químicas y físicas de las placas. Los resultados indicaron que la aplicación del activador tuvo un efecto importante sobre la mojabilidad de los adhesivos, pero pequeña influencia en el trabajo de adhesión medido. Por otro lado, se encontraron diferencias importantes en la respuesta de los dos adhesivos estudiados, fundamentalmente en virtud de su composición química y propiedades reológicas.

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

PROPOSTA DE IMPLANTAÇÃO DE UM JARDIM SENSORIAL COMO FERRAMENTA DE ENSINO NAS ESCOLAS DO ENSINO FUNDAMENTAL II.

OpenAIRE

Ariane Araújo Ferreira; Walderez Moreira Joaquim

2017-01-01

Jardim sensorial é um espaço para aguçar os cinco sentidos. Objetivou-se elaborar um manual para docentes do ensino fundamental II, propondo a implantação de um Jardim Sensorial como atividade lúdica e como ferramenta no processo de ensino-aprendizagem dos conteúdos de morfologia vegetal. Foi realizado um levantamento bibliográfico sobre jardim sensorial, ensino de ciências e botânica. O manual é constituído por cinco partes: 1) O que é um Jardim Sensorial, 2) Construção do Jardim Sensorial, ...

Modelagem e Simulação no Âmbito da Hidrologia

Directory of Open Access Journals (Sweden)

Vassiliki Terezinha Galvão Boulomytis

2011-04-01

Full Text Available A modelagem hidrológica pode ser considerada como um conjunto de ferramentas destinadas ao cálculo e à representação de dados que possibilita a previsão de eventos, a realização de projetos, o gerenciamento dos recursos hídricos, além de outros tipos de aplicação. No entanto, devido à variabilidade na ocorrência dos processos hidrológicos, escassez e dificuldade na obtenção de dados levantados em campo, os modelos conceituais vêm sendo combinados com os físicos e empíricos, utilizando-se de novas técnicas, entre elas, o sensoriamento remoto e o geoprocessamento para a coleta, processamento, análise e geração de resultados. Neste trabalho será apresentada a base conceitual e a importância do conhecimento do tipo de ferramenta que se deseja utilizar para a implementação ou uso de um modelo hidrológico, para que deste modo seja possível verificar a possibilidade do mesmo ser de fato desenvolvido.

Quebrando estereótipos e rompendo preconceitos na sala de aula

Directory of Open Access Journals (Sweden)

Daniela Jakubaszko

2015-04-01

Full Text Available Este texto se preocupa em contribuir para a reflexão que torna possível a identificação e ruptura dos estereótipos sociais que dão origem a preconceitos e ações discriminatórias. Com base nos estudos de Walter Lippann, Agnes Heller, Adam Shaff e Eclea Bosi, pretende-se discutir os conceitos de estereótipo e preconceito, buscando entender o que são e porque se formam. Para entender melhor o estereótipo temos que refletir sobre três elementos que a ele se ligam: a linguagem, o cotidiano e o senso comum. É no plano da linguagem - do diálogo e das práticas de linguagem - que se deve estudar e se pode romper e desconstruir os estereótipos, tomando consciência da própria formação discursiva. O texto oferece, ainda, algumas sugestões para trabalhar o conceito na sala de aula e para ampliar o repertório de textos e referências a serem debatidas com os alunos.

El modelo estocástico de Vasicek para la predicción de tipos de interés. Aplicación al tipo de interés interbancario EONIA

OpenAIRE

TAMARIT RAMOS, SALVADOR

2013-01-01

[ES] Las variaciones de los tipos de interés ofrecidos por el dinero en bancos y otras entidades financieras afectan directamente a los mercados bursátiles. Así, por ejemplo, cuando los tipos de interés suben, se producen bajadas en las cotizaciones de las acciones en la bolsa. Estos movimientos decrecientes pueden explicarse por diferentes razones. En primer lugar, los altos tipos de interés elevan las cargas financieras de las empresas y, por lo tanto, empeoran los resultados económicos, lo...

Influence of cryogenic treatment on microstructure and mechanical properties of high strength AISI D2 tool steel =

Science.gov (United States)

Ghasemi Nanesa, Hadi

Cryogenic treatment, known as treating materials at sub-zero temperatures, has been added to conventional heat treatment cycle of high alloyed steels where martensitic transformation is incomplete after quenching to room temperature. Incomplete martensitic transformation occurs due to the effect of high content of alloying elements on pushing down martensite start and finish temperatures to very low values, specifically, on tool steels. In spite of obtaining significant improvements in mechanical and wear properties after cryogenic treatment, there is no cohesive picture about what exactly modifies the microstructure of tool steels during cryogenic treatment and therefore divergent opinions on the influence of process parameters are still reported. For example, the suggested time length for cryogenic treatment starts from few seconds to several days indicating the lack of understanding about micromechanisms responsible for microstructural evolution while holding at cryogenic temperatures. In this regard, the main objective of this project is to develop a better understanding on the fundamental micromechanisms operating during cryogenic treatment. To attain this objective, the following milestones are pursued. - To study the conventional cryogenic treatment and finding challenges. - To identify and characterize the optimum starting microstructure before cryogenic treatment. - To determine the important processing parameters those control the evolution of microstructure and hardness. - To investigate the interaction between carbide precipitation and martensitic transformation in the AISI D2 steel. - To propose an optimal cryogenic treatment for AISI D2 steel.

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 ...

Taguchi Optimization of Cutting Parameters in Turning AISI 1020 MS with M2 HSS Tool

Science.gov (United States)

Sonowal, Dharindom; Sarma, Dhrupad; Bakul Barua, Parimal; Nath, Thuleswar

2017-08-01

In this paper the effect of three cutting parameters viz. Spindle speed, Feed and Depth of Cut on surface roughness of AISI 1020 mild steel bar in turning was investigated and optimized to obtain minimum surface roughness. All the experiments are conducted on HMT LB25 lathe machine using M2 HSS cutting tool. Ranges of parameters of interest have been decided through some preliminary experimentation (One Factor At a Time experiments). Finally a combined experiment has been carried out using Taguchi’s L27 Orthogonal Array (OA) to study the main effect and interaction effect of the all three parameters. The experimental results were analyzed with raw data ANOVA (Analysis of Variance) and S/N data (Signal to Noise ratio) ANOVA. Results show that Spindle speed, Feed and Depth of Cut have significant effects on both mean and variation of surface roughness in turning AISI 1020 mild steel. Mild two factors interactions are observed among the aforesaid factors with significant effects only on the mean of the output variable. From the Taguchi parameter optimization the optimum factor combination is found to be 630 rpm spindle speed, 0.05 mm/rev feed and 1.25 mm depth of cut with estimated surface roughness 2.358 ± 0.970 µm. A confirmatory experiment was conducted with the optimum factor combination to verify the results. In the confirmatory experiment the average value of surface roughness is found to be 2.408 µm which is well within the range (0.418 µm to 4.299 µm) predicted for confirmatory experiment.

Acoustic emission during tensile deformation and fracture of nuclear grade AISI type 304 stainless steel specimens with notches

International Nuclear Information System (INIS)

Mukhopadhyay, C.K.; Jayakumar, T.; Baldev Raj

1996-01-01

Acoustic emission generated during tensile deformation and fracture of nuclear grade AISI type 304 stainless steel specimens with notches has been studied. The extent of acoustic activity generated depends on notch tip severity, notch tip blunting and tearing of the notches. The equation N=AK m applied to the acoustic emission data of the notched specimens has shown good correlation. Acoustic emission technique can be used to estimate the size of an unknown notch. (author)

Modifications on the behaviour of AISI 304 stainless steel submitted to creep caused by intermediate treatment of annealing

International Nuclear Information System (INIS)

Barreto, L.F.P.; Monteiro, S.N.

1982-01-01

Type AISI 304 austenitic stainless steel samples which have been previously creep deformed at 750 0 C, were annealed at 1100 0 C. The effects of this heat treatment in the mechanical behavior of this material when retested in creep were investigated. The results were analysed by taking into account the structural modifications observed and the controlling mechanisms which operate during the deformation and fracture occurring in the creep process. (Author) [pt

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)

Estimulación de diferentes tipos de inteligencias a través de los videojuegos

OpenAIRE

Aliciardi, Agustina; De Cunto, Guillermo; Marcucci, Ricardo Martín

2016-01-01

Existen diferentes tipos de inteligencia (lógico-matemática, verbal-lingüística, corporal-cinestésica, musical, naturalista, visual-espacial, interpersonal, intrapersonal). Conocer las habilidades y capacidades típicas de cada tipo de inteligencia permite saber que tipo de actividades realizar para estimularlas y lograr generar un desarrollo más equilibrado, que le permita a las personas maximizar su potencial aprovechando sus fortalezas. Debido a esto, se investigaron diferentes tipos de jue...

ENDOMARKETING COMO FERRAMENTA DE MOTIVAÇÃO: ANÁLISE DAS SUAS APLICAÇÕES EM UMA REDE DE SUPERMERCADOS NO MUNICÍPIO DE CAMPOS DOS GOYTACAZES-RJ

Directory of Open Access Journals (Sweden)

Sabrina Silva

2014-04-01

Full Text Available O presente estudo tem por objetivo avaliar a valorização e motivação dos funcionários, através dos impactos do uso do Endomarketing em uma Rede de Supermercados no município de Campos dos Goytacazes. Foi realizado um estudo de caso por meio de uma entrevista com perguntas abertas, com a Gerente de Recursos Humanos da Rede e questionários distribuídos aos colaboradores de todos os setores, das maiores lojas do Grupo. O estudo demonstrou que apesar da empresa possuir algumas ferramentas de Endomarketing tais como; difusão da história da empresa, manual de normas e procedimentos, canais de comunicação e ouvidoria internos, de acordo com os colaboradores estas ferramentas não surtem o efeito desejado. Os canais de comunicação interna existem, mas são ineficientes e o sentimento de desvalorização é compartilhado pela maioria.

Optimization of Minimum Quantity Lubricant Conditions and Cutting Parameters in Hard Milling of AISI H13 Steel

OpenAIRE

The-Vinh Do; Quang-Cherng Hsu

2016-01-01

As a successful solution applied to hard machining, the minimum quantity lubricant (MQL) has already been established as an alternative to flood coolant processing. The optimization of MQL parameters and cutting parameters under MQL condition are essential and pressing. The study was divided into two parts. In the first part of this study, the Taguchi method was applied to find the optimal values of MQL condition in the hard milling of AISI H13 with consideration of reduced surface roughness....

The effect of some heat treatment parameters on the dimensional stability of AISI D2

Science.gov (United States)

Surberg, Cord Henrik; Stratton, Paul; Lingenhöle, Klaus

2008-01-01

The tool steel AISI D2 is usually processed by vacuum hardening followed by multiple tempering cycles. It has been suggested that a deep cold treatment in between the hardening and tempering processes could reduce processing time and improve the final properties and dimensional stability. Hardened blocks were then subjected to various combinations of single and multiple tempering steps (520 and 540 °C) and deep cold treatments (-90, -120 and -150 °C). The greatest dimensional stability was achieved by deep cold treatments at the lowest temperature used and was independent of the deep cold treatment time.

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)

Effect of Spreading Time on Contact Angle of Nanofluid on the Surface of Stainless Steel AISI 316 and Zircalloy 4

Science.gov (United States)

Prajitno, D. H.; Trisnawan, V.; Syarif, D. G.

2017-05-01

The solid surface tension plays an important role in the heat and mass transfer system for heat exchanger equipment. In the nuclear power plant industry, the stainless steel AISI 316 and Zircalloy 4 have been used for long time as structure materials. The purpose of the experimental is to study solid state surface tension behavior by measure contact angle Nano fluid contain nano particle alumina on metal surface of stainless steel AISI 316 and Zircalloy 4 by sessile drop method. The experiment is to measure the static contact angle and drop nano fluid contains nano particle alumina on stainless steel 316 and zircalloy 4 with different spreading time from 1 to 30 minute. It was observed that stainless steel 316 and zircalloy 4 lose their hydrophobic properties with increasing elapsed time during drop of nano fluid on the surface of alloy. As a result the contact angle of nano fluid on surface of metal is decrease with increasing elapsed time. While the magnitude diameter of drop nano fluid and wetting surface is increase with increasing elapsed time on the surface of the stainless steel SS 316 and Zircalloy 4.

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)

Regulação técnica para se obter melhor eficiência na motorização de pequenas centrais hidrelétricas no Brasil

OpenAIRE

Miranda, Roberto Lobo

2009-01-01

O propósito deste estudo é discutir um eventual aumento na produção de energia elétrica que é definida para as pequenas centrais hidrelétricas (PCH), tornando a escolha do tipo de turbina uma ferramenta para ampliar a oferta de energia de um mesmo aproveitamento hidrelétrico. O trabalho está voltado para as chamadas baixas quedas d água e destaca essas usinas em um cenário cada vez maior de exploração de usinas do tipo fio d água, em substituição àquelas de formação de grandes reservatórios. ...

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.

Effect of coatings obtanied by sputtering of chromium catode on the corrosion resistance of AISI H13 steel

International Nuclear Information System (INIS)

Sandoval, A; Peña, D; Piratoba, U

2013-01-01

Corrosion resistance of coatings obtained by sputtering a chromium target were evaluated. The films were deposited on substrates of disk-shaped AISI H13 steel. By means of potentiodynamic polarization curves were able to determine the current density vs. potential for the coated and uncoated substrate and the difference in the corrosion potential Ecorr. All samples with coating showed an increase in Ecorr respect to substrate. The electrochemical tests were conducted in an electrolytic solution of 3% NaCl

Representaciones mentales sobre los tipos de agresión en escolares

Directory of Open Access Journals (Sweden)

Yuly Fang Alandette

2009-01-01

Full Text Available Este artículo presenta un estudio descriptivo comparativo de corte transversal acerca de las representaciones mentales de los tipos de agresión en una muestra de 60 niños escolarizados, de 8 a 11 años de edad. Los niños provienen de los niveles socio-económicos alto y bajo de la ciudad de Cartagena. Para recolectar la información, se utilizó la técnica de entrevista clínica piagetiana de tipo semi-estructurada, apoyada con dibujos que permitieron explorar las ideas y sentimientos de los niños y las niñas. Las explicaciones de los niños son más claras y estructuradas respecto a las agresiones directas de tipo físico y verbal, adiferencia de las representaciones de agresiones, tales como la amenaza y exclusión que se muestran menos elaboradas. Aunque se observan diferencias de acuerdo con la edad al identificar los tipos de agresión y las categorías evaluadas, las explicaciones difieren en muchos casos de los resultados de otras investigaciones.

Ferramenta para Análise e Avaliação de Riscos no Planejamento de Projetos de Pesquisa e Desenvolvimento

Directory of Open Access Journals (Sweden)

Marta Fatima Vencato

2014-12-01

Full Text Available Este trabalho é parte da dissertação de mestrado apresentada ao Programa de Pós-Graduação em Desenvolvimento de Tecnologia, dos Institutos LACTEC, em parceria com o Instituto de Engenharia do Paraná – PRODETEC. A pesquisa teve como objetivo desenvolver um modelo para análise e avaliação de riscos inerentes em projetos de pesquisa e desenvolvimento (P&D, bem como classificar os riscos baseando-se na metodologia do Project Management Institute (PMI. A coleta de dados foi por meio da aplicação de questionário eletrônico para pesquisadores voluntários, vinculados a (1 uma instituição pública de ensino, a (2 uma instituição privada de ensino e a (3 uma instituição pública de pesquisa. Foi também objetivo deste trabalho elaborar uma ferramenta informatizada para análise e avaliação dos riscos durante o planejamento de projetos de P&D, identificando custos mínimos e máximos do projeto a partir da análise das ameaças e das oportunidades identificadas. Foi proposto ainda um índice de risco para apoio na análise das propostas de projetos pelas instituições de pesquisa como requisito para sua avaliação. A ferramenta informatizada foi validada por pesquisadores por meio de uma ficha de avaliação.

Proposição de ferramenta de gestão pós-obra a partir dos registros de solicitação de assistência técnica

Directory of Open Access Journals (Sweden)

Daniel Cupertino

Full Text Available ResumoEste trabalho tem o objetivo de apresentar a construção, aplicação e validação de uma ferramenta de gestão a partir dos registros de solicitação de assistência técnica. A metodologia abrangeu um levantamento de dados para maior compreensão dos processos pós-obra em empresas construtoras do mercado goiano e estudos de caso para aprofundamento das análises dos dados em duas empresas construtoras. Foram analisados mais de 3 000 dados que permitiram uma análise discriminativa por categorias de serviços, uma proposta de análise da origem das manifestações patológicas, a proposição e aplicação da técnica FMEA e a construção e validação da ferramenta eletrônica para gestão dos dados de assistência técnica. Foi possível constatar que os principais serviços que geram solicitações de assistências técnicas no Pós-obra são os serviços de instalações hidrossanitárias. Entre as origens das ocorrências de solicitações de assistências técnicas observou-se que 44% das manifestações patológicas detectadas podem ser decorrentes da fase de execução do empreendimento. O FMEA permitiu identificar que as solicitações com prioridade de risco mais elevado são provenientes principalmente de solicitações referentes a revestimentos de parede e piso. A ferramenta eletrônica evidenciou a sistematização dos dados e evidenciou a importância de diversas análises possíveis a partir do correto registro das informações pós obra. A pesquisa contribui para a minimização da lacuna do conhecimento no que abrange a construção e validação de ferramentas que comprovam a importância da retroalimentação dos dados para as demais etapas do processo construtivo.

Deformation induced martensite in AISI 316 stainless steel

International Nuclear Information System (INIS)

Solomon, N.; Solomon, I.

2010-01-01

The forming process leads to a considerable differentiation of the strain field within the billet, and finally causes the non-uniform distribution of the total strain, microstructure and properties of the material over the product cross-section. This paper focus on the influence of stress states on the deformation-induced a martensitic transformation in AISI Type 316 austenitic stainless steel. The formation of deformation-induced martensite is related to the austenite (g) instability at temperatures close or below room temperature. The structural transformation susceptibility is correlated to the stacking fault energy (SFE), which is a function not only of the chemical composition, but also of the testing temperature. Austenitic stainless steels possess high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Nevertheless, the deformation-induced martensite transformation may enhance the rate of work-hardening and it may or may not be in favour of further material processing. Due to their high corrosion resistance and versatile mechanical properties the austenitic stainless steels are used in pressing of heat exchanger plates. However, this corrosion resistance is influenced by the amount of martensite formed during processing. In order to establish the links between total plastic strain, and martensitic transformation, the experimental tests were followed by numerical simulation. (Author) 21 refs.

Quantitative Evaluation of Aged AISI 316L Stainless Steel Sensitization to Intergranular Corrosion: Comparison Between Microstructural Electrochemical and Analytical Methods

Science.gov (United States)

Sidhom, H.; Amadou, T.; Sahlaoui, H.; Braham, C.

2007-06-01

The evaluation of the degree of sensitization (DOS) to intergranular corrosion (IGC) of a commercial AISI 316L austenitic stainless steel aged at temperatures ranging from 550 °C to 800 °C during 100 to 80,000 hours was carried out using three different assessment methods. (1) The microstructural method coupled with the Strauss standard test (ASTM A262). This method establishes the kinetics of the precipitation phenomenon under different aging conditions, by transmission electronic microscope (TEM) examination of thin foils and electron diffraction. The subsequent chromium-depleted zones are characterized by X-ray microanalysis using scanning transmission electronic microscope (STEM). The superimposition of microstructural time-temperature-precipitation (TTP) and ASTM A262 time-temperature-sensitization (TTS) diagrams provides the relationship between aged microstructure and IGC. Moreover, by considering the chromium-depleted zone characteristics, sensitization and desensitization criteria could be established. (2) The electrochemical method involving the double loop-electrochemical potentiokinetic reactivation (DL-EPR) test. The operating conditions of this test were initially optimized using the experimental design method on the bases of the reliability, the selectivity, and the reproducibility of test responses for both annealed and sensitized steels. The TTS diagram of the AISI 316L stainless steel was established using this method. This diagram offers a quantitative assessment of the DOS and a possibility to appreciate the time-temperature equivalence of the IGC sensitization and desensitization. (3) The analytical method based on the chromium diffusion models. Using the IGC sensitization and desensitization criteria established by the microstructural method, numerical solving of the chromium diffusion equations leads to a calculated AISI 316L TTS diagram. Comparison of these three methods gives a clear advantage to the nondestructive DL-EPR test when it is

Corrosion protection of AISI 1018 steel using Co-doped TiO_2/polypyrrole nanocomposites in 3.5% NaCl solution

International Nuclear Information System (INIS)

Ladan, Magaji; Basirun, Wan Jeffrey; Kazi, Salim Newaz; Rahman, Fariza Abdul

2017-01-01

A polypyrrole nanocomposites (PPy NTCs) have been effectively synthesized in the presence of TiO_2 and Co-doped TiO_2 nanoparticles (NPs) by an in situ chemical oxidative polymerization. Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy revealed a tube shape structure of the PPy. The TEM results confirmed that the nanocomposite size of Co-doped TiO_2/PPy NTCs was smaller than TiO_2/PPy NTCs thereby increasing the interaction between the PPy nanotube and the AISI steel surface. The corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements in 3.5% NaCl solution. The EIS results show that the log |Z| of AISI 1018 coated with Co-doped TiO_2/PPy NTCs and TiO_2/PPy NTCs reached about 8.2 and 6.0 respectively after 30 days of exposure in 3.5% NaCl solution. This is likely due to the increased surface area of the PPy synthesized in the presence of Co-doped TiO_2 NPs. The EIS results are confirmed by the potentiodynamic polarization and open circuit potential values of the Co-doped TiO_2/PPy which indicated little changes between 1 and 30 days of exposure which confirms the protection ability of this coating. . It is evident that the presence of Co-doped TiO_2 NPs can enhance the resistance against corrosion at the steel/electrolyte interface. - Highlights: • Polymerization of pyrrole monomer in the presence of Co-doped TiO_2 decreases the size of the polypyrrole nanotube (PPy NT). • The corrosion protection increases with the increase in PPy NT dispersion. • The corrosion resistance of steel coated with Co-doped TiO_2/PPy NTCs is considerably higher. • TiO_2/PPy with Co doping reduces the charge transfer across the electrolyte/AISI 1018 steel interface.

Effects of microplasma arc AISI 316L welds on the corrosion behaviour of pipelines in LiBr cooling systems

International Nuclear Information System (INIS)

Sánchez-Tovar, R.; Montañés, M.T.; García-Antón, J.

2013-01-01

Highlights: •SECM tests reveal differences in electrochemical activity of base and welded alloys. •The highest electrochemical activity is obtained for the welded alloy. •Microplasma arc welding process hinders passivation in lithium bromide. •Microplasma arc welding increases corrosion rate and susceptibility to pitting. •The galvanic pair between base and welded alloys in LiBr is weak. -- Abstract: The effect of microplasma arc welding (MPAW) on the electrochemical and corrosion behaviour of AISI 316L stainless steel tubes has been studied. Scanning electrochemical measurements were performed in sodium chloride to evaluate the difference in the electrochemical activity of base (non-welded) and welded samples. Oxygen reduction rates increase in AISI 316L due to the heat treatment effect induced by welding, indicating a higher electrochemical activity in the welded samples. Additionally, the use of MPA weldments in lithium bromide (LiBr) absorption machines was also analysed at typical operating temperatures and Reynolds numbers. The welding process increases corrosion rates, hinders passivation and increases the susceptibility to pitting attack in LiBr. However, zero-resistance ammeter and localization index measurements show that the galvanic pair generated between the base and welded alloys is weak, both electrodes being in their passive state. Temperature greatly affects the corrosion process

Sliding properties of coevaporated and nitrogen-implanted Pt50Ti50 films on AISI 304 stainless steel

International Nuclear Information System (INIS)

Zheng, L.R.; Hung, L.S.; Mayer, J.W.

1988-01-01

Thin Pt 50 Ti 50 films were deposited on a AISI 304 stainless steel substrate by co-evaporation. Dry sliding tests and wear track measurements revealed some improvement in sliding properties compared with the bare substrate. Implantation of the coated substrate with xenon ions did not produce any further improvement in friction and wear but a dramatic improvement resulted from nitrogen ion implantation. This was accompanied by a change in microstructure arising from an amorphous to crystalline phase transformation in the alloy film. (U.K.)

Effect of filler metals on the mechanical properties of Inconel 625 and AISI 904L dissimilar weldments using gas tungsten arc welding

Science.gov (United States)

Senthur Prabu, S.; Devendranath Ramkumar, K.; Arivazhagan, N.

2017-11-01

In the present research work, dissimilar welding between Inconel 625 super alloy and AISI 904L super austenitic stainless steel using manual multi-pass continuous current gas tungsten arc (CCGTA) welding process employed with ERNiCrMo-4 and ERNiCrCoMo-1 fillers were performed to determine the mechanical properties and weldability. Tensile test results corroborated that the fracture had occurred at the parent metal of AISI 904L irrespective of filler used for all the trials. The presence of the macro and micro void coalescence in the fibrous matrix characterised for ductile mode of fracture. The hardness values at the weld interface of Inconel 625 side were observed to be higher for ERNiCrMo-4 filler due to the presence of strengthening elements such as W, Mo, Ni and Cr. The impact test accentuated that the weldments using ERNiCrMo-4 filler offered better impact toughness (41J) at room temperature. Bend test results showed that the weldments using these fillers exhibited good ductility without cracks.

Ictiosis congénita tipo laminar, reporte de un caso.

OpenAIRE

Joaquín Saavedra D.; María José Sierralta S.; Cristian Saavedra D; Vanesa Rivera C; Francisco Cerda C.

2014-01-01

RESUMEN INTRODUCCIÓN: La ictiosis tipo laminar es una enfermedad dermatológica infrecuente perteneciente al grupo de las llamadas genodermatosis. Es una forma de ictiosis congénita que es evidente desde el nacimiento. PRESENTACIÓN DEL CASO: Recién nacido por cesárea, sexo masculino, de 36 semanas de gestación, adecuado para la edad gestacional y con APGAR 8. Antecedentes familiares: padres no consanguíneos y hermano con ictiosis tipo laminar. Luego de nacer es hospital...

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.

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

Melhoria de processos com recurso a ferramentas Lean : um caso prático numa indústria de calçado

OpenAIRE

Ramos, Patrícia Maria da Silva

2015-01-01

Nos dias de hoje as indústrias recorrem cada vez mais à filosofia lean, para atingir níveis de produtividade excelentes. Esta filosofia permite a uma empresa otimizar os seus recursos e eliminar ou minimizar desperdícios. A ergonomia é um fator importante nesta filosofia, uma vez que os recursos humanos são um fator chave na busca da melhoria contínua. O presente trabalho incide sobre a implementação de ferramentas lean com o objetivo de aumentar a eficiência e reduzir desperdícios no proc...

La volatilidad del tipo de cambio paralelo en Venezuela 2005-2015

Directory of Open Access Journals (Sweden)

Laura Daniela Castillo Paredes

2017-02-01

Full Text Available El tipo de cambio paralelo constituye una de las principales variables económicas para la toma de decisiones en Venezuela. Para analizar el comportamiento de esta variable tomando en cuenta sus características inherentes, exceso de curtosis, persistencia y asimetría, se hace una síntesis teórica de los principales modelos estocásticos de volatilidad y, se estima un conjunto de modelos. El modelo que mejor ajusta el comportamiento de la variable es un EGARCH (1,1, que captura el efecto asimétrico de las perturbaciones estocásticas sobre la serie. Ante choques negativos (depreciación del tipo de cambio paralelo, la volatilidad asociada se incrementa, pero para choques positivos (apreciación del tipo de cambio paralelo, se mantiene constante.

CLAWS: uma ferramenta colaborativa para apoio à interação de surdos com páginas da web.

OpenAIRE

Stefan José Oliveira Martins

2012-01-01

Os deficientes auditivos têm uma forma peculiar de uso das tecnologias de informação e comunicação (TICs). Como grupo de usuários, essas pessoas nem sempre são consideradas como usuários nos modelos de interação de sistemas comerciais. O objetivo desta pesquisa é conceber uma ferramenta adequada às necessidades dos surdos, que os apoie na interação com páginas da web. Para isso, estudaram-se as particularidades da comunidade surda com as TICs e as barreiras encontradas durante a interação. Co...

A espectroscopia de RMN como ferramenta elucidativa: estruturas moleculares, mecanismos de reação e metabonômica

OpenAIRE

SILVA, Ricardo Oliveira da

2010-01-01

A espectroscopia de ressonância magnética nuclear é uma poderosa ferramenta para a elucidação estrutural e para o estudo de transformações químicas, intensamente utilizada na área de química orgânica. Recentemente, a fronteira de suas aplicações tem se expandido para incluir a análise de biofluidos com o fim de tentar identificar padrões associados às mais variadas condições fisiopatológicas que, ao afetarem o metabolismo, deixam sua marca de forma reconhecível nos espectros...

Study of the AISI 347 austenitic stainless steel sensitization through the potentiokinetic reactivation method

International Nuclear Information System (INIS)

Teodoro, Celso Antonio; Wolynec, Stephan

1996-01-01

The sensitization kinetics of AISI 347 austenitic stainless steel samples, removed from a forged bar, was investigated with an electrochemical potentiokinetic reactivation method. After the solution anneal at 1140 deg C, the steel was submitted to sensitization treatments at 550 deg C, 670 deg C, 790 deg C and 910 deg C during times that varied from 1 h to 62 h. It was found that samples treated at 550 deg C, 670 deg C and 790 deg C become sensitized. The activation energy was found to be 124 kJ/mol. The observed behaviour was discussed in terms of both carbon retention in solution after the solution anneal and kinetics of carbon combination with chromium and niobium. (author)

Improvement of the fatigue strength of AISI 4140 steel by an ion nitriding process

Energy Technology Data Exchange (ETDEWEB)

Celik, A. [Atatuerk Univ., Erzurum (Turkey). Dept. of Mech. Eng.; Karadeniz, S. [Dokuz Eyluel Univ., Izmir (Turkey). Dept. of Mech. Eng.

1995-06-01

The influence of plasma nitriding on the fatigue behaviour of AISI 4140 low-alloy steel was investigated under varying process conditions of temperature (500-600 C), time (1-12 h), heat treatment before ion nitriding (quenched and tempered, normalized) and gas mixture (50% H{sub 2}-50% N{sub 2}). A rotating bending fatigue machine was used to determine the fatigue strength. It was found that the plasma nitriding improves the fatigue strength and increases the fatigue limit depending on the surface hardness of the case depth. The microstructure of surface and diffusion layers was examined by optical microscopy. The fracture surface of specimens and the origin of fatigue cracks were observed by scanning electron microscopy.

Effect of the purging gas on properties of Ti stabilized AISI 321 stainless steel TIG welds

Energy Technology Data Exchange (ETDEWEB)

Taban, Emel; Kaluc, Erdinc; Aykan, T. Serkan [Kocaeli Univ. (Turkey). Dept. of Mechanical Engineering

2014-07-01

Gas purging is necessary to provide a high quality of stainless steel pipe welding in order to prevent oxidation of the weld zone inside the pipe. AISI 321 stabilized austenitic stainless steel pipes commonly preferred in refinery applications have been welded by the TIG welding process both with and without the use of purging gas. As purging gases, Ar, N{sub 2}, Ar + N{sub 2} and N{sub 2} + 10% H{sub 2} were used, respectively. The aim of this investigation is to detect the effect of purging gas on the weld joint properties such as microstructure, corrosion, strength and impact toughness. Macro sections and microstructures of the welds were investigated. Chemical composition analysis to obtain the nitrogen, oxygen and hydrogen content of the weld root was done by Leco analysis. Ferrite content of the beads including root and cap passes were measured by a ferritscope. Vickers hardness (HV10) values were obtained. Intergranular and pitting corrosion tests were applied to determine the corrosion resistance of all welds. Type of the purging gas affected pitting corrosion properties as well as the ferrite content and nitrogen, oxygen and hydrogen contents at the roots of the welds. Any hot cracking problems are not predicted as the weld still solidifies with ferrite in the primary phase as confirmed by microstructural and ferrite content analysis. Mechanical testing showed no significant change according to the purge gas. AISI 321 steel and 347 consumable compositions would permit use of nitrogen rich gases for root shielding without a risk of hot cracking.

Austenite Grain Growth Behavior of AISI 4140 Alloy Steel

Directory of Open Access Journals (Sweden)

Lin Wang

2013-01-01

Full Text Available AISI 4140 alloy steel is widely applied in the manufacture of various parts such as gears, rams, and spindles due to its good performance of strength, toughness, and wear resistance. The former researches most focused on its deformation and recrystallization behaviors under high temperature. However, the evolution laws of austenite grain growth were rarely studied. This behavior also plays an important role in the mechanical properties of parts made of this steel. In this study, samples are heated to a certain temperature of 1073 K, 1173 K, 1273 K, and 1373 K at a heating rate of 5 K per second and hold for different times of 0 s, 120 s, 240 s, 360 s, and 480 s before being quenched with water. The experimental results suggest that the austenite grains enlarge with increasing temperature and holding time. A mathematical model and an application developed in Matlab environment are established on the basis of previous works and experimental results to predict austenite grains size in hot deformation processes. The predicted results are in good agreement with experimental results which indicates that the model and the application are reliable.

Sistema integrado ABC-EVA como uma ferramenta de gestão: um estudo de caso

Directory of Open Access Journals (Sweden)

Raimundo Nonato Sousa da Silva

2010-01-01

Full Text Available Este artigo analisa a implementação e o uso do Sistema Integrado ABCEVA como uma ferramenta de gestão de engenharia, que identifica atividades criadoras de valor econômico agregado e, portanto contribuem para a riqueza do acionista. Os motivos para avaliação de custos indiretos e de capital são apresentados. Os passos de pré-implementação e implementação são ilustrados usando dados de uma implementação do sistema em uma empresa multinacional de serviços industriais. O impacto da crescente confiabilidade das informações de custo na tomada de decisão da empresa, desempenho comercial potencial de longo prazo e a esperada criação de riqueza para o acionista são discutidos.

Electromagnetic nondestructive evaluation of tempering process in AISI D2 tool steel

Science.gov (United States)

Kahrobaee, Saeed; Kashefi, Mehrdad

2015-05-01

The present paper investigates the potential of using eddy current technique as a reliable nondestructive tool to detect microstructural changes during the different stages of tempering treatment in AISI D2 tool steel. Five stages occur in tempering of the steel: precipitation of ɛ carbides, formation of cementite, retained austenite decomposition, secondary hardening effect and spheroidization of carbides. These stages were characterized by destructive methods, including dilatometry, differential scanning calorimetry, X-ray diffraction, scanning electron microscopic observations, and hardness measurements. The microstructural changes alter the electrical resistivity/magnetic saturation, which, in turn, influence the eddy current signals. Two EC parameters, induced voltage sensed by pickup coil and impedance point detected by excitation coil, were evaluated as a function of tempering temperature to characterize the microstructural features, nondestructively. The study revealed that a good correlation exists between the EC parameters and the microstructural changes.

Long-range effect in nitrogen ion-implanted AISI 316L stainless steel

Energy Technology Data Exchange (ETDEWEB)

Budzynski, P., E-mail: p.budzynski@pollub.pl

2015-01-01

The effect of nitrogen ion implantation on AISI 316L stainless steel was investigated. The microstructure and composition of an N implanted layer were studied by RBS, GIXRD, SEM, and EDX measurements. Friction and wear tests were also performed. The discrepancy between the measured and calculated stopped ion maximum range does not exceed 0.03 μm. After nitrogen implantation with a fluence of 5 × 10{sup 17} ion/cm{sup 2}, additional phases of expanded austenite were detected. At a 5-fold larger depth than the maximum ion range, improvement in the coefficient of friction and wear was detected. We have shown, for the first time, the long-range effect in tribological investigations. The long-range effect is caused by movement of not only defects along the depth of the sample, as assumed so far, but also nitrogen atoms.

Characterization of friction welding for IN713LC and AISI 4140 steel

International Nuclear Information System (INIS)

Yeom, J.T.; Park, N.K.; Park, J.H.; Lee, J.W.

2004-01-01

Friction welding of dissimilar materials, Ni-base superalloy IN713LC and oil-quench plus tempered AISI 4140 steel, was investigated. Friction welding was carried out with various process variables such as friction pressure and time. The quality of welded joints was tested by applying bending stresses in an appropriate jig. Microstructures of the heat-affected zone (HAZ) were investigated along with micro-hardness tests over the friction weld joints. DEFORM-2D FE code was used to simulate the effect of welding variables in friction welding process on the distributions of the state variables such as strain, strain rate and temperature. The formation of the metal burr during the friction welding process was successfully simulated, and the temperature distribution in the heat-affected zone indicated a good agreement with the variation of the microstructures in the HAZ. (orig.)

Characterization of friction welding for IN713LC and AISI 4140 steel

Energy Technology Data Exchange (ETDEWEB)

Yeom, J.T.; Park, N.K. [Dept. of Materials Processing, Korea Inst. of Machinery and Materials, Kyungnam (Korea); Park, J.H.; Lee, J.W. [ENPACO Co., Changwon (Korea)

2004-07-01

Friction welding of dissimilar materials, Ni-base superalloy IN713LC and oil-quench plus tempered AISI 4140 steel, was investigated. Friction welding was carried out with various process variables such as friction pressure and time. The quality of welded joints was tested by applying bending stresses in an appropriate jig. Microstructures of the heat-affected zone (HAZ) were investigated along with micro-hardness tests over the friction weld joints. DEFORM-2D FE code was used to simulate the effect of welding variables in friction welding process on the distributions of the state variables such as strain, strain rate and temperature. The formation of the metal burr during the friction welding process was successfully simulated, and the temperature distribution in the heat-affected zone indicated a good agreement with the variation of the microstructures in the HAZ. (orig.)

Nitriding of AISI 4140 steel by a low energy broad ion source

International Nuclear Information System (INIS)

Ochoa, E. A.; Figueroa, C. A.; Alvarez, F.

2006-01-01

A comprehensive study of the thermochemical nitriding process of steel AISI 4140 by low energy ion implantation (Kaufmann cell) is reported. Different times of implantation were employed and the studied samples were characterized by x-ray diffraction, in situ photoemission electron spectroscopy, scanning electron microscopy, and hardness (nanoindentation) measurements. The linear relationship between nitrogen content and hardness was verified. The structure of the nitrided layer was characterized yielding that the compound layer is formed by coarse precipitates, around small grains, constituted principally by ε-Fe 2-3 N and γ-Fe 4 N phases and the diffusion zone is formed by fine precipitates, around big grains of the original martensitic phase, constituted principally by γ-Fe 4 N phase. Finally, a diffusion model for multiphase systems was applied to determine effective diffusion coefficients of nitrogen in the different phases

Long-range effect in nitrogen ion-implanted AISI 316L stainless steel

Science.gov (United States)

Budzynski, P.

2015-01-01

The effect of nitrogen ion implantation on AISI 316L stainless steel was investigated. The microstructure and composition of an N implanted layer were studied by RBS, GIXRD, SEM, and EDX measurements. Friction and wear tests were also performed. The discrepancy between the measured and calculated stopped ion maximum range does not exceed 0.03 μm. After nitrogen implantation with a fluence of 5 × 1017 ion/cm2, additional phases of expanded austenite were detected. At a 5-fold larger depth than the maximum ion range, improvement in the coefficient of friction and wear was detected. We have shown, for the first time, the long-range effect in tribological investigations. The long-range effect is caused by movement of not only defects along the depth of the sample, as assumed so far, but also nitrogen atoms.

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.

Riesgo de tipo de cambio: cobertura con instrumentos financieros

OpenAIRE

Gutiérrez Blanco, Vidal

2017-01-01

RESUMEN: En el siguiente trabajo se hace una pequeña aproximación al mercado de divisas, explicando qué es el tipo de cambio y cuál es el riesgo que conlleva operar con monedas de diferentes países. En primer lugar, se define el mercado de divisas, poniendo énfasis sobre el hecho de que es el mercado más grande y líquido del mundo, y se identifican cuáles son las principales operaciones llevadas a cabo en este mercado. Seguidamente, se ha explicado lo que es el tipo de cambio, cuáles son l...

Investigating early stages of biocorrosion with XPS: AISI 304 stainless steel exposed to Burkholderia species

Science.gov (United States)

Johansson, Leena-Sisko; Saastamoinen, Tuomas

1999-04-01

We have investigated the interactions of an exopolymer-producing bacteria, Burkholderia sp. with polished AISI 304 stainless steel substrates using X-ray photoelectron spectroscopy (XPS). Steel coupons were exposed to the pure bacteria culture in a specially designed flowcell for 6 h during which the experiment was monitored in situ with an optical microscope. XPS results verified the formation of biofilm containing extracellular polymer on all the samples exposed to bacteria. Sputter results indicated that some ions needed for metabolic processes were trapped within the biofilm. Changes in the relative Fe concentration and Fe 2p peak shape indicated that also iron had accumulated into the biofilm.

Creep tests of AISI 316 stainless steel irradiated by alpha particles of 28 MeV

International Nuclear Information System (INIS)

Segura, E.; Lucki, G.

1986-01-01

He-embrittlement effect in AISI 316 SS type throught creep tests performed with annealed and cold worked thin specimens is analized. Measurements were carried out at 700 and 750 0 C, stress of 100 MPa in vacuum better than 10 -5 torr. The He-implantations were made with the cyclotron CV-28 IPEN-CNEN/SP. Using an alpha-particle beam of 28 MeV, with concentration of 26 appm. From the valves of rupture deformation, epsilon sub(R), and rupture time, t sub(R), it was verified that he had a great effect on the operational life and ductility of this material. (Author) [pt

Comportamiento de las aleaciones termorresistentes AISI HH y HK-40 ante los procesos de carburización y nitruración

Directory of Open Access Journals (Sweden)

Eleno Alfonso-Brindis

2001-03-01

Full Text Available Se evalúa el comportamiento de los aceros austeníticos fundidos AISI HH y HK- 40 (de producción nacional ante los procesos de carburización y nitruración en los rangos de temperaturas desde 750 hasta 1 000 °C. Se estudia la cinética y la termodinámica de las posibles reacciones y los productos de las mismas se caracterizan mediante técnicas de Microscopía Óptica, Microscopía Electrónica de Barrido y Microanálisis (MEB-EDAX. En el análisis microscópico se observó la formación de carburos de cromo después de la carburización, mientras que la nitruración dio lugar a la formación de nitruros de cromo. Se concluye que la aleación AISI HK-40 posee una elevada resistencia intrínseca a la carburización y a la nitruración, que hace factible su empleo en componentes de hornos de soleras múltiples para la reducción de minerales lateríticos

Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

Directory of Open Access Journals (Sweden)

Mahmoud Hassan R. S.

2014-07-01

Full Text Available High temperature gas nitriding performed on AISI 316L at the temperature of 1200°C. The microstructure of treated AISI 316L samples were observed to identify the formation of the microstructure of nitrided surface layer. The grain size of austenite tends to be enlarged when the nitriding time increases, but the austenite single phase structure is maintained even after the long-time solution nitriding. Using microhardness testing, the hardness values drop to the center of the samples. The increase in surface hardness is due to the high nitrogen concentration at or near the surface. At 245HV, the graph of the effective duration of nitriding process was plotted to achieve the maximum depth of nitrogen diffuse under the surface. Using Sigma Plot software best fit lines of the experimental result found and plotted to find out effective duration of nitriding equation as Y=1.9491(1-0.7947x, where Y is the thickness of nitrided layer below the surface and X is duration of nitriding process. Based on this equation, the duration of gas nitriding process can be estimated to produce desired thickness of nitrided layer.

PREJUÍZOS COGNITIVOS EM IDOSOS COM DIABETES MELLITUS TIPO 2

Directory of Open Access Journals (Sweden)

Regina Maria Fernandes Lopes

2009-01-01

Full Text Available El avance en las condiciones de salud propicia el progresivo aumento de la esperanza de vida. Estudios han identificado la existencia de una conexión entre la Diabetes Mellitus (DM y demencia. La hiperglicemia podría ser un factor importante en la incidencia de la enfermedad de Azheimer, la cual puede ser una causa secundaria de demencia. La diabetes mellitus tipo 2 (DM2 está asociada con déficits cognitivos y funcionales, y el WCST es una de las herramientas que puede ser utilizada para evaluar funcionamiento ejecutivo. El objetivo de este estudio fue evaluar los déficits cognitivos de ancianos con diabetes mellitus tipo 2. Los participantes fueron 254 ancianos de ambos sexos, mayores de 60 años; 44 de ellos diagnosticados de DM2 y 210 en un grupo control de población general. El diseño fue un estudio cuantitativo transversal. Los instrumentos utilizados fueron: datos sociodemográficos, WCST, MMSE, BDI, BAI, GD, junto a las Sub pruebas de: Vocabulario, códigos, números y Cubos del WAIS-III. Los resultados mostraron una diferencia significativa en el desempeño de los ancianos con diabetes tipo 2 en comparación con el grupo control en cuatro descriptores de WCST que indicaban un deterioro. Igualmente los ancianos con diabetes tipo 2 mostraron una intensidad de síntomas depresivos y de ansiedad estadísticamente mayor que el grupo control

Hot compression deformation behavior of AISI 321 austenitic stainless steel

Science.gov (United States)

Haj, Mehdi; Mansouri, Hojjatollah; Vafaei, Reza; Ebrahimi, Golam Reza; Kanani, Ali

2013-06-01

The hot compression behavior of AISI 321 austenitic stainless steel was studied at the temperatures of 950-1100°C and the strain rates of 0.01-1 s-1 using a Baehr DIL-805 deformation dilatometer. The hot deformation equations and the relationship between hot deformation parameters were obtained. It is found that strain rate and deformation temperature significantly influence the flow stress behavior of the steel. The work hardening rate and the peak value of flow stress increase with the decrease of deformation temperature and the increase of strain rate. In addition, the activation energy of deformation ( Q) is calculated as 433.343 kJ/mol. The microstructural evolution during deformation indicates that, at the temperature of 950°C and the strain rate of 0.01 s-1, small circle-like precipitates form along grain boundaries; but at the temperatures above 950°C, the dissolution of such precipitates occurs. Energy-dispersive X-ray analyses indicate that the precipitates are complex carbides of Cr, Fe, Mn, Ni, and Ti.

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)

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

Tipos de vegetación del llano de Paletará. Cordillera Central Colombia Tipos de vegetación del llano de Paletará. Cordillera Central Colombia

Directory of Open Access Journals (Sweden)

Restrepo Carla

1992-09-01

Full Text Available We studied the vegetation found in the Llano de Paletará, municipality of Coconuco, department of Cauca, Colombia. Based on the physiognomy and floristic composition of the vegetation we identified 8 paramo vegetation types. These units represent the most extensive azonal paramo vegetation types described up to now for the Cordillera Central. Four of the 8 vegetation types are herbaceous ("frailejonal-pajonal" with Espeletia, "chuscal abierto" with Chusquea,"swamp" with Carex, and "grassland" with Calamagrostis , three are bush tickets (thicket with Hypericum, thicket with Ageratina, and thicket with Diplostephium, and one is a forest of low stature (forest with Escallonia. We analyze some aspects of the ecology and distribution of the vegetation types and evaluate their degree of peril and value of conservation. Se estudiaron los tipos de vegetación del Llano de Paletará, municipio de Coconuco, departamento del Cauca, Colombia. Basados en la fisonomía y composición florística de la vegetación identificamos 8 tipos de vegetación, los cuales representan los tipos de vegetación paramunos de carácter azonal más extensos de la Cordillera Central registrados hasta el momento. De los 8 tipos de vegetación, cuatro son de porte herbáceo (''frailejonalpajonal'' con Espeletia. "chuscal abierto" con Chusquea. "pantano" con Carex y un "pajonal" con Calamagrostis, tres son de porte arbustivo (matorral con Hypericum, matorral con Ageratina y matorral con Diplostephium y uno es de porte arbóreo (bosque con Escallonia. Se analizan algunos aspectos de la ecología y distribución de los tipos de vegetación y se evalúa su grado de amenaza y valor de conservación.

A internet vai à escola: domínio e apropriação de ferramentas culturais The Internet goes to school: mastery and incorporation of cultural tools

Directory of Open Access Journals (Sweden)

Marcelo Giordan

2005-03-01

Full Text Available O objetivo deste artigo é descrever e analisar o processo de introdução da internet em uma comunidade escolar, e verificar como o domínio e a apropriação da ferramenta cultural e os propósitos da ação mediada condicionam esse processo. A partir da descrição e análise desse processo, identificam-se os elementos condicionantes do domínio e da apropriação das ferramentas culturais, tendo como suposto o conceito de ambientes telemáticos. Definem-se ambientes da internet a partir do conceito de ferramenta cultural e das propriedades da ação mediada. Descreve-se a introdução da internet em uma escola no curso de um programa de formação continuada, de onde se obtêm evidências da determinação dos propósitos e das formas de uso da ferramenta cultural pelos agentes sobre os processos de elaboração de significados, e de apropriação do correio eletrônico pelos professores e pela instituição. Analisam-se as modalidades discursivas observadas nos diálogos para explicar as ações internas e externas realizadas pelos professores, a partir das quais se discute a interação entre a estrutura discursiva e a estrutura das ações mediadas, bem como as funções do diálogo e da ferramenta cultural na elaboração de significados. Apresentam-se razões para se realizarem programas de formação continuada sobre o uso da internet, no interior da escola, justificadas pelas transformações observadas na ambiência de ensino e aprendizagem.The objective of this article is to describe and analyze the process of introduction of the Internet in a school community, and to observe how the mastery and incorporation of the cultural tool and the purposes of the mediated action intervene in that process. From the description and analysis of the process, the elements intervening in the mastery and incorporation of the cultural tools are identified, based on the concept of telematic environments. Internet environments are defined based on the

Fenótipo cintura hipertrigliceridêmica: associação com alterações metabólicas em adolescentes Hypertriglyceridemic waist phenotype: association with metabolic abnormalities in adolescents

Directory of Open Access Journals (Sweden)

Maria Ester P. da Conceição-Machado

2013-02-01

Full Text Available OBJETIVO: O presente estudo objetivou identificar a prevalência do fenótipo cintura hipertrigliceridêmica (CHT e avaliar sua associação com alterações metabólicas em adolescentes de baixa condição econômica. MÉTODO: Estudo transversal com amostra probabilística de 1.076 adolescentes entre 11 e 17 anos, de ambos os sexos, estudantes de escolas públicas. Os participantes foram submetidos à avaliação antropométrica (peso, altura e circunferência da cintura e à dosagem dos níveis de colesterol total, LDL-C, HDL-C, colesterol não HDL, triglicérides (TG e glicemia de jejum. Foram obtidas informações referentes às condições econômicas das famílias dos participantes.O fenótipo CHT foi definido pela presença simultânea da circunferência da cintura aumentada (> percentil 90 por idade e sexo e dos níveis séricos de triglicérides elevados (> 100 mg/dL. A análise de regressão logística foi utilizada para avaliação das associações de interesse. RESULTADOS: A prevalência do fenótipo CHT foi de 7,2% entre os adolescentes, sendo mais elevada na presença de obesidade (63,4%, do colesterol não HDL (16,6% e do LDL-C (13,7% altos. A análise bivariada indicou que, das variáveis metabólicas, apenas a glicemia não se associou ao fenótipo CHT. A análise multivariada, ajustada por sexo e idade, indicou que o fenótipo CHT se associou positivamente com o colesterol não HDL alto (odds ratio, 7,0; IC 95% 3,9-12,6 e com o HDL-C baixo (odds ratio, 2,7; IC 95%, 1,5-4,8. CONCLUSÕES: Este estudo mostrou que o fenótipo CHT se associou com um perfil lipídico aterogênico e sugere esse fenótipo como uma ferramenta de screening que pode ser utilizada para identificar adolescentes com alterações metabólicas.OBJECTIVE: This study aimed to identify the prevalence of hypertriglyceridemic waist (HTW phenotype, and to evaluate its association with metabolic abnormalities in adolescents of low socioeconomic status. METHOD: This

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

Oxidación cíclica de un acero refractario AISI 310 a alta temperatura en atmósferas con contenidos de oxígeno variables

Directory of Open Access Journals (Sweden)

Higuera-Hidalgo, V.

2005-06-01

Full Text Available High temperature oxidation tests of an AISI 310 stainless steel was performed in two different environments: in an standard atmosphere (21 % oxygen at 704, 800, 884 and 1,000 °C and in the typical environment of a gas turbine and vapor generator of a combined-cycle electric generation unit (10 % oxygen at 800 and 1,000 °C. The oxidation kinetics was determined by means of the measurement of the weight gain per unit surface of the specimen and also determining the thickness of the oxide layer. Comparable results have been obtained using both methodologies and the effect of the oxygen content along with the other experimental differences were determined observing the oxidation kinetics in both environments. The cyclic oxidation of AISI 310 deteriorates at temperatures higher than 1,000 °C.

Se ha llevado a cabo un estudio experimental sobre la oxidación a altas temperaturas de un acero inoxidable refractario AISI 310, en dos ambientes diferentes: en una atmósfera convencional (21 % de O₂, a 704, 800, 884 y 1.000 °C y en un ambiente simulativo de una turbina de gas y del generador de vapor de uña central eléctrica de ciclo combinado (10-11 % de O₂, a 800 y 1.000 °C. La cinética de la oxidación del material se ha determinado a partir, tanto de la ganancia de peso por unidad de superficie experimentada por las probetas objeto de ensayo como por la determinación de los espesores de las capas de óxido formados. Se han obtenido resultados comparables con ambas metodologías y se ha puesto de manifiesto el efecto del contenido de oxígeno y de las demás diferencias experimentales a partir de la comparación de las cinéticas de oxidación del acero en los dos medios oxidantes analizados. La oxidación del acero AISI 310 en situaciones térmicas cíclicas empieza ya a ser importante a partir de una temperatura de 1.000 °C.

A caixa de ferramentas de Michel Foucault, a reforma psiquiátrica e os desafios contemporâneos Michel Foucault's conceptual toolbox, psychiatric reform and contemporary challenges

Directory of Open Access Journals (Sweden)

Jardel Sander

2010-08-01

Full Text Available Este artigo busca discutir as influências das ideias de Michel Foucault - sua caixa de ferramentas conceituais - na reforma psiquiátrica brasileira. Nesse sentido, parte-se de um olhar mais amplo sobre o projeto do autor, buscando identificar sua atualidade no cenário da saúde mental brasileira. Para tanto, traça-se um percurso histórico que retoma, brevemente, os acontecimentos do final dos anos 1970 no Brasil até alcançar os dias atuais. O esforço é justamente o de colocar em questão a necessidade de outras ferramentas conceituais, no intuito de esclarecer as condições de possibilidade de noções como as de loucura, doença mental e desrazão, em busca de uma relação porosa com o Fora (Dehors. Sendo assim, busca-se refletir sobre a importância das artes, em sua potência de criação e invenção, nesse processo, como possível fornecedora de ferramentas de trabalho.This paper discusses the influences of Michel Foucault's ideas - its conceptual toolbox - to the Brazilian psychiatric reform, that composes the current scenario of mental health in Brazil. It is made a historic rescue retaking, although shortly, the events of the late 1970s in Brazil. Subsequently, it is questioned these changes actuality, as well as the need for further conceptual tools in order to point possibility conditions for notions such as madness, mental illness and déraison, seeking for a relationship with the outside (dehors. It is concluded by emphasizing the importance of arts (its creation and invention potency, in the process of constructing a new conceptual toolbox.

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.

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

Directory of Open Access Journals (Sweden)

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.

Corrosion protection of AISI 1018 steel using Co-doped TiO{sub 2}/polypyrrole nanocomposites in 3.5% NaCl solution

Energy Technology Data Exchange (ETDEWEB)

Ladan, Magaji, E-mail: ladanmagaji@yahoo.com [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Department of Pure and Industrial Chemistry, Bayero University Kano (Nigeria); Basirun, Wan Jeffrey, E-mail: jeff@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Institute of Nanotechnology and Catalysis (NanoCat), University of Malaya, Kuala Lumpur, 50603 (Malaysia); Kazi, Salim Newaz; Rahman, Fariza Abdul [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia)

2017-05-01

A polypyrrole nanocomposites (PPy NTCs) have been effectively synthesized in the presence of TiO{sub 2} and Co-doped TiO{sub 2} nanoparticles (NPs) by an in situ chemical oxidative polymerization. Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy revealed a tube shape structure of the PPy. The TEM results confirmed that the nanocomposite size of Co-doped TiO{sub 2}/PPy NTCs was smaller than TiO{sub 2}/PPy NTCs thereby increasing the interaction between the PPy nanotube and the AISI steel surface. The corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements in 3.5% NaCl solution. The EIS results show that the log |Z| of AISI 1018 coated with Co-doped TiO{sub 2}/PPy NTCs and TiO{sub 2}/PPy NTCs reached about 8.2 and 6.0 respectively after 30 days of exposure in 3.5% NaCl solution. This is likely due to the increased surface area of the PPy synthesized in the presence of Co-doped TiO{sub 2} NPs. The EIS results are confirmed by the potentiodynamic polarization and open circuit potential values of the Co-doped TiO{sub 2}/PPy which indicated little changes between 1 and 30 days of exposure which confirms the protection ability of this coating. . It is evident that the presence of Co-doped TiO{sub 2} NPs can enhance the resistance against corrosion at the steel/electrolyte interface. - Highlights: • Polymerization of pyrrole monomer in the presence of Co-doped TiO{sub 2} decreases the size of the polypyrrole nanotube (PPy NT). • The corrosion protection increases with the increase in PPy NT dispersion. • The corrosion resistance of steel coated with Co-doped TiO{sub 2}/PPy NTCs is considerably higher. • TiO{sub 2}/PPy with Co doping reduces the charge transfer across the electrolyte/AISI 1018 steel interface.

Actividad hidráulica de un cemento belítico obtenido a partir de cenizas volantes tipo C: influencia del aditivo y tipo de curado

OpenAIRE

Goñi Elizalde, Sara; Guerrero Bustos, Ana María

2006-01-01

En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A). Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C) como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 ...

Correlation of yield strength with irradiation-induced microstructure in AISI 316 stainless steel

International Nuclear Information System (INIS)

Simons, R.L.; Hulbert, L.A.

1985-10-01

Improvements in the correlation of radiation-induced change in yield strength in AISI 316 stainless steel with microstructure were made by re-examining the role of short-range obstacles. Effects due to the size of the obstacles relative to their spacing and shape of the obstacles were applied. The concept of shearing the precipitates instead of bowing around them was used to explain the effects of precipitate hardening. It is concluded that large changes in yield strength may be produced in high swelling materials. Voids will dominate the hardening at high dpa. The increase in hardening will depend on the diameter of the voids even though the swelling in the material is the same. Precipitate hardening at high fluence (>15 dpa) make a significant contribution for irradiation temperatures above 500 0 C

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

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......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...... 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...

Influencia del contacto precoz, nacionalidad, tipo de parto y prematuridad en la lactancia materna

OpenAIRE

Ana Belén Laviña Castan

2015-01-01

Conocer si en el HUMS existe asociación entre lactancia materna y nacionalidad, prematuridad, tipo de parto, contacto precoz piel con piel. Estudio de cohortes, en una muestra de 541 puérperas del HUMS en octubre-noviembre 2011. Las variables: nacionalidad, tipo de parto, contacto precoz, parto prematuro e inicio lactancia materna se recogieron antes del alta hospitalaria mediante cuestionario. A los dos meses postparto se contactó telefónicamente con las madres para conocer el tipo de lactan...

Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel

Science.gov (United States)

Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas

2015-11-01

In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 °C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

Estudio del fenotipo de haptoglobinas en pacientes con diabetes mellitus tipo 1, en Lima, Perú

OpenAIRE

Arias, Clever; Inga, Miriam; Oré, Raquel; Zapata, Luis; Aquije, Carmen

2013-01-01

Objetivos: Determinar el fenotipo de haptoglobina -1/1, 1/2 y 2/2- predominante en una muestra de 36 pacientes con diabetes mellitus tipo I (DM tipo I). Diseño: Observacional con sistema de medición, descriptivo. Institución: Centro de Investigación de Bioquímica y Nutrición, Facultad de Medicina, UNMSM. Participantes: Pacientes con diagnóstico de diabetes mellitus tipo I Intervenciones: En 36 pacientes con diagnóstico de diabetes mellitus tipo I, se realizó medidas antropométricas, evaluacio...

Uma ferramenta para avaliação de resultados de diversos modelos de otimização de dietas

Directory of Open Access Journals (Sweden)

Anderson Amendoeira Namen

2004-12-01

Full Text Available O presente trabalho visa apresentar uma ferramenta para avaliação de modelos matemáticos relacionados à otimização do planejamento de dietas. Inicialmente, o problema original da dieta é caracterizado, bem como sua importância para o desenvolvimento da Pesquisa Operacional, seus desdobramentos e aplicações posteriores. Em seguida, são apresentados os diversos enfoques e técnicas adotadas para a elaboração de dietas para seres humanos. Alguns desses modelos são então implementados, efetuando-se uma análise comparativa dos resultados obtidos. Para isso, é utilizado um software que permite a definição de parâmetros relacionados às demandas humanas, restrições adicionais relacionadas às quantidades de alimentos e escolha de alguns dos modelos apresentados. Finalmente, o estudo é concluído constatando-se a utilidade e a aplicação da ferramenta não somente para o planejamento de dietas, mas também para a área de ensino de Pesquisa Operacional.This paper presents an interactive tool which allows the comparison of different mathematical models for the menu planning problem. First, the original diet problem is characterized, as well as its importance to the development of operational research, its evolution and later applications. Several models for the diet problem are presented. Models are run and results are compared. This is done using an interactive tool which allows the definition of factors related to human needs, additional restrictions related to the amount of food and the selection of appropriate models. This tool may also be used for teaching purposes.

Tipos do Herbário Prisco Bezerra - EAC

Directory of Open Access Journals (Sweden)

Maria Stela Bezerra da Silva

1990-01-01

Full Text Available Com o presente trabalho pretende-se contribuir para a divulgação dos tipos do Herbário Prisco Bezerra - EAC. Um levantamento realizado no acervo do Herbário revelou o registro de dez tipos. Sete deles pertencentes à família Leguminosae distribuídas entre as subfamilias Caesalpinioideae: Peltogyne crenulata, Sentia dardanoi, Moldenhawera acuminata, Chamaecrista duckeana, Papilionoideae: Aeschynomene monteiroi, Cranocarpus gracilis e Mimosoideae: Mimosa niomarlei; dois, pertencentes à família Erythroxylaceae. As espécies Erythroxylum tianguanum e Erythroxylum bezerrae e um à família Euphorbiaceae: Dalechampia fernandesii recentemente descrita por G. Webster. Os tipos são apresentados na seqüência das indicações: nome das famílias, seguido do epíteto específico, habitat, com a transferência de todas as informações mencionadas na ficha de exsicata do material, bem como, a fotografia correspondente. Citam-se também alguns aspectos característicos das espécies, para melhor visualização dos detalhes fotográficos.The present paper repasts the type specimens in the Herbário Prisco Bezerra (University of Ceará. The Herbário has ten type, of which seven are Leguminosae: Peltoqyne crenulata, Senna dardanoi, Moldenhawera acuminata Chamaecrista duckeana, Aeschynomene monteiroi, Cranocarpus gracilis, Mimosa niomarlei, two the Erythroxylaceae: Erythroxylum tianquanum and Erythroxylum bezerrae and one Euphorbiaceae: Dalechampia fernandesii. Additional informations for these exsicata is presented.

FAUNA DE FORMIGAS COMO FERRAMENTA PARA MONITORAMENTO DE ÁREA DE MINERAÇÃO REABILITADA NA ILHA DA MADEIRA, ITAGUAÍ, RJ

OpenAIRE

Pereira, Marcos Paulo dos Santos; Queiroz, Jarbas Marçal; Valcarcel, Ricardo; Mayhé-Nunes, Antônio José

2007-01-01

RESUMO A riqueza e diversidade de espécies de formigas podem ser maiores em ambientes de complexidade mais elevada devido a uma maior disponibilidade de nichos presentes. Em razão da conexão entre os organismos e as características dos habitats, as formigas têm sido utilizadas como ferramentas no monitoramento ambiental de áreas perturbadas. Neste estudo, foi investigada a estrutura da comunidade de formigas em parcelas utilizadas para reabilitação de uma área de mineração na Ilha da Madeira,...

CRESCIMENTO INICIAL DE GENÓTIPOS DE PINHÃO MANSO REPRODUZIDOS ASSEXUADAMENTE

Directory of Open Access Journals (Sweden)

Amanda Macedo Facirolli

2012-09-01

Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4 /* 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:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Objetivou-se com este trabalho avaliar o crescimento inicial de genótipos de pinhão manso reproduzidos via propagação assexuada. O experimento constitui-se de dezoito tratamentos (dezoito genótipos de pinhão manso dispostos em blocos casualizados, com quatro repetições. Avaliou-se altura de planta, diâmetro de colmo, índice de pegamento, número de hastes, número de cachos, e índice de clorofila por planta. Houve significância da interação entre os genótipos, ao nível de 1% de probabilidade para todas as características avaliadas. Os genótipo 1, 4, e 17 mostraram-se superiores sobre os demais pois apresentaram maiores número de hastes e de cachos por planta, maior diâmetro do colmo, índice de pegamento e maior índice de clorofila, podendo ser apontados como genótipos promissores para futuros programas de melhoramento genéticos.

Processing of fine grained AISI 304L austenitic stainless steel by cold rolling and high-temperature short-term annealing

Science.gov (United States)

Naghizadeh, Meysam; Mirzadeh, Hamed

2018-05-01

An advanced thermomechanical process based on the formation and reversion of deformation-induced martensite was used to refine the grain size and enhance the hardness of an AISI 304L austenitic stainless steel. Both low and high reversion annealing temperatures and also the repetition of the whole thermomechanical cycle were considered. While a microstructure with average austenite grain size of a few micrometers was achieved based on cold rolling and high-temperature short-term annealing, an extreme grain refinement up to submicrometer regime was obtained by cold rolling followed by low-temperature long-term annealing. However, the required annealing time was found to be much longer, which negates its appropriateness for industrial production. While a magnificent grain refinement was achieved by one pass of the high-temperature thermomechanical process, the reduction in grain size was negligible by the repetition of the whole cycle. It was found that the hardness of the thermomechanically processed material is much higher than that of the as-received material. The results of the present work were shown to be compatible with the general trend of grain size dependence of hardness for AISI 304L stainless steel based on the Hall-Petch relationship. The results were also discussed based on the X-ray evaluation of dislocation density by modified Williamson-Hall plots.

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.

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.

Investigations on the creep-rupture behaviour of the austenitic stainless steel AISI 316 NET

International Nuclear Information System (INIS)

Schirra, M.; Ritter, B.

1988-12-01

The report describes the creep-rupture tests carried out with a 17/13/2 CrNiMo-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 programme on base material with a NET specified batch encompasses until now in the temperature range 500-750 0 C the rupture-time-range till 20 000 h. The results permit statements to the creep- and creep-rupture behaviour and ductility. Metallography examinations give information about fracture behaviour and demonstrate the complex precipitation happening. The results are compared with the literature and own test results from two batches of the Fast-Breeder-Program. (orig.) [de