Comprehensive analysis of the properties of stainless steel 308l tungsten inert gas wire arc additive manufactured

• Thermal accumulation during TIG-WAAM leads to microstructural variation along the build height, with grain coarsening and increased δ-ferrite at the top. • Mechanical anisotropy is observed, with longitudinal specimens achieving UTS ≈ 547 MPa and elongation ≈ 55.5%, outperforming transverse specimens. • A novel contribution of this study is the inclusion of corrosion testing, revealing a significant corrosion rate gradient absent in prior GMAW-AM and LP-AM research. This study provides a comprehensive evaluation of the microstructural evolution, mechanical properties, and corrosion behavior of 308L stainless steel fabricated using Tungsten Inert Gas Wire Arc Additive Manufacturing (TIG-WAAM). Deposition was conducted using ER308L wire (1.0 mm diameter) with a CNC-controlled TIG-WAAM system, yielding a wall structure measuring 90 mm in height, 7 mm in thickness, and 125 mm in length. Although layer-by-layer deposition was consistently achieved, heat accumulation during the process caused dimensional distortion and collapse zones in the upper layers. Metallographic examination revealed a vertical grain evolution, from fine equiaxed grains at the bottom to coarse columnar grains at the top, accompanied by increased δ-ferrite content. This gradient correlated with surface hardness, which decreased from 242.5 HV (bottom) to 176.5 HV (top). Tensile tests indicated anisotropic behavior, with longitudinal specimens showing higher tensile strength (UTS ≈ 547 MPa) and elongation (≈ 35.5%) than transverse specimens. Corrosion performance, assessed via Tafel polarization in 3.5% NaCl solution, showed a distinct gradient in corrosion rate, from 0.0048 mm/year at the bottom to 0.1112 mm/year at the top, highlighting the influence of microstructural variation on electrochemical stability. Compared to previous studies on GMAW- and LP-based AM processes, this research uniquely incorporates a detailed corrosion analysis, addressing a critical gap in the literature. The integrated findings enhance understanding of TIG-WAAM 308L’s performance, supporting its application in structural and corrosion-sensitive environments.