Browsing by Author "Aldalur, E."
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Item High deposition wire arc additive manufacturing of mild steel: Strategies and heat input effect on microstructure and mechanical properties(2020-10) Aldalur, E.; Veiga, F.; Suárez, A.; Bilbao, J.; Lamikiz, A.; FABRIC_INTEL; Tecnalia Research & InnovationWire Arc Additive Manufacturing (WAAM) is a layer-by-layer production concept that is proposed as a promising alternative to traditional subtractive techniques due to its potential to manufacture large metallic components of medium geometrical complexity. In recent years, this technology has created interest due to the advantages it proposes, such as a low cost and high deposition rates in comparison with other Additive Manufacturing (AM) techniques. In this study, the Gas Metal Arc Welding (GMAW)-based WAAM system was developed to deposit mild steel material. To that end, a comprehensive methodology to understand the main process variables and their influence in the final component properties is shown. The aim of the present study was to compare the influence of oscillatory and overlapping deposition strategies in terms of productivity, growth per layer, obtained microstructure and mechanical properties using the control volume concept to compare volume-dependent parameters. Although some characteristics of these strategies have been documented in literature, the heat input influence has not yet been comprehensively demonstrated and understood. For example, heat input, analyzed deeply in the present study, is a critical factor for the stability of the WAAM process, influencing the mechanical properties and microstructural evolution of as-fabricated parts. The results indicate that the oscillated strategy increases productivity.Item Metal transfer modes for Wire Arc Additive Manufacturing Al-Mg alloys: Influence of heat input in microstructure and porosity(2021-11) Aldalur, E.; Suárez, A.; Veiga, F.; FABRIC_INTEL; Tecnalia Research & InnovationWire Arc Additive Manufacturing (WAAM), an additive manufacturing technology for the manufacture of medium-to-large size metallic parts, is generating great interest. This technology employs aluminum alloys that are of immense interest for manufacturing, due to their high strength-weight ratio, corrosion resistance and utilization in different industries. Among these materials, some of the most widely used in various industrial fields are alloys classified within the 5000 series that are of good weldability and, consequently, very suitable for WAAM technology. In this paper, aluminum alloy 5356 is analyzed in the Gas Metal Arc Welding (GMAW)-based WAAM technological process. From among the various recommended working modes of different manufacturers, three working modes for aluminum alloys are compared: pulsed-GMAW mode, Cold Arc mode and pulsed-AC mode. To do so, test samples composed of single mono-layer weld beads and single-bead walls are manufactured using each working mode and micro and macro-structural properties, geometrical shape and porosity levels of the finished products are evaluated. As a novelty, this paper includes pulsed-AC as a new transfer mode for application on aluminum. Not only does it show its viability for the manufacture of parts by WAAM, but it also allows the reduction of the presence of pores by more than six times compared to Cold Arc mode and ten times compared to pulsed-GMAW mode. This aspect makes it a very attractive mode for use on this aluminum alloy.Item Tomography analysis of Al–Mg alloys manufactured by wire-arc directed energy deposition with different metal transfer modes(2023-11-01) Aldalur, E.; Suárez, A.; Veiga, F.; Holgado, I.; Ortega, N.; FABRIC_INTELThe interest in aluminum-magnesium alloy additive manufacturing through Wire-arc Directed Energy Deposition (DED) technology has substantially grown in recent years. The main challenge in additive manufactured aluminum-magnesium alloys is the occurrence of porosity. In this context, Gas Metal Arc Welding (GMAW) based additive technology is suitable for aluminum printing as it allows high deposition rates and reduces porosity levels through alternative metal transfer modes without adding any extra equipment. Therefore, this research explores the effects of these alternative metal transfer modes, which determine the current signal shape and polarity, on the distribution and morphology of micropores using X-ray computed tomography in both single-bead and double-bead walls. The novelty of this paper lies in the comparison of the porosity obtained using alternative transfer modes, which, unlike CMT (Cold Metal Transfer) modes, have not been exhaustively analyzed. Additionally, to date, there has been no comprehensive comparison of the porosity results obtained in single walls and overlapped walls. The results demonstrate that pulsed-AC transfer mode with a current signal featuring variable polarity yields acceptable porosity fraction values of less than 0.04% in single-bead walls and less than 0.01% in double-bead walls, achieving high productivity.