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Significant efforts have been spent determining or monitoring interlayer temperatures (IT) to increase quality in Wire Arc Additive Manufacturing (WAAM). However, an uneven thermal profile in the wall and a temperature gradient along the layer length are expected after a thin wall layer deposition, questioning the effectiveness of IT and its measuring approaches. After identifying the holistic meaning of IT, this work aimed at confronting two strategies using infrared pyrometers, elucidating their advantages and limitations for both open and closed‐loop control. The proposed Upper and Sideward Pyrometer strategies were presented in detail and then assessed at different distances from the heat source. A calibration procedure was proposed. The results confirmed the existence of a natural temperature gradient along the wall. In addition, they showed how differently the arc heat affects the measured points (in intensity and steadiness) according to the strategy. Therefore, the interlayer temperature measured at a specific point on a part manufactured by WAAM should be taken as a reference and not an absolute value; the absolute value changes according to the measuring approach, sensor positioning and calibration. Using a temperature reference, both strategies can be used in open‐loop control to reach repeatability (geometrical and metallurgical) between layers. However, the Sideward Pyrometer strategy is more recommended for feedback control of production, despite being less flexible. © 2022 by the authors. Licensee MDPI, Basel, Switzerland., This study was supported by the Brazilian National Council for Scientific and Technological Development (CNPq), through grants 165902/2020-5 and 302863/2016-8, and by the Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES), through Finance Code 001

This work aims to propose and assess a methodology for parameterization for WAAM of thin walls based on a previously existing working envelope built for a basic material (parameter transferability). This work also aimed at investigating whether the working envelope approach can be used to optimize the parameterization for a target wall width in terms of arc energy (which governs microstructure and microhardness), surface finish and active deposition time. To reach the main objective, first, a reference working envelope was developed through a series of deposited walls with a plain C-Mn steel wire. Wire feed speed (WFS) and travel speed (TS) were treated as independent variables, while the geometric wall features were considered dependent variables. After validation, three combinations of WFS and TS capable of achieving the same effective wall width were deposited with a 2.25Cr-1Mo steel wire. To evaluate the parameter transferability between the two materials, the geometric features of these walls were measured and compared with the predicted values. The results showed minor deviations between the predicted and measured values. As a result, WAAM parameter selection for another material showed to be feasible after only fewer experiments (shorter time and lower resource consumption) from a working envelope previously developed. The usage of the approach to optimize parameterization was also demonstrated. For this case, lower values of WFS and TS were capable of achieving a better surface finish. However, higher WFS and TS are advantageous in terms of production time. As long as the same wall width is maintained, variations in WFS and TS do not significantly affect microstructure and microhardness., Open access funding provided by University West. This work was supported by The National Council for Scientific and Technological Development – CNPq (grant numbers 302863/2016-8), The Coordination for the Improvement of Higher Education Personnel – CAPES (Finance Code 001) and PETROBRAS (project number 23117.018175/2019-80).

The successful and efficient production of parts with specific features by Wire + Arc Additive Manufacturing (WAAM) strongly depends on the selection of proper and typically interrelated deposition parameters. This task might be particularly challenging in the making of thin walls, which might be highly impacted by processing conditions and heat accumulation. In this context, this study aims at expanding the work envelope and optimizing the parametric conditions in WAAM with relative density and surface aspects of the preforms as quality constraints. The experimental approach was based on the deposition of thin Al5Mg walls by the CMT process on its standard welding setup and with an active cooling technique to enhance the deposition robustness. Internal voids were estimated by Archimedes’ method. The surface quality of the walls was assessed through the visual aspect and the surface waviness by cross-section analysis. All the conditions presented relative density higher than 98%. The upgrade of the standard welding hardware to WAAM purposes through the addition of a supplementary shielding gas nozzle to the torch and the intensity of the heat sinking from the part significantly expanded the process work envelope, with its applicability being successfully demonstrated with multi-objective optimization. To sum up, a decision-making procedure is presented towards achieving intended preform quality., This research was supported by the Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES), through Finance Code 001, and by the Brazilian National Council for Scientific and Technological Development (CNPq), through grants 302863/2016-8 and 315092/2018-1.