Vicente Ventrella - Academia.edu (original) (raw)
Papers by Vicente Ventrella
Journal of Materials Engineering and Performance, 2021
Super-duplex stainless steel (SDSS) exhibits an austenite-ferrite dual-phase structure, which pro... more Super-duplex stainless steel (SDSS) exhibits an austenite-ferrite dual-phase structure, which promotes many benefits upon single-phase grades, such as high mechanical strength and corrosion resistance. Welding process results in an unbalanced microstructure, with large amount of ferrite, which compromise SDSS’s properties. This paper investigates the effect of using electrolytic nickel foils as an addition metal on UNS S32750 SDSS Nd:YAG pulsed laser welding, through the evaluation of the microstructure, hardness, tensile strength, and corrosion resistance of the weld bead. Six conditions were investigated: autogenous welding and with addition of nickel, varying the thickness of nickel foil added. Microstructural analysis reveals an increase in volume fraction of austenite for the conditions with addition of nickel. Using a 30 µm thick nickel foil, approximately equal amount of austenite and ferrite was obtained in the weld bead. The higher microhardness was obtained for the autogenous welding, 400 HV and decreased with the addition of nickel. The tensile strength decreased 4% in the experimental conditions with high nickel addition. The corrosion resistances were the same for all the conditions with addition on nickel, regardless of the nickel foil thickness added, but it compared to autogenous welding the CPT’s increased approximately 14 °C.
Materials Science Forum, 2013
The aim of this study was to value the possibility to join, for pulsed Nd:YAG laser welding, thin... more The aim of this study was to value the possibility to join, for pulsed Nd:YAG laser welding, thin foils lap joints for sealing components in corrosive environment. Experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser weld to examine the influence of the pulse energy in the characteristics of the weld fillet. The pulse energy was varied from 1.0 to 2.5 J at increments of 0.25 J with a 4 ms pulse duration. The base materials used for this study were AISI 316L stainless steel and Ni-based alloys foils with 100μm thickness. The welds were analyzed by electronic and optical microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to thin foil weld quality because it can generate good mechanical properties and reduce discontinuities in weld joints. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. In a...
International Journal of Materials and Product Technology, 2014
Journal of Materials Processing Technology, 2010
Experimental investigations were carried out using a pulsed neodymium:yttrium aluminum garnet las... more Experimental investigations were carried out using a pulsed neodymium:yttrium aluminum garnet laser weld to examine the influence of the pulse energy in the characteristics of the weld fillet. The pulse energy was varied from 1.0 to 2.25 J at increments of 0.25 J with a 4 ms pulse duration. The base material used for this study was AISI 316L stainless steel foil with 100 m thickness. The welds were analyzed by optical microscopy, tensile shear tests and microhardness. The results indicate that pulse energy control is of considerable importance to thin foil weld quality because it can generate good mechanical properties and reduce discontinuities in weld joints. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. The process appeared to be very sensitive to the gap between couples.
Crystals
Super-duplex stainless steel (SDSS) shows high mechanical and corrosion resistance because of the... more Super-duplex stainless steel (SDSS) shows high mechanical and corrosion resistance because of the balanced structure of austenite and ferrite. However, maintaining this phase ratio after welding is a challenge. The use of austenite stabilizing components is recommended to balance the microstructure. The addition of alloying elements presents a challenge because of the characteristics of Nd:YAG pulsed laser welding. An approach, which has proven to be effective, is to use metal electroplating to prepare the surfaces of the mechanical SDSS components that will be welded, therefore promoting the phase balance in the fusion zone. While the effects of metals such as nickel as an austenite stabilizer are well recognized, cobalt’s effects require more research. The present work investigated the influence of the use of cobalt addition in the joining process by preliminary electroplating on UNS S32750 SDSS Nd: YAG pulsed laser welding, specifically regarding microstructure and microhardness....
Materials
The development of techniques to improve the welding of super duplex steels is necessary in order... more The development of techniques to improve the welding of super duplex steels is necessary in order to ensure that the phase balance and properties of the material are not affected during this process. Hybrid arc-laser welding is a perfect combination of the advantages of both processes, producing deeper weld beads with more balanced phases than the pulsed laser process. Here, the objective was to improve the corrosion resistance of UNS S32750 weld beads by increasing the volumetric austenite percentage in the fusion zone (FZ) with a hybrid process of GTAW (gas tungsten arc welding) and pulsed laser Nd-YAG (neodymium-doped yttrium aluminum garnet). Welds were performed in bead on plate conditions with fixed laser parameters and a varying heat input introduced through the GTAW process. Additionally, welds within a nitrogen atmosphere were performed. After base metal characterization, an analysis of the FZ and heat affected zone were performed with optical microscopy, scanning electron ...
Anais do Congresso Internacional de Engenharia Mecânica e Industrial, 2022
Os acos inoxidaveis duplex e super duplex vem conquistando cada vez mais espaco nas atividades li... more Os acos inoxidaveis duplex e super duplex vem conquistando cada vez mais espaco nas atividades ligadas a industria petroquimica, suprindo as carencias dos ja tradicionais acos inoxidaveis austeniticos e ferriticos, pois estes acos conseguem aliar as propriedades tanto do aco ferritico como do aco austenitico. Atribuindo-se suas altas resistencias a corrosao e mecânica a sua microestrutura balanceada em aproximadamente 50% de ferrita e 50% de austenita. A diferenca basica entre os acos inoxidaveis duplex e super duplex consiste principalmente nas concentracoes de cromo, niquel, molibdenio e nitrogenio que essas ligas apresentam, sendo que alguns desses elementos podem interferir diretamente na resistencia a corrosao por pite, que e uma forma altamente destrutiva de ataque que ocorre em ambientes contendo ions halogenios. O presente trabalho estudou os acos ASTM A995 GR 3A duplex e ASTM A995 GR 5A super duplex, ambos em estado fundido e solubilizado. Foram obtidos seus parâmetros elet...
Acos duplex sao utilizados na industria em condicoes severas de trabalho, sujeitos a corrosao ass... more Acos duplex sao utilizados na industria em condicoes severas de trabalho, sujeitos a corrosao associado a gradientes de altas tensoes e isso pode ser estudado e previsto por analises experimentais e numericas. Esse trabalho pretende comparar um aco inoxidavel duplex no estado fundido e solubilizado com um super-duplex no mesmo estado, verificando a evolucao da corrosao, em meios salinos, basicos e acidos, com a analise de propriedades eletroquimicas, mecânicas e microestruturais. Estas propriedades serao verificadas utilizando-se microscopia optica (MO), microscopia eletronica de varredura (MEV), ensaio de microdureza Vickers (EMV) e curvas de polarizacao potenciodinâmicas (CPP).
Metallurgical and Materials Transactions A, 2021
Obtaining a balanced microstructure in the fusion zone on a super duplex stainless steel (SDSS) w... more Obtaining a balanced microstructure in the fusion zone on a super duplex stainless steel (SDSS) weld is a challenge. The present work reports the use of the Watts bath to correct the phase balance on laser-welded SDSS. Three different Watts bath times were used, and the microstructure of the weld bead was evaluated. The Watts bath was efficient to correct the undesirable unbalanced microstructure resulting from SDSS laser welding as the austenite percentage increased.
Journal of Physics: Conference Series, 2019
Application of titanium alloys for orthodontic implants have increase in last years and it has ge... more Application of titanium alloys for orthodontic implants have increase in last years and it has generated a great amount of titanium chips which are disposed as metal scrap. Titanium carbide has high hardness and can be applied as coating reinforcement against wear. Chips of titanium alloys were processed and used in the fabrication of experimental hardfacing consumables for improving the resistance of wear of mechanical components. Coatings were produced in cast steel specimens using the gas tungsten arc welding process. Microstructure was investigated by means of scanning electron microscopy. Microhardness of the coatings was analyzed by a dynamic ultra-micro hardness tester. The microstructure of the welding metal was composed of circular particles of titanium carbide surrounded by a ferritic matrix. The measures made by electron dispersive spectroscopy showed a variation in titanium amount trough the weld, where larger contents of titanium were found, and the matrix. The crystall...
ABM Proceedings, 2014
Resumo A soldagem de peças de aço por arco submerso é um dos processos mais tradicionalmente usad... more Resumo A soldagem de peças de aço por arco submerso é um dos processos mais tradicionalmente usados na fabricação de componentes estruturais. A microestrutura do metal de solda é importante na definição das suas propriedades mecânicas, sendo a ferrita acicular um microconstituinte capaz de conferir à solda altos níveis de resistência mecânica e tenacidade. A nucleação da ferrita acicular depende da presença de inclusões não metálicas no metal de solda. No presente trabalho fez-se a caracterização microestrutural do metal de solda preparados com diferentes aportes térmicos. Lâminas finas foram observadas por microscopia eletrônica de transmissão, que possibilitou determinar alguns parâmetros morfológicos e químicos das partículas e a sua relação com a nucleação das ripas de ferrita acicular. Verificou-se que partículas irregulares com maior tamanho, mais ricas em titânio quando formadas com maior energia de soldagem, apresentam maior probabilidade de servirem como sítio preferencial para nucleação da ferrita acicular, se comparadas às partículas mais lisas e menores. Palavras-chave: Soldagem por arco submerso; Ferrita acicular; Inclusões; Microscopia eletrônica de transmissão. INCLUSIONS AND FORMATION OF ACICULAR FERRITE: CHARACTERIZATION BY TRANSMISSION ELECTRON MICROSCOPY Abstract Fabrication of steel parts by submerged arc welding is one of most traditional processes used in manufacturing structural components. The microstructure of the weld metal defines their mechanical properties, being acicular ferrite a microconstituent able to assign to the welding high levels of strength and toughness. The nucleation of acicular ferrite depends on the presence of non-metallic inclusions in the weld metal. In this work an extensive microstructural characterization of the weld metal prepared with different heat inputs was carried out by transmission electron microscopy. Thin foil sample observations have determined some morphological and chemical features of the particles and their relationship with the nucleation of acicular ferrite laths. It was found that larger irregular inclusions, richer in titanium when formed under higher heat input, are more effective as preferential site for nucleation of acicular ferrite, if compared to smaller and smoother particles.
ABM Proceedings, 2014
Resumo O laser é uma ferramenta flexível e poderosa com muitas aplicações relevantes na indústria... more Resumo O laser é uma ferramenta flexível e poderosa com muitas aplicações relevantes na indústria, principalmente na área de soldagem. Os lasers de hoje fornecem à indústria de soldagem soluções técnicas a muitos problemas, e além de substituírem a soldagem convencional já estabelecida, ainda apresentam maior produtividade. O presente trabalho estudou o metal de solda do aço inoxidável duplex UNS S32205 empregado na indústria de petróleo e gás natural, analisando a influência da variação da largura temporal nas características microestruturais do cordão de solda obtido por soldagem com laser pulsado de Nd:YAG. Os resultados mostraram que a dimensão da zona termicamente afetada é extremamente pequena e a microestrutura do metal de solda apresenta menor fração volumétrica de austenita em relação aos processos convencionais.
Materials, 2019
Duplex stainless steels (DSSs), a particular category of stainless steels, are employed in all ki... more Duplex stainless steels (DSSs), a particular category of stainless steels, are employed in all kinds of industrial applications where excellent corrosion resistance and high strength are necessary. These good properties are provided by their biphasic microstructure, consisting of ferrite and austenite in almost equal volume fractions of phases. In the present work, Nd: YAG pulsed laser dissimilar welding of UNS S32750 super duplex stainless steel (SDSS) with 316L austenitic stainless steel (ASS), with different heat inputs, was investigated. The results showed that the fusion zone microstructure observed consisted of a ferrite matrix with grain boundary austenite (GBA), Widmanstätten austenite (WA) and intragranular austenite (IA), with the same proportion of ferrite and austenite phases. Changes in the heat input (between 45, 90 and 120 J/mm) did not significantly affect the ferrite/austenite phase balance and the microhardness in the fusion zone.
Metallurgical and Materials Transactions A, 2019
Anais do X Congresso Nacional de Engenharia Mecânica, 2018
Journal of Materials Engineering and Performance, 2021
Super-duplex stainless steel (SDSS) exhibits an austenite-ferrite dual-phase structure, which pro... more Super-duplex stainless steel (SDSS) exhibits an austenite-ferrite dual-phase structure, which promotes many benefits upon single-phase grades, such as high mechanical strength and corrosion resistance. Welding process results in an unbalanced microstructure, with large amount of ferrite, which compromise SDSS’s properties. This paper investigates the effect of using electrolytic nickel foils as an addition metal on UNS S32750 SDSS Nd:YAG pulsed laser welding, through the evaluation of the microstructure, hardness, tensile strength, and corrosion resistance of the weld bead. Six conditions were investigated: autogenous welding and with addition of nickel, varying the thickness of nickel foil added. Microstructural analysis reveals an increase in volume fraction of austenite for the conditions with addition of nickel. Using a 30 µm thick nickel foil, approximately equal amount of austenite and ferrite was obtained in the weld bead. The higher microhardness was obtained for the autogenous welding, 400 HV and decreased with the addition of nickel. The tensile strength decreased 4% in the experimental conditions with high nickel addition. The corrosion resistances were the same for all the conditions with addition on nickel, regardless of the nickel foil thickness added, but it compared to autogenous welding the CPT’s increased approximately 14 °C.
Materials Science Forum, 2013
The aim of this study was to value the possibility to join, for pulsed Nd:YAG laser welding, thin... more The aim of this study was to value the possibility to join, for pulsed Nd:YAG laser welding, thin foils lap joints for sealing components in corrosive environment. Experimental investigations were carried out using a pulsed neodymium: yttrium aluminum garnet laser weld to examine the influence of the pulse energy in the characteristics of the weld fillet. The pulse energy was varied from 1.0 to 2.5 J at increments of 0.25 J with a 4 ms pulse duration. The base materials used for this study were AISI 316L stainless steel and Ni-based alloys foils with 100μm thickness. The welds were analyzed by electronic and optical microscopy, tensile shear tests and micro hardness. The results indicate that pulse energy control is of considerable importance to thin foil weld quality because it can generate good mechanical properties and reduce discontinuities in weld joints. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. In a...
International Journal of Materials and Product Technology, 2014
Journal of Materials Processing Technology, 2010
Experimental investigations were carried out using a pulsed neodymium:yttrium aluminum garnet las... more Experimental investigations were carried out using a pulsed neodymium:yttrium aluminum garnet laser weld to examine the influence of the pulse energy in the characteristics of the weld fillet. The pulse energy was varied from 1.0 to 2.25 J at increments of 0.25 J with a 4 ms pulse duration. The base material used for this study was AISI 316L stainless steel foil with 100 m thickness. The welds were analyzed by optical microscopy, tensile shear tests and microhardness. The results indicate that pulse energy control is of considerable importance to thin foil weld quality because it can generate good mechanical properties and reduce discontinuities in weld joints. The ultimate tensile strength of the welded joints increased at first and then decreased as the pulse energy increased. The process appeared to be very sensitive to the gap between couples.
Crystals
Super-duplex stainless steel (SDSS) shows high mechanical and corrosion resistance because of the... more Super-duplex stainless steel (SDSS) shows high mechanical and corrosion resistance because of the balanced structure of austenite and ferrite. However, maintaining this phase ratio after welding is a challenge. The use of austenite stabilizing components is recommended to balance the microstructure. The addition of alloying elements presents a challenge because of the characteristics of Nd:YAG pulsed laser welding. An approach, which has proven to be effective, is to use metal electroplating to prepare the surfaces of the mechanical SDSS components that will be welded, therefore promoting the phase balance in the fusion zone. While the effects of metals such as nickel as an austenite stabilizer are well recognized, cobalt’s effects require more research. The present work investigated the influence of the use of cobalt addition in the joining process by preliminary electroplating on UNS S32750 SDSS Nd: YAG pulsed laser welding, specifically regarding microstructure and microhardness....
Materials
The development of techniques to improve the welding of super duplex steels is necessary in order... more The development of techniques to improve the welding of super duplex steels is necessary in order to ensure that the phase balance and properties of the material are not affected during this process. Hybrid arc-laser welding is a perfect combination of the advantages of both processes, producing deeper weld beads with more balanced phases than the pulsed laser process. Here, the objective was to improve the corrosion resistance of UNS S32750 weld beads by increasing the volumetric austenite percentage in the fusion zone (FZ) with a hybrid process of GTAW (gas tungsten arc welding) and pulsed laser Nd-YAG (neodymium-doped yttrium aluminum garnet). Welds were performed in bead on plate conditions with fixed laser parameters and a varying heat input introduced through the GTAW process. Additionally, welds within a nitrogen atmosphere were performed. After base metal characterization, an analysis of the FZ and heat affected zone were performed with optical microscopy, scanning electron ...
Anais do Congresso Internacional de Engenharia Mecânica e Industrial, 2022
Os acos inoxidaveis duplex e super duplex vem conquistando cada vez mais espaco nas atividades li... more Os acos inoxidaveis duplex e super duplex vem conquistando cada vez mais espaco nas atividades ligadas a industria petroquimica, suprindo as carencias dos ja tradicionais acos inoxidaveis austeniticos e ferriticos, pois estes acos conseguem aliar as propriedades tanto do aco ferritico como do aco austenitico. Atribuindo-se suas altas resistencias a corrosao e mecânica a sua microestrutura balanceada em aproximadamente 50% de ferrita e 50% de austenita. A diferenca basica entre os acos inoxidaveis duplex e super duplex consiste principalmente nas concentracoes de cromo, niquel, molibdenio e nitrogenio que essas ligas apresentam, sendo que alguns desses elementos podem interferir diretamente na resistencia a corrosao por pite, que e uma forma altamente destrutiva de ataque que ocorre em ambientes contendo ions halogenios. O presente trabalho estudou os acos ASTM A995 GR 3A duplex e ASTM A995 GR 5A super duplex, ambos em estado fundido e solubilizado. Foram obtidos seus parâmetros elet...
Acos duplex sao utilizados na industria em condicoes severas de trabalho, sujeitos a corrosao ass... more Acos duplex sao utilizados na industria em condicoes severas de trabalho, sujeitos a corrosao associado a gradientes de altas tensoes e isso pode ser estudado e previsto por analises experimentais e numericas. Esse trabalho pretende comparar um aco inoxidavel duplex no estado fundido e solubilizado com um super-duplex no mesmo estado, verificando a evolucao da corrosao, em meios salinos, basicos e acidos, com a analise de propriedades eletroquimicas, mecânicas e microestruturais. Estas propriedades serao verificadas utilizando-se microscopia optica (MO), microscopia eletronica de varredura (MEV), ensaio de microdureza Vickers (EMV) e curvas de polarizacao potenciodinâmicas (CPP).
Metallurgical and Materials Transactions A, 2021
Obtaining a balanced microstructure in the fusion zone on a super duplex stainless steel (SDSS) w... more Obtaining a balanced microstructure in the fusion zone on a super duplex stainless steel (SDSS) weld is a challenge. The present work reports the use of the Watts bath to correct the phase balance on laser-welded SDSS. Three different Watts bath times were used, and the microstructure of the weld bead was evaluated. The Watts bath was efficient to correct the undesirable unbalanced microstructure resulting from SDSS laser welding as the austenite percentage increased.
Journal of Physics: Conference Series, 2019
Application of titanium alloys for orthodontic implants have increase in last years and it has ge... more Application of titanium alloys for orthodontic implants have increase in last years and it has generated a great amount of titanium chips which are disposed as metal scrap. Titanium carbide has high hardness and can be applied as coating reinforcement against wear. Chips of titanium alloys were processed and used in the fabrication of experimental hardfacing consumables for improving the resistance of wear of mechanical components. Coatings were produced in cast steel specimens using the gas tungsten arc welding process. Microstructure was investigated by means of scanning electron microscopy. Microhardness of the coatings was analyzed by a dynamic ultra-micro hardness tester. The microstructure of the welding metal was composed of circular particles of titanium carbide surrounded by a ferritic matrix. The measures made by electron dispersive spectroscopy showed a variation in titanium amount trough the weld, where larger contents of titanium were found, and the matrix. The crystall...
ABM Proceedings, 2014
Resumo A soldagem de peças de aço por arco submerso é um dos processos mais tradicionalmente usad... more Resumo A soldagem de peças de aço por arco submerso é um dos processos mais tradicionalmente usados na fabricação de componentes estruturais. A microestrutura do metal de solda é importante na definição das suas propriedades mecânicas, sendo a ferrita acicular um microconstituinte capaz de conferir à solda altos níveis de resistência mecânica e tenacidade. A nucleação da ferrita acicular depende da presença de inclusões não metálicas no metal de solda. No presente trabalho fez-se a caracterização microestrutural do metal de solda preparados com diferentes aportes térmicos. Lâminas finas foram observadas por microscopia eletrônica de transmissão, que possibilitou determinar alguns parâmetros morfológicos e químicos das partículas e a sua relação com a nucleação das ripas de ferrita acicular. Verificou-se que partículas irregulares com maior tamanho, mais ricas em titânio quando formadas com maior energia de soldagem, apresentam maior probabilidade de servirem como sítio preferencial para nucleação da ferrita acicular, se comparadas às partículas mais lisas e menores. Palavras-chave: Soldagem por arco submerso; Ferrita acicular; Inclusões; Microscopia eletrônica de transmissão. INCLUSIONS AND FORMATION OF ACICULAR FERRITE: CHARACTERIZATION BY TRANSMISSION ELECTRON MICROSCOPY Abstract Fabrication of steel parts by submerged arc welding is one of most traditional processes used in manufacturing structural components. The microstructure of the weld metal defines their mechanical properties, being acicular ferrite a microconstituent able to assign to the welding high levels of strength and toughness. The nucleation of acicular ferrite depends on the presence of non-metallic inclusions in the weld metal. In this work an extensive microstructural characterization of the weld metal prepared with different heat inputs was carried out by transmission electron microscopy. Thin foil sample observations have determined some morphological and chemical features of the particles and their relationship with the nucleation of acicular ferrite laths. It was found that larger irregular inclusions, richer in titanium when formed under higher heat input, are more effective as preferential site for nucleation of acicular ferrite, if compared to smaller and smoother particles.
ABM Proceedings, 2014
Resumo O laser é uma ferramenta flexível e poderosa com muitas aplicações relevantes na indústria... more Resumo O laser é uma ferramenta flexível e poderosa com muitas aplicações relevantes na indústria, principalmente na área de soldagem. Os lasers de hoje fornecem à indústria de soldagem soluções técnicas a muitos problemas, e além de substituírem a soldagem convencional já estabelecida, ainda apresentam maior produtividade. O presente trabalho estudou o metal de solda do aço inoxidável duplex UNS S32205 empregado na indústria de petróleo e gás natural, analisando a influência da variação da largura temporal nas características microestruturais do cordão de solda obtido por soldagem com laser pulsado de Nd:YAG. Os resultados mostraram que a dimensão da zona termicamente afetada é extremamente pequena e a microestrutura do metal de solda apresenta menor fração volumétrica de austenita em relação aos processos convencionais.
Materials, 2019
Duplex stainless steels (DSSs), a particular category of stainless steels, are employed in all ki... more Duplex stainless steels (DSSs), a particular category of stainless steels, are employed in all kinds of industrial applications where excellent corrosion resistance and high strength are necessary. These good properties are provided by their biphasic microstructure, consisting of ferrite and austenite in almost equal volume fractions of phases. In the present work, Nd: YAG pulsed laser dissimilar welding of UNS S32750 super duplex stainless steel (SDSS) with 316L austenitic stainless steel (ASS), with different heat inputs, was investigated. The results showed that the fusion zone microstructure observed consisted of a ferrite matrix with grain boundary austenite (GBA), Widmanstätten austenite (WA) and intragranular austenite (IA), with the same proportion of ferrite and austenite phases. Changes in the heat input (between 45, 90 and 120 J/mm) did not significantly affect the ferrite/austenite phase balance and the microhardness in the fusion zone.
Metallurgical and Materials Transactions A, 2019
Anais do X Congresso Nacional de Engenharia Mecânica, 2018