In-situ hot forging directed energy deposition-arc of CuAl8 alloy

Funding Information: Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). VD acknowledges Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for funding the PhD grant SFRH/BD/139454/2018 . TAR acknowledges Portuguese Fundação para a Ciência e a Tecnologia ( FCT - MCTES ) for funding the PhD grant SFRH/BD/144202/2019 . Funding of CENIMAT/i3N by national funds through the Portuguese Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units , reference UIDB/50025/2020–2023 is also acknowledge. This activity has received funding from the European Institute of Innovation and Technology (EIT) Raw Materials through the project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme. Parts of this research were carried out at PETRA III at DESY, a member of the Helmholtz Association. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 having benefitted from the access provided by PETRA III at DESY in Hamburg, Germany within the framework of the NFFA-Europe Transnational Access Activity. The authors acknowledge support by OCAS NV and GUARENTEED via Joachim Antonissen. Funding Information: Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). VD acknowledges Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for funding the PhD grant SFRH/BD/139454/2018. TAR acknowledges Portuguese Fundação para a Ciência e a Tecnologia (FCT - MCTES) for funding the PhD grant SFRH/BD/144202/2019. Funding of CENIMAT/i3N by national funds through the Portuguese Fundação para a Ciência e a Tecnologia, I.P. within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020–2023 is also acknowledge. This activity has received funding from the European Institute of Innovation and Technology (EIT) Raw Materials through the project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation programme. Parts of this research were carried out at PETRA III at DESY, a member of the Helmholtz Association. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 having benefitted from the access provided by PETRA III at DESY in Hamburg, Germany within the framework of the NFFA-Europe Transnational Access Activity. The authors acknowledge support by OCAS NV and GUARENTEED via Joachim Antonissen. Remark: The supplementary material is temporarily available in the Drive folder here: https://drive.google.com/drive/folders/1SFFlhJlmL5p3IkQis8cB6UVWva3wozGi?usp=sharing. Publisher Copyright: © 2022 Elsevier B.V.CuAl8 alloy finds applications in industrial components, where a good anti-corrosion and anti-wearing properties are required. The alloy has a medium strength and a good toughness with an elongation to fracture at room temperature of about 40%. Additionally, it has a good electrical conductivity, though lower than that of pure Al or pure Cu. Despite these characteristics, additive manufacturing of the CuAl8 alloy was not yet reported. In this work, the direct energy deposition-arc (DED-arc) with and without in-situ hot forging was used to determine the microstructure evolution and mechanical properties. No internal defects were seen on the parts produced. Hot forging combined with DED-arc was seen to reduce and homogenize the grain size, improve mechanical strength and isotropy of mechanical properties. Moreover, the use of this novel DED-arc variant was seen to reduce the magnitude of residual stresses throughout the fabricated part. We highlight that this alloy can be processed by DED-arc, and the hot forging operation concomitant with the material deposition has beneficial effects on the microstructure refinement and homogenization.publishersversionpublishe

Current Status and Perspectives on Wire and Arc Additive Manufacturing (WAAM)

Additive manufacturing has revolutionized the manufacturing paradigm in recent years due to the possibility of creating complex shaped three-dimensional parts which can be difficult or impossible to obtain by conventional manufacturing processes. Among the different additive manufacturing techniques, wire and arc additive manufacturing (WAAM) is suitable to produce large metallic parts owing to the high deposition rates achieved, which are significantly larger than powder-bed techniques, for example. The interest in WAAM is steadily increasing, and consequently, significant research efforts are underway. This review paper aims to provide an overview of the most significant achievements in WAAM, highlighting process developments and variants to control the microstructure, mechanical properties, and defect generation in the as-built parts; the most relevant engineering materials used; the main deposition strategies adopted to minimize residual stresses and the effect of post-processing heat treatments to improve the mechanical properties of the parts. An important aspect that still hinders this technology is certification and nondestructive testing of the parts, and this is discussed. Finally, a general perspective of future advancements is presented

Production of Al/NiTi composites by friction stir welding assisted by electrical current

Composite Al structures reinforced with NiTi have been produced by solid-state joining process in order to preventbrittle intermetallics to form. For this, friction stir welding (FSW)was used in both the conventional and thehybrid variant assisted by electrical current. The hybrid process allows for a better bonding along the NiTi/Al interfacesince the material viscoplasticity promoted by the higher temperatures achieved during the process facilitatesthe material flow around the reinforcement. Mechanical characterization of the composites showed thatupon bending and pull-out tests, the composites produced by FSWassisted by electrical current have increasingmechanical properties. Microstructural characterization using synchrotron X-ray diffraction, revealed that compositesproducedwith the hybrid process exhibited a different transformation temperature of the NiTi reinforcements.The originally fully austenitic NiTi presented both martensite and austenite at room temperature afterprocessing, which can be taken as an advantage for applications where damping capacity of the shape memoryalloy is required. The ability to successfully join NiTi to Al may open new structural applications based on thesecomposites

In-situ hot forging direct energy deposition-arc of CuAl8 alloy

CuAl8 alloy finds applications in industrial components, where a good anti-corrosion and anti-wearing propertiesare required. The alloy has a medium strength and a good toughness with an elongation to fracture at roomtemperature of about 40%. Additionally, it has a good electrical conductivity, though lower than that of pure Alor pure Cu. Despite these characteristics, additive manufacturing of the CuAl$_8$ alloy was not yet reported. In thiswork, the direct energy deposition-arc (DED-arc) with and without in-situ hot forging was used to determine themicrostructure evolution and mechanical properties. No internal defects were seen on the parts produced. Hotforging combined with DED-arc was seen to reduce and homogenize the grain size, improve mechanical strengthand isotropy of mechanical properties. Moreover, the use of this novel DED-arc variant was seen to reduce themagnitude of residual stresses throughout the fabricated part. We highlight that this alloy can be processed byDED-arc, and the hot forging operation concomitant with the material deposition has beneficial effects on themicrostructure refinement and homogenization

Hot forging wire and arc additive manufacturing (HF-WAAM)

In this study, we propose a new variant of wire and arc additive manufacturing (WAAM) based on hot forging. During WAAM, the material is locally forged immediately after deposition, and in-situ viscoplastic deformation occurs at high temperatures. In the subsequent layer deposition, recrystallization of the previous solidification structure occurs that refines the microstructure. Because of its similarity with hot forging, this variant was named hot forging wire and arc additive manufacturing (HF-WAAM). A customized WAAM torch was developed, manufactured, and tested in the production of samples of AISI316L stainless steel. Forging forces of 17 N and 55 N were applied to plastically deform the material. The results showed that this new variant refines the solidification microstructure and reduce texture effects, as determined via high energy synchrotron X-ray diffraction experiments, without interrupting the additive manufacturing process. Mechanical characterization was performed and improvements on both yield strength and ultimate tensile strength were achieved. Furthermore, it was observed that HF-WAAM significantly affects porosity; pores formed during the process were closed by the hot forging process. Because deformation occurs at high temperatures, the forces involved are small, and the WAAM equipment does not have specific requirements with respect to stiffness, thereby allowing the incorporation of this new variant into conventional moving equipment such as multi-axis robots or 3-axis table used in WAAM

Non-destructive microstructural analysis by electrical conductivity: Comparison with hardness measurements in different materials

J.P. Oliveira, R.M. Miranda and Telmo G. Santos acknowledgethe Portuguese Fundacao para a Ciencia e a Tecnologia (FCT, I.P.) for its financial support via the project PEst-OE/EME/UI0667/2014. Telmo G. Santos and R.M. Miranda also acknowledge Project Hi2TRUST, (Refa-3335), supported by Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Operacional Regional de Lisboa (Lisb@2020 and Portugal2020).The use of non-destructive evaluation (NDE) techniques for assessing microstructural changes in processed materials is of particular importance as it can be used to assess, qualitatively, the integrity of any material/structure. Among the several NDE techniques available, electrical conductivity measurements using eddy currents attract great attention owing to its simplicity and reliability. In this work, the electrical conductivity profiles of friction stir processed Ti6Al4V, Cu, Pb, S355 steel and gas tungsten arc welded AISI 304 stainless steel were determined through eddy currents and four-point probe. In parallel, hardness measurements were also performed. The profiles matched well with the optical macrographs of the materials: while entering in the processed region a variation in both profiles was always observed. One particular advantage of electrical conductivity profiles over hardness was evident: it provides a better resolution of the microstructural alterations in the processed materials. Moreover, when thermomechanical processing induces microstructural changes that modify the magnetic properties of a material, eddy currents testing can be used to qualitatively determine the phase fraction in a given region of the material. A qualitative relation between electrical conductivity measurements and hardness is observed.authorsversionpublishe

Recent developments in FSW assisted by electrical current hybrid process

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