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  • 1.
    Cruz-Crespo, Amado
    et al.
    Universidad Central "Marta Abreu" de Las Villas, Universidade Federal de Uberlandia.
    Gonzalez, Lorenzo Perdomo
    Anim Hlth & Vet Labs Agcy, VLA Lasswade Vet Labs Agcy Lasswade, King Abdulaziz University.
    Rafael, Quintana
    Universidad Central "Marta Abreu" de Las Villas.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Universidade Federal de Uberlandia University West - Sweden Fed Univ Uberlandia UFU.
    Flux for Hardfacing by Submerged Arc Welding from Ferrochrome-manganese and Slag from the Simultaneous Reduction of Chromite and Pyrolusite2019In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 24, article id e2424Article in journal (Refereed)
    Abstract [en]

    The obtaining of a flux for hardfacing by Submerged Arc Welding (SAW), using ferrochrome-manganese and slag obtained from the simultaneous carbothermal reduction of chromite and pyrolusite is addressed. The ferrochrome-manganese and the slag were obtained, conceiving that both products satisfy the requirements of the components (alloy system and matrix) of an agglomerated flux for hardfacing. The fusion-reduction process to obtain the alloy and the slag was carried out in a direct current electric arc furnace. The pouring was carried out into water to facilitate the separation and grinding of the cast products. An experimental flux was manufactured, using the obtained alloy and slag. Deposits were obtained by SAW, which were characterized in terms of: chemical composition, microstructure and hardness. It was concluded that the flux obtained from ferrochrome-manganese and slag from the simultaneous carbothermal reduction of chromite and pyrolusite, allows to deposit an appropriate metal for work under abrasion conditions, characterized by significant carbon and chromium contents and a martensitic microstructure predominantly, with hardness of 63 HRc.

  • 2.
    da Silva, Leandro João
    et al.
    SENAI Innovation Institute for Manufacturing Systems and Laser Processing, Joinville, SC, Brazil; Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Souza, Danielle Monteiro
    Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    de Araújo, Douglas Bezerra
    Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Reis, Ruham Pablo
    Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Federal University of Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding,Processes, Uberlandia, MG, Brazil.
    Concept and validation of an active cooling technique to mitigate heat accumulation in WAAM2020In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015Article in journal (Refereed)
    Abstract [en]

    This work aimed at introducing and exploring the potential of a thermal management technique, named as near-immersion active cooling (NIAC), to mitigate heat accumulation in Wire + Arc Additive Manufacturing (WAAM). According to this technique concept, the preform is deposited inside a work tank that is filled with water, whose level rises while the metal layers are deposited. For validation of the NIAC technique, Al5Mg single-pass multi-layer linear walls were deposited by the CMT® process under different thermal management approaches. During depositions, the temperature history of the preforms was measured. Porosity was assessed as a means of analyzing the potential negative effect of the water cooling in the NIAC technique. The preform geometry and mechanical properties were also assessed. The results showed that the NIAC technique was efficient to mitigate heat accumulation in WAAM of aluminum. The temperature of the preforms was kept low independently of its height. There was no measurable increase in porosity with the water cooling. In addition, the wall width was virtually constant, and the anisotropy of mechanical properties tends to be reduced, characterizing a preform quality improvement. Thus, the NIAC technique offers an efficient and low-cost thermal management approach to mitigate heat accumulation in WAAM and, consequently, also to cope with the deleterious issues related to such emerging alternative of additive manufacturing.

  • 3.
    Dahat, Shubham
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Welding Technology.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology.
    A Methodology to Parameterize Wire + Arc Additive Manufacturing: A Case Study for Wall Quality Analysis2020In: Journal of Manufacturing and Materials Processing, Vol. 4, no 1, article id 14Article in journal (Refereed)
    Abstract [en]

    The objective of this work was the development of a methodology to parametrize wire + arc additive manufacturing (WAAM), aiming dimension repeatability, and tolerances. Parametrization of WAAM is a difficult task, because multiple parameters are involved and parameters are inter-dependent on each other, making overall process complex. An approach to study WAAM would be through operational maps. The choice of current (Im) and travel speed (TS) for the desirable layer width (LW) determines a parametrization that leads to either more material or less material to be removed in post-operations, which is case study chosen for this work. The work development had four stages. First stage, named ‘mock design’, had the objective of visualizing the expected map and reduce further number of experiments. At the second stage, ‘pre-requisite for realistic operational map’, the objective was to determine the operating limits of TS and Im with the chosen consumables and equipment. Within the ‘realistic operational map’ stage, a design for the experiments was applied to cover a parametric area (working envelope) already defined in the previous stage and long and tall walls were additively manufactured. Actual values of LW (external and effective layer width) were measured and an actual operating envelope was reached. According to the geometry-oriented case study, a surface waviness index (SWindex) was defined, determined, and overlapped in the envelope. It was observed that the walls with parameters near the travel speed limits presented higher SWindex. This operational map was further validated (fourth stage) by selecting a target LW and finding corresponding three parametric set (covering the whole range of operational map) to produce walls on which geometry characterization was carried out. After geometry characterization, obtained LW was compared with the target LW (the maximum values were very tied, with deviations from +0.3 to 0.5 mm), with a SWindex deviation at the order of 0.05. Both results evidence high reproductivity of the process, validating the proposed methodology to parametrize WAAM.

  • 4.
    de Souza Amaral, Thiago
    et al.
    CBMM, Araxá, MG, Brasil.
    Carboneri Carboni, Marcelo
    CBMM, São Paulo, SP, Brasil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Universidade Federal de Uberlândia – UFU, Uberlândia, MG, Bras.
    Avaliação da Aplicação de um Atlas de Soldagem de um Aço Bainítico Microligado ao Nióbio: Application Assessment of a Welding Atlas of a Niobium Microalloyed Bainitic Steel2017In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 22, no 2, p. 163-173Article in journal (Refereed)
    Abstract [en]

    Niobium microalloyed steels have shown to be an excellent solution for fabrication of structural beams, employing concepts already developed for the oil and gas industry. However, the definition of the actual welding related needs of this family of bainite steels is not well described in the welding standards mostly used in the structural construction sector. This paper demonstrates the construction and assessment of a Welding Atlas, built from using physical simulations (Gleeble and dilatrometry) and mechanical tests of the simulated specimens. The objective is to have the Atlas as a guiding tool to improve the parametrization for welding this class of steels. The proposal methodology was applied to a HSLA bainitic steel class 65 ksi. It was possible to determine with more accuracy the recommended energy range of the weld, including the need or not of preheating, and show that they were comparable with actual welds. The methodology shows benefits including a safer parametrization and cost savings resulting from unnecessary preheating elimination.

  • 5.
    dos Santos Paes, Luiz Eduardo
    et al.
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Pereira, Milton
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Weingaertner, Walter Lindolfo
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Federal University of Uberlandia, Center for Research and Development of Welding Processes (Laprosolda), Uberlândia Brazil.
    Souza, Tiago
    Federal University of Santa Catarina, Department of Mechanical Engineering, Laboratory of Precision Engineering, Laser Division (LMP-Laser), Florianópolis, Brazil.
    Comparison of methods to correlate input parameters with depth of penetration in LASER welding2019In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 101, no 5-8, p. 1157-1169Article in journal (Refereed)
    Abstract [en]

    Despite the industrial relevance of LASER welding, determination of sustainable parameterization is still a challenge. Trial and error, or even not totally justified methodologies, are frequently applied on LASER welding parametrization. This approach potentially leads to a decrease of the process tolerance and, consequently, increasing the likelihood of imperfections, which means extra operational time and raising of the final cost. The present paper addresses a comparative discussion about five factors experimentally determined and frequently used to predict depth of penetration in LASER welding. The experiments were performed with a 10-kW fiber LASER. In a first batch, power was varied while welding speed was fixed at 1 m/min. In a second batch, welding speed was varied and power was kept at 10 kW. The first demonstrated concern on using these popular factors is the definition and quantification of LASER energy. For evidencing this aspect, two samples were processed with the same welding energy of 120 kJ/m, yet resulting in completely different penetrations. Eventually, an empirical model based on power as a factor allowed a more reliable prediction of the depth of penetration.

  • 6.
    Hurtig, Kjell
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Choquet, Isabelle
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    A critical analysis of weld heat input measurement through a water-cooled stationary anode calorimeter2015In: Proceedings of JOM 18 International conference on joining materials, Helsingör, Danmark, april 26-29, 2015, JOM-institute , 2015, p. 1-19Conference paper (Refereed)
    Abstract [en]

    A comprehensive model on heat transfer in welded plates is able to calculate the amount of heat losses from the surfaces. A model demands as input parameter the amount of heat delivered to the plate, independently of any loss (called here gross heat input for clarity). However, the great discrepancies among the results of calorimetric measurements have left many researchers skeptical about using this parameter in modeling as absolute term. The objective of this work was to assess the use of a water-cooled stationary anode calorimeter to obtain not only arc efficiency, but also gross heat input. A series of tests was carried out to determine the effect of current, material type and water flow rate on the calorimeter performance, as well as to evaluate some measures for reducing the calorimeter intrinsic errors. Finally, a sensitivity test was conducted to estimate the effect of measurement inaccuracies on the absorbed heat and arc efficiency values. The results showed that this calorimetric approach is a simple way for measuring gross heat inputs in arc welding. Nevertheless some improvement to reduce heat losses from the top surface and boost heat sinking from the opposite surface of the test coupon must be applied. This calorimeter is, on the other hand, highly sensitive to the parameter measurements, leading to errors up to ± 0.09 in arc efficiency determination if the instrument is not properly calibrated and installed.

  • 7.
    Hurtig, Kjell
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Choquet, Isabelle
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Production Engineering.
    A critical analysis of weld heat input measurement through a water-cooled stationary anode calorimeter2016In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 21, no 5, p. 339-350Article in journal (Refereed)
    Abstract [en]

    Comprehensive models of heat transfer require specification of the total amount of heat received by the workpiece. The objective of this work was to critically examine the use of a water-cooled stationary anode calorimeter to obtain both arc efficiency and total heat input into the workpiece. For simplicity and clarity, this last quantity is called the gross heat input. The effects of current, material type and water flow rate on the calorimeter performance were determined experimentally. Some measures for reducing errors in calorimetry were evaluated. Improvements were made to reduce heat losses from the top surface of the test coupon and boost heat removal from the opposite surface. A sensitivity test was conducted to estimate the effect of measurement inaccuracies. The results demonstrate the effectiveness of calorimetry for measuring gross heat input in arc welding.

  • 8.
    Jorge, Vinicius Lemes
    et al.
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Alves Santos, Cesar Henrique
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Scotti, Fernando Matos
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Larquer, Thiago Resende
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Mota, Carolina Pimenta
    Instituto Federal de Educação, Ciência e Tecnologia do Triângulo Mineiro – IFTM, Patos de Minas, MG, Brasil.
    Reis, Ruham Pablo
    Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Universidade Federal de Uberlândia – UFU, Centro para Pesquisa e Desenvolvimento de Processos de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Development and Evaluation of Wire Feeding Pulsing Techniques for Arc Welding: Desenvolvimento e Avaliação de Técnicas para Pulsação da Alimentação de Arame em Soldagem a Arco2018In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 23, no 3, p. 326-339Article in journal (Refereed)
    Abstract [en]

    Applying pulsed wire feeding techniques is one of the new approaches for welding, such as for GTAW and GMAW. However, these techniques invariably require specific feeders and/or welding torches, limiting its implementation due to the high costs of the equipment. Thus, the current work aims to introduce and exploratorily evaluate techniques to pulse the wire feeding that works independently from the feeder and/or torch. The first technique is electromechanically driven, and the second one based on electromagnetics. The effects of amplitude and frequency of the pulsed feeding were evaluated in terms of weld bead formation over plates and of the corresponding electric signals. For GTAW, the pulsed wire feeding is capable of modifying the weld bead and make the metal transfer from the wire to the pool more regular. For GMAW, it was found that the pulsing of the wire feeding can interfere with the process, being capable of turning an irregular globular metal transfer into a regular one, while decreasing the mean current and affecting the bead formation. Overall, it is concluded that pulsed wire feeding can affect the processes, even when made independently from the feeder and torch, opening a field for development of derivative welding technologies.

  • 9.
    Jorge, Vinicius Lemes
    et al.
    University of Uberlandia, Center for Research and Development of Welding Processes of the Federal, Uberlandia, Brazil.
    Gohrs, Raul
    IMC Soldagem, Palhoça, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology.
    Active power measurement in arc welding and its role in heat transfer to the plate2017In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 61, no 4, p. 847-856Article in journal (Refereed)
    Abstract [en]

    A contemporary paper claimed that a method using the resistance of impedance (active power) for arc power calculation is more accurate than the conventional approach, with consequences on the actual heat transfer to the plate. However, despite the comprehensive reasoning, no heat-related results are shown in this intriguing paper to support the claim. Thus, the aim of this work was to apply the proposed method for determining the weight of active power in the total arc power. A series of weldments was carried out, by using GTAW in constant and pulsed current modes and short-circuiting GMAW with different inductance settings. The effect of the active power on the heat transfers to the plate was assessed by both bead cross-section geometries and calorimetry. The results showed that even a significant fraction of active power of the total power was reached, no changes in bead geometry or heat input were found. A review of the assumptions used in the primal paper showed that an arc is better represented by an ER circuit than by an RLC circuit. As a conclusion, the arc as a reactance-free load presents no component such as non-active power and the conventional approaches are accurate methods to measure arc power, representing the actual active power. © 2017, The Author(s).

  • 10.
    Li, Peigang
    et al.
    ESAB AB, Gothenburg, Sweden.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Welding Technology.
    Högström, Mats
    University West, Department of Engineering Science, Division of Welding Technology.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Welding Technology.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology.
    A contribution to the study of negative polarity in GMA welding2018In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 95, no 5-8, p. 2543-2553Article in journal (Refereed)
    Abstract [en]

    GMAW using the electrode with negative polarity (DCEN) has been frequently suggested as a potential means of increasing production capacity. The objective of this work was to further study the performance of negative polarity in GMAW of carbon steels. In this project phase, bead-on-plate welds were carried out in flat position to assess the effect of different potential shielding gas compositions on bead geometry, finishing and spattering. The characteristics were compared with DCEP at the same current, but depositing the same volume of material per unit of length (more industrial related comparison). The arc length was kept the same by adjusting voltage to reach shortest arcs, yet with suitable non short-circuiting metal transfer mode. An approach to measure bead convexity was also proposed and assessed. The results showed that DCEN is feasible as a means of increasing GMAW production capacity. However, to become DCEN applicable with GMAW, the results suggest an Ar based blend with around 6.5 % of O2 is the most appropriate shielding gas, as much as that there is a demand for a standard electronic controlled power source able to work in constant current mode. 

  • 11.
    Liskevych, Olga
    et al.
    Center for Research and Development of Welding Processes of Federal University of Uberlandia (Laprosolda), Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Production Engineering.
    Influence of the CO2 Content on Operational Performance of Short-Circuit GMAW2015In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 59, no 2, p. 217-224Article in journal (Refereed)
    Abstract [en]

    CO2 blended with Ar is the most common shielding gas used for short-circuit GMAW. There has been some technical knowledge devised from the process application over the years (personal opinion and results from practice) on the selection of the gas blend composition. However, there is still lack of more scientific data to explain the performance of the mixtures. This paper presents a systematic study of the influence that CO2 content in mixture with Argon has on the operational performance of the short-circuit GMAW. The objective of this study was to describe, to quantify and to explain the alterations in the metal transfer behavior, spatter generation, weld bead geometry and bead finish due to the different CO2 contents in the shielding gas. Carbon steel plates were welded in adequate parametric conditions for each CO2+Ar shielding gas composition (CO2 ranging from 2% to 100%). These parametric conditions were found by applying a metal transfer regularity index over welds carried out at different voltage settings for each gas blend. A target of 130 A was applied as base for comparison. Laser shadowgraphy with high speed filming and current and voltage oscillograms were used as analysis tools. The results showed (and confirmed) that the increase of the CO2 content deteriorates metal transfer regularity, leading to excessive spatter generation and uneven bead appearance, but increases the penetration and the fusion area of the weld beads and improves bead convexity. In general, the CO2 content should neither be lower than 10% (unless for thin plates) nor higher than 30%.

  • 12.
    Mishchenko, Andrii
    et al.
    Universidade Federal de Uberlândia – UFU, Grupo Centro para Pesquisa e Desenvolvimento de Processo de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Universidade Federal de Uberlândia – UFU, Grupo Centro para Pesquisa e Desenvolvimento de Processo de Soldagem – Laprosolda, Uberlândia, MG, Brasil.
    Residual Stresses in Arc Welding: A Holistic Vision2018In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 23, no 1, p. 93-112Article in journal (Refereed)
    Abstract [en]

    There are several examples in current literature where assumptions regarding residual stresses are made, yet rarely confirmed in practice. To validate this statement, this work presents a critical view on the subject through a bibliographic review. A series of conflicting results were found when researchers attempted, both experimentally and by simulation, to define, quantify, or even qualify, the individual effect of each factor on residual stress generation. It was concluded that the reason for this would be the lack of a holistic view to study the subject. Therefore, a diagram is proposed, which lists and classifies as primary and secondary the governing factors related to the generation of residual stresses, to facilitate the understanding of the effect of each factor. It was also observed a lack of harmonization in publications, both in symbology and in terminology, of the residual stress axes and components. Therefore, a symbology and terminology proposal, with the intention of facilitating the comprehension and transportability of results, is presented. Eventually, from this work is therefore expected a better understanding of the reasons for the literature assumptions to be not always confirmed in practice.

  • 13.
    Mishchenko, Andrii
    et al.
    Federal University of Uberlandia (UFU),Laprosolda-Center for Research and Development of Welding Processes, Uberlândia, Brazil.
    Wu, Leonardo
    Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.
    da Silva, Vanessa K.
    Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Federal University of Uberlandia (UFU),Laprosolda-Center for Research and Development of Welding Processes, Uberlândia, Brazil.
    Analysis of residual stresses resulting from the surface preparation for X-ray diffraction measurement2018In: Journal of the Brazilian Society of Mechanical Sciences and Engineering, ISSN 1678-5878, E-ISSN 1806-3691, Vol. 40, no 2, article id 94Article in journal (Refereed)
    Abstract [en]

    There is no consensus in the literature on the need to remove preprocessing layers from the material prior to the measurement of residual stresses by X-ray diffractometer. Thus, the purpose of this work was to evaluate the residual stresses induced by material preprocessing and its evolution during the preparation of the surface by electrolytic removal. Sample surfaces were pre-processed by grinding and sandblasting and the resulting residual stresses were measured by X-ray diffractometry. At each removal stage, the evolution of residual stresses, hardness and microstructure of the surface were verified. It was concluded that different preprocessing methods can induce surface residual stresses of either tension or compression, reaching different depths. Removal by electrolytic method of the modified layer has shown itself capable of reducing significantly the magnitude of the residual stresses induced by preprocessing. On the other hand, the depth of deformed grains or surface hardness proved to be incapable of predicting the depth of induced residual stresses. Finally, it was discussed whether or not the layers removed by this method reveal the subsurface stresses and if the removal should take place before or after a second processing.

  • 14.
    Pablo Reis, Ruham
    et al.
    Universidade Federal de Uberlândia—UFU, Centro Para Pesquisa e Desenvolvimento de Processos de Soldagem—LAPROSOLDA, Uberlândia, Brazil.
    Skhabovskyi, Iaroslav
    Universidade Federal de Uberlândia—UFU, Centro Para Pesquisa e Desenvolvimento de Processos de Soldagem—LAPROSOLDA, Uberlândia, Brazil.
    Lima Santos, Alberto
    Universidade Estadual Paulista—UNESP, Departamento de Tecnologias e Materiais, Guaratinguetá, Brazil.
    Sanches, Leonardo
    Universidade Federal de Uberlândia—UFU, Centro Para Pesquisa e Desenvolvimento de Processos de Soldagem—LAPROSOLDA, Uberlândia, Brazil.
    Cocchieri Botelho, Edson
    Universidade Estadual Paulista—UNESP, Departamento de Tecnologias e Materiais, Guaratinguetá, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Universidade Federal de Uberlândia—UFU, Centro Para Pesquisa e Desenvolvimento de Processos de Soldagem—LAPROSOLDA, Uberlândia, Brazil.
    Fiber-metal laminate panels reinforced with metal pins2018In: Optimum Composite Structures / [ed] Maalawi. Karam, London: IntechOpen , 2018, p. 93-120Chapter in book (Other academic)
    Abstract [en]

    Fiber-metal laminates (FMLs) are key to modern composite structures and metal-compositecoupling is crucial to improve their effectiveness. Cold-metal transfer (CMT) PIN welding,in correlated efforts, has been successfully explored as a metal-composite hybrid joiningapproach. This work proposes a novel development on FMLs, which consists of introducingmetal pins welded by CMT PIN for anchoring their metal and composite layers together.Thus, miniaturized FML panels with different pin deposition spacing and patterns are evaluatedwith emphasis in drop-weight testing followed by buckling and by means of Iosipescushear test as complement. They are also subjected to cosmetic and preliminary modal analyses.Besides not adding significant weight, the pins does not make the panels more brittleand their distribution does not imply significant effect in the capacity that the panels have todissipate impact. The panels with pins exhibit a less catastrophic trend, indicating damagetolerance improvement as significantly higher loads at longer axial displacements in bucklingtest after impact are achieved. The anchoring effect of the pins is confirmed throughoutthe shear test results. The pins also significantly increase the damping factor of the panelsand the changes in their metal surfaces by the CMT PIN process are considered as irrelevant.

  • 15.
    Skhabovskyi, Iaroslav
    et al.
    Universidade Federal de Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding Processes, Faculty of Mechanical Engineering, Uberlândia, Brazil.
    Batista, Natassia Lona
    Universidade Estadual Paulista (UNESP), Materials and Technology Department, School of Engineering, Guaratinguetá, Brazil.
    Damato, Cesar Augusto
    ALLTEC Materiais Compostos, São José dos Campos, Brazil.
    Reis, Ruham Pablo
    Universidade Federal de Uberlândia (UFU), Laprosolda – Center for Research and Development of Welding Processes, Faculty of Mechanical Engineering, Uberlândia, Brazil.
    Botelho, Edson Cocchieri
    Universidade Estadual Paulista (UNESP), Materials and Technology Department, School of Engineering, Guaratinguetá, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Laprosolda – Center for Research and Development of Welding Processes, Faculty of Mechanical Engineering, Universidade Federal de Uberlândia (UFU), Uberlândia, Brazil.
    Appraisal of fiber-metal laminate panels reinforced with metal pins deposited by CMT welding2017In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 180, no Supplement C, p. 263-275Article in journal (Refereed)
  • 16.
    Teixeira, Felipe Ribeiro
    et al.
    Federal University of Pará, Department of Mechanical Engineering/PPGEM, 1 Augusto Corrêa St., Guamá, Belém, PA, 66075-110, Brazil.
    Mota, Carlos Alberto Mendes
    Federal University of Pará, Department of Mechanical Engineering/PPGEM, 1 Augusto Corrêa St., Guamá, Belém, PA, 66075-110, Brazil.
    Almeida, Hélio Antônio Lameira
    Federal Institute of Education, Science and Technology of Pará, Mechanics, 1155 Alm. Barroso Ave., Marco, Belém, PA, 66093-020, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Federal University of Uberlandia, Laprosolda (Center for Research and Development of Welding Processes), 2121 João Naves de Ávila Ave., Santa Mônica, Uberlandia, MG, 38400-902, Brazil.
    Operational behavior of the switchback GMAW process using a mechanized rig for arc movement2019In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 269, p. 135-149Article in journal (Refereed)
    Abstract [en]

    Switchback Gas Metal Arc Welding (GMAW) consists of a forward and backward periodic oscillation of the welding torch in the longitudinal direction of the joint. The present work has two objectives, to evaluate the use of a simple and practical device proposed for the switchback manipulation of the torch and to analyze the effect of the switchback parameters on the operational characteristic of the process. Two series of bead-on-plate depositions were planned, using the GMAW process with or without the switchback technique. To find an operational envelope, two levels of equivalent welding speeds were used for covering ranges of oscillation frequency and amplitude. A Ni superalloy was employed as deposition material, aiming at simulating weld overlays. Wire feeding speed, set voltage and contact tip-to-work distance (CTWD) were kept constant. The proposed device was evaluated and proved to be able to make the overlays with all combinations of planned parameters. It was demonstrated that if the backward length (B) is larger than half of the forward's (F), the torch passes more often over the same point of the deposit, and the oftener the torch passes over the same point, the lower the incidence of intermittent narrowing of the bead. By evaluating the surface aspect of the beads, the greater the F, the higher the likelihood of this irregularity. Penetration is shallower with switchback (reason demonstrated based on the fraction of stroke length that the arc is over the subtract), yet the bead surface presents more ripples. Another incident non-geometric conformity is the "dragon back" aspect of the bead, which is favored by faster equivalent welding speeds and high values of forward and backward speeds. The found operational envelope for the GMAW process with switchback was stablished with low-values of speeds and lengths of forward and backward strokes.

  • 17.
    Yehorov, Yuri
    et al.
    Center for Research and Development of Welding Processes, Federal University of Uberlandia, Uberlândia, Brazil.
    da Silva, Leandro João
    Center for Research and Development of Welding Processes, Federal University of Uberlandia, Uberlândia, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Center for Research and Development of Welding Processes, Federal University of Uberlandia, Uberlândia, Brazil.
    Balancing WAAM Production Costs and Wall Surface Quality through Parameter Selection: A Case Study of an Al-Mg5 Alloy Multilayer-Non-Oscillated Single Pass Wall2019In: Journal of Manufacturing and Materials Processing, E-ISSN 2504-4494, Vol. 3, no 2, p. 1-19Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to propose a strategy to assess the potential reduction of the production cost during wire+arc additive manufacturing (WAAM) based on the combination of wire feed speed (related to deposition rate) and travel speed (related to deposition time). A series of experiments, using a multilayer-non-oscillated single pass wall made of an Al-Mg alloy, was conducted. The quality of the wall was assessed through the lateral surface waviness and top layer undulation. The concepts of Surface Waviness and Buy-to-Apply indices were introduced. Initially, the range of travel speed (TS) that provided layers with acceptable quality was determined for a given wire feed speed (WFS), corresponding to a constant current. Then, the effect of the increase of production capacity of the process (though current raising, yet maintaining the ratio WFS/TS constant) on the wall quality for a given condition within the TS range was assessed. The results showed that the useful range of TS prevents too rough a waving surface below the lower limit and top surface undulation over the higher limit. However, inside the range, there is little quality variation for the case under study. Finally, simulations of deposition time were developed to demonstrate the weight of the TS on the final deposition time and wall quality as a function of a target wall width. This respective weight showed the existence of a complex and unpredictable, yet determined, power of a combination of TS, target wall geometry, and dead time between subsequent layers. It was verified to be possible to find optimized TS as a function of different target geometries. 

  • 18.
    Yehorov, Yurii
    et al.
    Federal University of Uberlandia (UFU),Center for Research and Development of Welding Processes, Laprosolda, Uberlândia, MG 38408-100, Brazil.
    da Silva, Leandro João
    Federal University of Uberlandia (UFU),Center for Research and Development of Welding Processes, Laprosolda, Uberlândia, MG 38408-100, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Federal University of Uberlandia (UFU),Center for Research and Development of Welding Processes, Laprosolda, Uberlândia, MG 38408-100, Brazil.
    Exploring the use of switchback for mitigating homoepitaxial unidirectional grain growth and porosity in WAAM of aluminium alloys2019In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 104, no 1-4, p. 1581-1592Article in journal (Refereed)
    Abstract [en]

    In this work, an alternative approach to prevent unidirectional grain growth in wire + arc additive manufacturing (WAAM) is proposed and assessed, by moving cyclically the torch forward and backward, likewise the welding technique known as switchback. A series of tests were planned with CMT (cold metal transfer) process to compare three wall-like build-ups, which uses different deposition patterns, namely, in one-way direction, reverse direction, and switchback. The same equivalent travel speed and number of deposited layers were kept among them. Longitudinal sections were taken to identify the grain growth behaviour. Finally, samples were removed from the walls for porosity evaluation. The results confirmed the characteristics of unidirectional grain growth, when one-way direction condition was employed, and the break of growth direction between layers, when reverse direction was used, yet a zig-zag pattern became present. Differently, the application of switchback showed no preferential or unidirectional grain growth, suggesting less anisotropy of mechanical properties. In addition, switchback reduced porosity. © 2019, The Author(s).

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