• WAAM-fabricated 308L stainless steel exhibits anisotropic tensile properties, with higher strength in the horizontal orientation and higher ductility in the vertical orientation.
• At 600°C, dynamic strain aging (DSA) occurs, leading to serrated flow and a transition from ductile to mixed ductile-brittle fracture with intergranular facets.
• The ferrite number (FN) varies along the build direction (2.30–4.80), influencing mechanical behavior and microstructural stability at elevated temperatures.
• The study provides critical data for the application of WAAM 308L in high-temperature structural components, highlighting its potential and limitations.