Influence of scanning strategy and building direction on microstructure and corrosion behaviour of selective laser melted 316L stainless steel

Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective

“…106 Investigations of the influence of melt pool boundaries on localized pitting corrosion of L-PBF 316L in chloride solutions are still limited. 43 However, recent reports 34,107 have shown that they could be preferential nucleation sites for pits, likely due to the local variation in elemental distribution, porosity, or residual stress. Using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests coupled with optical microscopy and SEM of corroded surfaces, Zhao et al 107 showed that, regardless of the surface orientation, pit initiation was found to primarily occur at melt pool boundaries.…”

“…43 However, recent reports 34,107 have shown that they could be preferential nucleation sites for pits, likely due to the local variation in elemental distribution, porosity, or residual stress. Using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests coupled with optical microscopy and SEM of corroded surfaces, Zhao et al 107 showed that, regardless of the surface orientation, pit initiation was found to primarily occur at melt pool boundaries. However, more pit initiation sites were observed on surfaces built parallel to the building direction.…”

Excellent strength–ductility balance of Sc-Zr-modified Al–Mg alloy by tuning bimodal microstructure via hatch spacing in laser powder bed fusion

“…Specifically, numerous metallic alloys used today cannot be manufactured through LPBF because the melting and solidification dynamics of the fabrication process conducted at a rapid cooling rate ($10 6 K/s) lead to the formation of undesirable microstructures, such as cracks and hot tears [5]. Currently, stainless steel [6][7][8], Ti-based alloys [9,10], Ni-based alloys [11,12], and Al-based alloys [13][14][15] are fabricated by LPBF. Albased alloys include near-eutectic Si-containing alloys, such as AlSi12 [16] and AlSi10Mg [17], and Sc-and/or Zr-modified Al-Mg-based alloys (typically referred to as Scalmalloy) have been applied for the LPBF process [18,19].…”

The Optimisation of Hot Isostatic Pressing Treatments for Enhanced Mechanical and Corrosion Performance of Stainless Steel 316l Produced by Laser Powder Bed Fusion

“…This pore measured approximately 22 µm in width prior to localised corrosion attack which increased to 156 µm after corroding. Irregularly shaped porosity at melt pool boundaries can lead to pits forming in unconventional shapes, which can be attributed to the electrochemical reaction evolving along cellular structures that typically have a higher dislocation density than within the melt pool [63]. Further to this, porosity with semi-occluded regions are conducive to facilitating localised corrosion through differential aeration due to the restricted diffusion of oxygen into these regions, as per the Fontana Greene mechanism of crevice corrosion [64].…”