Development of crystallographic misorientation in laser powder bed fusion 316L stainless steel

This study examines the development of crystallographic misorientation and its relations to the solidification microstructure in Laser Powder Bed Fusion (LPBF) alloys. We performed a single laser track experiment on an SS316L single-crystal substrate to characterize the correlation between solidification features and misorientation evolution within a single LPBF melt pool and found that the sources of misorientations inside the melt pool can be attributed to both rapid solidification (misorientation aligning precisely with the cell walls & colony boundaries) and residual stress-induced plastic deformation (misorientation independent of solidification morphology), while the residual stress-induced plastic deformation acts as the sole mechanism to extend this misorientation outside of the melt pool boundary. The misorientation development both inside and outside of the melt pool always occurs through a crystal rotation around one of the {111} axes without any obvious correlation with the sample orientations. Additionally, we conducted a comprehensive literature overview of mechanisms in the solidification process and critically assessed the current understanding of misorientation formation and the causes of the loss of epitaxial grain growth.