This study examines the impact of deposition orientations on ASS 308LSi thin-walled structure via the Wire Arc Additive Manufacturing (WAAM) technique in order to investigate the microstructural characteristics, tensile strength, microhardness, Charpy impact testing, and fracture morphology of the WAAM 308LSi. The analysis of the microstructure reveals that the deposition orientation promotes transitioning from columnar to equiaxed fine grain structure. The tensile strength results show that specimens with a 45° deposition orientation exhibit lower anisotropy and higher tensile properties compared to those with a 0° deposition orientation, with improvements of 33.1% in the transverse direction and 26.7% in the longitudinal deposition directions, respectively. The microhardness in WAAM SS308LSi demonstrates variations in the bottom, middle, and top regions, with the highest average value observed at a 45° deposition orientation (213.3 ± 6.5 HV, 201.1 ± 10.7 HV, and 191.5 ± 5.2
HV) as well. The impact testing results indicate that the highest absorbed energy occurs at a
45° deposition orientation, with 75 ± 4.2 J and 74 ± 4.0 J for the transverse and longitudinal directions, respectively. The fractures observed during testing exhibit ductile characteristics, with the presence of dimples and particles. This study demonstrates the significant potential of the 45° deposition orientation with the implementation of double-sided substrate deposition, resulting in a refined microstructure, nearly isotropic behavior, and excellent mechanical performance.