Electrochemical insight into the passivity and corrosion of 316 L stainless steel fabricated through wire arc additive manufacturing

This study explores the microstructure of AISI 316 L stainless steel fabricated by wire arc additive manufacturing (WAAM) and establishes correlations with its passivity and corrosion characteristics in a 0.9 wt.% NaCl solution, while making comparisons with the wrought alloy counterpart. The WAAM-fabricated alloy demonstrates a favorable chemical composition in comparison to the wrought alloy, exhibiting a heterogeneous microstructure comprised of residual delta ferrite within the austenitic matrix. The pitting vulnerability of the WAAM-printed alloy is observed to be lower than that of the wrought counterpart, a phenomenon further investigated through passive film behavior analysis. Mott-Schottky analysis and the point defect model (PDM) revealed the development of a less defective passive layer on the WAAM-fabricated alloy, enhancing overall passivity and electrochemical response, attributed to the interplay between microstructural features and chemical composition.