Understanding Spatter and its Spatial Variations in Laser Powder Bed Fusion of Ti6Al4V

Abstract

Laser Powder Bed Fusion (LPBF) is rapidly expanding for the fabrication of metal engineering components that are traditionally produced by conventional manufacturing processes. However, in applications involving the manufacture of stress-critical and safety-critical components, it is limited by the need to certify the parts for their reliability and service life. Methods of non-destructive evaluation (NDE) exist but can often be costly and/or time consuming. Spatter occurs as a byproduct of the LPBF process and consists of the discharge of molten media from within the meltpool. Spatter is influenced by, and thus representative of other process variables, such as gas flow, laser-powder interaction dynamics, and thermal gradients in the build environment. To this end, we explore the opportunity for using predictive technologies for LPBF that are based on spatter, particularly the examination of spatter obtained through in-situ imaging. Results show that the generation of spatter is dependent on powder type (i.e. processing) and for a specific powder the orientation of spatter trajectories is found to be influenced by both scan angle and gas flow. Trends in concentration of spatter content with respect to distance from build regions are presented.