Impact of welding thermal cycle on corrosion rate in the bottom area of AISI 308 L deposits fabricated by WAAM-GTAW

This study investigates the impact of welding thermal cycles on the corrosion rate in the first layer deposite of AISI 308 L produced using Wire Arc Additive Manufacturing (WAAM) with GTA Welding (GTAW). Seven specimens, each representing a different thermal cycle, were fabricated and evaluated using potentiodynamic polarization in 3.5 wt% NaCl solution and 10% HCl solution for weight loss test. The corrosion rate varied significantly across the specimens, ranging from 3.67 × 10⁻⁸ mmpy (specimen 7) to 3.99 × 10⁻⁶ mmpy (specimen 3). X-ray diffraction (XRD) analysis revealed that specimen 3 contained a high proportion of chromium iron carbide (Cr₂Fe₁₄C), which contributed to its poor corrosion resistance. In contrast, specimens subjected to lower peak temperatures (specimen 5-7) exhibited higher levels of chromium oxides (CrO, Cr₃O, CrO₃), which improved resistance to passivation and corrosion. Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersion Spectroscopy (EDS) further confirmed the redistribution of chromium elements mapping and microstructural changes, particularly the increase in Cr concentration at the grain boundaries of δ-ferrite. These findings underscore the important influence of thermal cycling in the WAAM process on the phase composition and corrosion performance of stainless steel components, offering insights for optimizing additive manufacturing parameters for durability in corrosive environments.