Advancing the industrial utilization of additive manufacturing: Understanding early-stage corrosion dynamics through advanced electrochemical and microstructural characterization

Additive manufacturing (AM) is transforming manufacturing by enabling the production of complex, multi-material components with enhanced design flexibility and faster production cycles. However, the microstructures and properties of AM-produced materials, such as those fabricated using Laser Powder Bed Fusion (LPBF), differ significantly from conventionally manufactured materials, necessitating new characterization approaches. This study investigates the early-stage corrosion behavior of 316L stainless steel (SS316L) produced via LPBF. Unlike traditional studies focused on advanced corrosion stages, this research emphasizes corrosion initiation and passive layer formation, critical for long-term performance. By understanding how defects in the initial passive layer impact corrosion resistance, we aim to optimize LPBF process parameters to enhance durability. We examined the effects of LPBF parameters—laser power, scanning speed, hatch distance, and powder layer thickness—on the corrosion performance of as-printed SS316L in simulated reservoir brine with continuous CO₂ exposure. Electrochemical Impedance Spectroscopy (EIS) after 1 h of open-circuit potential stabilization was used to assess early passive layer formation and interfacial dynamics. Potentiodynamic Polarization (PDP) was performed to determine corrosion current densities (i_corr) and corrosion potentials (E_corr), providing corrosion rate estimates. X-ray Computed Tomography (XCT) assessed porosity distribution, correlating microstructural characteristics with corrosion resistance. Scanning Electron Microscopy (SEM) before and after immersion at identical locations elucidated corrosion initiation and evolution. Our findings show that by optimizing LPBF parameters, it is possible to improve the corrosion resistance of SS316L, reducing porosity and enhancing surface integrity. This study provides crucial insights into early corrosion mechanisms and strategies for developing durable, corrosion-resistant materials.