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Dive into the research topics where Guttemberg Chagas de Souza is active.

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Featured researches published by Guttemberg Chagas de Souza.


Welding International | 2016

Mechanical properties and corrosion resistance evaluation of superduplex stainless steel UNS S32760 repaired by GTAW process

Guttemberg Chagas de Souza; Adriana Loureiro da Silva; S.S.M. Tavares; Juan Manuel Pardal; Miguel Luiz Ribeiro Ferreira; Ismael Cardote Filho

Abstract Superduplex stainless steels (SDSSs) are alloys widely used in the exploration and production of oil. They are used in marine and offshore components such as heat exchangers, umbilicals, sea water injection lines and various other equipment that requires high corrosion resistance with elevated mechanical strength values. These characteristics are due to its fine two-phase microstructure composed of similar proportions of austenite and ferrite and the alloying elements of Cr, Ni, Mo, N and W. However, during welding, and also in the stages of fabrication and pipe assembly, the presence of defects may occur that requires the need for repair procedures to be carried out on the welded joint. This study aims to characterise the microstructure, mechanical properties, nitrogen content and critical pitting temperature (CPT) of a SDSS pipe, UNS S32760, in certain regions of a welded joint, where the gas tungsten arc welding process was performed, with the completion of two sequential repair procedures. The results show that there is a decrease in the value of the CPT at the root of the weld, though there are not substantial variations in the mechanical properties analysed.


Welding International | 2016

Influence of interpass temperature on the properties of duplex stainless steel during welding by submerged arc welding process

Tatiana Resende Alvarez; Marjorie Rosemback Correia Pavarino; Guttemberg Chagas de Souza; Juan Manuel Pardal; S.S.M. Tavares; Miguel Luiz Ribeiro Ferreira; Ismael Cardote Filho

Abstract Duplex stainless steels are materials that present high corrosion resistance with high values of mechanical strength, therefore motivating their use in various components in the offshore industry. However, there are major challenges in the welding of these materials in terms of the productivity and quality of the joint produced, considering its extensive use for components of small thickness, such as umbilicals, to those of large thickness, such as salt water injection pipelines. In relation to pipes of small thickness, the gas tungsten arc welding process is successfully used. In thick-walled pipes, the automatic process of submerged arc welding (SAW) has been recently implemented in lines of pre-assembled piping, and this has considerably increased the productivity of the joints produced, though, a great deal of time is required to perform a new weld pass, due to the fact that the maximum interpass temperature needs to be lower than 150 °C. This work presents the results of characterization and the evaluation of corrosion resistance of a welded joint corresponding to DSS UNS S31803, with a wall thickness of 21.4 mm, welded by the gas metal arc welding process in the root and SAW process in the filling and cap passes, employing an interpass temperature between 150 and 290 °C. The results of the characterization of the mechanical properties, chemical composition and corrosion resistance in different regions of the welded joint were compared with those obtained for the base metal of the pipe, as well as with the minimum values required by the project standards. Therefore, this study has made an evaluation of the influence of the interpass temperature in the properties of the joints produced, motivated by a possible increase in productivity in pipe welding.


Welding International | 2015

Evaluation of proportion of phases in joints welded from duplex stainless steel pipes by means of non-destructive testing

Guttemberg Chagas de Souza; Juan Manuel Pardal; S.S.M. Tavares; Maria da Penha Cindra Fonseca; José L. F Martins; Elineudo Pinho de Moura; Ismael Cardote Filho

Duplex stainless steels (DSSs) combine excellent corrosion resistance and high mechanical strength, due to the fine two-phase microstructure composed of similar amounts of ferrite (δ) and austenite (γ). These alloys are used in piping and industrial equipment for which a high strength-to-weight ratio is required, especially in building construction and off-shore assembly. However, welding operating conditions can promote a significant microstructural imbalance of these phases, resulting in a decrease of the properties cited above. Evaluation by feritscope is normally used in these activities. During evaluation with a feritscope, the welded joint may be rejected when the weld metal is found to have ferrite values outside of the range established by project specifications. Thus, analysis of these joints is important, along with complementary techniques such as the use of metallographic replicas. This study aimed to evaluate the proportion of phases in relatively thin spools of DSS, welded in the field, comparing the non-destructive techniques described. The results show similar values, yet the result may be influenced by the shape and surface conditions of the welded joint.


Materials Research-ibero-american Journal of Materials | 2015

Influence of Deleterious Phases Precipitation in the Corrosion Resistance Measured by Double Loop Electrochemical Polarization Reactivation Test in Superduplex Stainless Steel

Juan Manuel Pardal; S.S.M. Tavares; Guttemberg Chagas de Souza; Maria da Penha Cindra Fonseca; Eduardo A. Ponzio; Marcelo Camargo Severo de Macêdo

This work investigates the influence of deleterious phases precipitation on the corrosion resistance of two wrought superduplex stainless steels UNS S32750 with similar composition, but different grain sizes. Isothermal treatments were carried out to introduce different amounts of deleterious phases, such as chi (χ), sigma (σ) and secondary austenite (γ2). The specimens were tested by double loop electrochemical potentiodynamic reactivation test (DL-EPR). The kinetics of precipitation in the two steels was different due to the difference of the grain sizes. The results show a correlation between the sensitization degrees, measured by DL-EPR, with the amount of deleterious phases precipitated.


Soldagem & Inspecao | 2013

Avaliação da proporção de fases em juntas soldadas de tubulações de aço inoxidável duplex mediante aplicação de ensaios não destrutivos

Guttemberg Chagas de Souza; Juan Manuel Pardal; S.S.M. Tavares; Maria da Penha Cindra Fonseca; José L. F Martins; Elineudo Pinho de Moura; Ismael Cardote Filho

Duplex stainless steels are high strength and corrosion resistant alloys, whose properties are devoted to the fine microstructure composed by similar amounts of ferrite and austenite and also to the high concentrations of Cr, Mo and N in solid solution. Not for coincidence, duplex steels are extensively used in chemical and petrochemical industries. However, welding operations conditions can promote the unbalance of the ferrite/austenite proportions mainly in the welding metal, with decrease of the properties mentioned. For this reason, non destructive measurements of ferrite content, by ferritoscope, is used after welding pipes. Ferritoscope is a commercial instrument which uses the initial magnetic permeability to analyze the ferrite content in duplex and austenitic stainless steels. The inspection with ferritoscope is a procedure commonly used in building and assembly of spools of duplex and superduplex stainless steels. The objective of this work was to evaluate the amounts of phases in the welding metal for different spools welded in the field by use of ferritoscope and metallographic replica techniques. The results showed that the two techniques measured similar values of ferrite and austenite, but ferritoscope analysis can be influenced by shape and surface conditions of the welded joint.


Soldagem & Inspecao | 2014

Análise da influência do gás de purga na raiz de juntas soldadas pelo processo GTAW em aço inoxidável superduplex UNS S32750

Tobias Carvalho Campos Paiva; Tabatta Regina de Brito Martins; Guttemberg Chagas de Souza; Juan Manuel Pardal; S.S.M. Tavares; Maria da Penha Cindra Fonseca; Ismael Cardote Filho

Os acos inoxidaveis superduplex (AISD) sao materiais que aliam altos valores de resistencia mecânica com elevados niveis de resistencia a corrosao. Por tal motivo, esta familia de acos inoxidaveis e muito utilizada em componentes de processo na industria offshore. No entanto, existem grandes desafios na soldagem destes materiais em termos de produtividade e custos mantendo-se a qualidade da junta produzida. Atualmente, a protecao gasosa da raiz e efetuada ate o ultimo passe de acabamento na soldagem durante a pre-montagem e montagem de tubulacoes de AISD em plataformas offshore. Neste tipo de protecao sao usualmente empregados os gases helio, argonio e nitrogenio, ou misturas destes. O nitrogenio e tipicamente adicionado no gas de protecao em teores de ate 3% de modo a promover a estabilizacao da fase austenitica na superficie da raiz da solda. Devido ao alto custo do gas de protecao utilizado, e necessario determinar o passe ou camada na qual a protecao gasosa na raiz seja efetiva em termos das propriedades mecânicas e da resistencia a corrosao, considerando ser esta uma regiao critica, que ficara em contato com o fluido operante durante o servico do componente. Neste sentido, o presente trabalho apresenta os resultados da influencia da utilizacao de gas de purga na raiz de juntas soldadas correspondente a uma tubulacao de aco inoxidavel superduplex (AISD) UNS S32750 de 9 mm de espessura de parede soldada pelo processo de soldagem TIG (GTAW). Foram avaliados o ciclo termico, o teor de nitrogenio e a tenacidade ao impacto da raiz da solda em funcao do aporte termico para diversas juntas soldadas com diferentes niveis de protecao gasosa na raiz. Deste modo, o presente trabalho tem como objetivo a reducao de custos na soldagem de tubulacoes indicando ate qual camada e requerida a protecao gasosa na raiz em funcao do aporte de calor empregado.


Soldagem & Inspecao | 2014

Influência da temperatura interpasse nas propriedades do aço inoxidável duplex durante a soldagem pelo processo a arco submerso

Tatiana Resende Alvarez; Marjorie Rosemback Correia Pavarino; Guttemberg Chagas de Souza; Juan Manuel Pardal; S.S.M. Tavares; Miguel Luiz Ribeiro Ferreira; Ismael Cardote Filho

Duplex stainless steels (DSS) are materials that present high corrosion resistance with high values of mechanical strength, therefore motivating their use in various components in the offshore industry. However, there are major challenges in the welding of these materials in terms of the productivity and quality of the joint produced, considering its extensive use for components of small thickness, such as umbilicals, to those of large thickness, such as salt water injection pipe lines. In relation to pipes of small thickness, the gas tungsten arc welding process (GTAW) is successfully used. In thick-walled pipes the automatic process of submerged arc welding (SAW) has been recently implemented in lines of pre-assembled piping, and this has considerably increased the productivity of the joints produced. Though, a great deal of time is required to perform a new weld pass, due to the fact that the maximum interpass temperature needs to be lower than 150°C. This work presents the results of characterization and the evaluation of corrosion resistance of a welded joint corresponding to DSS UNS S31803, with a wall thickness of 21.4 mm, welded by the gas metal arc welding process (GMAW), in the root, and submerged arc welding process (SAW), in the filling and cap passes, employing an interpass temperature between 150 and 290oC. The results of the characterization of the mechanical properties, chemical composition and corrosion resistance in different regions of the welded joint were compared with those obtained for the base metal of the pipe, as well as, with the minimum values required by the project standards. Therefore, this study has made an evaluation of the influence of the interpass temperature in the properties of the joints produced, motivated by a possible increase of productivity in pipe welding.


Soldagem & Inspecao | 2014

Efeitos do envelhecimento térmico na microestrutura e na resistência à corrosão do metal de solda de aço AISI 317L

Humberto Nogueira Farneze; S.S.M. Tavares; Juan Manuel Pardal; Guttemberg Chagas de Souza

Aiming at an analysis of the microstructural evolution and corrosion resistance of the weld metal in steel AISI 317L, obtained by GTAW process, conducted to evaluate the effect of prolonged exposure at 550 ° C by thermal treatment for 200h, 300h and 400h. After each treatment microstructural characterization was performed by scanning electron microscopy (SEM). Double loop electrochemical polarization reactivation tests (DL-EPR) were performed to evaluate the degree of sensitization of the samples. The results indicated that increasing the exposure time at 550 oC promoted the progressive formation of intermetallic phases, which caused corrosion decay of the weld metal. These results contribute to a better prediction of the behavior of AISI 317L welded joins during operation of the process equipment industry.


Engineering Failure Analysis | 2015

Study of cracks in the weld metal joint of p91 steel of a superheater steam pipe

S.S.M. Tavares; Juan Manuel Pardal; Guttemberg Chagas de Souza; P.S.P. Garcia; E.S. Barbosa; C. Barbosa; I. Cardote Filho


Soldagem & Inspecao | 2011

Caracterização e Avaliação da Resistência à Corrosão na Soldagem de Tubulação de Aço Inoxidável Duplex UNS S31803 pelo Processo a Arco Submerso (Characterization and Evaluation of Corrosion Resistance of Welded Joint of Duplex Stainless Steel Pipe UNS S31803 by Submerged Arc Process)

Juan Manuel Pardal; Guttemberg Chagas de Souza; S.S.M. Tavares; Maria da Penha Cindra Fonseca; Miguel Luiz Ribeiro Ferreira; Leandro M. Martins; Omar A. Samra Filho

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Juan Manuel Pardal

Federal Fluminense University

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S.S.M. Tavares

Federal Fluminense University

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José L. F Martins

Federal Fluminense University

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E.S. Barbosa

Federal Fluminense University

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