| Abstract Scope |
Although the epitaxial growth from the substrate dominates the initial grain development during LPBF, epitaxial solidification is lost quickly after a small transition region of several layer thicknesses. Inside the transition region, gradual accumulation of misorientation occurs. Both transition region thickness and the rate of misorientation accumulation depend on processing conditions and substrate texture. This study examines the origin of this misorientation development & its formation mechanism. A single laser track was printed on an SS316L Single-Crystal substrate to investigate the two types of misorientation development mechanisms, either solidification morphology-dependent or residual stress-induced plastic deformation. Misorientation analysis from the cellular-solidification features and the EBSD map shows that inside the melt pool, misorientation development is both solidification & deformation dependent, whereas, deformation-based misorientation develops ~100µm outside of meltpool during the cooling process. Furthermore, the misorientation development isn’t random but always around a fixed <111> crystal axis, both meltpool inside & outside. |