On the process of designing material qualification type specimens manufactured using laser powder bed fusion

Abstract

Recent investigations involving specimens for material and process qualification related to the Laser Powder Bed Fusion (L-PBF) additive manufacturing (AM) method, point that microstructural quality and surface properties vary significantly based on feedstock material and process parameters. There is currently the need, therefore, to create systematic ways to design specimens for process and material qualification. This manuscript provides an approach to evaluate the effects on the as-built quality based on specific metrics for specimens produced by L-PBF. Surface quality, as well as micro- and sub-microstructures and defects are related to specific aspects of the L-PBF process. To accomplish this goal, a digital engineering approach was first developed to design geometries based on process simulations to account for mechanical and thermal process effects. A parametric AM fabrication plan was then chosen to produce statistically significant populations of AM parts. Moreover, on axis, melt-pool scale, in-situ monitoring data, collected during the AM process, was examined in conjunction with the formation of flaws. X-ray micro-computer tomography analysis was additionally used to characterize porosity levels. Finally, scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD), as well as surface profilometry were combined to correlate specific process parameters and conditions with microstructural and surface effects.

Keywords

• Additive Manufacturing
• Laser powder bed fusion
• In-situ monitoring data
• Microstructure
• Defects
• Design