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au:Souza, Luís Felipe Guimarães de

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Evaluation of High Strength Cast Steel Welded Joints Suitable to Mooring Components
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Jorge, Jorge Carlos Ferreira

; Santos Filho, Antonio Manuel Ferreira dos

; Diniz, Jorge Luiz Coutinho

; Souza, Luís Felipe Guimarães de

; Mendes, Matheus Campolina

Soldagem & Inspeção

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2022, Volume 27 elocation e2720

Abstract: En | Text: En | PDF: En

Abstract This work investigates the performance of high strength cast steel welded joints to confirm their feasibility for application in mooring components. Three welded joints, with ultimate tensile strength in the range of 700 to 900 MPa, were obtained by the shielded metal arc welding process, the most applied in repair operation. After welding, a post welding heat treatment was performed to relieve the residual stresses. The results obtained in tension, impact Charpy-V, and hardness tests, at different positions of the heat affected zone were compared with equivalent welded joints performed with rolled steels currently applied in mooring chain links. These results showed that cast steels can obtain results equivalent to the rolled steels. Furthermore, the composition of cast steels for more stringent requirements (UTS > 860 MPa) is adjusted with higher nickel contents, while rolled and forged steels show increased C, Cr, and Mo contents. As a consequence, a refined microstructure with excellent impact toughness was obtained. Thus, these steels present a high potential to be used in this application contributing to reduce manufacturing costs.

https://doi.org/10.1590/0104-9224/si27.20

Desempenho de metal de solda adequado para soldagem de componentes de ancoragem
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Gomes, Antonio José de Carvalho

; Jorge, Jorge Carlos Ferreira

; Souza, Luís Felipe Guimarães de

; Bott, Ivani de Souza

; Araújo, Leonardo Sales

; Mendes, Matheus Campolina

Matéria (Rio de Janeiro)

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2020, Volume 25 N. 2 elocation e-12646

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

RESUMO O presente trabalho apresenta os resultados de um programa de pesquisa cujo objetivo principal é o desenvolvimento de consumíveis adequados para a soldagem de componentes de ancoragem fabricados em aços de alta resistência. Após avaliação de diferentes composições químicas, com base no balanço de Mn e Ni é feita uma análise detalhada das propriedades mecânicas e microestruturais da composição química que propiciou os melhores resultados para permitir uma conclusão decisiva. Foram soldadas juntas pelo processo eletrodo revestido utilizando consumíveis de 4,0 mm de diâmetro, com preaquecimento de 200 ºC, corrente contínua, posição plana e energia de soldagem nominal de 1,5 kJ / mm. Após a soldagem, foram realizados ensaios mecânicos (tensão, impacto Charpy-V, dureza) e metalográficos por microscopia ótica, microscopia eletrônica de varredura e EBSD em amostras removidas integralmente do metal de solda, tanto na condição de como soldado quanto após tratamento térmico pós-soldagem (TTPS) realizado a 600 ºC. Os resultados mostram que os metais de solda obtiveram propriedades mecânicas satisfatórias após o TTPS, sendo adequados para aplicação em componentes de ancoragem de acordo com a especificação IACS W22. Além disso, observou-se que a tenacidade ao impacto experimentou uma melhoria com o aumento do tempo de TTPS, o que é crucial para componentes com maiores espessuras.

ABSTRACT The present work show the results of an extensive working program whose the main goal is the development of consumables suitable for welding of mooring components manufactured in high strength steels. After an exhaustive evaluation of different chemical compositions, based on a balance of Mn and Ni, a detailed analysis of the mechanical and microstructural properties is done for the heat which proposed the best results in order to allow a decisive conclusion. Welded joints were produced by using 4,0 mm diameter covered electrodes, with preheat of 200 ºC, direct current, flat position and nominal heat input of 1.5 kJ/mm. After welding, mechanical tests (tension, impact Charpy-V, hardness) and metallographic examination (optical microscopy and scanning electron microscopy, electron back scattering diffraction) were performed in specimens removed integrally from the weld metal both in the as welded condition and post weld heat treatment at 600 º C. The results show that the weld metals obtained satisfactory mechanical properties after PWHT, being adequate for application on high strength steel mooring components with several grades according to the IACS W22 specification. In addition, it was noted that impact Charpy-V results were improved with increasing the time of PWHT, which is crucial for larger components.

https://doi.org/10.1590/s1517-707620200002.1046 562 downloads

Investigation into the Impact Toughness of API 5L X80 Steel Weldments and its Relationship with Safe Welding Procedures
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Carbos, Thiago Rodrigues

; Jorge, Jorge Carlos Ferreira

; Souza, Luís Felipe Guimarães de

; Bott, Ivani de Souza

; Mendes, Matheus Campolina

Materials Research

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2020, Volume 23 N. 6 elocation e20200363

Abstract: En | Text: En | PDF: En

API 5L X80 steels are widely used in welded pipes in the petroleum industry. However, microstructural changes in the heat affected zone are a concern when welding such pipes due to the potential formation of regions with low toughness. Despite all the research concerning mechanical properties of welded joints, the acceptance criteria for the qualification of welding procedures are still limited. Welded joints do not always guarantee the safe operation of industrial equipment, because the current Standards adopted are not able to evaluate the properties at some critical regions of the welded joint. This work studied the characteristics of a girth welded joint and showed evidences of low toughness at 0.5 mm from the fusion line due to the micro-phases necklacing the prior austenite grain boundaries. As this feature is not considered by the current Standards for approval of welding procedures, this work proposes an alternative approach to improve the safety of welded structures.

https://doi.org/10.1590/1980-5373-mr-2020-0363 679 downloads

Comportamento de Juntas Soldadas de Aço C-Mn Obtidas Pelo Processo GMAW-RE com Eletrodo Rotativo
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Costa, Jeferson Frederico Monteiro

; Silva Filho, Walker Andrade da

; Silveira, Guilherme Mastrange dos Santos

; Almeida, Felipe Augusto de Castro

; Lobato, Marcos Muller

; Chuvas, Tatiane de Campos

; Mendes, Matheus Campolina

; Souza, Luís Felipe Guimarães de

; Jorge, Jorge Carlos Ferreira

Soldagem & Inspeção

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2019, Volume 24 elocation e2411

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Resumo O presente trabalho tem como objetivo estudar o comportamento de juntas soldadas obtidas pelo processo GMAW com eletrodo rotativo (GMAW-RE), de modo a permitir uma análise comparativa de produtividade e propriedades mecânicas com o processo GMAW convencional (GMAW). Foram realizadas soldagens multipasse pelos dois processos GMAW com preaquecimento de 100 °C em chapas de dimensões 500 × 150 × 10 mm em aço ASTM A36, na posição plana e energia de soldagem média de 2,30 kJ/mm. Após a soldagem, foram realizados ensaios de impacto Charpy-V, microdureza e metalográficos em corpos-de-prova removidos transversalmente ao cordão de solda. Adicionalmente, foi realizada uma análise comparativa de produtividade entre os processos. Os resultados mostram que o processo GMAW-RE propicia um aumento de produtividade e redução de custos significativos em relação ao processo GMAW. Adicionalmente, foram observados valores equivalentes de tenacidade ao impacto para o metal de solda, mas uma redução nesta propriedade na zona termicamente afetada. Embora a literatura disponível destaque o elevado potencial deste processo para substituição do processo GMAW convencional em aplicações industriais, verifica-se a necessidade de mais evidências experimentais para um maior suporte a esta indicação.

Abstract The main goal of the present work is to evaluate the behavior of welded joints obtained by the GMAW with rotating electrode process (GMAW-RE) in comparison to the Conventional GMAW process (GMAW). Multipass welding by both processes were performed in ASTM A36 steel plates with dimensions of 500 × 150 × 10 mm, preheating of 100 °C in the flat position and average welding energy of 2.30kJ/mm. After welding, Charpy-V notch and microhardness tests and metallographic examination were performed in samples removed transversally to the weld bead. Additionally, a comparative analysis of productivity and costs between processes were done. The results show that the GMAW-RE promotes higher productivity and reduction of costs in comparison to GMAW. Additionally, similar impact toughness results were observed in weld metals and a reduction on this property at the HAZ. Although the literature states the high potential of the GMAW-RE for replacement of the conventional GMAW in industrial applications, it was concluded that other experimental results are still necessary before the final conclusion.

https://doi.org/10.1590/0104-9224/si24.11 1457 downloads

Performance of the INCONEL 625 alloy weld overlay obtained by FCAW process
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Alvarães, Camila Pereira

; Madalena, Francisco Carlos Albuquerque

; Souza, Luís Felipe Guimarães de

; Jorge, Jorge Carlos Ferreira

; Araújo, Leonardo Sales

; Mendes, Matheus Campolina

Matéria (Rio de Janeiro)

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2019, Volume 24 N. 1 elocation e-12290

Abstract: En | Text: En | PDF: En

ABSTRACT Nickel-based weld overlays (cladding) are commonly used in oil & gas industry to extend the life of equipment under corrosive environment, as it improves the corrosion resistance without a significant increase in the manufacturing cost, when compared to a full nickel-based alloy equipment. Although there are extensive literature involving overlays applied by SMAW, GMAW or GTAW processes, works about the use of FCAW process are limited. Consequently, an investigation of the performance of the overlays deposited by this process, which provides a higher productivity in comparison to the processes usually used, can be an interesting option for this application. The present work evaluates the mechanical and microstructural properties of the nickel-based superalloy 625 weld overlay deposited on a ASTM A516 Grade 70 carbon steel plate by the flux cored arc welding process (FCAW), both in as welded and heat treated conditions. Bending and microhardness tests were performed in order to verify possible effects of welding thermal cycles on the mechanical properties. The microstructure was evaluated through both optical (OM) and scanning electron microscopy (SEM), with the use of electron backscatter diffraction (EBSD) technique. Corrosion tests were conducted on samples removed from the top layer of the weld overlay according to ASTM G 48 Method A. All results obtained with this welding process, in both as welded and heat treated samples, were considered satisfactory.

https://doi.org/10.1590/s1517-707620190001.0627 3669 downloads

Avaliação de Juntas Soldadas de um Aço Fundido de Alta Resistência para a Indústria Offshore
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Santos Filho, Olavo Ribeiro dos

; Diniz, Jorge Luiz Coutinho

; Coêlho, Manoel José da Silva

; Souza, Luis Felipe Guimarães de

; Jorge, Jorge Carlos Ferreira

; Mendes, Matheus Campolina

; Araújo, Leonardo Sales

Soldagem & Inspeção

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jun 2018, Volume 23 N. 2 Pages 205 - 224

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Resumo Os torpedos de ancoragem são estruturas tubulares de aço carbono soldadas, e que tem sua ligação com as linhas de ancoragem que impedem o movimento das plataformas através de olhais de carregamento que são soldados nos tubos de construção. Como estes olhais apresentam geometria complexa, é importante a utilização de peças fundidas para a fabricação destes componentes, de forma a possibilitar o atendimento da demanda do mercado. Como a literatura técnica sobre este tipo de união soldada é ainda limitada, o presente trabalho estuda o comportamento de juntas soldadas de um aço fundido de alta resistência para utilização em olhais de torpedos de ancoragem de plataformas offshore. Para tanto, foram produzidas juntas soldadas com chanfro em K utilizando um aço de classificação ASTM A 148 Gr. 105-85 com resistência mecânica da ordem de 700 MPa, pelo processo eletrodo revestido, na posição plana, com preaquecimento de 200 °C e energia de soldagem média de 1,5 kJ/mm. Após a soldagem, foi realizado tratamento térmico pós-soldagem (TTPS) consistindo de aquecimento a 620 °C por 1 hora com resfriamento ao ar. As propriedades foram avaliadas por ensaios de tração, dureza, impacto Charpy-V e metalográficos por microscopia óptica e eletrônica de varredura com utilização da técnica de EBSD (eléctron backscatering difraction), tanto na condição de como soldado quanto após TTPS. Os resultados revelaram que, embora as propriedades mecânicas obtidas na junta soldada atendam os requisitos para a aplicação em todas as condições de análise, recomenda-se a execução do TTPS para alívio das tensões residuais e promover um revenimento da martensita de alta dureza do último passe de soldagem. Adicionalmente, verificou-se ser possível obter propriedades similares as de juntas soldadas de aços laminados usualmente utilizados em componentes de ancoragem.

Abstract Torpedo anchor piles are tubular carbon steel welded structures that are connected to the mooring lines, which prevent the oil platform from moving, through padeyes welded to the structural pipes. Due to the complex geometry of these padeyes, cast pieces are an important option in the manufacturing of these items, in order to meet market demand. Considering the limited availability of information about such type of welded junction in the technical literature, the present work studies the behavior of welded joints of a high strength cast steel used on offshore platforms torpedo anchor padeyes. Thus, K-type joints were used for the welding of an ASTM A 148 Gr. 105-85 steel with an ultimate tensile strength of about 700 MPa, by using shielded metal arc welding process, in flat position, with a preheating of 200 °C and an average welding energy of 1.5 kJ/mm. After welding, a post weld heat treatment (PWHT) was applied, at 620 °C for 1 hour, followed by air cooling. The properties were evaluated through tensile, hardness and Charpy-V impact tests, as well as metallographic examination by optical and scanning electron microscopy with the use of EBSD (electron backscatter diffraction) technique, in both as welded and after PWHT conditions. The results shown that, although the mechanical properties obtained for the welded joint achieved the requirements for the application in all analyzed conditions, the execution of PWHT is recommended for the relief of residual stresses and promotion of a tempering of the high hardness martensite of the last welding pass. Additionally, it was verified that it is possible to obtain properties that are similar to those of welded joints of rolled steels, which are usually used on mooring components.

https://doi.org/10.1590/0104-9224/si2302.08 1506 downloads

Assessing the Notch Sensitivity of High Strength Wires
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Bandeira, Carlos Filipe Cardoso

; Kenedi, Paulo Pedro

; Souza, Luis Felipe Guimarães de

Latin American Journal of Solids and Structures

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2017, Volume 14 N. 13 Pages 2423 - 2438

Abstract: En | Text: En | PDF: En

Abstract High strength wires, which have a poor notch sensitivity performance, are currently been used on many offshore applications where high stresses without yielding are demanded. To assess these wires notch sensitivity, an integrated approach was implemented. An experimental program was conducted, through the realization of fatigue tests to obtain the fatigue limit for notched and notched free specimens to assess the fatigue stress concentration factor. A numerical approach using Finite Element Method, and an analytical model, available in technical literature, were used to assess the stress concentration factor. With both results, the notch sensitivity could be obtained.

https://doi.org/10.1590/1679-78253728 1287 downloads

Influence of heat treatments on the microstructure and degree of sensitization of base metal and weld of AISI 430 stainless steel
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Tavares, Sérgio Souto Maior

; Souza, Luis Felipe Guimarães de

; Chuvas, Tatiane de Campos

; Machado, Cássio Lapate da Costa

; Almeida, Brígida Bastos de

Matéria (Rio de Janeiro)

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2017, Volume 22 Suppl. 1 elocation e11939

Abstract: En | Text: En | PDF: En

ABSTRACT AISI 430 is a non-stabilized ferritic stainless steel grade with carbon content lower than 0.12%.After hot and cold rolling this material is annealed. The slow cooling after soaking at temperatures between 900oC and 1000oC promotes the formation of a high quantity of carbides and nitrides, while the rapid cooling partially suppresses the formation of these precipitates, but introduces martensite in the microstructure. Intergranular martensite can also be produced in the weld metal and in the heat affected zone (HAZ) of welds of non-stabilized ferritic stainless steels. In this work, several heat treatments between 900oC and 1000oC, with different cooling rates, were performed in a commercial sheet of AISI 430 grade. Also, an autogenous welding was produced with GTAW process, and post weld heat treatment at 700°C was carried out. The different microstructures produced were analyzed by optical and scanning electron microscopy (SEM). The degree of sensitization was measured by double loop electrochemical potentiodynamic tests (DL-EPR). The pitting corrosion resistance was evaluated by cyclic polarization tests in 3.5%NaCl solution. Hardness and toughness tests were also performed in selected heat treatment conditions. The results indicate that the slow cooling results in a higher degree of sensitization than observed in the material rapid cooled from the annealing temperature. The ferritic martensitic structure produced by water cooling has higher pitting potential and lower degree of sensitization, but is brittle at room temperature. A subsequent tempering treatment between 600 and 800oC can increase the toughness, but the corrosion resistance may decrease due to carbides precipitation.The heat affected zone of AISI 430 welds contains intergranular martensite, which is brittle and susceptible to corrosion attack. Post weld heat treatment at 700oC decomposed the martensite into ferrite and carbides and improved the corrosion resistance.

https://doi.org/10.1590/s1517-707620170005.0275 2480 downloads

Avaliação de Revestimentos de Liga de Níquel 625 Depositados pelo Processo Eletroescória
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Sandes, Soraia Simões

; Alvarães, Camila Pereira

; Mendes, Matheus Campolina

; Araújo, Leonardo Sales

; Souza, Luis Felipe Guimarães de

; Jorge, Jorge Carlos Ferreira

Soldagem & Inspeção

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dec 2016, Volume 21 N. 4 Pages 417 - 427

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Resumo A aplicação de revestimentos de ligas de níquel é comumente realizada na indústria de petróleo e gás para aumento da vida de equipamentos em ambientes agressivos, dado que este procedimento melhora a resistência à corrosão, sem um aumento significativo do custo de produção quando comparado com equipamentos maciços fabricados com outras ligas. Normalmente, as juntas são soldadas pelos processos de eletrodos revestidos, MIG/MAG ou TIG. Neste aspecto, o processo eletroescória realiza deposições com elevada energia de soldagem e baixa diluição, podendo ser uma opção interessante, uma vez que proporciona uma elevada produtividade, permitindo a soldagem com aplicação de apenas uma camada. O presente trabalho avalia propriedades mecânicas, microestruturais e de corrosão de revestimentos de liga de níquel 625 depositada em aço carbono ASTM A516 Grau 70 pelo processo eletroescória, tanto na condição como soldado quanto tratado termicamente. A deposição foi realizada com uma e duas camadas sobre chapas de dimensão 50x400x400 mm, na posição plana e energia de soldagem média de 11,7 kJ/mm. Após a soldagem realizou-se tratamento térmico a 620°C por 10 horas, sendo esta condição comparada ao estado de como soldado. Os ensaios de dobramento não indicaram evidências de defeitos. A avaliação microestrutural realizada por microscopia ótica (MO), eletrônica de varredura (MEV) e eletrônica de transmissão (MET) mostrou uma microestrutura austenítica para o depósito com pequena fração volumétrica de fases secundárias e o tratamento térmico de alívio de tensões não promoveu mudanças significativas nas propriedades. Na região de grãos grosseiros da zona termicamente afetada (RGGZTA) foi observada a ocorrência de ferrita pró-eutetóide, perlita e bainita para o depósito com 1 camada e basicamente ferrita e perlita refinadas para o deposito com 2 passes devido às baixas taxas de resfriamento. Adicionalmente, não foi verificada evidência de zona parcialmente diluída (ZPD). Os ensaios de corrosão realizados de acordo com a norma ASTM G-48 em amostras retiradas a partir da camada superior do depósito foram considerados satisfatórios, uma vez que não mostraram evidências de pites e a perda de massa foi pequena.

Abstract Nickel base alloy weld overlays are commonly used in oil & gas industry to extend the life of equipments under aggressive corrosion environments, since the overlays improve the corrosion resistance without a significant increase the cost of manufacture when compared to massive equipment. Usually, the joints are welded by SMAW, GMAW or GTAW processes. In this respect, the electro slag welding process (ESW), which promotes high heat inputs and low dilution welds, can be an interesting option for this application as it provides a high productivity, once only one layer is necessary. The present work evaluates mechanical, microstructural and corrosion properties of an Alloy 625 weld overlay deposited on ASTM A516 Grade 70 carbon steel by ESW process. The deposition was done with 1 and 2 layers in plates of dimension 50x400x400 mm, in the flat position and an average energy welding 11.7 kJ/mm. After welding, a post weld heat treatment at 620°C for 10 hours was performed, this condition being compared with the as welded condition. Bending tests showed no evidences of cracks. Microstructural evaluation performed using both optical (OM), scanning (SEM) and transmission electron microscopy (TEM) techniques showed an austenitic microstructure of the weld deposit with low proportion of secondary phases for all conditions and the post welding heat treatment did not promote significant changes on the mechanical properties. At the coarse grain heat affected zone (CGHAZ) the occurrence of proeutectoid ferrite, pearlite and bainite were found for 1 layer deposit and refined pearlite and ferrite for 2 layer deposits were the microstructural constituents observed due to the low cooling rate. In addition, no evidences of partially diluted zones (PDZ) were verified. Corrosion tests conducted on samples removed from top layer of weld overlay cladding deposit according to ASTM G 48 Method A Standard were considered satisfactory once no evidences of pittings were verified and the loss of mass was very reduced.

https://doi.org/10.1590/0104-9224/si2104.03 1877 downloads

10.

Formation of Microphases and Constituents from Remaining Austenite Decomposition in API X80 Steel Under Different Processing Conditions
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Silva, Rafael de Araujo

; Souza, Luís Felipe Guimarães de

; Morales, Eduardo Valencia

; Rios, Paulo Rangel

; Bott, Ivani de Souza

Materials Research

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oct 2015, Volume 18 N. 5 Pages 908 - 917

Abstract: En | Text: En | PDF: En

AbstractThe main goal this work is to evaluate the occurrence of the constituents and microphases observed in as-received API X80 pipe through the microstructures transformed from rich-carbon remaining austenite obtained via heat treatments. These heat treatments comprised austenitization at 1000 °C for 30 minutes, followed by annealing at 700 °C, 623 °C, 542 °C and 462 °C for 15, 60 and 300 minutes and then cooling in water or still air. The effects of the increase in annealing parameters were: 1) the increase of microhardness values of the MA constituents and martensite islands, 2) the grain size of both ferritic phase and the martensite islands were increased, 3) the rise in the mean free path of ferrite and 4) the microstrains of samples were decreased. The cooling rates influenced significantly the transformation of carbon-rich remaining austenite to hard constituents and several microphases. After annealing at 700 °C during 60 min followed by quenching, the morphology of the MA constituents and its microhardness values were compatible for both heat-treated and as-received conditions.

https://doi.org/10.1590/1516-1439.315214 6036 downloads

11.

Propriedades Mecânicas e Microestruturais de Juntas Soldadas pelo Processo a Arco Submerso com Elevado Aporte Térmico
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Jorge, Jorge Carlos Ferreira

; Souza, Luis Felipe Guimarães de

; Marouco, Erick de Souza

; Santos Filho, Olavo Ribeiro dos

; Diniz, Jorge Luiz Coutinho

Soldagem & Inspeção

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sep 2015, Volume 20 N. 3 Pages 347 - 358

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Resumo Este trabalho tem por objetivo apresentar um estudo das propriedades mecânicas e microestruturais de juntas soldadas de aço carbono obtidas pelo processo a arco submerso automatizado com elevada energia de soldagem, visando o aumento de produtividade na fabricação de tubulações para equipamentos de ancoragem. Foram soldadas juntas de aço ASTM A-572 Gr.50 com 25mm de espessura pelo processo a arco submerso em passe único, com energia de soldagem variando de 7,8 até 14,0 kJ/mm. As juntas foram avaliadas através de ensaios de impacto Charpy-V realizados à temperatura de 0°C, microdureza Vickers com carga de 1 kgf. e metalográficos em corpos-de-prova retirados do metal de solda e zona termicamente afetada. Os resultados mostraram que as juntas soldadas apresentaram tenacidade ao impacto superior aos mínimos requeridos para a utilização na soldagem de aços C-Mn baixa liga com requisitos de impacto de 34 Joules à 0°C. Foi observado um aumento significativo da produtividade, sem prejuízo das propriedades mecânicas, permitindo a fabricação de tubulações para equipamentos de petróleo com redução significativa do tempo envolvido na fabricação.

Abstract The objective of the current work is to present a study of the mechanical and microstructural properties of welded joints of carbon steel obtained from automatic submerged arc welding process with high welding energy, in order to improve productivity on the fabrication of pipes for mooring equipment. Joints of 25mm-thick ASTM A-572 Gr.50 steel were welded by a single pass of submerged arc welding process, with heat input varying from 7.8 to 14.0kJ/mm. The welded joints were evaluated through Charpy-V impact test performed at 0°C temperature, hardness test with 1 kgf load and metallographic examination, performed on samples removed from weld metal and heat affected zone (HAZ). The results showed that the welded joints presented impact toughness higher than the minimum requirements for the welding of low-alloy C-Mn steel with impact toughness requirement of 34 Joules at 0°C. A significant increase on productivity was observed, without prejudice to the mechanical properties, allowing the fabrication of pipes for oil equipment with significant reduction of production time.

https://doi.org/10.1590/0104-9224/SI2004.04 4070 downloads

12.

Propriedades mecânicas e microestruturais de juntas soldadas do aço HY-80 pelos processos eletrodo revestido e GMAW
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Lins Junior, Amilton Sousa

; Costa, Hector Reynaldo Meneses

; Souza, Luís Felipe Guimarães de

; Jorge, Jorge Carlos Ferreira

Soldagem & Inspeção

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sep 2014, Volume 19 N. 3 Pages 200 - 211

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

A soldagem de aços de alta resistência representa um desafio constante devido a grande variedade de ligas disponíveis, que necessitam associar requisitos rigorosos de elevada resistência mecânica e tenacidade simultaneamente. Neste contexto, os aços da classe HY-80 amplamente utilizados na Marinha Brasileira, são ainda preferencialmente soldados pelo processo eletrodo revestido apesar das limitações deste processo em comparação com outros processos de soldagem. Com o objetivo de avaliar a possibilidade de uma melhoria de produtividade na soldagem manual deste aço, o presente trabalho apresenta uma análise comparativa entre as propriedades mecânicas de juntas soldadas do aço HY-80 realizadas pelos processos eletrodo revestido e GMAW. Foram realizadas soldagem multipasses pelos processos eletrodo revestido e GMAW com preaquecimento de 90°C e temperatura interpasses máxima de 150°C em chapas de dimensões 850X150X30mm em aço HY-80, na posição plana e energia de soldagem média de 1,29 e 1,36 kJ/mm, respectivamente. Posteriormente, realizou-se tratamento térmico pós-soldagem a 600°C por 1 hora, sendo esta condição comparada com a condição de como soldada. Foram realizados ensaios de tração, impacto Charpy-V, dureza e metalográficos para caracterização microestrutural por microscopia eletrônica de varredura. Adicionalmente, foi realizada uma análise comparativa de produtividade entre os processos. Os resultados mostraram ser possível obter propriedades mecânicas adequadas para todas as condições de análise. Além disso, verificou-se que a produtividade propiciada pelo processo GMAW foi muito superior à do processo eletrodo revestido.

The welding of high strength steels represents a continuous challenge taking into account the great variety of alloys systems, which present stringent requirements of high strength and toughness. Into this context the HY-80 steels largely employed in the Naval Industry are still welded preferentially by the SMAW process, despite its limitations when compared with other welding processes. In order to promote an improvement on productivity, the present work presents a comparative analysis between the mechanical properties of the HY-80 welded joints performed by the GMAW and SMAW processes. Multipass welding by shielded metal(SMAW) arc and gas metal arc welding (GMAW) processes were performed with preheating and inter-pass temperatures of 90°C and 150°C respectively in plates of dimensions 850X150X30 mm in HY-80 steel, in the flat position and average energy welding of 1.29 for SMAW and 1.36kJ/mm for GMAW process. After welding a post weld heat treatment at 600°C for 1 hour was performed, this condition being compared with the as welded condition. Tensile, Charpy-V notch and hardness tests and metallographic examination by scanning electron microscopy were performed for mechanical and microstructural characterization. Additionally, it was carried out a comparative analysis between processes. The results show that it is possible to achieve adequate mechanical properties for all analyzed conditions. Furthermore, it was observed that the productivity provided by the gas metal arc welding process was greater than shield metal arc welding.

https://doi.org/10.1590/0104-9224/SI1903.02 5662 downloads

13.

Asymmetric optic nerve sheath diameter as an outcome factor following cranioplasty in patients harboring the 'syndrome of the trephined'
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Araujo Junior, Antonio Santos de

; Arlant, Pedro Alberto

; Salvestrini Jr, Arnaldo

; Altieri, Carlos Eduardo

; Santos, Jasper Guimaraes

; Pinto, Lauro Figueira

; Fazzito, Mirella Martins

; Lee, Hae Won

; Godoy, Luis Felipe de Souza

Arquivos de Neuro-Psiquiatria

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dec 2013, Volume 71 N. 12 Pages 963 - 966

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

A craniectomia descompressiva (CD) tem papel fundamental no tratamento da hipertensão intracraniana refratária, mas não é isenta de complicações. Uma complicação rara é a “síndrome do trefinado” (ST). Ela ocorre quando as forças gravitacionais se sobrepõem à pressão intracraniana. Objetivo Determinar a utilidade do diâmetro da bainha do nervo óptico (DBNO) como fator prognóstico após cranioplastia. Método Foram acompanhados 5 pacientes trefinados portadores da ST. Estes pacientes foram submetidos à ressonância magnética com medida do diâmetro da bainha do nervo óptico (DBNO). Resultados Dois pacientes apresentaram uma assimetria do DBNO, sendo o diâmetro maior do lado craniectomizado. Para nossa surpresa estes evoluíram melhor do que os que apresentavam o DBNO simétrico. Estes pacientes se tornaram independentes uma semana após, e estatisticamente mais cedo do que os outros. Conclusão Há evidências de que a assimetria do DBNO sirva como fator de bom prognóstico após cranioplastia no pacientes portadores da ST.

Decompressive craniectomy (DC) is gaining an increasing role in the neurosurgical treatment of intractable intracranial hypertension, but not without complications. A rare complication is the “syndrome of the trephined” (ST). It occurs when the forces of gravity overwhelm intracranial pressures, leading the brain to become sunken. Objective To determine the usefulness of asymmetric optic nerve sheath diameter (ONSD) as an outcome factor after cranioplasty. Method We followed-up 5 patients submitted to DC and diagnosed with ST. All were submitted to brain MRI to calculate the ONSD. Results Only two patients presented an asymmetric ONSD, being ONSD larger at the site of craniectomy. Surprisingly these patients had a marked neurological improvement after cranioplasty. They became independent a week after and statistically earlier than others. Conclusion It is presumed that the presence of an asymmetric ONSD in trephined patients is an independent factor of good outcome after cranioplasty.

https://doi.org/10.1590/0004-282X20130176 4506 downloads

14.

Efeito do tratamento térmico pós-soldagem nas propriedades mecânicas e microestruturais de metal de solda de aço de extra alta resistência para utilização em equipamentos de ancoragem
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Jorge, Jorge Carlos Ferreira

; Faragasso, Sérgio Maciel

; Souza, Luís Felipe Guimarães de

; Bott, Ivaní de Souza

Soldagem & Inspeção

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jun 2013, Volume 18 N. 2 Pages 138 - 148

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Realizou-se a avaliação de metal de solda com resistência a tração superior à 860MPa, para utilização na soldagem de aço grau R4 da norma IACS W22. Para tanto, foram soldadas juntas multipasse com preaquecimentos realizados à 200 e 250ºC pelo processo eletrodo revestido, utilizando um consumível com 4,0mm de diâmetro e cuja composição base é C-0,06%, Mn-1,89%, e Ni-2,95%. Após a soldagem foram realizados ensaios mecânicos e metalográficos em corpos-de-prova retirados integralmente do metal depositado nas condições de como soldado e após tratamento térmico pós-soldagem realizados à 600ºC por 2 horas. Os resultados mostraram que os metais de solda obtidos apresentaram propriedades mecânicas adequadas para todas as condições de análise, propiciando resultados superiores aos mínimos requeridos para a utilização na soldagem do aço grau R4 utilizados em equipamentos de ancoragem de plataformas de petróleo. A análise metalográfica permitiu clarificar a microestrutura presente e explicar o comportamento das propriedades mecânicas após o tratamento térmico.

A weld metal with tensile strength higher than 860 MPa for the welding of a IACS W22 R4 Grade Steel was evaluated. Welded joints with preheat of 200 and 250ºC were produced by SMAW process using 4.0 mm diameter covered electrodes in multipass technique whose basic composition was: C-0,06%, Mn-1,89%, e Ni-2,95%. After welding, mechanical and metallographic tests were done in all-weld metal samples in both as-welded and post welded heat treatment conditions performed at600ºC for 2 hours. The results show that the obtained weld metals have mechanical properties higher than the minimum required for the welding of a IACS W22 R4 Grade steel in all condition analysis, which makes possible to attain an adequate strength/toughness relationship for high strength steel applied in mooring equipments. The metallographic analysis allowed the identification of microstructure and, consequently, the behavior of the mechanical properties after post weld heat treatment.

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15.

Brazilian coffee genome project: an EST-based genomic resource
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Vieira, Luiz Gonzaga Esteves

; Andrade, Alan Carvalho

; Colombo, Carlos Augusto

; Moraes, Ana Heloneida de Araújo

; Metha, Ângela

; Oliveira, Angélica Carvalho de

; Labate, Carlos Alberto

; Marino, Celso Luis

; Monteiro-Vitorello, Claúdia de Barros

; Monte, Damares de Castro

; Giglioti, Éder

; Kimura, Edna Teruko

; Romano, Eduardo

; Kuramae, Eiko Eurya

; Lemos, Eliana Gertrudes Macedo

; Almeida, Elionor Rita Pereira de

; Jorge, Érika C.

; Albuquerque, Érika V. S.

; Silva, Felipe Rodrigues da

; Vinecky, Felipe

; Sawazaki, Haiko Enok

; Dorry, Hamza Fahmi A.

; Carrer, Helaine

; Abreu, Ilka Nacif

; Batista, João A. N.

; Teixeira, João Batista

; Kitajima, João Paulo

; Xavier, Karem Guimarães

; Lima, Liziane Maria de

; Camargo, Luis Eduardo Aranha de

; Pereira, Luiz Filipe Protasio

; Coutinho, Luiz Lehmann

; Lemos, Manoel Victor Franco

; Romano, Marcelo Ribeiro

; Machado, Marcos Antonio

; Costa, Marcos Mota do Carmo

; Sá, Maria Fátima Grossi de

; Goldman, Maria Helena S.

; Ferro, Maria Inês T.

; Tinoco, Maria Laine Penha

; Oliveira, Mariana C.

; Van Sluys, Marie-Anne

; Shimizu, Milton Massao

; Maluf, Mirian Perez

; Eira, Mirian Therezinha Souza da

; Guerreiro Filho, Oliveiro

; Arruda, Paulo

; Mazzafera, Paulo

; Mariani, Pilar Drummond Sampaio Correa

; Oliveira, Regina L.B.C. de

; Harakava, Ricardo

; Balbao, Silvia Filippi

; Tsai, Siu Mui

; Mauro, Sonia Marli Zingaretti di

; Santos, Suzana Neiva

; Siqueira, Walter José

; Costa, Gustavo Gilson Lacerda

; Formighieri, Eduardo Fernandes

; Carazzolle, Marcelo Falsarella

; Pereira, Gonçalo Amarante Guimarães

Brazilian Journal of Plant Physiology

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mar 2006, Volume 18 N. 1 Pages 95 - 108

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

O café é um dos principais produtos agrícolas, sendo considerado o segundo item em importância do comércio internacional de "commodities". O gênero Coffea pertence à família Rubiaceae que também inclui outras plantas importantes. Este gênero contém aproximadamente 100 espécies, mas a produção comercial é baseada somente em duas espécies, Coffea arabica e Coffea canephora, que representam aproximadamente 70 % e 30 % do mercado total de café, respectivamente. O Projeto Genoma Café Brasileiro foi desenvolvido com o objetivo de disponibilizar os modernos recursos da genômica à comunidade científica e aos diferentes segmentos da cadeia produtiva do café. Para isso, foram seqüenciados 214.964 clones escolhidos aleatoriamente de 37 bibliotecas de cDNA de C. arabica, C. canephora e C. racemosa representando estádios específicos do desenvolvimento de células e de tecidos do cafeeiro, resultando em 130.792, 12.381 e 10.566 seqüências de cada espécie, respectivamente, após processo de trimagem. Os ESTs foram agrupados em 17.982 contigs e em 32.155 singletons. A comparação destas seqüências pelo programa BLAST revelou que 22 % não tiveram nenhuma similaridade significativa às seqüências no banco de dados do National Center for Biotechnology Information (de função conhecida ou desconhecida). A base de dados de ESTs do cafeeiro resultou na identificação de cerca de 33.000 unigenes diferentes. Os resultados de anotação das seqüências foram armazenados em base de dados "online" em <A HREF="http://www.lge.ibi.unicamp.br/cafe">http://www.lge.ibi.unicamp.br/cafe</A>. Os recursos desenvolvidos por este projeto disponibilizam ferramentas genéticas e genômicas que podem ser decisivas para a sustentabilidade, a competitividade e a futura viabilidade da agroindústria cafeeira nos mercados interno e externo.

Coffee is one of the most valuable agricultural commodities and ranks second on international trade exchanges. The genus Coffea belongs to the Rubiaceae family which includes other important plants. The genus contains about 100 species but commercial production is based only on two species, Coffea arabica and Coffea canephora that represent about 70 % and 30 % of the total coffee market, respectively. The Brazilian Coffee Genome Project was designed with the objective of making modern genomics resources available to the coffee scientific community, working on different aspects of the coffee production chain. We have single-pass sequenced a total of 214,964 randomly picked clones from 37 cDNA libraries of C. arabica, C. canephora and C. racemosa, representing specific stages of cells and plant development that after trimming resulted in 130,792, 12,381 and 10,566 sequences for each species, respectively. The ESTs clustered into 17,982 clusters and 32,155 singletons. Blast analysis of these sequences revealed that 22 % had no significant matches to sequences in the National Center for Biotechnology Information database (of known or unknown function). The generated coffee EST database resulted in the identification of close to 33,000 different unigenes. Annotated sequencing results have been stored in an online database at <A HREF="http://www.lge.ibi.unicamp.br/cafe">http://www.lge.ibi.unicamp.br/cafe</A>. Resources developed in this project provide genetic and genomic tools that may hold the key to the sustainability, competitiveness and future viability of the coffee industry in local and international markets.

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