Moisés L U I Z Lagares Jr | UFJF - Federal University of Juiz de Fora (original) (raw)
Papers by Moisés L U I Z Lagares Jr
The union between two dissimilar materials has been widely applied in the oil and gas industry. I... more The union between two dissimilar materials has been widely applied in the oil and gas industry. In general, this type of welding is more sensitive to differences in chemical composition between the metals involved. From this perspective, this work aims, by autogenous welding, to evaluate the microstructure of a joint welded between a high strength and low alloy steel of class API 5L X80 and a duplex stainless steel UNS UNS S32304. Furthermore, the corrosion resistance of the dissimilar welding region was evaluated in a solution which simulates the seawater environment. The microstructural properties and composition of the welding region were studied using optical microscopy, scanning electronic microscopy (SEM) with energy dispersive spectroscopy (EDS). The corrosion resistance was studied by anodic potentiodynamic polarization and by electrochemical impedance spectroscopy. The dissimilar region differs from both materials in their microstructural characteristics and presented signi...
Soldagem & Inspeção, 2019
Resumo A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo... more Resumo A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo e gás. Em geral, este tipo de soldagem é mais sensível às diferenças de composição química existente entre os metais envolvidos. Diante dessa perspectiva, este trabalho tem por objetivo avaliar, por união autógena, a microestrutura de uma junta soldada entre um aço de alta resistência e baixa liga da classe API 5L X80 e um aço inoxidável duplex UNS S32304. Além disso, estudou-se o comportamento quanto à resistência à corrosão em uma solução simuladora de água do mar. A microestrutura e composição da junta soldada foram avaliadas por microscopia ótica e eletrônica, espectrometria de energia dispersiva (EDS). A resistência à corrosão foi estudada por polarização potenciodinâmica anódica e por ensaios de espectroscopia de impedância eletroquímica. As juntas soldadas apresentaram uma microestrutura que se difere em morfologia de ambos os metais de base, além disso, notou-se a migração de cr...
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021
The welding process stability is a critical factor regarding the quality of the manufactured prod... more The welding process stability is a critical factor regarding the quality of the manufactured products in the Industry. There are two approaches to assess the metal transfer stability based on droplet transfer period: scanning arc voltage or scanning wire feed speed. Studies based on each of the approaches can be found in current literature, but there are no reported studies evaluating the role of the arc reignition voltage peak (RiVP) on stability. Thus, this paper aimed to propose a novel method to assess the short-circuiting gas metal arc welding metal transfer stability based on arc reignition voltage peak distribution, via wire feed speed scanning route, and compare the effectiveness of the proposed method to the existing ones. First, the authors depicted the fundamentals of the ideal metal transfer (the most stable). A novel stability index based on the RiVP distribution was introduced. The results showed that the methodology was capable of defining a locus of maximum metal transfer stability through the arc RiVP regularity. It also demonstrated that, in a regular short-circuiting transfer mode, the RiVP obeys an expected distribution. Besides, the most regular arc reignition-related quantity was directly related to the most regular period-related characteristic. After validating the methodology, the proposed method was demonstrated to be, potentially, a novel manner to assess and seek the maximum stability of the short-circuiting gas metal arc welding process.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
This work focuses on the identification of five of the most common ferritic morphologies present ... more This work focuses on the identification of five of the most common ferritic morphologies present in welded fusion zones of low carbon steel through images acquired by photomicrographies. With this regards, we discuss the importance of the gray-level co-occurrence matrix to extract the features to be used as the input of the computational intelligence techniques. We use artificial neural networks and support vector machines to identify the proportions of each morphology and present the error identification rate for each technique. The results show that the use of gray-level co-occurrence extraction allows a less intense computational model with statistical validity and the support vector machine as a computational intelligence technique allows smaller variability when compared to the artificial neural networks.
Soldagem & Inspeção, 2019
Resumo A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sina... more Resumo A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sinais de tensão de arco e corrente de soldagem. Histogramas e cálculo de estatísticas dos parâmetros tempo de arco aberto e tempo de curto circuito são meios de avaliação da estabilidade dos processos de soldagem. Contudo, estudos relacionados aos picos de tensão de reignição do arco elétrico ainda são pouco explorados. Desta forma, este trabalho apresenta uma metodologia de avaliação da distribuição de picos de reignição do arco do processo Gas Metal Arc Welding por curto-circuito (GMAW-CC). Cordões de solda depositados em chapa plana, variando o gás, foram executados a fim de produzir diferentes distribuições de picos de reignição. O teste qui-quadrado foi aplicado para avaliar a distribuição de frequências observadas de picos de tensão e compará-la com a distribuição hipotética. Um cordão padrão foi comparado com sua repetição e testada a hipótese de distribuições iguais. Os resultados m...
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
The short-circuit gas metal arc welding has been continuously studied over the years, due to its ... more The short-circuit gas metal arc welding has been continuously studied over the years, due to its important role in manufacturing processes. Concerning the process, many kinds of research are carried out aiming to understand the influence of the shielding gas in welds quality. In this context, this work treats the voltage and current welding signals as time series and applies a feature extraction based on scalable hypothesis tests, which is called FRESH algorithm, in order to obtain the signal features. After that, these features are applied in a multilayer perceptron artificial neural network, trained by the scaled conjugate gradient method, which classifies the welds according to the flow rate and type of shielding gas used in the process. The model presented excellent performance, which shows that the proposal is suitable to be used in welding quality monitoring.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
The short-circuit gas metal arc welding has been continuously studied over the years, due to its ... more The short-circuit gas metal arc welding has been continuously studied over the years, due to its important role in manufacturing processes. Concerning the process, many kinds of research are carried out aiming to understand the influence of the shielding gas in welds quality. In this context, this work treats the voltage and current welding signals as time series and applies a feature extraction based on scalable hypothesis tests, which is called FRESH algorithm, in order to obtain the signal features. After that, these features are applied in a multilayer perceptron artificial neural network, trained by the scaled conjugate gradient method, which classifies the welds according to the flow rate and type of shielding gas used in the process. The model presented excellent performance, which shows that the proposal is suitable to be used in welding quality monitoring.
Soldagem & Inspeção, 2019
A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo e gás.... more A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo e gás. Em geral, este tipo de soldagem é mais sensível às diferenças de composição química existente entre os metais envolvidos. Diante dessa perspectiva, este trabalho tem por objetivo avaliar, por união autógena, a microestrutura de uma junta soldada entre um aço de alta resistência e baixa liga da classe API 5L X80 e um aço inoxidável duplex UNS S32304. Além disso, estudou-se o comportamento quanto à resistência à corrosão em uma solução simuladora de água do mar. A microestrutura e composição da junta soldada foram avaliadas por microscopia ótica e eletrônica, espectrometria de energia dispersiva (EDS). A resistência à corrosão foi estudada por polarização potenciodinâmica anódica e por ensaios de espectroscopia de impedância eletroquímica. As juntas soldadas apresentaram uma microestrutura que se difere em morfologia de ambos os metais de base, além disso, notou-se a migração de cromo e níquel do duplex para esta região que apresentou uma resistência à corrosão ligeiramente superior ao API. Desta forma, podemos concluir que as propriedades da junta dissimilar são compatíveis com as aplicações, sendo possível sua utilização usufruindo-se das vantagens da soldagem dissimilar.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021
The welding process stability is a critical factor regarding the quality of the manufactured prod... more The welding process stability is a critical factor regarding the quality of the manufactured products in the Industry. There
are two approaches to assess the metal transfer stability based on droplet transfer period: scanning arc voltage or scanning
wire feed speed. Studies based on each of the approaches can be found in current literature, but there are no reported studies
evaluating the role of the arc reignition voltage peak (RiVP) on stability. Thus, this paper aimed to propose a novel method
to assess the short-circuiting gas metal arc welding metal transfer stability based on arc reignition voltage peak distribution,
via wire feed speed scanning route, and compare the effectiveness of the proposed method to the existing ones. First, the
authors depicted the fundamentals of the ideal metal transfer (the most stable). A novel stability index based on the RiVP
distribution was introduced. The results showed that the methodology was capable of defining a locus of maximum metal
transfer stability through the arc RiVP regularity. It also demonstrated that, in a regular short-circuiting transfer mode, the
RiVP obeys an expected distribution. Besides, the most regular arc reignition-related quantity was directly related to the
most regular period-related characteristic. After validating the methodology, the proposed method was demonstrated to be,
potentially, a novel manner to assess and seek the maximum stability of the short-circuiting gas metal arc welding process.
Data in Brief, 2020
This paper presents high quality (2048 ×1532 pixels) Light Microscope steel images sampled from t... more This paper presents high quality (2048 ×1532 pixels) Light Microscope steel images sampled from the welding fusion zone. The microstructure images were acquired from the Design of Experiments (2 2 full factorial design) planned to compare two different arc welding processes at two differ- ent arc welding energies [1]. The 400 raw images appear as they were captured by the microscope and they are catego- rized into four groups: that acquired from the Flux Cored Arc Welding process and that acquired from the Shielded Metal Arc Welding process; both of them run for high and low levels of arc energy. For the Flux Cored Arc Welding process, ASME SFA 5.20 E71T-5C(M) tubular wire was used, with a nominal diameter of 1.2 mm. For the Shielded Metal Arc Welding process, AWS E7018 coated electrodes were used, with nominal diameters of 3.25 mm (for the low en- ergy level) and 5.00 mm (for the high energy level). The deposition of the beads was run on AISI 1010 steel plates in the flat position (bead-on-plate). Different proportions of primary grain boundary ferrite; polygonal ferrite; acicular ferrite; nonaligned side-plate ferrite and aligned side-plate ferrite can be observed in each image. This image dataset is ready to visual and automatic microstructure recognition and quantification. It can be a useful resource for computa- tional intelligence research teams by offering images
Proc IMechE Part C: J Mechanical Engineering Science, 2020
This work focuses on the identification of five of the most common ferritic morphologies present ... more This work focuses on the identification of five of the most common ferritic morphologies present in welded fusion zones
of low carbon steel through images acquired by photomicrographies. With this regards, we discuss the importance of the
gray-level co-occurrence matrix to extract the features to be used as the input of the computational intelligence
techniques. We use artificial neural networks and support vector machines to identify the proportions of each morphology
and present the error identification rate for each technique. The results show that the use of gray-level
co-occurrence extraction allows a less intense computational model with statistical validity and the support vector machine
as a computational intelligence technique allows smaller variability when compared to the artificial neural networks.
Soldagem & Inspeção, 2019
A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sinais de t... more A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sinais de tensão de arco e corrente de soldagem. Histogramas e cálculo de estatísticas dos parâmetros tempo de arco aberto e tempo de curto circuito são meios de avaliação da estabilidade dos processos de soldagem. Contudo, estudos relacionados aos picos de tensão de reignição do arco elétrico ainda são pouco explorados. Desta forma, este trabalho apresenta uma metodologia de avaliação da distribuição de picos de reignição do arco do processo Gas Metal Arc Welding por curto-circuito (GMAW-CC). Cordões de solda depositados em chapa plana, variando o gás, foram executados a fim de produzir diferentes distribuições de picos de reignição. O teste qui-quadrado foi aplicado para avaliar a distribuição de frequências observadas de picos de tensão e compará-la com a distribuição hipotética. Um cordão padrão foi comparado com sua repetição e testada a hipótese de distribuições iguais. Os resultados mostraram que existem distribuições estatisticamente iguais de picos de tensão entre cordões de solda. Concluiu-se que a metodologia proposta permitiu o estudo da distribuição de picos de reignição. Também foi demonstrada haver potencialmente uma outra forma de avaliar a estabilidade de arcos em soldagem GMAW-CC, através do teste χ2.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
The welding seams procedure is widely used in the manufacturing industries for intermediary steps... more The welding seams procedure is widely used in the manufacturing industries for intermediary steps of the steel production or joints of parts of several manufactured products such as automobile, ships and aircrafts. The weld seams can be produced through a number of different arc welding processes, but the comparison of two different welding processes for the production of a quality weld seam is not trivial, and a quantitative method, which gives comparable parameters, is necessary to be devel-oped. In this work, a method is proposed for comparing between two welding processes through the statistical study of the effects that two welding energy levels have on the selected output variables of each one. A 22 full factorial design of experi-ment was applied. The process responses are one-dimensional weld bead geometry (penetration, width and reinforcement), two-dimensional weld bead geometry (penetration area and reinforcement area), dilution and weld bead microstructure. The statistical analyses showed that the methodology presented is capable of determining objective parameters (statistically based) which can be useful in comparing and selecting a suitable process for a specific application. The comparison of the results between fluxed core arc welding (FCAW) and shielded metal arc welding processes reveled that both produced weld seams with the same penetration. Therefore, in this study, it was recommended the selection of the FCAW process at low energy level, which was able to produce larger width weld seams and improved microstructure quality, saving 30% of the energy consumption.
The short circuit gas metal arc welding is widely used in the industry, having an important role ... more The short circuit gas metal arc welding is widely used in the industry, having an important role in manufacturing processes. In order to achieve high-quality control levels in weldments, researches are carried out aiming to find a way to monitor the quality of weldments in real time. In this context, this work proposes to use a type-1 and singleton fuzzy logic system classifier to identify the gas flow rate in short circuit gas metal arc welding. The investigated dataset was performed in laboratory, consisting of the current and voltage signals related with weld beads, for different gas flow rates. In addition, the feature extraction uses the statistics from the data signal and a criterion to quantify the metal transfer stability in short circuit processes, denominated Laprosolda Criterion. Based on the excellent performance of the model, the proposal is suitable to be used in welding quality monitoring.
The union between two dissimilar materials has been widely applied in the oil and gas industry. I... more The union between two dissimilar materials has been widely applied in the oil and gas industry. In general, this type of welding is more sensitive to differences in chemical composition between the metals involved. From this perspective, this work aims, by autogenous welding, to evaluate the microstructure of a joint welded between a high strength and low alloy steel of class API 5L X80 and a duplex stainless steel UNS UNS S32304. Furthermore, the corrosion resistance of the dissimilar welding region was evaluated in a solution which simulates the seawater environment. The microstructural properties and composition of the welding region were studied using optical microscopy, scanning electronic microscopy (SEM) with energy dispersive spectroscopy (EDS). The corrosion resistance was studied by anodic potentiodynamic polarization and by electrochemical impedance spectroscopy. The dissimilar region differs from both materials in their microstructural characteristics and presented signi...
Soldagem & Inspeção, 2019
Resumo A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo... more Resumo A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo e gás. Em geral, este tipo de soldagem é mais sensível às diferenças de composição química existente entre os metais envolvidos. Diante dessa perspectiva, este trabalho tem por objetivo avaliar, por união autógena, a microestrutura de uma junta soldada entre um aço de alta resistência e baixa liga da classe API 5L X80 e um aço inoxidável duplex UNS S32304. Além disso, estudou-se o comportamento quanto à resistência à corrosão em uma solução simuladora de água do mar. A microestrutura e composição da junta soldada foram avaliadas por microscopia ótica e eletrônica, espectrometria de energia dispersiva (EDS). A resistência à corrosão foi estudada por polarização potenciodinâmica anódica e por ensaios de espectroscopia de impedância eletroquímica. As juntas soldadas apresentaram uma microestrutura que se difere em morfologia de ambos os metais de base, além disso, notou-se a migração de cr...
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021
The welding process stability is a critical factor regarding the quality of the manufactured prod... more The welding process stability is a critical factor regarding the quality of the manufactured products in the Industry. There are two approaches to assess the metal transfer stability based on droplet transfer period: scanning arc voltage or scanning wire feed speed. Studies based on each of the approaches can be found in current literature, but there are no reported studies evaluating the role of the arc reignition voltage peak (RiVP) on stability. Thus, this paper aimed to propose a novel method to assess the short-circuiting gas metal arc welding metal transfer stability based on arc reignition voltage peak distribution, via wire feed speed scanning route, and compare the effectiveness of the proposed method to the existing ones. First, the authors depicted the fundamentals of the ideal metal transfer (the most stable). A novel stability index based on the RiVP distribution was introduced. The results showed that the methodology was capable of defining a locus of maximum metal transfer stability through the arc RiVP regularity. It also demonstrated that, in a regular short-circuiting transfer mode, the RiVP obeys an expected distribution. Besides, the most regular arc reignition-related quantity was directly related to the most regular period-related characteristic. After validating the methodology, the proposed method was demonstrated to be, potentially, a novel manner to assess and seek the maximum stability of the short-circuiting gas metal arc welding process.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
This work focuses on the identification of five of the most common ferritic morphologies present ... more This work focuses on the identification of five of the most common ferritic morphologies present in welded fusion zones of low carbon steel through images acquired by photomicrographies. With this regards, we discuss the importance of the gray-level co-occurrence matrix to extract the features to be used as the input of the computational intelligence techniques. We use artificial neural networks and support vector machines to identify the proportions of each morphology and present the error identification rate for each technique. The results show that the use of gray-level co-occurrence extraction allows a less intense computational model with statistical validity and the support vector machine as a computational intelligence technique allows smaller variability when compared to the artificial neural networks.
Soldagem & Inspeção, 2019
Resumo A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sina... more Resumo A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sinais de tensão de arco e corrente de soldagem. Histogramas e cálculo de estatísticas dos parâmetros tempo de arco aberto e tempo de curto circuito são meios de avaliação da estabilidade dos processos de soldagem. Contudo, estudos relacionados aos picos de tensão de reignição do arco elétrico ainda são pouco explorados. Desta forma, este trabalho apresenta uma metodologia de avaliação da distribuição de picos de reignição do arco do processo Gas Metal Arc Welding por curto-circuito (GMAW-CC). Cordões de solda depositados em chapa plana, variando o gás, foram executados a fim de produzir diferentes distribuições de picos de reignição. O teste qui-quadrado foi aplicado para avaliar a distribuição de frequências observadas de picos de tensão e compará-la com a distribuição hipotética. Um cordão padrão foi comparado com sua repetição e testada a hipótese de distribuições iguais. Os resultados m...
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
The short-circuit gas metal arc welding has been continuously studied over the years, due to its ... more The short-circuit gas metal arc welding has been continuously studied over the years, due to its important role in manufacturing processes. Concerning the process, many kinds of research are carried out aiming to understand the influence of the shielding gas in welds quality. In this context, this work treats the voltage and current welding signals as time series and applies a feature extraction based on scalable hypothesis tests, which is called FRESH algorithm, in order to obtain the signal features. After that, these features are applied in a multilayer perceptron artificial neural network, trained by the scaled conjugate gradient method, which classifies the welds according to the flow rate and type of shielding gas used in the process. The model presented excellent performance, which shows that the proposal is suitable to be used in welding quality monitoring.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
The short-circuit gas metal arc welding has been continuously studied over the years, due to its ... more The short-circuit gas metal arc welding has been continuously studied over the years, due to its important role in manufacturing processes. Concerning the process, many kinds of research are carried out aiming to understand the influence of the shielding gas in welds quality. In this context, this work treats the voltage and current welding signals as time series and applies a feature extraction based on scalable hypothesis tests, which is called FRESH algorithm, in order to obtain the signal features. After that, these features are applied in a multilayer perceptron artificial neural network, trained by the scaled conjugate gradient method, which classifies the welds according to the flow rate and type of shielding gas used in the process. The model presented excellent performance, which shows that the proposal is suitable to be used in welding quality monitoring.
Soldagem & Inspeção, 2019
A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo e gás.... more A união entre materiais dissimilares tem sido amplamente aplicada na indústria de petróleo e gás. Em geral, este tipo de soldagem é mais sensível às diferenças de composição química existente entre os metais envolvidos. Diante dessa perspectiva, este trabalho tem por objetivo avaliar, por união autógena, a microestrutura de uma junta soldada entre um aço de alta resistência e baixa liga da classe API 5L X80 e um aço inoxidável duplex UNS S32304. Além disso, estudou-se o comportamento quanto à resistência à corrosão em uma solução simuladora de água do mar. A microestrutura e composição da junta soldada foram avaliadas por microscopia ótica e eletrônica, espectrometria de energia dispersiva (EDS). A resistência à corrosão foi estudada por polarização potenciodinâmica anódica e por ensaios de espectroscopia de impedância eletroquímica. As juntas soldadas apresentaram uma microestrutura que se difere em morfologia de ambos os metais de base, além disso, notou-se a migração de cromo e níquel do duplex para esta região que apresentou uma resistência à corrosão ligeiramente superior ao API. Desta forma, podemos concluir que as propriedades da junta dissimilar são compatíveis com as aplicações, sendo possível sua utilização usufruindo-se das vantagens da soldagem dissimilar.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2021
The welding process stability is a critical factor regarding the quality of the manufactured prod... more The welding process stability is a critical factor regarding the quality of the manufactured products in the Industry. There
are two approaches to assess the metal transfer stability based on droplet transfer period: scanning arc voltage or scanning
wire feed speed. Studies based on each of the approaches can be found in current literature, but there are no reported studies
evaluating the role of the arc reignition voltage peak (RiVP) on stability. Thus, this paper aimed to propose a novel method
to assess the short-circuiting gas metal arc welding metal transfer stability based on arc reignition voltage peak distribution,
via wire feed speed scanning route, and compare the effectiveness of the proposed method to the existing ones. First, the
authors depicted the fundamentals of the ideal metal transfer (the most stable). A novel stability index based on the RiVP
distribution was introduced. The results showed that the methodology was capable of defining a locus of maximum metal
transfer stability through the arc RiVP regularity. It also demonstrated that, in a regular short-circuiting transfer mode, the
RiVP obeys an expected distribution. Besides, the most regular arc reignition-related quantity was directly related to the
most regular period-related characteristic. After validating the methodology, the proposed method was demonstrated to be,
potentially, a novel manner to assess and seek the maximum stability of the short-circuiting gas metal arc welding process.
Data in Brief, 2020
This paper presents high quality (2048 ×1532 pixels) Light Microscope steel images sampled from t... more This paper presents high quality (2048 ×1532 pixels) Light Microscope steel images sampled from the welding fusion zone. The microstructure images were acquired from the Design of Experiments (2 2 full factorial design) planned to compare two different arc welding processes at two differ- ent arc welding energies [1]. The 400 raw images appear as they were captured by the microscope and they are catego- rized into four groups: that acquired from the Flux Cored Arc Welding process and that acquired from the Shielded Metal Arc Welding process; both of them run for high and low levels of arc energy. For the Flux Cored Arc Welding process, ASME SFA 5.20 E71T-5C(M) tubular wire was used, with a nominal diameter of 1.2 mm. For the Shielded Metal Arc Welding process, AWS E7018 coated electrodes were used, with nominal diameters of 3.25 mm (for the low en- ergy level) and 5.00 mm (for the high energy level). The deposition of the beads was run on AISI 1010 steel plates in the flat position (bead-on-plate). Different proportions of primary grain boundary ferrite; polygonal ferrite; acicular ferrite; nonaligned side-plate ferrite and aligned side-plate ferrite can be observed in each image. This image dataset is ready to visual and automatic microstructure recognition and quantification. It can be a useful resource for computa- tional intelligence research teams by offering images
Proc IMechE Part C: J Mechanical Engineering Science, 2020
This work focuses on the identification of five of the most common ferritic morphologies present ... more This work focuses on the identification of five of the most common ferritic morphologies present in welded fusion zones
of low carbon steel through images acquired by photomicrographies. With this regards, we discuss the importance of the
gray-level co-occurrence matrix to extract the features to be used as the input of the computational intelligence
techniques. We use artificial neural networks and support vector machines to identify the proportions of each morphology
and present the error identification rate for each technique. The results show that the use of gray-level
co-occurrence extraction allows a less intense computational model with statistical validity and the support vector machine
as a computational intelligence technique allows smaller variability when compared to the artificial neural networks.
Soldagem & Inspeção, 2019
A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sinais de t... more A estabilidade do arco tem sido estudada através de análises estatísticas obtidas dos sinais de tensão de arco e corrente de soldagem. Histogramas e cálculo de estatísticas dos parâmetros tempo de arco aberto e tempo de curto circuito são meios de avaliação da estabilidade dos processos de soldagem. Contudo, estudos relacionados aos picos de tensão de reignição do arco elétrico ainda são pouco explorados. Desta forma, este trabalho apresenta uma metodologia de avaliação da distribuição de picos de reignição do arco do processo Gas Metal Arc Welding por curto-circuito (GMAW-CC). Cordões de solda depositados em chapa plana, variando o gás, foram executados a fim de produzir diferentes distribuições de picos de reignição. O teste qui-quadrado foi aplicado para avaliar a distribuição de frequências observadas de picos de tensão e compará-la com a distribuição hipotética. Um cordão padrão foi comparado com sua repetição e testada a hipótese de distribuições iguais. Os resultados mostraram que existem distribuições estatisticamente iguais de picos de tensão entre cordões de solda. Concluiu-se que a metodologia proposta permitiu o estudo da distribuição de picos de reignição. Também foi demonstrada haver potencialmente uma outra forma de avaliar a estabilidade de arcos em soldagem GMAW-CC, através do teste χ2.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019
The welding seams procedure is widely used in the manufacturing industries for intermediary steps... more The welding seams procedure is widely used in the manufacturing industries for intermediary steps of the steel production or joints of parts of several manufactured products such as automobile, ships and aircrafts. The weld seams can be produced through a number of different arc welding processes, but the comparison of two different welding processes for the production of a quality weld seam is not trivial, and a quantitative method, which gives comparable parameters, is necessary to be devel-oped. In this work, a method is proposed for comparing between two welding processes through the statistical study of the effects that two welding energy levels have on the selected output variables of each one. A 22 full factorial design of experi-ment was applied. The process responses are one-dimensional weld bead geometry (penetration, width and reinforcement), two-dimensional weld bead geometry (penetration area and reinforcement area), dilution and weld bead microstructure. The statistical analyses showed that the methodology presented is capable of determining objective parameters (statistically based) which can be useful in comparing and selecting a suitable process for a specific application. The comparison of the results between fluxed core arc welding (FCAW) and shielded metal arc welding processes reveled that both produced weld seams with the same penetration. Therefore, in this study, it was recommended the selection of the FCAW process at low energy level, which was able to produce larger width weld seams and improved microstructure quality, saving 30% of the energy consumption.
The short circuit gas metal arc welding is widely used in the industry, having an important role ... more The short circuit gas metal arc welding is widely used in the industry, having an important role in manufacturing processes. In order to achieve high-quality control levels in weldments, researches are carried out aiming to find a way to monitor the quality of weldments in real time. In this context, this work proposes to use a type-1 and singleton fuzzy logic system classifier to identify the gas flow rate in short circuit gas metal arc welding. The investigated dataset was performed in laboratory, consisting of the current and voltage signals related with weld beads, for different gas flow rates. In addition, the feature extraction uses the statistics from the data signal and a criterion to quantify the metal transfer stability in short circuit processes, denominated Laprosolda Criterion. Based on the excellent performance of the model, the proposal is suitable to be used in welding quality monitoring.