# Mechanical Properties Analysis of WAAM Produced Wall Made from 6063 Alloy Using AC MIG Process
## 2 Materials and Methods  
A Fronius FlexTrack 45 PRO Rail-guided welding carriage and OTC Daihen WB-W400 AC-MIG welding power supply were employed for wire and arc additive manufacturing (WAAM) of four samples. In this study, a 6063 aluminum alloy welding wire, an advanced Al-Mg-Si alloy (tailored to improve processability using a TiB\({}_{2}\)-containing structural refiner) with a diameter of 1.0 mm, was selected as the deposition material (chemical composition is provided in Table 1). As the substrate material, a 5083 aluminum alloy with dimensions of 300 mm \(\times\) 70 mm \(\times\) 8 mm was used, while the total length of the fabricated samples was approximately 250 mm. Prior to welding, the substrate surface was cleaned with alcohol to remove any surface contamination that could compromise the integrity of the weld metal. The selected deposition parameters, along with the corresponding sample designations, are presented in Table 2. The interpass temperature was maintained at 100 \({}^{\circ}\)C. To ensure a constant interpass temperature, the time between individual layers was adjusted, with temperature measurements taken using an infrared thermometer (Fluke 568 Infrared Thermometer, Fluke Corporation, Everett, WA, USA). The contact tip-to-workpiece distance was fixed at 10 mm, and the welding speed was set to 76 cm/min. Argon (Ar \(\geq\) 99.996%, Group I1 according to EN ISO 14175) was used as the shielding gas, with a constant flow rate of 19.5 L/min. All samples were fabricated with 50 overlapping layers using a zig-zag method, with the starting position for each subsequent layer placed at the opposite side of the previously deposited wall. To investigate the effects of polarity balance while maintaining process stability, the current was kept constant during all experiments. Accordingly, the wire feed rate and other parameters were adjusted to ensure arc stability. Sample 11 represents an aluminum wall fabricated using an alternating current (AC) with an electrode-negative (EN) ratio of 50. This indicates that, within a single cycle, the duration of the negative polarity is maximized, while the positive polarity is minimized. In contrast, Sample 13 was also fabricated using an AC, but with an EN ratio of \(-\)50, signifying a cycle in which the negative polarity duration is minimized, and the positive polarity is maximized. Sample 12 was produced using an EN ratio of 0, corresponding to a conventional AC waveform, where the durations of the positive and negative polarities are equal within each cycle. Adjustments to the EN ratio inherently modify the welding voltage and wire feed speed, thereby contributing to improved process stability and weld quality. Sample 14 was fabricated using a direct current (DC). Based on the sample height data presented in Table 2, it may be concluded that an increased duration of the negative polarity within the pulse cycle correlates with reduced heat input and enhanced material deposition. Upon completion of the welding process, residual stress measurements were conducted on both the upper and lateral surfaces of the samples using the cos\(\alpha\) X-ray diffraction method [25; 26]. The measurements were performed using the Pulstec \(\upmu\)-X360 system (Pulstec Industrial Co., Ltd., Hamamatsu, Japan). Tensile test specimens were extracted from the additively manufactured thin-walled structures, as shown in Figure 1. All specimens had identical dimensions of 175 mm in length, 22 mm in width and 5 mm in thickness, with all geometrical parameters defined \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Composition** & **Si** & **Fe** & **Cu** & **Mn** & **Mg** & **Cr** & **Zn** & **Be** & **Ti** & **B** & **Other** & **Al** \\ \hline
**6063** & 0.2–0.6 & \textless{}0.35 & \textless{}0.1 & \textless{}0.1 & \textless{}0.45–0.9 & \textless{}0.1 & \textless{}0.01 & \textless{}0.0003 & 0.2–0.3 & 0.04–0.06 & \textless{}0.05 & balance \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of the filler wire and base metal (wt.%).