Papers by Rodrigo Madeira
International Journal of Postharvest Technology and Innovation, 2013
ABSTRACT The aim of this study was to evaluate the stability of Lactobacillus acidophilus and Lac... more ABSTRACT The aim of this study was to evaluate the stability of Lactobacillus acidophilus and Lactobacillus rhamnosus in minimally processed cabbage as well as physical-chemical and microbiological characteristics of this product. After minimal process, the cabbage was soaked in solution with probiotic cultures of L. acidophilus and L. rhamnosus, which resulted in three treatments, one added with L. acidophilus, another added with L. rhamnosus, and the control treatment, without addition of probiotic. Samples were stored at 8°C for 96 hours. Analyses for acidity, pH, colour, coliforms at 45°C, Salmonella sp. and probiotic microorganisms were all carried out. Differences on pH, acidity and colour during storage period were not detected. Results of microbiological analyses showed that the samples were within standards set by Brazilian laws for Salmonella sp. and coliforms at 45°C. The probiotic microorganisms were viable in the product with counts at approximately 10<sup align="right"> 7 CFU.g<sup align="right"> −1 , which shows that minimally processed cabbage can be a vehicle for these microorganisms.
Welding International, 2010
Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stai... more Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stainless steel wires have been recently introduced in the fabrication of these components to reduce costs (hot and cold parts) and improve the quality of hot part components, mainly thermo-mechanical fatigue resistance, and their use has been growing since. This study compares mechanical and metallurgical characteristics of fusion zones obtained with 430Ti and 430LNb welding wires. The influence of Ar 2%O2 and Ar 2%N2 3%CO2 shielding gases was also studied. Metallographic analysis was performed by optical and electronic microscopy, revealing the main characteristics of the fusion zone obtained with these welding wires and shielding gases. Welded joint ductility was measured using the Erichsen test. The results indicated that ferritic stainless steel wires could be used to produce welds with adequate ductility. However, this depends critically on the choice of the welding wire and the shielding gas to maximize mechanical and metallurgical properties and to avoid any future problems.
Welding International, 2012
Mechanical tests are frequently used to assess welded joint performance and to approve the joint ... more Mechanical tests are frequently used to assess welded joint performance and to approve the joint for certain applications. Among others, the Erichsen test has been used to evaluate low thickness joint ductility. However, for this kind of application the use of the Erichsen test is not well established. This paper aims to contribute to the understanding of this application by comparing results from Erichsen, tensile, and bending tests of 1.5 mm thick ferritic stainless steel welded samples. Joints that were welded using the GTAW process were used to optimize Erichsen test conditions. Strain distribution around these welds after testing was quantitatively evaluated by specialized software. Tensile, bending, and the Erichsen test results were compared in gas metal arc welding weld beads. It was shown that the Erichsen test can detect ductility variations in the weld bead caused by changes in the welding variables more effectively.
Resumo: Para obter uma boa soldabilidade dos aços inoxidáveis ferríticos, na maioria das vezes, a... more Resumo: Para obter uma boa soldabilidade dos aços inoxidáveis ferríticos, na maioria das vezes, as empresas recorrem ao arames inoxidáveis austenítico em função de sua boa resistência mecânica, tenacidade e ductilidade. Arames de aço inoxidável ferrítico estabilizados ao nióbio e titânio estão sendo desenvolvidos para obter boa qualidade e baixo custo. O objetivo deste trabalho é estudar a influência da composição do gás de proteção (argônio puro e misturas com oxigênio ou dióxido de carbono) na composição química e microestrutura do cordão de solda do processo GMAW com transferência por curto-circuito. Foram utilizados dois arames eletrodos estabilizados (ER430Ti e ER430LNb) e um arame eletrodo não estabilizado (ER430) e como metal de base o aço inoxidável ferrítico UNS 43932. Os resultados mostraram que o aumento do dióxido de carbono no gás de proteção aumenta o teor de carbono no cordão de solda, tendo como conseqüência para o arame não estabilizado um aumento significativo da quantidade de martensita no cordão de solda, caso não observado de forma significativa com o aumento do oxigênio. Para o arame ER430LNb não verificou a presença da martensita de contorno de grão. O aumento tanto do dióxido de carbono como do oxigênio diminuiu os teores de Mn e Si para os arames ER430LNb e ER430, caso não verificado no arame ER430Ti.
Welding International, 2010
Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stai... more Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stainless steel wires have been recently introduced in the fabrication of these components to reduce costs (hot and cold parts) and improve the quality of hot part components, mainly thermo-mechanical fatigue resistance, and their use has been growing since. This study compares mechanical and metallurgical characteristics of fusion
Welding International, 2012
Mechanical tests are frequently used to assess welded joint performance and to approve the joint ... more Mechanical tests are frequently used to assess welded joint performance and to approve the joint for certain applications. Among others, the Erichsen test has been used to evaluate low thickness joint ductility. However, for this kind of application the use of the Erichsen test is not well established. This paper aims to contribute to the understanding of this application by
Soldagem & Inspeção (Impresso), 2010
Welding International, 2010
Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stai... more Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stainless steel wires have been recently introduced in the fabrication of these components to reduce costs (hot and cold parts) and improve the quality of hot part components, mainly thermo-mechanical fatigue resistance, and their use has been growing since. This study compares mechanical and metallurgical characteristics of fusion zones obtained with 430Ti and 430LNb welding wires. The influence of Ar 2%O2 and Ar 2%N2 3%CO2 shielding gases was also studied. Metallographic analysis was performed by optical and electronic microscopy, revealing the main characteristics of the fusion zone obtained with these welding wires and shielding gases. Welded joint ductility was measured using the Erichsen test. The results indicated that ferritic stainless steel wires could be used to produce welds with adequate ductility. However, this depends critically on the choice of the welding wire and the shielding gas to maximize mechanical and metallurgical properties and to avoid any future problems.
Welding International, 2012
Mechanical tests are frequently used to assess welded joint performance and to approve the joint ... more Mechanical tests are frequently used to assess welded joint performance and to approve the joint for certain applications. Among others, the Erichsen test has been used to evaluate low thickness joint ductility. However, for this kind of application the use of the Erichsen test is not well established. This paper aims to contribute to the understanding of this application by comparing results from Erichsen, tensile, and bending tests of 1.5 mm thick ferritic stainless steel welded samples. Joints that were welded using the GTAW process were used to optimize Erichsen test conditions. Strain distribution around these welds after testing was quantitatively evaluated by specialized software. Tensile, bending, and the Erichsen test results were compared in gas metal arc welding weld beads. It was shown that the Erichsen test can detect ductility variations in the weld bead caused by changes in the welding variables more effectively.
Resumo: Para obter uma boa soldabilidade dos aços inoxidáveis ferríticos, na maioria das vezes, a... more Resumo: Para obter uma boa soldabilidade dos aços inoxidáveis ferríticos, na maioria das vezes, as empresas recorrem ao arames inoxidáveis austenítico em função de sua boa resistência mecânica, tenacidade e ductilidade. Arames de aço inoxidável ferrítico estabilizados ao nióbio e titânio estão sendo desenvolvidos para obter boa qualidade e baixo custo. O objetivo deste trabalho é estudar a influência da composição do gás de proteção (argônio puro e misturas com oxigênio ou dióxido de carbono) na composição química e microestrutura do cordão de solda do processo GMAW com transferência por curto-circuito. Foram utilizados dois arames eletrodos estabilizados (ER430Ti e ER430LNb) e um arame eletrodo não estabilizado (ER430) e como metal de base o aço inoxidável ferrítico UNS 43932. Os resultados mostraram que o aumento do dióxido de carbono no gás de proteção aumenta o teor de carbono no cordão de solda, tendo como conseqüência para o arame não estabilizado um aumento significativo da quantidade de martensita no cordão de solda, caso não observado de forma significativa com o aumento do oxigênio. Para o arame ER430LNb não verificou a presença da martensita de contorno de grão. O aumento tanto do dióxido de carbono como do oxigênio diminuiu os teores de Mn e Si para os arames ER430LNb e ER430, caso não verificado no arame ER430Ti.
Welding International, 2010
Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stai... more Ferritic stainless steels have been extensively used in automotive exhaust systems. Ferritic stainless steel wires have been recently introduced in the fabrication of these components to reduce costs (hot and cold parts) and improve the quality of hot part components, mainly thermo-mechanical fatigue resistance, and their use has been growing since. This study compares mechanical and metallurgical characteristics of fusion
Welding International, 2012
Mechanical tests are frequently used to assess welded joint performance and to approve the joint ... more Mechanical tests are frequently used to assess welded joint performance and to approve the joint for certain applications. Among others, the Erichsen test has been used to evaluate low thickness joint ductility. However, for this kind of application the use of the Erichsen test is not well established. This paper aims to contribute to the understanding of this application by
Soldagem & Inspeção (Impresso), 2010
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Papers by Rodrigo Madeira