In this study, an ER5356 aluminium alloy wall was fabricated using a GMAW-based arc additive manufacturing (WAAM) process to examine build-height-dependent microstructure, phase constitution, tensile behaviour, microhardness, and tribological performance. Microscopy and SEM analysis reveal a refined α-Al matrix at the bottom of the build, with progressively coarser microstructural features toward the top. X-ray diffraction analysis confirms α-Al as the dominant face-centred cubic phase, and Mg-rich intermetallic phases (β-Al 3 Mg 2 and Al 12 Mg 17 ), with no significant qualitative variation in phase constitution along the built height. Tensile testing shows a clear built direction dependence where horizontally extracted specimens achieve a maximum ultimate strength of 261.7 MPa, yield strength of 180 MPa with 23.4% elongation, while vertically extracted specimens exhibit lower strength and ductility (UTS 236.1 MPa, yield strength 148 MPa and 15.4% elongation). Microhardness measurements show a gradual decrease from 71.05 HV at the bottom to 67.63 HV at the top region. Tribological evaluation using a dry pin-on-disc configuration across five built zones shows a stable and controlled wear behaviour, with a low wear rate of 6.06 × 10 -5 mm 3 /Nm and moderate coefficient of friction (0.28–0.48) at low to intermediate loads, followed by a gradual increase in wear rate (up to 7.58 × 10 -4 mm3/Nm) and COF (up to 0.64) with increasing load and sliding distance. The observed low wear rate indicates favourable tribological behaviour, supporting the potential applicability of WAAM-fabricated ER5356 aluminium for marine-based applications. The result established a detailed process-structure-property relationship, layer-by-layer mechanical and tribological gradients inherent to the WAAM process.
G et al. (Tue,) studied this question.