| Title |
Localised Corrosion Behaviour of PBF 316L Stainless Steel Heat-Treated at 900°C |
| Authors |
이준섭(Jun-Seob Lee) ; 주티앤유앤(Tian-Yuan Zhu) ; 이정미(Jeongmi Lee) ; 김성윤(Seong-Yoon Kim) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.6.504 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Localised corrosion; Chloride ion; Additive manufacturing; Electrochemical techniques |
| Abstract |
In this study, the localised corrosion behaviour of the type 316L stainless steel manufactured by
powder bed fusion (PBF) and heat-treated at 900°C for 2 h was examined in 3.5 wt% NaCl solution by cyclic
potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). Three-dimensional defects
were observed on both the building-direction (BD) and transverse-direction (TD) planes. Microstructural
observations revealed melt-pool features and boundaries, whereas sub-cellular solidification features were not
clearly distinguished. Electron backscatter diffraction (EBSD) indicated orientation partitioning by melt-pool
boundaries, with local misorientation concentrated near boundaries and defect sites. Energy-dispersive X-ray
spectroscopy (EDS) mapping results confirmed the absence of macroscopic Cr?Mo segregation, and the matrix
was identified as single-phase face-centred cubic without detectable σ-phase or δ-ferrite phase. The
polarisation response was characterised by a gradual and irregular rise in anodic current during anodic
scanning, rather than a stable passive-current region. SEM observations after polarisation confirmed localised
corrosion around and inside defects. The Bode plot contained both capacitive and low-frequency inductive
components, and the impedance behaviour was similar irrespective of the specimen build direction. These
results indicate that occluded reactions associated with three-dimensional defects can dominate the measured
electrochemical response in PBF components and can govern the apparent localised corrosion resistance. The
key contribution of this study is the direct linkage between exposed three-dimensional defects and localised
corrosion features identified by electrochemical testing and post-test surface observation. |