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 316L stainless steel fabricated by wire arc additive manufacturing (WAAM) and establishes correlations with its passivity and corrosion characteristics in a 0.9wt.% 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.